Merge branch 'main' into dependabot/nuget/src/Runner.Sdk/main/System.Text.Encoding.CodePages-10.0.6

Add vulnerability-alerts permission (#4350 )
Bump System.Text.Encoding.CodePages from 10.0.3 to 10.0.6
2026-04-21 17:34:12 +01:00 · 2026-04-21 17:31:10 +01:00 · 2026-04-21 16:09:16 +00:00 · 2026-04-21 16:06:40 +00:00 · 2026-04-21 15:15:02 +01:00 · 2026-04-20 17:06:35 +00:00
113 changed files with 14175 additions and 1080 deletions
@@ -1,10 +1,10 @@
 {
  "name": "Actions Runner Devcontainer",
-  "image": "mcr.microsoft.com/devcontainers/base:focal",
+  "image": "mcr.microsoft.com/devcontainers/base:noble",
  "features": {
-    "ghcr.io/devcontainers/features/docker-in-docker:1": {},
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {},
    "ghcr.io/devcontainers/features/dotnet": {
-      "version": "8.0.417"
+      "version": "8.0.420"
    },
    "ghcr.io/devcontainers/features/node:1": {
      "version": "20"
@@ -78,7 +78,7 @@ jobs:
    # Upload runner package tar.gz/zip as artifact
    - name: Publish Artifact
      if: github.event_name != 'pull_request'
-      uses: actions/upload-artifact@v6
+      uses: actions/upload-artifact@v7
      with:
        name: runner-package-${{ matrix.runtime }}
        path: |
@@ -99,7 +99,7 @@ jobs:

    - name: Get latest runner version
      id: latest_runner
-      uses: actions/github-script@v8
+      uses: actions/github-script@v9
      with:
        github-token: ${{secrets.GITHUB_TOKEN}}
        script: |
@@ -111,10 +111,10 @@ jobs:
          core.setOutput('version', version);

    - name: Setup Docker buildx
-      uses: docker/setup-buildx-action@v3
+      uses: docker/setup-buildx-action@v4

    - name: Build Docker image
-      uses: docker/build-push-action@v6
+      uses: docker/build-push-action@v7
      with:
        context: ./images
        load: true
@@ -26,7 +26,7 @@ jobs:

      - name: Compute image version
        id: image
-        uses: actions/github-script@v8
+        uses: actions/github-script@v9
        with:
          script: |
            const fs = require('fs');
@@ -38,10 +38,10 @@ jobs:
            core.setOutput('version', runnerVersion);

      - name: Setup Docker buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4

      - name: Log into registry ${{ env.REGISTRY }}
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
@@ -49,7 +49,7 @@ jobs:

      - name: Build and push Docker image
        id: build-and-push
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v7
        with:
          context: ./images
          platforms: |
@@ -68,7 +68,7 @@ jobs:
            org.opencontainers.image.description=https://github.com/actions/runner/releases/tag/v${{ steps.image.outputs.version }}

      - name: Generate attestation
-        uses: actions/attest-build-provenance@v3
+        uses: actions/attest-build-provenance@v4
        with:
          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          subject-digest: ${{ steps.build-and-push.outputs.digest }}
@@ -159,18 +159,36 @@ jobs:
          git config --global user.name "github-actions[bot]"
          git config --global user.email "<41898282+github-actions[bot]@users.noreply.github.com>"

+          # Build version summary for commit message and PR body (only include changed versions)
+          COMMIT_VERSIONS=""
+          PR_VERSION_LINES=""
+
+          if [ "${{ steps.node-versions.outputs.needs_update20 }}" == "true" ]; then
+            COMMIT_VERSIONS="20: $NODE20_VERSION"
+            PR_VERSION_LINES="- Node 20: ${{ steps.node-versions.outputs.current_node20 }} → $NODE20_VERSION"
+          fi
+
+          if [ "${{ steps.node-versions.outputs.needs_update24 }}" == "true" ]; then
+            if [ -n "$COMMIT_VERSIONS" ]; then
+              COMMIT_VERSIONS="$COMMIT_VERSIONS, 24: $NODE24_VERSION"
+            else
+              COMMIT_VERSIONS="24: $NODE24_VERSION"
+            fi
+            PR_VERSION_LINES="${PR_VERSION_LINES:+$PR_VERSION_LINES
+          }- Node 24: ${{ steps.node-versions.outputs.current_node24 }} → $NODE24_VERSION"
+          fi
+
          # Create branch and commit changes
          branch_name="chore/update-node"
          git checkout -b "$branch_name"
-          git commit -a -m "chore: update Node versions (20: $NODE20_VERSION, 24: $NODE24_VERSION)"
+          git commit -a -m "chore: update Node versions ($COMMIT_VERSIONS)"
          git push --force origin "$branch_name"

          # Create PR body using here-doc for proper formatting
          cat > pr_body.txt << EOF
          Automated Node.js version update:

-          - Node 20: ${{ steps.node-versions.outputs.current_node20 }} → $NODE20_VERSION
-          - Node 24: ${{ steps.node-versions.outputs.current_node24 }} → $NODE24_VERSION
+          $PR_VERSION_LINES

          This update ensures we're using the latest stable Node.js versions for security and performance improvements.

@@ -16,7 +16,7 @@ jobs:
    # Make sure ./releaseVersion match ./src/runnerversion
    # Query GitHub release ensure version is not used
    - name: Check version
-      uses: actions/github-script@v8
+      uses: actions/github-script@v9
      with:
        github-token: ${{secrets.GITHUB_TOKEN}}
        script: |
@@ -118,7 +118,7 @@ jobs:
    # Upload runner package tar.gz/zip as artifact.
    - name: Publish Artifact
      if: github.event_name != 'pull_request'
-      uses: actions/upload-artifact@v6
+      uses: actions/upload-artifact@v7
      with:
        name: runner-packages-${{ matrix.runtime }}
        path: |
@@ -133,37 +133,37 @@ jobs:

    # Download runner package tar.gz/zip produced by 'build' job
    - name: Download Artifact (win-x64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-win-x64
        path: ./
    - name: Download Artifact (win-arm64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-win-arm64
        path: ./
    - name: Download Artifact (osx-x64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-osx-x64
        path: ./
    - name: Download Artifact (osx-arm64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-osx-arm64
        path: ./
    - name: Download Artifact (linux-x64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-linux-x64
        path: ./
    - name: Download Artifact (linux-arm)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-linux-arm
        path: ./
    - name: Download Artifact (linux-arm64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
      with:
        name: runner-packages-linux-arm64
        path: ./
@@ -171,7 +171,7 @@ jobs:
    # Create ReleaseNote file
    - name: Create ReleaseNote
      id: releaseNote
-      uses: actions/github-script@v8
+      uses: actions/github-script@v9
      with:
        github-token: ${{secrets.GITHUB_TOKEN}}
        script: |
@@ -300,7 +300,7 @@ jobs:

      - name: Compute image version
        id: image
-        uses: actions/github-script@v8
+        uses: actions/github-script@v9
        with:
          script: |
            const fs = require('fs');
@@ -309,10 +309,10 @@ jobs:
            core.setOutput('version', runnerVersion);

      - name: Setup Docker buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4

      - name: Log into registry ${{ env.REGISTRY }}
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
@@ -320,7 +320,7 @@ jobs:

      - name: Build and push Docker image
        id: build-and-push
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v7
        with:
          context: ./images
          platforms: |
@@ -339,7 +339,7 @@ jobs:
            org.opencontainers.image.description=https://github.com/actions/runner/releases/tag/v${{ steps.image.outputs.version }}

      - name: Generate attestation
-        uses: actions/attest-build-provenance@v3
+        uses: actions/attest-build-provenance@v4
        with:
          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          subject-digest: ${{ steps.build-and-push.outputs.digest }}
@@ -32,7 +32,7 @@ We are taking the following steps to better direct requests related to GitHub Ac

 2. High Priority bugs can be reported through Community Discussions or you can report these to our support team https://support.github.com/contact/bug-report.

-3. Security Issues should be handled as per our [security.md](security.md)
+3. Security Issues should be handled as per our [SECURITY.md](https://github.com/actions/runner?tab=security-ov-file)

 We will still provide security updates for this project and fix major breaking changes during this time.

@@ -28,8 +28,8 @@ Debian based OS (Debian, Ubuntu, Linux Mint)
 - liblttng-ust1 or liblttng-ust0
 - libkrb5-3
 - zlib1g
- libssl1.1, libssl1.0.2 or libssl1.0.0
- libicu63, libicu60, libicu57 or libicu55
+- libssl3t64, libssl3, libssl1.1, libssl1.0.2 or libssl1.0.0
+- libicu76, libicu75, ..., libicu66, libicu65, libicu63, libicu60, libicu57, libicu55, or libicu52

 Fedora based OS (Fedora, Red Hat Enterprise Linux, CentOS, Oracle Linux 7)

@@ -5,8 +5,8 @@ ARG TARGETOS
 ARG TARGETARCH
 ARG RUNNER_VERSION
 ARG RUNNER_CONTAINER_HOOKS_VERSION=0.7.0
-ARG DOCKER_VERSION=29.2.0
-ARG BUILDX_VERSION=0.31.1
+ARG DOCKER_VERSION=29.4.0
+ARG BUILDX_VERSION=0.33.0

 RUN apt update -y && apt install curl unzip -y

@@ -21,7 +21,7 @@ RUN curl -f -L -o runner-container-hooks.zip https://github.com/actions/runner-c
    && unzip ./runner-container-hooks.zip -d ./k8s \
    && rm runner-container-hooks.zip

-RUN curl -f -L -o runner-container-hooks.zip https://github.com/actions/runner-container-hooks/releases/download/v0.8.0/actions-runner-hooks-k8s-0.8.0.zip \
+RUN curl -f -L -o runner-container-hooks.zip https://github.com/actions/runner-container-hooks/releases/download/v0.8.1/actions-runner-hooks-k8s-0.8.1.zip \
    && unzip ./runner-container-hooks.zip -d ./k8s-novolume \
    && rm runner-container-hooks.zip

@@ -1,27 +1,33 @@
 ## What's Changed
-* Fix owner of /home/runner directory by @nikola-jokic in https://github.com/actions/runner/pull/4132
-* Update Docker to v29.0.2 and Buildx to v0.30.1 by @github-actions[bot] in https://github.com/actions/runner/pull/4135
-* Update workflow around runner docker image. by @TingluoHuang in https://github.com/actions/runner/pull/4133
-* Fix regex for validating runner version format by @TingluoHuang in https://github.com/actions/runner/pull/4136
-* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4144
-* Ensure safe_sleep tries alternative approaches by @TingluoHuang in https://github.com/actions/runner/pull/4146
-* Bump actions/github-script from 7 to 8 by @dependabot[bot] in https://github.com/actions/runner/pull/4137
-* Bump actions/checkout from 5 to 6 by @dependabot[bot] in https://github.com/actions/runner/pull/4130
-* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4149
-* Bump docker image to use ubuntu 24.04 by @TingluoHuang in https://github.com/actions/runner/pull/4018
-* Add support for case function by @AllanGuigou in https://github.com/actions/runner/pull/4147
-* Cleanup feature flag actions_container_action_runner_temp by @ericsciple in https://github.com/actions/runner/pull/4163
-* Bump actions/download-artifact from 6 to 7 by @dependabot[bot] in https://github.com/actions/runner/pull/4155
-* Bump actions/upload-artifact from 5 to 6 by @dependabot[bot] in https://github.com/actions/runner/pull/4157
-* Set ACTIONS_ORCHESTRATION_ID as env to actions. by @TingluoHuang in https://github.com/actions/runner/pull/4178
-* Allow hosted VM report job telemetry via .setup_info file. by @TingluoHuang in https://github.com/actions/runner/pull/4186
-* Bump typescript from 5.9.2 to 5.9.3 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4184
-* Bump Azure.Storage.Blobs from 12.26.0 to 12.27.0 by @dependabot[bot] in https://github.com/actions/runner/pull/4189
+* Log inner exception message. by @TingluoHuang in https://github.com/actions/runner/pull/4265
+* Fix composite post-step marker display names by @ericsciple in https://github.com/actions/runner/pull/4267
+* Bump actions/download-artifact from 7 to 8 by @dependabot[bot] in https://github.com/actions/runner/pull/4269
+* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4272
+* Avoid throw in SelfUpdaters. by @TingluoHuang in https://github.com/actions/runner/pull/4274
+* Fix parser comparison mismatches by @ericsciple in https://github.com/actions/runner/pull/4273
+* Devcontainer: bump base image Ubuntu version by @MaxHorstmann in https://github.com/actions/runner/pull/4277
+* Support `entrypoint` and `command` for service containers by @ericsciple in https://github.com/actions/runner/pull/4276
+* Bump actions/upload-artifact from 6 to 7 by @dependabot[bot] in https://github.com/actions/runner/pull/4270
+* Bump docker/login-action from 3 to 4 by @dependabot[bot] in https://github.com/actions/runner/pull/4278
+* Fix positional arg bug in ExpressionParser.CreateTree by @ericsciple in https://github.com/actions/runner/pull/4279
+* Bump docker/build-push-action from 6 to 7 by @dependabot[bot] in https://github.com/actions/runner/pull/4283
+* Bump docker/setup-buildx-action from 3 to 4 by @dependabot[bot] in https://github.com/actions/runner/pull/4282
+* Bump actions/attest-build-provenance from 3 to 4 by @dependabot[bot] in https://github.com/actions/runner/pull/4266
+* Bump @stylistic/eslint-plugin from 5.9.0 to 5.10.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4281
+* Update Docker to v29.3.0 and Buildx to v0.32.1 by @github-actions[bot] in https://github.com/actions/runner/pull/4286
+* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4287
+* Fix cancellation token race during parser comparison by @ericsciple in https://github.com/actions/runner/pull/4280
+* Bump @typescript-eslint/eslint-plugin from 8.47.0 to 8.54.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4230
+* Exit with specified exit code when runner is outdated by @nikola-jokic in https://github.com/actions/runner/pull/4285
+* Report infra_error for action download failures. by @TingluoHuang in https://github.com/actions/runner/pull/4294
+* Update dotnet sdk to latest version @8.0.419 by @github-actions[bot] in https://github.com/actions/runner/pull/4301
+* Node 24 enforcement + Linux ARM32 deprecation support by @salmanmkc in https://github.com/actions/runner/pull/4303
+* Bump @typescript-eslint/eslint-plugin from 8.54.0 to 8.57.1 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4304

 ## New Contributors
-* @AllanGuigou made their first contribution in https://github.com/actions/runner/pull/4147
+* @MaxHorstmann made their first contribution in https://github.com/actions/runner/pull/4277

-**Full Changelog**: https://github.com/actions/runner/compare/v2.330.0...v2.331.0
+**Full Changelog**: https://github.com/actions/runner/compare/v2.332.0...v2.333.0

 _Note: Actions Runner follows a progressive release policy, so the latest release might not be available to your enterprise, organization, or repository yet.
 To confirm which version of the Actions Runner you should expect, please view the download instructions for your enterprise, organization, or repository.
@@ -32,20 +32,20 @@
  "author": "GitHub Actions",
  "license": "MIT",
  "dependencies": {
-    "@actions/glob": "^0.4.0"
+    "@actions/glob": "^0.6.1"
  },
  "devDependencies": {
-    "@stylistic/eslint-plugin": "^3.1.0",
+    "@stylistic/eslint-plugin": "^5.10.0",
    "@types/node": "^22.0.0",
-    "@typescript-eslint/eslint-plugin": "^8.0.0",
-    "@typescript-eslint/parser": "^8.0.0",
+    "@typescript-eslint/eslint-plugin": "^8.58.1",
+    "@typescript-eslint/parser": "^8.59.0",
    "@vercel/ncc": "^0.38.3",
    "eslint": "^8.47.0",
    "eslint-plugin-github": "^4.10.2",
    "eslint-plugin-prettier": "^5.0.0",
    "husky": "^9.1.7",
-    "lint-staged": "^15.5.0",
+    "lint-staged": "^16.4.0",
    "prettier": "^3.0.3",
-    "typescript": "^5.9.3"
+    "typescript": "^6.0.2"
  }
 }
@@ -6,8 +6,8 @@ NODE_URL=https://nodejs.org/dist
 NODE_ALPINE_URL=https://github.com/actions/alpine_nodejs/releases/download
 # When you update Node versions you must also create a new release of alpine_nodejs at that updated version.
 # Follow the instructions here: https://github.com/actions/alpine_nodejs?tab=readme-ov-file#getting-started
-NODE20_VERSION="20.20.0"
-NODE24_VERSION="24.13.0"
+NODE20_VERSION="20.20.2"
+NODE24_VERSION="24.15.0"

 get_abs_path() {
  # exploits the fact that pwd will print abs path when no args
@@ -102,7 +102,7 @@ then
            exit 1
        fi

-        apt_get_with_fallbacks libssl1.1$ libssl1.0.2$ libssl1.0.0$
+        apt_get_with_fallbacks libssl3t64$ libssl3$ libssl1.1$ libssl1.0.2$ libssl1.0.0$
        if [ $? -ne 0 ]
        then
            echo "'$apt_get' failed with exit code '$?'"
@@ -10,6 +10,13 @@ if %ERRORLEVEL% EQU 0 (
  exit /b 0
 )

+if "%ACTIONS_RUNNER_RETURN_VERSION_DEPRECATED_EXIT_CODE%"=="1" (
+  if %ERRORLEVEL% EQU 7 (
+    echo "Runner listener exit with deprecated version error code: %ERRORLEVEL%."
+    exit /b %ERRORLEVEL%
+  )
+)
+
 if %ERRORLEVEL% EQU 1 (
  echo "Runner listener exit with terminated error, stop the service, no retry needed."
  exit /b 0
@@ -34,11 +34,13 @@ fi

 updateFile="update.finished"
 "$DIR"/bin/Runner.Listener run $*
-
 returnCode=$?
 if [[ $returnCode == 0 ]]; then
    echo "Runner listener exit with 0 return code, stop the service, no retry needed."
    exit 0
+elif [[ "$ACTIONS_RUNNER_RETURN_VERSION_DEPRECATED_EXIT_CODE" == "1" && $returnCode -eq 7 ]]; then
+    echo "Runner listener exit with deprecated version exit code: ${returnCode}."
+    exit "$returnCode"
 elif [[ $returnCode == 1 ]]; then
    echo "Runner listener exit with terminated error, stop the service, no retry needed."
    exit 0
@@ -25,7 +25,14 @@ call "%~dp0run-helper.cmd" %*
 if %ERRORLEVEL% EQU 1 (
  echo "Restarting runner..."
  goto :launch_helper
-) else (  
-  echo "Exiting runner..."
-  exit /b 0
 )
+
+if "%ACTIONS_RUNNER_RETURN_VERSION_DEPRECATED_EXIT_CODE%"=="1" (
+  if %ERRORLEVEL% EQU 7 (
+    echo "Exiting runner with deprecated version error code: %ERRORLEVEL%"
+    exit /b %ERRORLEVEL%
+  )
+)
+
+echo "Exiting runner..."
+exit /b 0
@@ -19,6 +19,9 @@ run() {
        returnCode=$?
        if [[ $returnCode -eq 2 ]]; then
            echo "Restarting runner..."
+        elif [[ "$ACTIONS_RUNNER_RETURN_VERSION_DEPRECATED_EXIT_CODE" == "1" && $returnCode -eq 7 ]]; then
+            echo "Exiting runner..."
+            exit "$returnCode"
        else
            echo "Exiting runner..."
            exit 0
@@ -42,6 +45,9 @@ runWithManualTrap() {
        returnCode=$?
        if [[ $returnCode -eq 2 ]]; then
            echo "Restarting runner..."
+        elif [[ "$ACTIONS_RUNNER_RETURN_VERSION_DEPRECATED_EXIT_CODE" == "1" && $returnCode -eq 7 ]]; then
+            echo "Exiting runner..."
+            exit "$returnCode"
        else
            echo "Exiting runner..."
            # Unregister signal handling before exit
@@ -204,6 +204,26 @@ namespace GitHub.Runner.Common
            return unescaped;
        }

+        /// <summary>
+        /// Escapes special characters in a value using the standard action command escape mappings.
+        /// Iterates in reverse so that '%' is escaped first to avoid double-encoding.
+        /// </summary>
+        public static string EscapeValue(string value)
+        {
+            if (string.IsNullOrEmpty(value))
+            {
+                return value;
+            }
+
+            string escaped = value;
+            for (int i = _escapeMappings.Length - 1; i >= 0; i--)
+            {
+                escaped = escaped.Replace(_escapeMappings[i].Token, _escapeMappings[i].Replacement);
+            }
+
+            return escaped;
+        }
+
        private static string UnescapeProperty(string escaped)
        {
            if (string.IsNullOrEmpty(escaped))
@@ -75,6 +75,41 @@ namespace GitHub.Runner.Common
                {
                    return UrlUtil.IsHostedServer(new UriBuilder(GitHubUrl));
                }
+                else
+                {
+                    // feature flag env in case the new logic is wrong.
+                    if (StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("GITHUB_ACTIONS_RUNNER_FORCE_EMPTY_GITHUB_URL_IS_HOSTED")))
+                    {
+                        return true;
+                    }
+
+                    // GitHubUrl will be empty for jit configured runner
+                    // We will try to infer it from the ServerUrl/ServerUrlV2
+                    if (StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("GITHUB_ACTIONS_RUNNER_FORCE_GHES")))
+                    {
+                        // Allow env to override and force GHES in case the inference logic is wrong.
+                        return false;
+                    }
+
+                    if (!string.IsNullOrEmpty(ServerUrl))
+                    {
+                        // pipelines services
+                        var serverUrl = new UriBuilder(ServerUrl);
+                        return serverUrl.Host.EndsWith(".actions.githubusercontent.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrl.Host.EndsWith(".codedev.ms", StringComparison.OrdinalIgnoreCase);
+                    }
+
+                    if (!string.IsNullOrEmpty(ServerUrlV2))
+                    {
+                        // broker-listener
+                        var serverUrlV2 = new UriBuilder(ServerUrlV2);
+                        return serverUrlV2.Host.EndsWith(".actions.githubusercontent.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".githubapp.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".ghe.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".actions.localhost", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".ghe.localhost", StringComparison.OrdinalIgnoreCase);
+                    }
+                }

                // Default to true since Hosted runners likely don't have this property set.
                return true;
@@ -159,6 +159,7 @@ namespace GitHub.Runner.Common
                // and the runner should be restarted. This is a temporary code and will be removed in the future after
                // the runner is migrated to runner admin.
                public const int RunnerConfigurationRefreshed = 6;
+                public const int RunnerVersionDeprecated = 7;
            }

            public static class Features
@@ -172,8 +173,12 @@ namespace GitHub.Runner.Common
                public static readonly string SnapshotPreflightHostedRunnerCheck = "actions_snapshot_preflight_hosted_runner_check";
                public static readonly string SnapshotPreflightImageGenPoolCheck = "actions_snapshot_preflight_image_gen_pool_check";
                public static readonly string CompareWorkflowParser = "actions_runner_compare_workflow_parser";
+                public static readonly string ServiceContainerCommand = "actions_service_container_command";
                public static readonly string SetOrchestrationIdEnvForActions = "actions_set_orchestration_id_env_for_actions";
                public static readonly string SendJobLevelAnnotations = "actions_send_job_level_annotations";
+                public static readonly string EmitCompositeMarkers = "actions_runner_emit_composite_markers";
+                public static readonly string BatchActionResolution = "actions_batch_action_resolution";
+                public static readonly string UseBearerTokenForCodeload = "actions_use_bearer_token_for_codeload";
            }

            // Node version migration related constants
@@ -190,6 +195,24 @@ namespace GitHub.Runner.Common
                // Feature flags for controlling the migration phases
                public static readonly string UseNode24ByDefaultFlag = "actions.runner.usenode24bydefault";
                public static readonly string RequireNode24Flag = "actions.runner.requirenode24";
+                public static readonly string WarnOnNode20Flag = "actions.runner.warnonnode20";
+
+                // Feature flags for Linux ARM32 deprecation
+                public static readonly string DeprecateLinuxArm32Flag = "actions_runner_deprecate_linux_arm32";
+                public static readonly string KillLinuxArm32Flag = "actions_runner_kill_linux_arm32";
+
+                // Blog post URL for Node 20 deprecation
+                public static readonly string Node20DeprecationUrl = "https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/";
+
+                // Node 20 migration dates (hardcoded fallbacks, can be overridden via job variables)
+                public static readonly string Node24DefaultDate = "June 2nd, 2026";
+                public static readonly string Node20RemovalDate = "September 16th, 2026";
+
+                // Variable keys for server-overridable dates
+                public static readonly string Node24DefaultDateVariable = "actions_runner_node24_default_date";
+                public static readonly string Node20RemovalDateVariable = "actions_runner_node20_removal_date";
+
+                public static readonly string LinuxArm32DeprecationMessage = "Linux ARM32 runners are deprecated and will no longer be supported after {0}. Please migrate to a supported platform.";
            }

            public static readonly string InternalTelemetryIssueDataKey = "_internal_telemetry";
@@ -271,6 +294,7 @@ namespace GitHub.Runner.Common
                public static readonly string AllowUnsupportedCommands = "ACTIONS_ALLOW_UNSECURE_COMMANDS";
                public static readonly string AllowUnsupportedStopCommandTokens = "ACTIONS_ALLOW_UNSECURE_STOPCOMMAND_TOKENS";
                public static readonly string RequireJobContainer = "ACTIONS_RUNNER_REQUIRE_JOB_CONTAINER";
+                public static readonly string ReturnVersionDeprecatedExitCode = "ACTIONS_RUNNER_RETURN_VERSION_DEPRECATED_EXIT_CODE";
                public static readonly string RunnerDebug = "ACTIONS_RUNNER_DEBUG";
                public static readonly string StepDebug = "ACTIONS_STEP_DEBUG";
            }
@@ -284,6 +308,8 @@ namespace GitHub.Runner.Common
                public static readonly string ForcedActionsNodeVersion = "ACTIONS_RUNNER_FORCE_ACTIONS_NODE_VERSION";
                public static readonly string PrintLogToStdout = "ACTIONS_RUNNER_PRINT_LOG_TO_STDOUT";
                public static readonly string ActionArchiveCacheDirectory = "ACTIONS_RUNNER_ACTION_ARCHIVE_CACHE";
+                public static readonly string SymlinkCachedActions = "ACTIONS_RUNNER_SYMLINK_CACHED_ACTIONS";
+                public static readonly string EmitCompositeMarkers = "ACTIONS_RUNNER_EMIT_COMPOSITE_MARKERS";
            }

            public static class System
@@ -17,9 +17,9 @@
  <ItemGroup>
    <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
-    <PackageReference Include="System.Text.Encoding.CodePages" Version="8.0.0" />
-    <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="10.0.3" />
+    <PackageReference Include="System.Threading.Channels" Version="10.0.3" />
  </ItemGroup>

  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
@@ -12,6 +12,13 @@ namespace GitHub.Runner.Common
        private ISecretMasker _secretMasker;
        private TraceSource _traceSource;

+        /// <summary>
+        /// The underlying <see cref="System.Diagnostics.TraceSource"/> for this instance.
+        /// Useful when third-party libraries require a <see cref="System.Diagnostics.TraceSource"/>
+        /// to route their diagnostics into the runner's log infrastructure.
+        /// </summary>
+        public TraceSource Source => _traceSource;
+
        public Tracing(string name, ISecretMasker secretMasker, SourceSwitch sourceSwitch, HostTraceListener traceListener, StdoutTraceListener stdoutTraceListener = null)
        {
            ArgUtil.NotNull(secretMasker, nameof(secretMasker));
@@ -58,7 +58,7 @@ namespace GitHub.Runner.Common.Util
            {
                return (Constants.Runner.NodeMigration.Node24, null);
            }
-            
+
            // Get environment variable details with source information
            var forceNode24Details = GetEnvironmentVariableDetails(
                Constants.Runner.NodeMigration.ForceNode24Variable, workflowEnvironment);
@@ -108,14 +108,50 @@ namespace GitHub.Runner.Common.Util

        /// <summary>
        /// Checks if Node24 is requested but running on ARM32 Linux, and determines if fallback is needed.
+        /// Also handles ARM32 deprecation and kill switch phases.
        /// </summary>
        /// <param name="preferredVersion">The preferred Node version</param>
+        /// <param name="deprecateArm32">Feature flag indicating ARM32 Linux is deprecated</param>
+        /// <param name="killArm32">Feature flag indicating ARM32 Linux should no longer work</param>
        /// <returns>A tuple containing the adjusted node version and an optional warning message</returns>
-        public static (string nodeVersion, string warningMessage) CheckNodeVersionForLinuxArm32(string preferredVersion)
+        public static (string nodeVersion, string warningMessage) CheckNodeVersionForLinuxArm32(
+            string preferredVersion,
+            bool deprecateArm32 = false,
+            bool killArm32 = false,
+            string node20RemovalDate = null)
        {
-            if (string.Equals(preferredVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase) &&
-                Constants.Runner.PlatformArchitecture.Equals(Constants.Architecture.Arm) &&
-                Constants.Runner.Platform.Equals(Constants.OSPlatform.Linux))
+            bool isArm32Linux = Constants.Runner.PlatformArchitecture.Equals(Constants.Architecture.Arm) &&
+                                Constants.Runner.Platform.Equals(Constants.OSPlatform.Linux);
+
+            if (!isArm32Linux)
+            {
+                return (preferredVersion, null);
+            }
+
+            // ARM32 kill switch: runner should no longer work on this platform
+            if (killArm32)
+            {
+                return (null, "Linux ARM32 runners are no longer supported. Please migrate to a supported platform.");
+            }
+
+            // ARM32 deprecation warning: continue using node20 but warn about upcoming end of support
+            if (deprecateArm32)
+            {
+                string effectiveDate = string.IsNullOrEmpty(node20RemovalDate) ? Constants.Runner.NodeMigration.Node20RemovalDate : node20RemovalDate;
+                string deprecationWarning = string.Format(
+                    Constants.Runner.NodeMigration.LinuxArm32DeprecationMessage,
+                    effectiveDate);
+
+                if (string.Equals(preferredVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase))
+                {
+                    return (Constants.Runner.NodeMigration.Node20, deprecationWarning);
+                }
+
+                return (preferredVersion, deprecationWarning);
+            }
+
+            // Legacy behavior: fall back to node20 if node24 was requested on ARM32
+            if (string.Equals(preferredVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase))
            {
                return (Constants.Runner.NodeMigration.Node20, "Node 24 is not supported on Linux ARM32 platforms. Falling back to Node 20.");
            }
@@ -178,8 +178,12 @@ namespace GitHub.Runner.Listener.Configuration
                        }
                    }

-                    // Validate can connect.
-                    await _runnerServer.ConnectAsync(new Uri(runnerSettings.ServerUrl), creds);
+                    // Validate can connect using the obtained vss credentials.
+                    // In Runner Admin flow there's nothing new to test connection to at this point as registerToken is already validated via GetTenantCredential.
+                    if (!runnerSettings.UseRunnerAdminFlow)
+                    {
+                        await _runnerServer.ConnectAsync(new Uri(runnerSettings.ServerUrl), creds);
+                    }

                    _term.WriteLine();
                    _term.WriteSuccessMessage("Connected to GitHub");
@@ -24,7 +24,7 @@ namespace GitHub.Runner.Listener
    public interface IJobDispatcher : IRunnerService
    {
        bool Busy { get; }
-        TaskCompletionSource<bool> RunOnceJobCompleted { get; }
+        TaskCompletionSource<TaskResult> RunOnceJobCompleted { get; }
        void Run(Pipelines.AgentJobRequestMessage message, bool runOnce = false);
        bool Cancel(JobCancelMessage message);
        Task WaitAsync(CancellationToken token);
@@ -56,7 +56,7 @@ namespace GitHub.Runner.Listener
        // timeout limit can be overwritten by environment GITHUB_ACTIONS_RUNNER_CHANNEL_TIMEOUT
        private TimeSpan _channelTimeout;

-        private TaskCompletionSource<bool> _runOnceJobCompleted = new();
+        private TaskCompletionSource<TaskResult> _runOnceJobCompleted = new();

        public event EventHandler<JobStatusEventArgs> JobStatus;

@@ -82,7 +82,7 @@ namespace GitHub.Runner.Listener
            Trace.Info($"Set runner/worker IPC timeout to {_channelTimeout.TotalSeconds} seconds.");
        }

-        public TaskCompletionSource<bool> RunOnceJobCompleted => _runOnceJobCompleted;
+        public TaskCompletionSource<TaskResult> RunOnceJobCompleted => _runOnceJobCompleted;

        public bool Busy { get; private set; }

@@ -340,18 +340,19 @@ namespace GitHub.Runner.Listener

        private async Task RunOnceAsync(Pipelines.AgentJobRequestMessage message, string orchestrationId, WorkerDispatcher previousJobDispatch, CancellationToken jobRequestCancellationToken, CancellationToken workerCancelTimeoutKillToken)
        {
+            var jobResult = TaskResult.Succeeded;
            try
            {
-                await RunAsync(message, orchestrationId, previousJobDispatch, jobRequestCancellationToken, workerCancelTimeoutKillToken);
+                jobResult = await RunAsync(message, orchestrationId, previousJobDispatch, jobRequestCancellationToken, workerCancelTimeoutKillToken);
            }
            finally
            {
                Trace.Info("Fire signal for one time used runner.");
-                _runOnceJobCompleted.TrySetResult(true);
+                _runOnceJobCompleted.TrySetResult(jobResult);
            }
        }

-        private async Task RunAsync(Pipelines.AgentJobRequestMessage message, string orchestrationId, WorkerDispatcher previousJobDispatch, CancellationToken jobRequestCancellationToken, CancellationToken workerCancelTimeoutKillToken)
+        private async Task<TaskResult> RunAsync(Pipelines.AgentJobRequestMessage message, string orchestrationId, WorkerDispatcher previousJobDispatch, CancellationToken jobRequestCancellationToken, CancellationToken workerCancelTimeoutKillToken)
        {
            Busy = true;
            try
@@ -399,7 +400,7 @@ namespace GitHub.Runner.Listener
                    {
                        // renew job request task complete means we run out of retry for the first job request renew.
                        Trace.Info($"Unable to renew job request for job {message.JobId} for the first time, stop dispatching job to worker.");
-                        return;
+                        return TaskResult.Abandoned;
                    }

                    if (jobRequestCancellationToken.IsCancellationRequested)
@@ -412,7 +413,7 @@ namespace GitHub.Runner.Listener

                        // complete job request with result Cancelled
                        await CompleteJobRequestAsync(_poolId, message, systemConnection, lockToken, TaskResult.Canceled);
-                        return;
+                        return TaskResult.Canceled;
                    }

                    HostContext.WritePerfCounter($"JobRequestRenewed_{requestId.ToString()}");
@@ -523,7 +524,7 @@ namespace GitHub.Runner.Listener
                            await renewJobRequest;

                            // not finish the job request since the job haven't run on worker at all, we will not going to set a result to server.
-                            return;
+                            return TaskResult.Failed;
                        }

                        // we get first jobrequest renew succeed and start the worker process with the job message.
@@ -604,7 +605,7 @@ namespace GitHub.Runner.Listener
                                    Trace.Error(detailInfo);
                                }

-                                return;
+                                return TaskResultUtil.TranslateFromReturnCode(returnCode);
                            }
                            else if (completedTask == renewJobRequest)
                            {
@@ -706,6 +707,8 @@ namespace GitHub.Runner.Listener

                            // complete job request
                            await CompleteJobRequestAsync(_poolId, message, systemConnection, lockToken, resultOnAbandonOrCancel);
+
+                            return resultOnAbandonOrCancel;
                        }
                        finally
                        {
@@ -141,9 +141,9 @@ namespace GitHub.Runner.Listener
            }
            catch (AccessDeniedException e) when (e.ErrorCode == 1)
            {
-                terminal.WriteError($"An error occured: {e.Message}");
+                terminal.WriteError($"An error occurred: {e.Message}");
                trace.Error(e);
-                return Constants.Runner.ReturnCode.TerminatedError;
+                return GetRunnerVersionDeprecatedExitCode();
            }
            catch (RunnerNotFoundException e)
            {
@@ -159,6 +159,16 @@ namespace GitHub.Runner.Listener
            }
        }

+        private static int GetRunnerVersionDeprecatedExitCode()
+        {
+            if (StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable(Constants.Variables.Actions.ReturnVersionDeprecatedExitCode)))
+            {
+                return Constants.Runner.ReturnCode.RunnerVersionDeprecated;
+            }
+
+            return Constants.Runner.ReturnCode.TerminatedError;
+        }
+
        private static void LoadAndSetEnv()
        {
            var binDir = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
@@ -22,8 +22,8 @@
    <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
    <PackageReference Include="System.IO.FileSystem.AccessControl" Version="5.0.0" />
-    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
-    <PackageReference Include="System.ServiceProcess.ServiceController" Version="8.0.1" />
+    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
+    <PackageReference Include="System.ServiceProcess.ServiceController" Version="10.0.3" />
  </ItemGroup>

  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
@@ -5,8 +5,8 @@ using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
-using System.Security.Cryptography;
 using System.Security.Claims;
+using System.Security.Cryptography;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -324,8 +324,11 @@ namespace GitHub.Runner.Listener
                        HostContext.EnableAuthMigration("EnableAuthMigrationByDefault");
                    }

+                    // hosted runner only run one job and would like to know the result of the job for telemetry and alerting on failure spike.
+                    var returnJobResultForHosted = StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_RUNNER_RETURN_JOB_RESULT_FOR_HOSTED"));
+
                    // Run the runner interactively or as service
-                    return await ExecuteRunnerAsync(settings, command.RunOnce || settings.Ephemeral);
+                    return await ExecuteRunnerAsync(settings, command.RunOnce || settings.Ephemeral || returnJobResultForHosted, returnJobResultForHosted);
                }
                else
                {
@@ -401,17 +404,32 @@ namespace GitHub.Runner.Listener
        }

        //create worker manager, create message listener and start listening to the queue
-        private async Task<int> RunAsync(RunnerSettings settings, bool runOnce = false)
+        private async Task<int> RunAsync(RunnerSettings settings, bool runOnce = false, bool returnRunOnceJobResult = false)
        {
            try
            {
                Trace.Info(nameof(RunAsync));
-                
+
+                // Validate directory permissions.
+                string workDirectory = HostContext.GetDirectory(WellKnownDirectory.Work);
+                Trace.Info($"Validating directory permissions for: '{workDirectory}'");
+                try
+                {
+                    Directory.CreateDirectory(workDirectory);
+                    IOUtil.ValidateExecutePermission(workDirectory);
+                }
+                catch (Exception ex)
+                {
+                    Trace.Error(ex);
+                    _term.WriteError($"Fail to create and validate runner's work directory '{workDirectory}'.");
+                    return Constants.Runner.ReturnCode.TerminatedError;
+                }
+
                // First try using migrated settings if available
                var configManager = HostContext.GetService<IConfigurationManager>();
                RunnerSettings migratedSettings = null;
-                
-                try 
+
+                try
                {
                    migratedSettings = configManager.LoadMigratedSettings();
                    Trace.Info("Loaded migrated settings from .runner_migrated file");
@@ -422,15 +440,15 @@ namespace GitHub.Runner.Listener
                    // If migrated settings file doesn't exist or can't be loaded, we'll use the provided settings
                    Trace.Info($"Failed to load migrated settings: {ex.Message}");
                }
-                
+
                bool usedMigratedSettings = false;
-                
+
                if (migratedSettings != null)
                {
                    // Try to create session with migrated settings first
                    Trace.Info("Attempting to create session using migrated settings");
                    _listener = GetMessageListener(migratedSettings, isMigratedSettings: true);
-                    
+
                    try
                    {
                        CreateSessionResult createSessionResult = await _listener.CreateSessionAsync(HostContext.RunnerShutdownToken);
@@ -450,7 +468,7 @@ namespace GitHub.Runner.Listener
                        Trace.Error($"Exception when creating session with migrated settings: {ex}");
                    }
                }
-                
+
                // If migrated settings weren't used or session creation failed, use original settings
                if (!usedMigratedSettings)
                {
@@ -503,7 +521,7 @@ namespace GitHub.Runner.Listener
                            restartSession = true;
                            break;
                        }
-                        
+
                        TaskAgentMessage message = null;
                        bool skipMessageDeletion = false;
                        try
@@ -565,6 +583,21 @@ namespace GitHub.Runner.Listener
                                        Trace.Info($"Ignore any exception after cancel message loop. {ex}");
                                    }

+                                    if (returnRunOnceJobResult)
+                                    {
+                                        try
+                                        {
+                                            var jobResult = await jobDispatcher.RunOnceJobCompleted.Task;
+                                            return TaskResultUtil.TranslateToReturnCode(jobResult);
+                                        }
+                                        catch (Exception ex)
+                                        {
+                                            Trace.Error("run once job finished with error.");
+                                            Trace.Error(ex);
+                                            return Constants.Runner.ReturnCode.TerminatedError;
+                                        }
+                                    }
+
                                    return Constants.Runner.ReturnCode.Success;
                                }
                            }
@@ -851,15 +884,15 @@ namespace GitHub.Runner.Listener
            return Constants.Runner.ReturnCode.Success;
        }

-        private async Task<int> ExecuteRunnerAsync(RunnerSettings settings, bool runOnce)
+        private async Task<int> ExecuteRunnerAsync(RunnerSettings settings, bool runOnce, bool returnRunOnceJobResult)
        {
            int returnCode = Constants.Runner.ReturnCode.Success;
            bool restart = false;
            do
            {
                restart = false;
-                returnCode = await RunAsync(settings, runOnce);
-                
+                returnCode = await RunAsync(settings, runOnce, returnRunOnceJobResult);
+
                if (returnCode == Constants.Runner.ReturnCode.RunnerConfigurationRefreshed)
                {
                    Trace.Info("Runner configuration was refreshed, restarting session...");
@@ -120,8 +120,10 @@ namespace GitHub.Runner.Listener
            }
            catch (Exception ex)
            {
+                Trace.Error(ex);
+                _terminal.WriteError($"Runner update failed: {ex.Message}");
                _updateTrace.Enqueue(ex.ToString());
-                throw;
+                return false;
            }
            finally
            {
@@ -120,8 +120,10 @@ namespace GitHub.Runner.Listener
            }
            catch (Exception ex)
            {
+                Trace.Error(ex);
+                _terminal.WriteError($"Runner update failed: {ex.Message}");
                _updateTrace.Enqueue(ex.ToString());
-                throw;
+                return false;
            }
            finally
            {
@@ -15,9 +15,9 @@
  </ItemGroup>

  <ItemGroup>
-    <PackageReference Include="System.Text.Encoding.CodePages" Version="8.0.0" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="10.0.6" />
    <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
-    <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="System.Threading.Channels" Version="10.0.3" />
  </ItemGroup>

  <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
@@ -93,6 +93,16 @@ namespace GitHub.Runner.Sdk
            }
        }

+        public static FileSystemInfo CreateSymbolicLink(string destDirectory, string srcDirectory)
+        {
+            // ensure directory chain exists
+            Directory.CreateDirectory(destDirectory);
+            // delete leaf directory
+            Directory.Delete(destDirectory);
+            // create symlink for the leaf directory
+            return Directory.CreateSymbolicLink(destDirectory, srcDirectory);
+        }
+
        public static void Delete(string path, CancellationToken cancellationToken)
        {
            DeleteDirectory(path, cancellationToken);
@@ -318,6 +318,17 @@ namespace GitHub.Runner.Worker
                context.AddIssue(issue, ExecutionContextLogOptions.Default);
            }

+            if (!context.Global.HasDeprecatedSetOutput)
+            {
+                context.Global.HasDeprecatedSetOutput = true;
+                var telemetry = new JobTelemetry
+                {
+                    Type = JobTelemetryType.ActionCommand,
+                    Message = "DeprecatedCommand: set-output"
+                };
+                context.Global.JobTelemetry.Add(telemetry);
+            }
+
            if (!command.Properties.TryGetValue(SetOutputCommandProperties.Name, out string outputName) || string.IsNullOrEmpty(outputName))
            {
                throw new Exception("Required field 'name' is missing in ##[set-output] command.");
@@ -353,6 +364,17 @@ namespace GitHub.Runner.Worker
                context.AddIssue(issue, ExecutionContextLogOptions.Default);
            }

+            if (!context.Global.HasDeprecatedSaveState)
+            {
+                context.Global.HasDeprecatedSaveState = true;
+                var telemetry = new JobTelemetry
+                {
+                    Type = JobTelemetryType.ActionCommand,
+                    Message = "DeprecatedCommand: save-state"
+                };
+                context.Global.JobTelemetry.Add(telemetry);
+            }
+
            if (!command.Properties.TryGetValue(SaveStateCommandProperties.Name, out string stateName) || string.IsNullOrEmpty(stateName))
            {
                throw new Exception("Required field 'name' is missing in ##[save-state] command.");
@@ -79,6 +79,13 @@ namespace GitHub.Runner.Worker
                PreStepTracker = new Dictionary<Guid, IActionRunner>()
            };
            var containerSetupSteps = new List<JobExtensionRunner>();
+            var batchActionResolution = (executionContext.Global.Variables.GetBoolean(Constants.Runner.Features.BatchActionResolution) ?? false)
+                || StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION"));
+            // Stack-local cache: same action (owner/repo@ref) is resolved only once,
+            // even if it appears at multiple depths in a composite tree.
+            var resolvedDownloadInfos = batchActionResolution
+                ? new Dictionary<string, WebApi.ActionDownloadInfo>(StringComparer.Ordinal)
+                : null;
            var depth = 0;
            // We are running at the start of a job
            if (rootStepId == default(Guid))
@@ -105,13 +112,23 @@ namespace GitHub.Runner.Worker
            PrepareActionsState result = new PrepareActionsState();
            try
            {
-                result = await PrepareActionsRecursiveAsync(executionContext, state, actions, depth, rootStepId);
+                result = batchActionResolution
+                    ? await PrepareActionsRecursiveAsync(executionContext, state, actions, resolvedDownloadInfos, depth, rootStepId)
+                    : await PrepareActionsRecursiveLegacyAsync(executionContext, state, actions, depth, rootStepId);
            }
            catch (FailedToResolveActionDownloadInfoException ex)
            {
                // Log the error and fail the PrepareActionsAsync Initialization.
                Trace.Error($"Caught exception from PrepareActionsAsync Initialization: {ex}");
-                executionContext.InfrastructureError(ex.Message, category: "resolve_action");
+                executionContext.InfrastructureError(ex.InnerException?.Message ?? ex.Message, category: "resolve_action");
+                executionContext.Result = TaskResult.Failed;
+                throw;
+            }
+            catch (FailedToDownloadActionException ex)
+            {
+                // Log the error and fail the PrepareActionsAsync Initialization.
+                Trace.Error($"Caught exception from PrepareActionsAsync Initialization: {ex}");
+                executionContext.InfrastructureError(ex.InnerException?.Message ?? ex.Message, category: "error_download_action");
                executionContext.Result = TaskResult.Failed;
                throw;
            }
@@ -161,7 +178,192 @@ namespace GitHub.Runner.Worker
            return new PrepareResult(containerSetupSteps, result.PreStepTracker);
        }

-        private async Task<PrepareActionsState> PrepareActionsRecursiveAsync(IExecutionContext executionContext, PrepareActionsState state, IEnumerable<Pipelines.ActionStep> actions, Int32 depth = 0, Guid parentStepId = default(Guid))
+        private async Task<PrepareActionsState> PrepareActionsRecursiveAsync(IExecutionContext executionContext, PrepareActionsState state, IEnumerable<Pipelines.ActionStep> actions, Dictionary<string, WebApi.ActionDownloadInfo> resolvedDownloadInfos, Int32 depth = 0, Guid parentStepId = default(Guid))
+        {
+            ArgUtil.NotNull(executionContext, nameof(executionContext));
+            if (depth > Constants.CompositeActionsMaxDepth)
+            {
+                throw new Exception($"Composite action depth exceeded max depth {Constants.CompositeActionsMaxDepth}");
+            }
+
+            var repositoryActions = new List<Pipelines.ActionStep>();
+
+            foreach (var action in actions)
+            {
+                if (action.Reference.Type == Pipelines.ActionSourceType.ContainerRegistry)
+                {
+                    ArgUtil.NotNull(action, nameof(action));
+                    var containerReference = action.Reference as Pipelines.ContainerRegistryReference;
+                    ArgUtil.NotNull(containerReference, nameof(containerReference));
+                    ArgUtil.NotNullOrEmpty(containerReference.Image, nameof(containerReference.Image));
+
+                    if (!state.ImagesToPull.ContainsKey(containerReference.Image))
+                    {
+                        state.ImagesToPull[containerReference.Image] = new List<Guid>();
+                    }
+
+                    Trace.Info($"Action {action.Name} ({action.Id}) needs to pull image '{containerReference.Image}'");
+                    state.ImagesToPull[containerReference.Image].Add(action.Id);
+                }
+                else if (action.Reference.Type == Pipelines.ActionSourceType.Repository)
+                {
+                    repositoryActions.Add(action);
+                }
+            }
+
+            if (repositoryActions.Count > 0)
+            {
+                // Resolve download info, skipping any actions already cached.
+                await ResolveNewActionsAsync(executionContext, repositoryActions, resolvedDownloadInfos);
+
+                // Download each action.
+                foreach (var action in repositoryActions)
+                {
+                    var lookupKey = GetDownloadInfoLookupKey(action);
+                    if (string.IsNullOrEmpty(lookupKey))
+                    {
+                        continue;
+                    }
+                    if (!resolvedDownloadInfos.TryGetValue(lookupKey, out var downloadInfo))
+                    {
+                        throw new Exception($"Missing download info for {lookupKey}");
+                    }
+                    await DownloadRepositoryActionAsync(executionContext, downloadInfo);
+                }
+
+                // Parse action.yml and collect composite sub-actions for batched
+                // resolution below. Pre/post step registration is deferred until
+                // after recursion so that HasPre/HasPost reflect the full subtree.
+                var nextLevel = new List<(Pipelines.ActionStep action, Guid parentId)>();
+
+                foreach (var action in repositoryActions)
+                {
+                    var setupInfo = PrepareRepositoryActionAsync(executionContext, action);
+                    if (setupInfo != null && setupInfo.Container != null)
+                    {
+                        if (!string.IsNullOrEmpty(setupInfo.Container.Image))
+                        {
+                            if (!state.ImagesToPull.ContainsKey(setupInfo.Container.Image))
+                            {
+                                state.ImagesToPull[setupInfo.Container.Image] = new List<Guid>();
+                            }
+
+                            Trace.Info($"Action {action.Name} ({action.Id}) from repository '{setupInfo.Container.ActionRepository}' needs to pull image '{setupInfo.Container.Image}'");
+                            state.ImagesToPull[setupInfo.Container.Image].Add(action.Id);
+                        }
+                        else
+                        {
+                            ArgUtil.NotNullOrEmpty(setupInfo.Container.ActionRepository, nameof(setupInfo.Container.ActionRepository));
+
+                            if (!state.ImagesToBuild.ContainsKey(setupInfo.Container.ActionRepository))
+                            {
+                                state.ImagesToBuild[setupInfo.Container.ActionRepository] = new List<Guid>();
+                            }
+
+                            Trace.Info($"Action {action.Name} ({action.Id}) from repository '{setupInfo.Container.ActionRepository}' needs to build image '{setupInfo.Container.Dockerfile}'");
+                            state.ImagesToBuild[setupInfo.Container.ActionRepository].Add(action.Id);
+                            state.ImagesToBuildInfo[setupInfo.Container.ActionRepository] = setupInfo.Container;
+                        }
+                    }
+                    else if (setupInfo != null && setupInfo.Steps != null && setupInfo.Steps.Count > 0)
+                    {
+                        foreach (var step in setupInfo.Steps)
+                        {
+                            nextLevel.Add((step, action.Id));
+                        }
+                    }
+                }
+
+                // Resolve all next-level sub-actions in one batch API call,
+                // then recurse per parent (which hits the cache, not the API).
+                if (nextLevel.Count > 0)
+                {
+                    var nextLevelRepoActions = nextLevel
+                        .Where(x => x.action.Reference.Type == Pipelines.ActionSourceType.Repository)
+                        .Select(x => x.action)
+                        .ToList();
+                    await ResolveNewActionsAsync(executionContext, nextLevelRepoActions, resolvedDownloadInfos);
+
+                    foreach (var group in nextLevel.GroupBy(x => x.parentId))
+                    {
+                        var groupActions = group.Select(x => x.action).ToList();
+                        state = await PrepareActionsRecursiveAsync(executionContext, state, groupActions, resolvedDownloadInfos, depth + 1, group.Key);
+                    }
+                }
+
+                // Register pre/post steps after recursion so that HasPre/HasPost
+                // are correct (they depend on _cachedEmbeddedPreSteps/PostSteps
+                // being populated by the recursive calls above).
+                foreach (var action in repositoryActions)
+                {
+                    var repoAction = action.Reference as Pipelines.RepositoryPathReference;
+                    if (repoAction.RepositoryType != Pipelines.PipelineConstants.SelfAlias)
+                    {
+                        var definition = LoadAction(executionContext, action);
+                        if (definition.Data.Execution.HasPre)
+                        {
+                            Trace.Info($"Add 'pre' execution for {action.Id}");
+                            // Root Step
+                            if (depth < 1)
+                            {
+                                var actionRunner = HostContext.CreateService<IActionRunner>();
+                                actionRunner.Action = action;
+                                actionRunner.Stage = ActionRunStage.Pre;
+                                actionRunner.Condition = definition.Data.Execution.InitCondition;
+                                state.PreStepTracker[action.Id] = actionRunner;
+                            }
+                            // Embedded Step
+                            else
+                            {
+                                if (!_cachedEmbeddedPreSteps.ContainsKey(parentStepId))
+                                {
+                                    _cachedEmbeddedPreSteps[parentStepId] = new List<Pipelines.ActionStep>();
+                                }
+                                // Clone action so we can modify the condition without affecting the original
+                                var clonedAction = action.Clone() as Pipelines.ActionStep;
+                                clonedAction.Condition = definition.Data.Execution.InitCondition;
+                                _cachedEmbeddedPreSteps[parentStepId].Add(clonedAction);
+                            }
+                        }
+
+                        if (definition.Data.Execution.HasPost && depth > 0)
+                        {
+                            if (!_cachedEmbeddedPostSteps.ContainsKey(parentStepId))
+                            {
+                                // If we haven't done so already, add the parent to the post steps
+                                _cachedEmbeddedPostSteps[parentStepId] = new Stack<Pipelines.ActionStep>();
+                            }
+                            // Clone action so we can modify the condition without affecting the original
+                            var clonedAction = action.Clone() as Pipelines.ActionStep;
+                            clonedAction.Condition = definition.Data.Execution.CleanupCondition;
+                            _cachedEmbeddedPostSteps[parentStepId].Push(clonedAction);
+                        }
+                    }
+                    else if (depth > 0)
+                    {
+                        // if we're in a composite action and haven't loaded the local action yet
+                        // we assume it has a post step
+                        if (!_cachedEmbeddedPostSteps.ContainsKey(parentStepId))
+                        {
+                            // If we haven't done so already, add the parent to the post steps
+                            _cachedEmbeddedPostSteps[parentStepId] = new Stack<Pipelines.ActionStep>();
+                        }
+                        // Clone action so we can modify the condition without affecting the original
+                        var clonedAction = action.Clone() as Pipelines.ActionStep;
+                        _cachedEmbeddedPostSteps[parentStepId].Push(clonedAction);
+                    }
+                }
+            }
+
+            return state;
+        }
+
+        /// <summary>
+        /// Legacy (non-batched) action resolution. Each composite resolves its
+        /// sub-actions individually, with no cross-depth deduplication.
+        /// Used when the BatchActionResolution feature flag is disabled.
+        /// </summary>
+        private async Task<PrepareActionsState> PrepareActionsRecursiveLegacyAsync(IExecutionContext executionContext, PrepareActionsState state, IEnumerable<Pipelines.ActionStep> actions, Int32 depth = 0, Guid parentStepId = default(Guid))
        {
            ArgUtil.NotNull(executionContext, nameof(executionContext));
            if (depth > Constants.CompositeActionsMaxDepth)
@@ -247,7 +449,7 @@ namespace GitHub.Runner.Worker
                    }
                    else if (setupInfo != null && setupInfo.Steps != null && setupInfo.Steps.Count > 0)
                    {
-                        state = await PrepareActionsRecursiveAsync(executionContext, state, setupInfo.Steps, depth + 1, action.Id);
+                        state = await PrepareActionsRecursiveLegacyAsync(executionContext, state, setupInfo.Steps, depth + 1, action.Id);
                    }
                    var repoAction = action.Reference as Pipelines.RepositoryPathReference;
                    if (repoAction.RepositoryType != Pipelines.PipelineConstants.SelfAlias)
@@ -754,6 +956,33 @@ namespace GitHub.Runner.Worker
            return actionDownloadInfos.Actions;
        }

+        /// <summary>
+        /// Only resolves actions not already in resolvedDownloadInfos.
+        /// Results are cached for reuse at deeper recursion levels.
+        /// </summary>
+        private async Task ResolveNewActionsAsync(IExecutionContext executionContext, List<Pipelines.ActionStep> actions, Dictionary<string, WebApi.ActionDownloadInfo> resolvedDownloadInfos)
+        {
+            var actionsToResolve = new List<Pipelines.ActionStep>();
+            var pendingKeys = new HashSet<string>(StringComparer.Ordinal);
+            foreach (var action in actions)
+            {
+                var lookupKey = GetDownloadInfoLookupKey(action);
+                if (!string.IsNullOrEmpty(lookupKey) && !resolvedDownloadInfos.ContainsKey(lookupKey) && pendingKeys.Add(lookupKey))
+                {
+                    actionsToResolve.Add(action);
+                }
+            }
+
+            if (actionsToResolve.Count > 0)
+            {
+                var downloadInfos = await GetDownloadInfoAsync(executionContext, actionsToResolve);
+                foreach (var kvp in downloadInfos)
+                {
+                    resolvedDownloadInfos[kvp.Key] = kvp.Value;
+                }
+            }
+        }
+
        private async Task DownloadRepositoryActionAsync(IExecutionContext executionContext, WebApi.ActionDownloadInfo downloadInfo)
        {
            Trace.Entering();
@@ -773,10 +1002,6 @@ namespace GitHub.Runner.Worker
            }
            else
            {
-                // make sure we get a clean folder ready to use.
-                IOUtil.DeleteDirectory(destDirectory, executionContext.CancellationToken);
-                Directory.CreateDirectory(destDirectory);
-
                if (downloadInfo.PackageDetails != null)
                {
                    executionContext.Output($"##[group]Download immutable action package '{downloadInfo.NameWithOwner}@{downloadInfo.Ref}'");
@@ -811,6 +1036,50 @@ namespace GitHub.Runner.Worker
                if (!string.IsNullOrEmpty(actionArchiveCacheDir) &&
                    Directory.Exists(actionArchiveCacheDir))
                {
+                    var symlinkCachedActions = StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable(Constants.Variables.Agent.SymlinkCachedActions));
+                    if (symlinkCachedActions)
+                    {
+                        Trace.Info($"Checking if can symlink '{downloadInfo.ResolvedNameWithOwner}@{downloadInfo.ResolvedSha}'");
+
+                        var cacheDirectory = Path.Combine(actionArchiveCacheDir, downloadInfo.ResolvedNameWithOwner.Replace(Path.DirectorySeparatorChar, '_').Replace(Path.AltDirectorySeparatorChar, '_'), downloadInfo.ResolvedSha);
+                        if (Directory.Exists(cacheDirectory))
+                        {
+                            try
+                            {
+                                Trace.Info($"Found unpacked action directory '{cacheDirectory}' in cache directory '{actionArchiveCacheDir}'");
+
+                                // repository archive from github always contains a nested folder
+                                var nestedDirectories = new DirectoryInfo(cacheDirectory).GetDirectories();
+                                if (nestedDirectories.Length != 1)
+                                {
+                                    throw new InvalidOperationException($"'{cacheDirectory}' contains '{nestedDirectories.Length}' directories");
+                                }
+                                else
+                                {
+                                    executionContext.Debug($"Symlink '{nestedDirectories[0].Name}' to '{destDirectory}'");
+                                    // make sure we get a clean folder ready to use.
+                                    IOUtil.DeleteDirectory(destDirectory, executionContext.CancellationToken);
+                                    IOUtil.CreateSymbolicLink(destDirectory, nestedDirectories[0].FullName);
+                                }
+
+                                executionContext.Debug($"Created symlink from cached directory '{cacheDirectory}' to '{destDirectory}'");
+                                executionContext.Global.JobTelemetry.Add(new JobTelemetry()
+                                {
+                                    Type = JobTelemetryType.General,
+                                    Message = $"Action archive cache usage: {downloadInfo.ResolvedNameWithOwner}@{downloadInfo.ResolvedSha} use cache {useActionArchiveCache} has cache {hasActionArchiveCache} via symlink"
+                                });
+
+                                Trace.Info("Finished getting action repository.");
+                                return;
+                            }
+                            catch (Exception ex)
+                            {
+                                Trace.Error($"Failed to create symlink from cached directory '{cacheDirectory}' to '{destDirectory}'. Error: {ex}");
+                                // Fall through to normal download logic
+                            }
+                        }
+                    }
+
                    hasActionArchiveCache = true;
                    Trace.Info($"Check if action archive '{downloadInfo.ResolvedNameWithOwner}@{downloadInfo.ResolvedSha}' already exists in cache directory '{actionArchiveCacheDir}'");
 #if OS_WINDOWS
@@ -892,6 +1161,10 @@ namespace GitHub.Runner.Worker
                }
 #endif

+                // make sure we get a clean folder ready to use.
+                IOUtil.DeleteDirectory(destDirectory, executionContext.CancellationToken);
+                Directory.CreateDirectory(destDirectory);
+
                // repository archive from github always contains a nested folder
                var subDirectories = new DirectoryInfo(stagingDirectory).GetDirectories();
                if (subDirectories.Length != 1)
@@ -1094,16 +1367,29 @@ namespace GitHub.Runner.Worker
            return $"{repositoryReference.Name}@{repositoryReference.Ref}";
        }

-        private AuthenticationHeaderValue CreateAuthHeader(string token)
+        private AuthenticationHeaderValue CreateAuthHeader(IExecutionContext executionContext, string downloadUrl, string token)
        {
            if (string.IsNullOrEmpty(token))
            {
                return null;
            }

-            var base64EncodingToken = Convert.ToBase64String(Encoding.UTF8.GetBytes($"x-access-token:{token}"));
-            HostContext.SecretMasker.AddValue(base64EncodingToken);
-            return new AuthenticationHeaderValue("Basic", base64EncodingToken);
+            if (executionContext.Global.Variables.GetBoolean(Constants.Runner.Features.UseBearerTokenForCodeload) == true &&
+                Uri.TryCreate(downloadUrl, UriKind.Absolute, out var parsedUrl) &&
+                !string.IsNullOrEmpty(parsedUrl?.Host) &&
+                !string.IsNullOrEmpty(parsedUrl?.PathAndQuery) &&
+                (parsedUrl.Host.StartsWith("codeload.", StringComparison.OrdinalIgnoreCase) || parsedUrl.PathAndQuery.StartsWith("/_codeload/", StringComparison.OrdinalIgnoreCase)))
+            {
+                Trace.Info("Using Bearer token for action archive download directly to codeload.");
+                return new AuthenticationHeaderValue("Bearer", token);
+            }
+            else
+            {
+                Trace.Info("Using Basic token for action archive download.");
+                var base64EncodingToken = Convert.ToBase64String(Encoding.UTF8.GetBytes($"x-access-token:{token}"));
+                HostContext.SecretMasker.AddValue(base64EncodingToken);
+                return new AuthenticationHeaderValue("Basic", base64EncodingToken);
+            }
        }

        private async Task DownloadRepositoryArchive(IExecutionContext executionContext, string downloadUrl, string downloadAuthToken, string archiveFile)
@@ -1113,93 +1399,102 @@ namespace GitHub.Runner.Worker

            // Allow up to 20 * 60s for any action to be downloaded from github graph.
            int timeoutSeconds = 20 * 60;
-            while (retryCount < 3)
+            try
            {
-                string requestId = string.Empty;
-                using (var actionDownloadTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(timeoutSeconds)))
-                using (var actionDownloadCancellation = CancellationTokenSource.CreateLinkedTokenSource(actionDownloadTimeout.Token, executionContext.CancellationToken))
+                while (retryCount < 3)
                {
-                    try
+                    string requestId = string.Empty;
+                    using (var actionDownloadTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(timeoutSeconds)))
+                    using (var actionDownloadCancellation = CancellationTokenSource.CreateLinkedTokenSource(actionDownloadTimeout.Token, executionContext.CancellationToken))
                    {
-                        //open zip stream in async mode
-                        using (FileStream fs = new(archiveFile, FileMode.Create, FileAccess.Write, FileShare.None, bufferSize: _defaultFileStreamBufferSize, useAsync: true))
-                        using (var httpClientHandler = HostContext.CreateHttpClientHandler())
-                        using (var httpClient = new HttpClient(httpClientHandler))
+                        try
                        {
-                            httpClient.DefaultRequestHeaders.Authorization = CreateAuthHeader(downloadAuthToken);
-
-                            httpClient.DefaultRequestHeaders.UserAgent.AddRange(HostContext.UserAgents);
-                            using (var response = await httpClient.GetAsync(downloadUrl))
+                            //open zip stream in async mode
+                            using (FileStream fs = new(archiveFile, FileMode.Create, FileAccess.Write, FileShare.None, bufferSize: _defaultFileStreamBufferSize, useAsync: true))
+                            using (var httpClientHandler = HostContext.CreateHttpClientHandler())
+                            using (var httpClient = new HttpClient(httpClientHandler))
                            {
-                                requestId = UrlUtil.GetGitHubRequestId(response.Headers);
-                                if (!string.IsNullOrEmpty(requestId))
-                                {
-                                    Trace.Info($"Request URL: {downloadUrl} X-GitHub-Request-Id: {requestId} Http Status: {response.StatusCode}");
-                                }
+                                httpClient.DefaultRequestHeaders.Authorization = CreateAuthHeader(executionContext, downloadUrl, downloadAuthToken);

-                                if (response.IsSuccessStatusCode)
+                                httpClient.DefaultRequestHeaders.UserAgent.AddRange(HostContext.UserAgents);
+                                using (var response = await httpClient.GetAsync(downloadUrl))
                                {
-                                    using (var result = await response.Content.ReadAsStreamAsync())
+                                    requestId = UrlUtil.GetGitHubRequestId(response.Headers);
+                                    if (!string.IsNullOrEmpty(requestId))
                                    {
-                                        await result.CopyToAsync(fs, _defaultCopyBufferSize, actionDownloadCancellation.Token);
-                                        await fs.FlushAsync(actionDownloadCancellation.Token);
-
-                                        // download succeed, break out the retry loop.
-                                        break;
+                                        Trace.Info($"Request URL: {downloadUrl} X-GitHub-Request-Id: {requestId} Http Status: {response.StatusCode}");
+                                    }
+
+                                    if (response.IsSuccessStatusCode)
+                                    {
+                                        using (var result = await response.Content.ReadAsStreamAsync())
+                                        {
+                                            await result.CopyToAsync(fs, _defaultCopyBufferSize, actionDownloadCancellation.Token);
+                                            await fs.FlushAsync(actionDownloadCancellation.Token);
+
+                                            // download succeed, break out the retry loop.
+                                            break;
+                                        }
+                                    }
+                                    else if (response.StatusCode == HttpStatusCode.NotFound)
+                                    {
+                                        // It doesn't make sense to retry in this case, so just stop
+                                        throw new ActionNotFoundException(new Uri(downloadUrl), requestId);
+                                    }
+                                    else
+                                    {
+                                        // Something else bad happened, let's go to our retry logic
+                                        response.EnsureSuccessStatusCode();
                                    }
-                                }
-                                else if (response.StatusCode == HttpStatusCode.NotFound)
-                                {
-                                    // It doesn't make sense to retry in this case, so just stop
-                                    throw new ActionNotFoundException(new Uri(downloadUrl), requestId);
-                                }
-                                else
-                                {
-                                    // Something else bad happened, let's go to our retry logic
-                                    response.EnsureSuccessStatusCode();
                                }
                            }
                        }
-                    }
-                    catch (OperationCanceledException) when (executionContext.CancellationToken.IsCancellationRequested)
-                    {
-                        Trace.Info("Action download has been cancelled.");
-                        throw;
-                    }
-                    catch (OperationCanceledException ex) when (!executionContext.CancellationToken.IsCancellationRequested && retryCount >= 2)
-                    {
-                        Trace.Info($"Action download final retry timeout after {timeoutSeconds} seconds.");
-                        throw new TimeoutException($"Action '{downloadUrl}' download has timed out. Error: {ex.Message} {requestId}");
-                    }
-                    catch (ActionNotFoundException)
-                    {
-                        Trace.Info($"The action at '{downloadUrl}' does not exist");
-                        throw;
-                    }
-                    catch (Exception ex) when (retryCount < 2)
-                    {
-                        retryCount++;
-                        Trace.Error($"Fail to download archive '{downloadUrl}' -- Attempt: {retryCount}");
-                        Trace.Error(ex);
-                        if (actionDownloadTimeout.Token.IsCancellationRequested)
+                        catch (OperationCanceledException) when (executionContext.CancellationToken.IsCancellationRequested)
                        {
-                            // action download didn't finish within timeout
-                            executionContext.Warning($"Action '{downloadUrl}' didn't finish download within {timeoutSeconds} seconds. {requestId}");
+                            Trace.Info("Action download has been cancelled.");
+                            throw;
                        }
-                        else
+                        catch (OperationCanceledException ex) when (!executionContext.CancellationToken.IsCancellationRequested && retryCount >= 2)
                        {
-                            executionContext.Warning($"Failed to download action '{downloadUrl}'. Error: {ex.Message} {requestId}");
+                            Trace.Info($"Action download final retry timeout after {timeoutSeconds} seconds.");
+                            throw new TimeoutException($"Action '{downloadUrl}' download has timed out. Error: {ex.Message} {requestId}");
+                        }
+                        catch (ActionNotFoundException)
+                        {
+                            Trace.Info($"The action at '{downloadUrl}' does not exist");
+                            throw;
+                        }
+                        catch (Exception ex) when (retryCount < 2)
+                        {
+                            retryCount++;
+                            Trace.Error($"Fail to download archive '{downloadUrl}' -- Attempt: {retryCount}");
+                            Trace.Error(ex);
+                            if (actionDownloadTimeout.Token.IsCancellationRequested)
+                            {
+                                // action download didn't finish within timeout
+                                executionContext.Warning($"Action '{downloadUrl}' didn't finish download within {timeoutSeconds} seconds. {requestId}");
+                            }
+                            else
+                            {
+                                executionContext.Warning($"Failed to download action '{downloadUrl}'. Error: {ex.Message} {requestId}");
+                            }
                        }
                    }
-                }

-                if (String.IsNullOrEmpty(Environment.GetEnvironmentVariable("_GITHUB_ACTION_DOWNLOAD_NO_BACKOFF")))
-                {
-                    var backOff = BackoffTimerHelper.GetRandomBackoff(TimeSpan.FromSeconds(10), TimeSpan.FromSeconds(30));
-                    executionContext.Warning($"Back off {backOff.TotalSeconds} seconds before retry.");
-                    await Task.Delay(backOff);
+                    if (String.IsNullOrEmpty(Environment.GetEnvironmentVariable("_GITHUB_ACTION_DOWNLOAD_NO_BACKOFF")))
+                    {
+                        var backOff = BackoffTimerHelper.GetRandomBackoff(TimeSpan.FromSeconds(10), TimeSpan.FromSeconds(30));
+                        executionContext.Warning($"Back off {backOff.TotalSeconds} seconds before retry.");
+                        await Task.Delay(backOff);
+                    }
                }
            }
+            catch (Exception ex) when (!(ex is OperationCanceledException) && !executionContext.CancellationToken.IsCancellationRequested)
+            {
+                Trace.Error($"Failed to download archive '{downloadUrl}' after {retryCount + 1} attempts.");
+                Trace.Error(ex);
+                throw new FailedToDownloadActionException($"Failed to download archive '{downloadUrl}' after {retryCount + 1} attempts.", ex);
+            }

            ArgUtil.NotNullOrEmpty(archiveFile, nameof(archiveFile));
            executionContext.Debug($"Download '{downloadUrl}' to '{archiveFile}'");
@@ -316,7 +316,6 @@ namespace GitHub.Runner.Worker
                Schema = _actionManifestSchema,
                // TODO: Switch to real tracewriter for cutover
                TraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter(),
-                AllowCaseFunction = false,
            };

            // Expression values from execution context
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Threading;
@@ -315,7 +315,6 @@ namespace GitHub.Runner.Worker
                    maxBytes: 10 * 1024 * 1024),
                Schema = _actionManifestSchema,
                TraceWriter = executionContext.ToTemplateTraceWriter(),
-                AllowCaseFunction = false,
            };

            // Expression values from execution context
@@ -84,7 +84,8 @@ namespace GitHub.Runner.Worker
                "EvaluateContainerEnvironment",
                () => _legacyManager.EvaluateContainerEnvironment(executionContext, token, extraExpressionValues),
                () => _newManager.EvaluateContainerEnvironment(executionContext, ConvertToNewToken(token) as GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.MappingToken, ConvertToNewExpressionValues(extraExpressionValues)),
-                (legacyResult, newResult) => {
+                (legacyResult, newResult) =>
+                {
                    var trace = HostContext.GetTrace(nameof(ActionManifestManagerWrapper));
                    return CompareDictionaries(trace, legacyResult, newResult, "ContainerEnvironment");
                });
@@ -165,9 +166,150 @@ namespace GitHub.Runner.Worker
                return null;
            }

-            // Serialize new steps and deserialize to old steps
-            var json = StringUtil.ConvertToJson(newSteps, Newtonsoft.Json.Formatting.None);
-            return StringUtil.ConvertFromJson<List<GitHub.DistributedTask.Pipelines.ActionStep>>(json);
+            var result = new List<GitHub.DistributedTask.Pipelines.ActionStep>();
+            foreach (var step in newSteps)
+            {
+                var actionStep = new GitHub.DistributedTask.Pipelines.ActionStep
+                {
+                    ContextName = step.Id,
+                };
+
+                if (step is GitHub.Actions.WorkflowParser.RunStep runStep)
+                {
+                    actionStep.Condition = ExtractConditionString(runStep.If);
+                    actionStep.DisplayNameToken = ConvertToLegacyToken<TemplateToken>(runStep.Name);
+                    actionStep.ContinueOnError = ConvertToLegacyToken<TemplateToken>(runStep.ContinueOnError);
+                    actionStep.TimeoutInMinutes = ConvertToLegacyToken<TemplateToken>(runStep.TimeoutMinutes);
+                    actionStep.Environment = ConvertToLegacyToken<TemplateToken>(runStep.Env);
+                    actionStep.Reference = new GitHub.DistributedTask.Pipelines.ScriptReference();
+                    actionStep.Inputs = BuildRunStepInputs(runStep);
+                }
+                else if (step is GitHub.Actions.WorkflowParser.ActionStep usesStep)
+                {
+                    actionStep.Condition = ExtractConditionString(usesStep.If);
+                    actionStep.DisplayNameToken = ConvertToLegacyToken<TemplateToken>(usesStep.Name);
+                    actionStep.ContinueOnError = ConvertToLegacyToken<TemplateToken>(usesStep.ContinueOnError);
+                    actionStep.TimeoutInMinutes = ConvertToLegacyToken<TemplateToken>(usesStep.TimeoutMinutes);
+                    actionStep.Environment = ConvertToLegacyToken<TemplateToken>(usesStep.Env);
+                    actionStep.Reference = ParseActionReference(usesStep.Uses?.Value);
+                    actionStep.Inputs = ConvertToLegacyToken<MappingToken>(usesStep.With);
+                }
+
+                result.Add(actionStep);
+            }
+            return result;
+        }
+
+        private string ExtractConditionString(GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.BasicExpressionToken ifToken)
+        {
+            if (ifToken == null)
+            {
+                return null;
+            }
+
+            // The Expression property is internal, so we use ToString() which formats as "${{ expr }}"
+            // Then strip the delimiters to get just the expression
+            var str = ifToken.ToString();
+            if (str.StartsWith("${{") && str.EndsWith("}}"))
+            {
+                return str.Substring(3, str.Length - 5).Trim();
+            }
+            return str;
+        }
+
+        private MappingToken BuildRunStepInputs(GitHub.Actions.WorkflowParser.RunStep runStep)
+        {
+            var inputs = new MappingToken(null, null, null);
+
+            // script (from run)
+            if (runStep.Run != null)
+            {
+                inputs.Add(
+                    new StringToken(null, null, null, "script"),
+                    ConvertToLegacyToken<TemplateToken>(runStep.Run));
+            }
+
+            // shell
+            if (runStep.Shell != null)
+            {
+                inputs.Add(
+                    new StringToken(null, null, null, "shell"),
+                    ConvertToLegacyToken<TemplateToken>(runStep.Shell));
+            }
+
+            // working-directory
+            if (runStep.WorkingDirectory != null)
+            {
+                inputs.Add(
+                    new StringToken(null, null, null, "workingDirectory"),
+                    ConvertToLegacyToken<TemplateToken>(runStep.WorkingDirectory));
+            }
+
+            return inputs.Count > 0 ? inputs : null;
+        }
+
+        private GitHub.DistributedTask.Pipelines.ActionStepDefinitionReference ParseActionReference(string uses)
+        {
+            if (string.IsNullOrEmpty(uses))
+            {
+                return null;
+            }
+
+            // Docker reference: docker://image:tag
+            if (uses.StartsWith("docker://", StringComparison.OrdinalIgnoreCase))
+            {
+                return new GitHub.DistributedTask.Pipelines.ContainerRegistryReference
+                {
+                    Image = uses.Substring("docker://".Length)
+                };
+            }
+
+            // Local path reference: ./path/to/action
+            if (uses.StartsWith("./") || uses.StartsWith(".\\"))
+            {
+                return new GitHub.DistributedTask.Pipelines.RepositoryPathReference
+                {
+                    RepositoryType = "self",
+                    Path = uses
+                };
+            }
+
+            // Repository reference: owner/repo@ref or owner/repo/path@ref
+            var atIndex = uses.LastIndexOf('@');
+            string refPart = null;
+            string repoPart = uses;
+
+            if (atIndex > 0)
+            {
+                refPart = uses.Substring(atIndex + 1);
+                repoPart = uses.Substring(0, atIndex);
+            }
+
+            // Split by / to get owner/repo and optional path
+            var parts = repoPart.Split('/');
+            string name;
+            string path = null;
+
+            if (parts.Length >= 2)
+            {
+                name = $"{parts[0]}/{parts[1]}";
+                if (parts.Length > 2)
+                {
+                    path = string.Join("/", parts, 2, parts.Length - 2);
+                }
+            }
+            else
+            {
+                name = repoPart;
+            }
+
+            return new GitHub.DistributedTask.Pipelines.RepositoryPathReference
+            {
+                RepositoryType = "GitHub",
+                Name = name,
+                Ref = refPart,
+                Path = path
+            };
        }

        private T ConvertToLegacyToken<T>(GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.TemplateToken newToken) where T : TemplateToken
@@ -633,6 +775,14 @@ namespace GitHub.Runner.Worker
                return false;
            }

+            // Check for known equivalent error patterns (e.g., JSON parse errors)
+            // where both parsers correctly reject invalid input but with different wording
+            if (PipelineTemplateEvaluatorWrapper.HasJsonExceptionType(legacyException) && PipelineTemplateEvaluatorWrapper.HasJsonExceptionType(newException))
+            {
+                trace.Info("CompareExceptions - both exceptions are JSON parse errors, treating as matched");
+                return true;
+            }
+
            // Compare exception messages recursively (including inner exceptions)
            var legacyMessages = GetExceptionMessages(legacyException);
            var newMessages = GetExceptionMessages(newException);
@@ -697,5 +847,6 @@ namespace GitHub.Runner.Worker

            return messages;
        }
+
    }
 }
@@ -36,6 +36,8 @@ namespace GitHub.Runner.Worker.Container
            this.ContainerImage = containerImage;
            this.ContainerDisplayName = $"{container.Alias}_{Pipelines.Validation.NameValidation.Sanitize(containerImage)}_{Guid.NewGuid().ToString("N").Substring(0, 6)}";
            this.ContainerCreateOptions = container.Options;
+            this.ContainerEntryPoint = container.Entrypoint;
+            this.ContainerEntryPointArgs = container.Command;
            _environmentVariables = container.Environment;
            this.IsJobContainer = isJobContainer;
            this.ContainerNetworkAlias = networkAlias;
@@ -0,0 +1,369 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.Runner.Common;
+using GitHub.Runner.Common.Util;
+using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Handlers;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Executes <see cref="RunCommand"/> objects in the job's runtime context.
+    ///
+    /// Mirrors the behavior of a normal workflow <c>run:</c> step as closely
+    /// as possible by reusing the runner's existing shell-resolution logic,
+    /// script fixup helpers, and process execution infrastructure.
+    ///
+    /// Output is streamed to the debugger via DAP <c>output</c> events with
+    /// secrets masked before emission.
+    /// </summary>
+    internal sealed class DapReplExecutor
+    {
+        private readonly IHostContext _hostContext;
+        private readonly Action<string, string> _sendOutput;
+        private readonly Tracing _trace;
+
+        public DapReplExecutor(IHostContext hostContext, Action<string, string> sendOutput)
+        {
+            _hostContext = hostContext ?? throw new ArgumentNullException(nameof(hostContext));
+            _sendOutput = sendOutput ?? throw new ArgumentNullException(nameof(sendOutput));
+            _trace = hostContext.GetTrace(nameof(DapReplExecutor));
+        }
+
+        /// <summary>
+        /// Executes a <see cref="RunCommand"/> and returns the exit code as a
+        /// formatted <see cref="EvaluateResponseBody"/>.
+        /// </summary>
+        public async Task<EvaluateResponseBody> ExecuteRunCommandAsync(
+            RunCommand command,
+            IExecutionContext context,
+            CancellationToken cancellationToken)
+        {
+            if (context == null)
+            {
+                return ErrorResult("No execution context available. The debugger must be paused at a step to run commands.");
+            }
+
+            try
+            {
+                return await ExecuteScriptAsync(command, context, cancellationToken);
+            }
+            catch (Exception ex)
+            {
+                _trace.Error($"REPL run command failed ({ex.GetType().Name})");
+                var maskedError = _hostContext.SecretMasker.MaskSecrets(ex.Message);
+                return ErrorResult($"Command failed: {maskedError}");
+            }
+        }
+
+        private async Task<EvaluateResponseBody> ExecuteScriptAsync(
+            RunCommand command,
+            IExecutionContext context,
+            CancellationToken cancellationToken)
+        {
+            // 1. Resolve shell — same logic as ScriptHandler
+            string shellCommand;
+            string argFormat;
+
+            if (!string.IsNullOrEmpty(command.Shell))
+            {
+                // Explicit shell from the DSL
+                var parsed = ScriptHandlerHelpers.ParseShellOptionString(command.Shell);
+                shellCommand = parsed.shellCommand;
+                argFormat = string.IsNullOrEmpty(parsed.shellArgs)
+                    ? ScriptHandlerHelpers.GetScriptArgumentsFormat(shellCommand)
+                    : parsed.shellArgs;
+            }
+            else
+            {
+                // Default shell — mirrors ScriptHandler platform defaults
+                shellCommand = ResolveDefaultShell(context);
+                argFormat = ScriptHandlerHelpers.GetScriptArgumentsFormat(shellCommand);
+            }
+
+            _trace.Info("Resolved REPL shell");
+
+            // 2. Expand ${{ }} expressions in the script body, just like
+            //    ActionRunner evaluates step inputs before ScriptHandler sees them
+            var contents = ExpandExpressions(command.Script, context);
+            contents = ScriptHandlerHelpers.FixUpScriptContents(shellCommand, contents);
+
+            // Write to a temp file (same pattern as ScriptHandler)
+            var extension = ScriptHandlerHelpers.GetScriptFileExtension(shellCommand);
+            var scriptFilePath = Path.Combine(
+                _hostContext.GetDirectory(WellKnownDirectory.Temp),
+                $"dap_repl_{Guid.NewGuid()}{extension}");
+
+            Encoding encoding = new UTF8Encoding(false);
+#if OS_WINDOWS
+            contents = contents.Replace("\r\n", "\n").Replace("\n", "\r\n");
+            encoding = Console.InputEncoding.CodePage != 65001
+                ? Console.InputEncoding
+                : encoding;
+#endif
+            File.WriteAllText(scriptFilePath, contents, encoding);
+
+            try
+            {
+                // 3. Format arguments with script path
+                var resolvedPath = scriptFilePath.Replace("\"", "\\\"");
+                if (string.IsNullOrEmpty(argFormat) || !argFormat.Contains("{0}"))
+                {
+                    return ErrorResult($"Invalid shell option '{shellCommand}'. Shell must be a valid built-in (bash, sh, cmd, powershell, pwsh) or a format string containing '{{0}}'");
+                }
+                var arguments = string.Format(argFormat, resolvedPath);
+
+                // 4. Resolve shell command path
+                string prependPath = string.Join(
+                    Path.PathSeparator.ToString(),
+                    Enumerable.Reverse(context.Global.PrependPath));
+                var commandPath = WhichUtil.Which(shellCommand, false, _trace, prependPath)
+                    ?? shellCommand;
+
+                // 5. Build environment — merge from execution context like a real step
+                var environment = BuildEnvironment(context, command.Env);
+
+                // 6. Resolve working directory
+                var workingDirectory = command.WorkingDirectory;
+                if (string.IsNullOrEmpty(workingDirectory))
+                {
+                    var githubContext = context.ExpressionValues.TryGetValue("github", out var gh)
+                        ? gh as DictionaryContextData
+                        : null;
+                    var workspace = githubContext?.TryGetValue("workspace", out var ws) == true
+                        ? (ws as StringContextData)?.Value
+                        : null;
+                    workingDirectory = workspace ?? _hostContext.GetDirectory(WellKnownDirectory.Work);
+                }
+
+                _trace.Info("Executing REPL command");
+
+                // Stream execution info to debugger
+                SendOutput("console", $"$ {shellCommand} {command.Script.Substring(0, Math.Min(command.Script.Length, 80))}{(command.Script.Length > 80 ? "..." : "")}\n");
+
+                // 7. Execute via IProcessInvoker (same as DefaultStepHost)
+                int exitCode;
+                using (var processInvoker = _hostContext.CreateService<IProcessInvoker>())
+                {
+                    processInvoker.OutputDataReceived += (sender, args) =>
+                    {
+                        if (!string.IsNullOrEmpty(args.Data))
+                        {
+                            var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
+                            SendOutput("stdout", masked + "\n");
+                        }
+                    };
+
+                    processInvoker.ErrorDataReceived += (sender, args) =>
+                    {
+                        if (!string.IsNullOrEmpty(args.Data))
+                        {
+                            var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
+                            SendOutput("stderr", masked + "\n");
+                        }
+                    };
+
+                    exitCode = await processInvoker.ExecuteAsync(
+                        workingDirectory: workingDirectory,
+                        fileName: commandPath,
+                        arguments: arguments,
+                        environment: environment,
+                        requireExitCodeZero: false,
+                        outputEncoding: null,
+                        killProcessOnCancel: true,
+                        cancellationToken: cancellationToken);
+                }
+
+                _trace.Info($"REPL command exited with code {exitCode}");
+
+                // 8. Return only the exit code summary (output was already streamed)
+                return new EvaluateResponseBody
+                {
+                    Result = exitCode == 0 ? $"(exit code: {exitCode})" : $"Process completed with exit code {exitCode}.",
+                    Type = exitCode == 0 ? "string" : "error",
+                    VariablesReference = 0
+                };
+            }
+            finally
+            {
+                // Clean up temp script file
+                try { File.Delete(scriptFilePath); }
+                catch { /* best effort */ }
+            }
+        }
+
+        /// <summary>
+        /// Expands <c>${{ }}</c> expressions in the input string using the
+        /// runner's template evaluator — the same evaluation path that processes
+        /// step inputs before <see cref="ScriptHandler"/> runs them.
+        ///
+        /// Each <c>${{ expr }}</c> occurrence is individually evaluated and
+        /// replaced with its masked string result, mirroring the semantics of
+        /// expression interpolation in a workflow <c>run:</c> step body.
+        /// </summary>
+        internal string ExpandExpressions(string input, IExecutionContext context)
+        {
+            if (string.IsNullOrEmpty(input) || !input.Contains("${{"))
+            {
+                return input ?? string.Empty;
+            }
+
+            var result = new StringBuilder();
+            int pos = 0;
+
+            while (pos < input.Length)
+            {
+                var start = input.IndexOf("${{", pos, StringComparison.Ordinal);
+                if (start < 0)
+                {
+                    result.Append(input, pos, input.Length - pos);
+                    break;
+                }
+
+                // Append the literal text before the expression
+                result.Append(input, pos, start - pos);
+
+                var end = input.IndexOf("}}", start + 3, StringComparison.Ordinal);
+                if (end < 0)
+                {
+                    // Unterminated expression — keep literal
+                    result.Append(input, start, input.Length - start);
+                    break;
+                }
+
+                var expr = input.Substring(start + 3, end - start - 3).Trim();
+                end += 2; // skip past "}}"
+
+                // Evaluate the expression
+                try
+                {
+                    var templateEvaluator = context.ToPipelineTemplateEvaluator();
+                    var token = new GitHub.DistributedTask.ObjectTemplating.Tokens.BasicExpressionToken(
+                        null, null, null, expr);
+                    var evaluated = templateEvaluator.EvaluateStepDisplayName(
+                        token,
+                        context.ExpressionValues,
+                        context.ExpressionFunctions);
+                    result.Append(_hostContext.SecretMasker.MaskSecrets(evaluated ?? string.Empty));
+                }
+                catch (Exception ex)
+                {
+                    _trace.Warning($"Expression expansion failed ({ex.GetType().Name})");
+                    // Keep the original expression literal on failure
+                    result.Append(input, start, end - start);
+                }
+
+                pos = end;
+            }
+
+            return result.ToString();
+        }
+
+        /// <summary>
+        /// Resolves the default shell the same way <see cref="ScriptHandler"/>
+        /// does: check job defaults, then fall back to platform default.
+        /// </summary>
+        internal string ResolveDefaultShell(IExecutionContext context)
+        {
+            // Check job defaults
+            if (context.Global?.JobDefaults != null &&
+                context.Global.JobDefaults.TryGetValue("run", out var runDefaults) &&
+                runDefaults.TryGetValue("shell", out var defaultShell) &&
+                !string.IsNullOrEmpty(defaultShell))
+            {
+                _trace.Info("Using job default shell");
+                return defaultShell;
+            }
+
+#if OS_WINDOWS
+            string prependPath = string.Join(
+                Path.PathSeparator.ToString(),
+                context.Global?.PrependPath != null ? Enumerable.Reverse(context.Global.PrependPath) : Array.Empty<string>());
+            var pwshPath = WhichUtil.Which("pwsh", false, _trace, prependPath);
+            return !string.IsNullOrEmpty(pwshPath) ? "pwsh" : "powershell";
+#else
+            return "sh";
+#endif
+        }
+
+        /// <summary>
+        /// Merges the job context environment with any REPL-specific overrides.
+        /// </summary>
+        internal Dictionary<string, string> BuildEnvironment(
+            IExecutionContext context,
+            Dictionary<string, string> replEnv)
+        {
+            var env = new Dictionary<string, string>(VarUtil.EnvironmentVariableKeyComparer);
+
+            // Pull environment from the execution context (same as ActionRunner)
+            if (context.ExpressionValues.TryGetValue("env", out var envData))
+            {
+                if (envData is DictionaryContextData dictEnv)
+                {
+                    foreach (var pair in dictEnv)
+                    {
+                        if (pair.Value is StringContextData str)
+                        {
+                            env[pair.Key] = str.Value;
+                        }
+                    }
+                }
+                else if (envData is CaseSensitiveDictionaryContextData csEnv)
+                {
+                    foreach (var pair in csEnv)
+                    {
+                        if (pair.Value is StringContextData str)
+                        {
+                            env[pair.Key] = str.Value;
+                        }
+                    }
+                }
+            }
+
+            // Expose runtime context variables to the environment (GITHUB_*, RUNNER_*, etc.)
+            foreach (var ctxPair in context.ExpressionValues)
+            {
+                if (ctxPair.Value is IEnvironmentContextData runtimeContext && runtimeContext != null)
+                {
+                    foreach (var rtEnv in runtimeContext.GetRuntimeEnvironmentVariables())
+                    {
+                        env[rtEnv.Key] = rtEnv.Value;
+                    }
+                }
+            }
+
+            // Apply REPL-specific overrides last (so they win),
+            // expanding any ${{ }} expressions in the values
+            if (replEnv != null)
+            {
+                foreach (var pair in replEnv)
+                {
+                    env[pair.Key] = ExpandExpressions(pair.Value, context);
+                }
+            }
+
+            return env;
+        }
+
+        private void SendOutput(string category, string text)
+        {
+            _sendOutput(category, text);
+        }
+
+        private static EvaluateResponseBody ErrorResult(string message)
+        {
+            return new EvaluateResponseBody
+            {
+                Result = message,
+                Type = "error",
+                VariablesReference = 0
+            };
+        }
+    }
+}
@@ -0,0 +1,411 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Base type for all REPL DSL commands.
+    /// </summary>
+    internal abstract class DapReplCommand
+    {
+    }
+
+    /// <summary>
+    /// <c>help</c> or <c>help("run")</c>
+    /// </summary>
+    internal sealed class HelpCommand : DapReplCommand
+    {
+        public string Topic { get; set; }
+    }
+
+    /// <summary>
+    /// <c>run("echo hello")</c> or
+    /// <c>run("echo hello", shell: "bash", env: { FOO: "bar" }, working_directory: "/tmp")</c>
+    /// </summary>
+    internal sealed class RunCommand : DapReplCommand
+    {
+        public string Script { get; set; }
+        public string Shell { get; set; }
+        public Dictionary<string, string> Env { get; set; }
+        public string WorkingDirectory { get; set; }
+    }
+
+    /// <summary>
+    /// Parses REPL input into typed <see cref="DapReplCommand"/> objects.
+    ///
+    /// Grammar (intentionally minimal — extend as the DSL grows):
+    /// <code>
+    ///   help                                → HelpCommand { Topic = null }
+    ///   help("run")                         → HelpCommand { Topic = "run" }
+    ///   run("script body")                  → RunCommand  { Script = "script body" }
+    ///   run("script", shell: "bash")        → RunCommand  { Shell = "bash" }
+    ///   run("script", env: { K: "V" })      → RunCommand  { Env = { K → V } }
+    ///   run("script", working_directory: "p")→ RunCommand  { WorkingDirectory = "p" }
+    /// </code>
+    ///
+    /// Parsing is intentionally hand-rolled rather than regex-based so it can
+    /// handle nested braces, quoted strings with escapes, and grow to support
+    /// future commands without accumulating regex complexity.
+    /// </summary>
+    internal static class DapReplParser
+    {
+        /// <summary>
+        /// Attempts to parse REPL input into a command. Returns null if the
+        /// input does not match any known DSL command (i.e. it should be
+        /// treated as an expression instead).
+        /// </summary>
+        internal static DapReplCommand TryParse(string input, out string error)
+        {
+            error = null;
+            if (string.IsNullOrWhiteSpace(input))
+            {
+                return null;
+            }
+
+            var trimmed = input.Trim();
+
+            // help / help("topic")
+            if (trimmed.Equals("help", StringComparison.OrdinalIgnoreCase) ||
+                trimmed.StartsWith("help(", StringComparison.OrdinalIgnoreCase))
+            {
+                return ParseHelp(trimmed, out error);
+            }
+
+            // run("...")
+            if (trimmed.StartsWith("run(", StringComparison.OrdinalIgnoreCase))
+            {
+                return ParseRun(trimmed, out error);
+            }
+
+            // Not a DSL command
+            return null;
+        }
+
+        internal static string GetGeneralHelp()
+        {
+            return """
+                Actions Debug Console
+
+                Commands:
+                  help                  Show this help
+                  help("run")           Show help for the run command
+                  run("script")         Execute a script (like a workflow run step)
+
+                Anything else is evaluated as a GitHub Actions expression.
+                  Example: github.repository
+                  Example: ${{ github.event_name }}
+
+                """;
+        }
+
+        internal static string GetRunHelp()
+        {
+            return """
+                run command — execute a script in the job context
+
+                Usage:
+                  run("echo hello")
+                  run("echo $FOO", shell: "bash")
+                  run("echo $FOO", env: { FOO: "bar" })
+                  run("ls", working_directory: "/tmp")
+                  run("echo $X", shell: "bash", env: { X: "1" }, working_directory: "/tmp")
+
+                Options:
+                  shell:             Shell to use (default: job default, e.g. bash)
+                  env:               Extra environment variables as { KEY: "value" }
+                  working_directory:  Working directory for the command
+
+                Behavior:
+                  - Equivalent to a workflow `run:` step
+                  - Expressions in the script body are expanded (${{ ... }})
+                  - Output is streamed in real time and secrets are masked
+
+                """;
+        }
+
+        #region Parsers
+
+        private static HelpCommand ParseHelp(string input, out string error)
+        {
+            error = null;
+            if (input.Equals("help", StringComparison.OrdinalIgnoreCase))
+            {
+                return new HelpCommand();
+            }
+
+            // help("topic")
+            var inner = ExtractParenthesizedArgs(input, "help", out error);
+            if (error != null) return null;
+
+            var topic = ExtractQuotedString(inner.Trim(), out error);
+            if (error != null) return null;
+
+            return new HelpCommand { Topic = topic };
+        }
+
+        private static RunCommand ParseRun(string input, out string error)
+        {
+            error = null;
+
+            var inner = ExtractParenthesizedArgs(input, "run", out error);
+            if (error != null) return null;
+
+            // Split into argument list respecting quotes and braces
+            var args = SplitArguments(inner, out error);
+            if (error != null) return null;
+            if (args.Count == 0)
+            {
+                error = "run() requires a script argument. Example: run(\"echo hello\")";
+                return null;
+            }
+
+            // First arg must be the script body (a quoted string)
+            var script = ExtractQuotedString(args[0].Trim(), out error);
+            if (error != null)
+            {
+                error = $"First argument to run() must be a quoted string. {error}";
+                return null;
+            }
+
+            var cmd = new RunCommand { Script = script };
+
+            // Parse remaining keyword arguments
+            for (int i = 1; i < args.Count; i++)
+            {
+                var kv = args[i].Trim();
+                var colonIdx = kv.IndexOf(':');
+                if (colonIdx <= 0)
+                {
+                    error = $"Expected keyword argument (e.g. shell: \"bash\"), got: {kv}";
+                    return null;
+                }
+
+                var key = kv.Substring(0, colonIdx).Trim();
+                var value = kv.Substring(colonIdx + 1).Trim();
+
+                switch (key.ToLowerInvariant())
+                {
+                    case "shell":
+                        cmd.Shell = ExtractQuotedString(value, out error);
+                        if (error != null) { error = $"shell: {error}"; return null; }
+                        break;
+
+                    case "working_directory":
+                        cmd.WorkingDirectory = ExtractQuotedString(value, out error);
+                        if (error != null) { error = $"working_directory: {error}"; return null; }
+                        break;
+
+                    case "env":
+                        cmd.Env = ParseEnvBlock(value, out error);
+                        if (error != null) { error = $"env: {error}"; return null; }
+                        break;
+
+                    default:
+                        error = $"Unknown option: {key}. Valid options: shell, env, working_directory";
+                        return null;
+                }
+            }
+
+            return cmd;
+        }
+
+        #endregion
+
+        #region Low-level parsing helpers
+
+        /// <summary>
+        /// Given "cmd(...)" returns the inner content between the outer parens.
+        /// </summary>
+        private static string ExtractParenthesizedArgs(string input, string prefix, out string error)
+        {
+            error = null;
+            var start = prefix.Length; // skip "cmd"
+            if (start >= input.Length || input[start] != '(')
+            {
+                error = $"Expected '(' after {prefix}";
+                return null;
+            }
+
+            if (input[input.Length - 1] != ')')
+            {
+                error = $"Expected ')' at end of {prefix}(...)";
+                return null;
+            }
+
+            return input.Substring(start + 1, input.Length - start - 2);
+        }
+
+        /// <summary>
+        /// Extracts a double-quoted string value, handling escaped quotes.
+        /// </summary>
+        internal static string ExtractQuotedString(string input, out string error)
+        {
+            error = null;
+            if (string.IsNullOrEmpty(input))
+            {
+                error = "Expected a quoted string, got empty input";
+                return null;
+            }
+
+            if (input[0] != '"')
+            {
+                error = $"Expected a quoted string starting with \", got: {Truncate(input, 40)}";
+                return null;
+            }
+
+            var sb = new StringBuilder();
+            for (int i = 1; i < input.Length; i++)
+            {
+                if (input[i] == '\\' && i + 1 < input.Length)
+                {
+                    sb.Append(input[i + 1]);
+                    i++;
+                }
+                else if (input[i] == '"')
+                {
+                    // Check nothing meaningful follows the closing quote
+                    var rest = input.Substring(i + 1).Trim();
+                    if (rest.Length > 0)
+                    {
+                        error = $"Unexpected content after closing quote: {Truncate(rest, 40)}";
+                        return null;
+                    }
+                    return sb.ToString();
+                }
+                else
+                {
+                    sb.Append(input[i]);
+                }
+            }
+
+            error = "Unterminated string (missing closing \")";
+            return null;
+        }
+
+        /// <summary>
+        /// Splits a comma-separated argument list, respecting quoted strings
+        /// and nested braces so that <c>"a, b", env: { K: "V, W" }</c> is
+        /// correctly split into two arguments.
+        /// </summary>
+        internal static List<string> SplitArguments(string input, out string error)
+        {
+            error = null;
+            var result = new List<string>();
+            var current = new StringBuilder();
+            int depth = 0;
+            bool inQuote = false;
+
+            for (int i = 0; i < input.Length; i++)
+            {
+                var ch = input[i];
+
+                if (ch == '\\' && inQuote && i + 1 < input.Length)
+                {
+                    current.Append(ch);
+                    current.Append(input[++i]);
+                    continue;
+                }
+
+                if (ch == '"')
+                {
+                    inQuote = !inQuote;
+                    current.Append(ch);
+                    continue;
+                }
+
+                if (!inQuote)
+                {
+                    if (ch == '{')
+                    {
+                        depth++;
+                        current.Append(ch);
+                        continue;
+                    }
+                    if (ch == '}')
+                    {
+                        depth--;
+                        current.Append(ch);
+                        continue;
+                    }
+                    if (ch == ',' && depth == 0)
+                    {
+                        result.Add(current.ToString());
+                        current.Clear();
+                        continue;
+                    }
+                }
+
+                current.Append(ch);
+            }
+
+            if (inQuote)
+            {
+                error = "Unterminated string in arguments";
+                return null;
+            }
+            if (depth != 0)
+            {
+                error = "Unmatched braces in arguments";
+                return null;
+            }
+
+            if (current.Length > 0)
+            {
+                result.Add(current.ToString());
+            }
+
+            return result;
+        }
+
+        /// <summary>
+        /// Parses <c>{ KEY: "value", KEY2: "value2" }</c> into a dictionary.
+        /// </summary>
+        internal static Dictionary<string, string> ParseEnvBlock(string input, out string error)
+        {
+            error = null;
+            var trimmed = input.Trim();
+            if (!trimmed.StartsWith("{") || !trimmed.EndsWith("}"))
+            {
+                error = "Expected env block in the form { KEY: \"value\" }";
+                return null;
+            }
+
+            var inner = trimmed.Substring(1, trimmed.Length - 2).Trim();
+            if (string.IsNullOrEmpty(inner))
+            {
+                return new Dictionary<string, string>();
+            }
+
+            var pairs = SplitArguments(inner, out error);
+            if (error != null) return null;
+
+            var result = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            foreach (var pair in pairs)
+            {
+                var colonIdx = pair.IndexOf(':');
+                if (colonIdx <= 0)
+                {
+                    error = $"Expected KEY: \"value\" pair, got: {Truncate(pair.Trim(), 40)}";
+                    return null;
+                }
+
+                var key = pair.Substring(0, colonIdx).Trim();
+                var val = ExtractQuotedString(pair.Substring(colonIdx + 1).Trim(), out error);
+                if (error != null) return null;
+
+                result[key] = val;
+            }
+
+            return result;
+        }
+
+        private static string Truncate(string value, int maxLength)
+        {
+            if (value == null) return "(null)";
+            return value.Length <= maxLength ? value : value.Substring(0, maxLength) + "...";
+        }
+
+        #endregion
+    }
+}
@@ -0,0 +1,373 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using GitHub.DistributedTask.Logging;
+using GitHub.DistributedTask.ObjectTemplating.Tokens;
+using GitHub.DistributedTask.Pipelines.ContextData;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Maps runner execution context data to DAP scopes and variables.
+    ///
+    /// This is the single point where runner context values are materialized
+    /// for the debugger. All values pass through the runner's existing
+    /// <see cref="GitHub.DistributedTask.Logging.ISecretMasker"/> so the DAP
+    /// surface never exposes anything beyond what a normal CI log would show.
+    ///
+    /// The secrets scope is intentionally opaque: keys are visible but every
+    /// value is replaced with a constant redaction marker.
+    ///
+    /// Designed to be reusable by future DAP features (evaluate, hover, REPL)
+    /// so that masking policy is never duplicated.
+    /// </summary>
+    internal sealed class DapVariableProvider
+    {
+        // Well-known scope names that map to top-level expression contexts.
+        // Order matters: the index determines the stable variablesReference ID.
+        private static readonly string[] _scopeNames =
+        {
+            "github", "env", "runner", "job", "steps",
+            "secrets", "inputs", "vars", "matrix", "needs"
+        };
+
+        // Scope references occupy the range [1, ScopeReferenceMax].
+        private const int _scopeReferenceBase = 1;
+        private const int _scopeReferenceMax = 100;
+
+        // Dynamic (nested) variable references start above the scope range.
+        private const int _dynamicReferenceBase = 101;
+
+        private const string _redactedValue = "***";
+
+        private readonly ISecretMasker _secretMasker;
+
+        // Maps dynamic variable reference IDs to the backing data and its
+        // dot-separated path (e.g. "github.event.pull_request").
+        private readonly Dictionary<int, (PipelineContextData Data, string Path)> _variableReferences = new();
+        private int _nextVariableReference = _dynamicReferenceBase;
+
+        public DapVariableProvider(ISecretMasker secretMasker)
+        {
+            _secretMasker = secretMasker ?? throw new ArgumentNullException(nameof(secretMasker));
+        }
+
+        /// <summary>
+        /// Clears all dynamic variable references.
+        /// Call this whenever the paused execution context changes (e.g. new step)
+        /// so that stale nested references are not served to the client.
+        /// </summary>
+        public void Reset()
+        {
+            _variableReferences.Clear();
+            _nextVariableReference = _dynamicReferenceBase;
+        }
+
+        /// <summary>
+        /// Returns the list of DAP scopes for the given execution context.
+        /// Each scope corresponds to a well-known runner expression context
+        /// (github, env, secrets, …) and carries a stable variablesReference
+        /// that the client can use to drill into variables.
+        /// </summary>
+        public List<Scope> GetScopes(IExecutionContext context)
+        {
+            var scopes = new List<Scope>();
+
+            if (context?.ExpressionValues == null)
+            {
+                return scopes;
+            }
+
+            for (int i = 0; i < _scopeNames.Length; i++)
+            {
+                var scopeName = _scopeNames[i];
+                if (!context.ExpressionValues.TryGetValue(scopeName, out var value) || value == null)
+                {
+                    continue;
+                }
+
+                var scope = new Scope
+                {
+                    Name = scopeName,
+                    VariablesReference = _scopeReferenceBase + i,
+                    Expensive = false,
+                    PresentationHint = scopeName == "secrets" ? "registers" : null
+                };
+
+                if (value is DictionaryContextData dict)
+                {
+                    scope.NamedVariables = dict.Count;
+                }
+                else if (value is CaseSensitiveDictionaryContextData csDict)
+                {
+                    scope.NamedVariables = csDict.Count;
+                }
+
+                scopes.Add(scope);
+            }
+
+            return scopes;
+        }
+
+        /// <summary>
+        /// Returns the child variables for a given variablesReference.
+        /// The reference may point at a top-level scope (1–100) or a
+        /// dynamically registered nested container (101+).
+        /// </summary>
+        public List<Variable> GetVariables(IExecutionContext context, int variablesReference)
+        {
+            var variables = new List<Variable>();
+
+            if (context?.ExpressionValues == null)
+            {
+                return variables;
+            }
+
+            PipelineContextData data = null;
+            string basePath = null;
+            bool isSecretsScope = false;
+
+            if (variablesReference >= _scopeReferenceBase && variablesReference <= _scopeReferenceMax)
+            {
+                var scopeIndex = variablesReference - _scopeReferenceBase;
+                if (scopeIndex < _scopeNames.Length)
+                {
+                    var scopeName = _scopeNames[scopeIndex];
+                    isSecretsScope = scopeName == "secrets";
+                    if (context.ExpressionValues.TryGetValue(scopeName, out data))
+                    {
+                        basePath = scopeName;
+                    }
+                }
+            }
+            else if (_variableReferences.TryGetValue(variablesReference, out var refData))
+            {
+                data = refData.Data;
+                basePath = refData.Path;
+                isSecretsScope = basePath?.StartsWith("secrets", StringComparison.OrdinalIgnoreCase) == true;
+            }
+
+            if (data == null)
+            {
+                return variables;
+            }
+
+            ConvertToVariables(data, basePath, isSecretsScope, variables);
+            return variables;
+        }
+
+        /// <summary>
+        /// Evaluates a GitHub Actions expression (e.g. "github.repository",
+        /// "${{ github.event_name }}") in the context of the current step and
+        /// returns a masked result suitable for the DAP evaluate response.
+        ///
+        /// Uses the runner's standard <see cref="GitHub.DistributedTask.Pipelines.ObjectTemplating.IPipelineTemplateEvaluator"/>
+        /// so the full expression language is available (functions, operators,
+        /// context access).
+        /// </summary>
+        public EvaluateResponseBody EvaluateExpression(string expression, IExecutionContext context)
+        {
+            if (context?.ExpressionValues == null)
+            {
+                return new EvaluateResponseBody
+                {
+                    Result = "(no execution context available)",
+                    Type = "string",
+                    VariablesReference = 0
+                };
+            }
+
+            // Strip ${{ }} wrapper if present
+            var expr = expression?.Trim() ?? string.Empty;
+            if (expr.StartsWith("${{") && expr.EndsWith("}}"))
+            {
+                expr = expr.Substring(3, expr.Length - 5).Trim();
+            }
+
+            if (string.IsNullOrEmpty(expr))
+            {
+                return new EvaluateResponseBody
+                {
+                    Result = string.Empty,
+                    Type = "string",
+                    VariablesReference = 0
+                };
+            }
+
+            try
+            {
+                var templateEvaluator = context.ToPipelineTemplateEvaluator();
+                var token = new BasicExpressionToken(null, null, null, expr);
+
+                var result = templateEvaluator.EvaluateStepDisplayName(
+                    token,
+                    context.ExpressionValues,
+                    context.ExpressionFunctions);
+
+                result = _secretMasker.MaskSecrets(result ?? "null");
+
+                return new EvaluateResponseBody
+                {
+                    Result = result,
+                    Type = InferResultType(result),
+                    VariablesReference = 0
+                };
+            }
+            catch (Exception ex)
+            {
+                var errorMessage = _secretMasker.MaskSecrets($"Evaluation error: {ex.Message}");
+                return new EvaluateResponseBody
+                {
+                    Result = errorMessage,
+                    Type = "string",
+                    VariablesReference = 0
+                };
+            }
+        }
+
+        /// <summary>
+        /// Infers a simple DAP type hint from the string representation of a result.
+        /// </summary>
+        internal static string InferResultType(string value)
+        {
+            value = value?.ToLower();
+            if (value == null || value == "null")
+                return "null";
+            if (value == "true" || value == "false")
+                return "boolean";
+            if (double.TryParse(value, NumberStyles.Any,
+                    CultureInfo.InvariantCulture, out _))
+                return "number";
+            if (value.StartsWith("{") || value.StartsWith("["))
+                return "object";
+            return "string";
+        }
+
+        #region Private helpers
+
+        private void ConvertToVariables(
+            PipelineContextData data,
+            string basePath,
+            bool isSecretsScope,
+            List<Variable> variables)
+        {
+            switch (data)
+            {
+                case DictionaryContextData dict:
+                    foreach (var pair in dict)
+                    {
+                        variables.Add(CreateVariable(pair.Key, pair.Value, basePath, isSecretsScope));
+                    }
+                    break;
+
+                case CaseSensitiveDictionaryContextData csDict:
+                    foreach (var pair in csDict)
+                    {
+                        variables.Add(CreateVariable(pair.Key, pair.Value, basePath, isSecretsScope));
+                    }
+                    break;
+
+                case ArrayContextData array:
+                    for (int i = 0; i < array.Count; i++)
+                    {
+                        var variable = CreateVariable($"[{i}]", array[i], basePath, isSecretsScope);
+                        variables.Add(variable);
+                    }
+                    break;
+            }
+        }
+
+        private Variable CreateVariable(
+            string name,
+            PipelineContextData value,
+            string basePath,
+            bool isSecretsScope)
+        {
+            var childPath = string.IsNullOrEmpty(basePath) ? name : $"{basePath}.{name}";
+            var variable = new Variable
+            {
+                Name = name,
+                EvaluateName = $"${{{{ {childPath} }}}}"
+            };
+
+            // Secrets scope: redact ALL values regardless of underlying type.
+            // Keys are visible but values are always replaced with the
+            // redaction marker, and nested containers are not drillable.
+            if (isSecretsScope)
+            {
+                variable.Value = _redactedValue;
+                variable.Type = "string";
+                variable.VariablesReference = 0;
+                return variable;
+            }
+
+            if (value == null)
+            {
+                variable.Value = "null";
+                variable.Type = "null";
+                variable.VariablesReference = 0;
+                return variable;
+            }
+
+            switch (value)
+            {
+                case StringContextData str:
+                    variable.Value = _secretMasker.MaskSecrets(str.Value);
+                    variable.Type = "string";
+                    variable.VariablesReference = 0;
+                    break;
+
+                case NumberContextData num:
+                    variable.Value = _secretMasker.MaskSecrets(num.Value.ToString("G15", CultureInfo.InvariantCulture));
+                    variable.Type = "number";
+                    variable.VariablesReference = 0;
+                    break;
+
+                case BooleanContextData boolVal:
+                    variable.Value = boolVal.Value ? "true" : "false";
+                    variable.Type = "boolean";
+                    variable.VariablesReference = 0;
+                    break;
+
+                case DictionaryContextData dict:
+                    variable.Value = $"Object ({dict.Count} properties)";
+                    variable.Type = "object";
+                    variable.VariablesReference = RegisterVariableReference(dict, childPath);
+                    variable.NamedVariables = dict.Count;
+                    break;
+
+                case CaseSensitiveDictionaryContextData csDict:
+                    variable.Value = $"Object ({csDict.Count} properties)";
+                    variable.Type = "object";
+                    variable.VariablesReference = RegisterVariableReference(csDict, childPath);
+                    variable.NamedVariables = csDict.Count;
+                    break;
+
+                case ArrayContextData array:
+                    variable.Value = $"Array ({array.Count} items)";
+                    variable.Type = "array";
+                    variable.VariablesReference = RegisterVariableReference(array, childPath);
+                    variable.IndexedVariables = array.Count;
+                    break;
+
+                default:
+                    var rawValue = value.ToJToken()?.ToString() ?? "unknown";
+                    variable.Value = _secretMasker.MaskSecrets(rawValue);
+                    variable.Type = value.GetType().Name;
+                    variable.VariablesReference = 0;
+                    break;
+            }
+
+            return variable;
+        }
+
+        private int RegisterVariableReference(PipelineContextData data, string path)
+        {
+            var reference = _nextVariableReference++;
+            _variableReferences[reference] = (data, path);
+            return reference;
+        }
+
+        #endregion
+    }
+}
@@ -0,0 +1,33 @@
+using GitHub.DistributedTask.Pipelines;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Consolidated runtime configuration for the job debugger.
+    /// Populated once from the acquire response and owned by <see cref="GlobalContext"/>.
+    /// </summary>
+    public sealed class DebuggerConfig
+    {
+        public DebuggerConfig(bool enabled, DebuggerTunnelInfo tunnel)
+        {
+            Enabled = enabled;
+            Tunnel = tunnel;
+        }
+
+        /// <summary>Whether the debugger is enabled for this job.</summary>
+        public bool Enabled { get; }
+
+        /// <summary>
+        /// Dev Tunnel details for remote debugging.
+        /// Required when <see cref="Enabled"/> is true.
+        /// </summary>
+        public DebuggerTunnelInfo Tunnel { get; }
+
+        /// <summary>Whether the tunnel configuration is complete and valid.</summary>
+        public bool HasValidTunnel => Tunnel != null
+            && !string.IsNullOrEmpty(Tunnel.TunnelId)
+            && !string.IsNullOrEmpty(Tunnel.ClusterId)
+            && !string.IsNullOrEmpty(Tunnel.HostToken)
+            && Tunnel.Port >= 1024 && Tunnel.Port <= 65535;
+    }
+}
@@ -0,0 +1,26 @@
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    public enum DapSessionState
+    {
+        NotStarted,
+        WaitingForConnection,
+        Initializing,
+        Ready,
+        Paused,
+        Running,
+        Terminated
+    }
+
+    [ServiceLocator(Default = typeof(DapDebugger))]
+    public interface IDapDebugger : IRunnerService
+    {
+        Task StartAsync(IExecutionContext jobContext);
+        Task WaitUntilReadyAsync();
+        Task OnStepStartingAsync(IStep step);
+        void OnStepCompleted(IStep step);
+        Task OnJobCompletedAsync();
+    }
+}
@@ -0,0 +1,12 @@
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    [ServiceLocator(Default = typeof(WebSocketDapBridge))]
+    public interface IWebSocketDapBridge : IRunnerService
+    {
+        void Start(int listenPort, int targetPort);
+        Task ShutdownAsync();
+    }
+}
@@ -0,0 +1,839 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Net.Sockets;
+using System.Net.WebSockets;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    internal sealed class WebSocketDapBridge : RunnerService, IWebSocketDapBridge
+    {
+        internal enum IncomingStreamPrefixKind
+        {
+            Unknown,
+            HttpWebSocketUpgrade,
+            PreUpgradedWebSocket,
+            WebSocketReservedBits,
+            Http2Preface,
+            TlsClientHello,
+        }
+
+        private const int _bufferSize = 32 * 1024;
+        private const int _maxHeaderLineLength = 8 * 1024;
+        private const int _defaultMaxInboundMessageSize = 10 * 1024 * 1024; // 10 MB
+        private static readonly TimeSpan _keepAliveInterval = TimeSpan.FromSeconds(30);
+        private static readonly TimeSpan _closeTimeout = TimeSpan.FromSeconds(5);
+        private static readonly TimeSpan _handshakeTimeout = TimeSpan.FromSeconds(10);
+        private const string _webSocketAcceptMagic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
+        private const int _maxHeaderCount = 64;
+        private static readonly byte[] _headerEndMarker = new byte[] { (byte)'\r', (byte)'\n', (byte)'\r', (byte)'\n' };
+
+        private int _listenPort;
+        private int _targetPort;
+
+        private TcpListener _listener;
+        private CancellationTokenSource _loopCts;
+        private Task _acceptLoopTask;
+
+        public int MaxInboundMessageSize { get; set; } = _defaultMaxInboundMessageSize;
+
+        internal int ListenPort => (_listener?.LocalEndpoint as IPEndPoint)?.Port ?? 0;
+
+        public void Start(int listenPort, int targetPort)
+        {
+            if (_listener != null)
+            {
+                throw new InvalidOperationException("WebSocket DAP bridge already started.");
+            }
+
+            _listenPort = listenPort;
+            _targetPort = targetPort;
+
+            _listener = new TcpListener(IPAddress.Loopback, _listenPort);
+            _listener.Start();
+            _loopCts = new CancellationTokenSource();
+            _acceptLoopTask = AcceptLoopAsync(_loopCts.Token);
+
+            Trace.Info($"WebSocket DAP bridge listening on {_listener.LocalEndpoint} -> 127.0.0.1:{_targetPort}");
+        }
+
+        public async Task ShutdownAsync()
+        {
+            _loopCts?.Cancel();
+
+            try
+            {
+                _listener?.Stop();
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning($"Error stopping listener during shutdown ({ex.GetType().Name})");
+            }
+
+            if (_acceptLoopTask != null)
+            {
+                try
+                {
+                    await _acceptLoopTask;
+                }
+                catch (OperationCanceledException)
+                {
+                    // expected on shutdown
+                }
+            }
+
+            _loopCts?.Dispose();
+            _loopCts = null;
+            _listener = null;
+            _acceptLoopTask = null;
+        }
+
+        private async Task AcceptLoopAsync(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                TcpClient client = null;
+                try
+                {
+                    client = await _listener.AcceptTcpClientAsync(cancellationToken);
+                    client.NoDelay = true;
+                    await HandleClientAsync(client, cancellationToken);
+                }
+                catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+                {
+                    break;
+                }
+                catch (Exception ex)
+                {
+                    client?.Dispose();
+                    Trace.Error($"WebSocket DAP bridge connection error");
+                    Trace.Error(ex);
+                }
+                finally
+                {
+                    client?.Dispose();
+                }
+            }
+
+            Trace.Info("WebSocket DAP bridge accept loop ended");
+        }
+
+        private async Task HandleClientAsync(TcpClient incomingClient, CancellationToken cancellationToken)
+        {
+            using (var incomingStream = incomingClient.GetStream())
+            {
+                Trace.Info($"WebSocket DAP bridge accepted client {incomingClient.Client.RemoteEndPoint}");
+
+                WebSocket webSocket;
+                using (var handshakeCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
+                {
+                    handshakeCts.CancelAfter(_handshakeTimeout);
+                    try
+                    {
+                        webSocket = await AcceptWebSocketAsync(incomingStream, handshakeCts.Token);
+                    }
+                    catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
+                    {
+                        Trace.Warning("WebSocket handshake timed out");
+                        return;
+                    }
+                }
+                if (webSocket == null)
+                {
+                    return;
+                }
+
+                using (webSocket)
+                using (var dapClient = new TcpClient())
+                {
+                    dapClient.NoDelay = true;
+                    await dapClient.ConnectAsync(IPAddress.Loopback, _targetPort, cancellationToken);
+
+                    using (var dapStream = dapClient.GetStream())
+                    using (var sessionCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
+                    {
+                        var proxyToken = sessionCts.Token;
+                        var wsToTcpTask = PumpWebSocketToTcpAsync(webSocket, dapStream, proxyToken);
+                        var tcpToWsTask = PumpTcpToWebSocketAsync(dapStream, webSocket, proxyToken);
+
+                        await Task.WhenAny(wsToTcpTask, tcpToWsTask);
+                        sessionCts.Cancel();
+
+                        await CloseWebSocketAsync(webSocket);
+
+                        try
+                        {
+                            await Task.WhenAll(wsToTcpTask, tcpToWsTask);
+                        }
+                        catch (OperationCanceledException) when (proxyToken.IsCancellationRequested)
+                        {
+                            // expected during shutdown
+                        }
+                        catch (Exception ex)
+                        {
+                            Trace.Warning($"DAP protocol error: {ex}");
+                        }
+                    }
+                }
+            }
+        }
+
+        private async Task<WebSocket> AcceptWebSocketAsync(NetworkStream stream, CancellationToken cancellationToken)
+        {
+            var initialBytes = await ReadInitialBytesAsync(stream, cancellationToken);
+            if (initialBytes == null || initialBytes.Length == 0)
+            {
+                return null;
+            }
+
+            var prefixKind = ClassifyIncomingStreamPrefix(initialBytes);
+            if (prefixKind == IncomingStreamPrefixKind.PreUpgradedWebSocket)
+            {
+                Trace.Info($"Treating incoming tunnel stream as an already-upgraded websocket connection ({DescribeInitialBytes(initialBytes)})");
+                return WebSocket.CreateFromStream(
+                    new ReplayableStream(stream, initialBytes),
+                    isServer: true,
+                    subProtocol: null,
+                    keepAliveInterval: _keepAliveInterval);
+            }
+
+            if (prefixKind != IncomingStreamPrefixKind.HttpWebSocketUpgrade)
+            {
+                Trace.Warning($"Unsupported debugger tunnel stream prefix ({prefixKind}): {DescribeInitialBytes(initialBytes)}");
+                return null;
+            }
+
+            var handshakeStream = new ReplayableStream(stream, initialBytes);
+            var requestLine = await ReadLineAsync(handshakeStream, cancellationToken);
+            if (string.IsNullOrEmpty(requestLine))
+            {
+                return null;
+            }
+
+            var headers = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                if (headers.Count >= _maxHeaderCount)
+                {
+                    Trace.Warning($"Rejected WebSocket request with too many headers (>{_maxHeaderCount})");
+                    await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Too many headers.", cancellationToken);
+                    return null;
+                }
+
+                var line = await ReadLineAsync(handshakeStream, cancellationToken);
+                if (line == null)
+                {
+                    return null;
+                }
+
+                if (line.Length == 0)
+                {
+                    break;
+                }
+
+                var separatorIndex = line.IndexOf(':');
+                if (separatorIndex <= 0)
+                {
+                    await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Invalid HTTP header.", cancellationToken);
+                    return null;
+                }
+
+                var headerName = line.Substring(0, separatorIndex).Trim();
+                var headerValue = line.Substring(separatorIndex + 1).Trim();
+
+                if (headers.TryGetValue(headerName, out var existingValue))
+                {
+                    headers[headerName] = $"{existingValue}, {headerValue}";
+                }
+                else
+                {
+                    headers[headerName] = headerValue;
+                }
+            }
+
+            if (!IsValidWebSocketRequest(requestLine, headers))
+            {
+                var method = requestLine.Split(' ')[0];
+                Trace.Info($"Rejected non-websocket request (method={method})");
+                await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Expected a websocket upgrade request.", cancellationToken);
+                return null;
+            }
+
+            if (!headers.TryGetValue("Sec-WebSocket-Version", out var webSocketVersion) ||
+                !string.Equals(webSocketVersion.Trim(), "13", StringComparison.Ordinal))
+            {
+                Trace.Warning("Rejected WebSocket request with unsupported version");
+                await WriteHttpErrorAsync(stream, (HttpStatusCode)426, "Unsupported WebSocket version. Expected: 13.", cancellationToken);
+                return null;
+            }
+
+            var webSocketKey = headers["Sec-WebSocket-Key"];
+            if (!IsValidWebSocketKey(webSocketKey))
+            {
+                Trace.Warning("Rejected WebSocket request with invalid Sec-WebSocket-Key");
+                await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Invalid Sec-WebSocket-Key.", cancellationToken);
+                return null;
+            }
+
+            var acceptValue = ComputeAcceptValue(webSocketKey);
+            var responseBytes = Encoding.ASCII.GetBytes(
+                "HTTP/1.1 101 Switching Protocols\r\n" +
+                "Connection: Upgrade\r\n" +
+                "Upgrade: websocket\r\n" +
+                $"Sec-WebSocket-Accept: {acceptValue}\r\n" +
+                "\r\n");
+
+            await handshakeStream.WriteAsync(responseBytes, 0, responseBytes.Length, cancellationToken);
+            await handshakeStream.FlushAsync(cancellationToken);
+
+            Trace.Info("WebSocket DAP bridge completed websocket handshake");
+            return WebSocket.CreateFromStream(handshakeStream, isServer: true, subProtocol: null, keepAliveInterval: _keepAliveInterval);
+        }
+
+        private async Task PumpWebSocketToTcpAsync(WebSocket source, NetworkStream destination, CancellationToken cancellationToken)
+        {
+            var buffer = new byte[_bufferSize];
+
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                using (var messageStream = new MemoryStream())
+                {
+                    WebSocketReceiveResult result;
+                    do
+                    {
+                        result = await source.ReceiveAsync(new ArraySegment<byte>(buffer), cancellationToken);
+                        if (result.MessageType == WebSocketMessageType.Close)
+                        {
+                            return;
+                        }
+
+                        if (result.MessageType != WebSocketMessageType.Binary &&
+                            result.MessageType != WebSocketMessageType.Text)
+                        {
+                            break;
+                        }
+
+                        if (result.Count > 0)
+                        {
+                            if (messageStream.Length + result.Count > MaxInboundMessageSize)
+                            {
+                                Trace.Warning($"WebSocket message exceeds maximum allowed size of {MaxInboundMessageSize} bytes, closing connection");
+                                await source.CloseAsync(
+                                    WebSocketCloseStatus.MessageTooBig,
+                                    $"Message exceeds {MaxInboundMessageSize} byte limit",
+                                    CancellationToken.None);
+                                return;
+                            }
+
+                            messageStream.Write(buffer, 0, result.Count);
+                        }
+                    }
+                    while (!result.EndOfMessage && !cancellationToken.IsCancellationRequested);
+
+                    if (result.MessageType != WebSocketMessageType.Binary &&
+                        result.MessageType != WebSocketMessageType.Text)
+                    {
+                        continue;
+                    }
+
+                    var messageBytes = messageStream.ToArray();
+                    if (messageBytes.Length == 0)
+                    {
+                        continue;
+                    }
+
+                    var contentLengthHeader = Encoding.ASCII.GetBytes($"Content-Length: {messageBytes.Length}\r\n\r\n");
+                    await destination.WriteAsync(contentLengthHeader, 0, contentLengthHeader.Length, cancellationToken);
+                    await destination.WriteAsync(messageBytes, 0, messageBytes.Length, cancellationToken);
+                    await destination.FlushAsync(cancellationToken);
+                }
+            }
+        }
+
+        private static async Task PumpTcpToWebSocketAsync(NetworkStream source, WebSocket destination, CancellationToken cancellationToken)
+        {
+            var readBuffer = new byte[_bufferSize];
+            var dapBuffer = new List<byte>();
+
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                var bytesRead = await source.ReadAsync(readBuffer, 0, readBuffer.Length, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    break;
+                }
+
+                dapBuffer.AddRange(new ArraySegment<byte>(readBuffer, 0, bytesRead));
+
+                while (TryParseDapMessage(dapBuffer, out var messageBody))
+                {
+                    await destination.SendAsync(
+                        new ArraySegment<byte>(messageBody),
+                        WebSocketMessageType.Text,
+                        endOfMessage: true,
+                        cancellationToken);
+                }
+            }
+        }
+
+        private static bool TryParseDapMessage(List<byte> buffer, out byte[] messageBody)
+        {
+            messageBody = null;
+
+            var headerEndIndex = FindSequence(buffer, _headerEndMarker);
+            if (headerEndIndex == -1)
+            {
+                return false;
+            }
+
+            var headerBytes = buffer.GetRange(0, headerEndIndex).ToArray();
+            var headerText = Encoding.ASCII.GetString(headerBytes);
+
+            var contentLength = -1;
+            foreach (var line in headerText.Split(new[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries))
+            {
+                if (line.StartsWith("Content-Length:", StringComparison.OrdinalIgnoreCase))
+                {
+                    var valueStart = line.IndexOf(':') + 1;
+                    if (int.TryParse(line.Substring(valueStart).Trim(), out var parsedLength))
+                    {
+                        contentLength = parsedLength;
+                        break;
+                    }
+                }
+            }
+
+            if (contentLength < 0)
+            {
+                throw new InvalidOperationException("DAP message missing or unparseable Content-Length header; tearing down session.");
+            }
+
+            var messageStart = headerEndIndex + 4;
+            var messageEnd = messageStart + contentLength;
+
+            if (buffer.Count < messageEnd)
+            {
+                return false;
+            }
+
+            messageBody = buffer.GetRange(messageStart, contentLength).ToArray();
+            buffer.RemoveRange(0, messageEnd);
+            return true;
+        }
+
+        private static int FindSequence(List<byte> buffer, byte[] sequence)
+        {
+            if (buffer.Count < sequence.Length)
+            {
+                return -1;
+            }
+
+            for (int i = 0; i <= buffer.Count - sequence.Length; i++)
+            {
+                var match = true;
+                for (int j = 0; j < sequence.Length; j++)
+                {
+                    if (buffer[i + j] != sequence[j])
+                    {
+                        match = false;
+                        break;
+                    }
+                }
+
+                if (match)
+                {
+                    return i;
+                }
+            }
+
+            return -1;
+        }
+
+        private static bool IsValidWebSocketRequest(string requestLine, IDictionary<string, string> headers)
+        {
+            if (string.IsNullOrWhiteSpace(requestLine))
+            {
+                return false;
+            }
+
+            var requestLineParts = requestLine.Split(' ');
+            if (requestLineParts.Length < 3 || !string.Equals(requestLineParts[0], "GET", StringComparison.OrdinalIgnoreCase))
+            {
+                return false;
+            }
+
+            return HeaderContainsToken(headers, "Connection", "Upgrade") &&
+                HeaderContainsToken(headers, "Upgrade", "websocket") &&
+                headers.ContainsKey("Sec-WebSocket-Key");
+        }
+
+        private static bool HeaderContainsToken(IDictionary<string, string> headers, string headerName, string expectedToken)
+        {
+            if (!headers.TryGetValue(headerName, out var headerValue) || string.IsNullOrWhiteSpace(headerValue))
+            {
+                return false;
+            }
+
+            return headerValue
+                .Split(',')
+                .Select(token => token.Trim())
+                .Any(token => string.Equals(token, expectedToken, StringComparison.OrdinalIgnoreCase));
+        }
+
+        private static string ComputeAcceptValue(string webSocketKey)
+        {
+            using (var sha1 = SHA1.Create())
+            {
+                var inputBytes = Encoding.ASCII.GetBytes($"{webSocketKey}{_webSocketAcceptMagic}");
+                var hashBytes = sha1.ComputeHash(inputBytes);
+                return Convert.ToBase64String(hashBytes);
+            }
+        }
+
+        private static bool IsValidWebSocketKey(string key)
+        {
+            if (string.IsNullOrEmpty(key) || key.IndexOfAny(new[] { '\r', '\n' }) >= 0)
+            {
+                return false;
+            }
+
+            try
+            {
+                var decoded = Convert.FromBase64String(key);
+                return decoded.Length == 16;
+            }
+            catch (FormatException)
+            {
+                return false;
+            }
+        }
+
+        private static async Task<string> ReadLineAsync(Stream stream, CancellationToken cancellationToken)
+        {
+            var lineBuilder = new StringBuilder();
+            var buffer = new byte[1];
+            var previousWasCarriageReturn = false;
+
+            while (true)
+            {
+                var bytesRead = await stream.ReadAsync(buffer, 0, 1, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    return lineBuilder.Length > 0 ? lineBuilder.ToString() : null;
+                }
+
+                var currentChar = (char)buffer[0];
+                if (currentChar == '\n' && previousWasCarriageReturn)
+                {
+                    if (lineBuilder.Length > 0 && lineBuilder[lineBuilder.Length - 1] == '\r')
+                    {
+                        lineBuilder.Length--;
+                    }
+
+                    return lineBuilder.ToString();
+                }
+
+                previousWasCarriageReturn = currentChar == '\r';
+                lineBuilder.Append(currentChar);
+
+                if (lineBuilder.Length > _maxHeaderLineLength)
+                {
+                    throw new InvalidDataException($"HTTP header line exceeds maximum length of {_maxHeaderLineLength}");
+                }
+            }
+        }
+
+        private static async Task<byte[]> ReadInitialBytesAsync(NetworkStream stream, CancellationToken cancellationToken)
+        {
+            var buffer = new byte[4];
+            var totalRead = 0;
+
+            while (totalRead < buffer.Length)
+            {
+                var bytesRead = await stream.ReadAsync(buffer, totalRead, buffer.Length - totalRead, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    break;
+                }
+
+                totalRead += bytesRead;
+            }
+
+            if (totalRead == 0)
+            {
+                return Array.Empty<byte>();
+            }
+
+            if (totalRead == buffer.Length)
+            {
+                return buffer;
+            }
+
+            var initialBytes = new byte[totalRead];
+            Array.Copy(buffer, initialBytes, totalRead);
+            return initialBytes;
+        }
+
+        internal static IncomingStreamPrefixKind ClassifyIncomingStreamPrefix(byte[] initialBytes)
+        {
+            if (LooksLikeHttpUpgrade(initialBytes))
+            {
+                return IncomingStreamPrefixKind.HttpWebSocketUpgrade;
+            }
+
+            if (LooksLikeHttp2Preface(initialBytes))
+            {
+                return IncomingStreamPrefixKind.Http2Preface;
+            }
+
+            if (LooksLikeTlsClientHello(initialBytes))
+            {
+                return IncomingStreamPrefixKind.TlsClientHello;
+            }
+
+            if (LooksLikeWebSocketFramePrefix(initialBytes, requireReservedBitsClear: false))
+            {
+                return HasReservedBitsSet(initialBytes[0])
+                    ? IncomingStreamPrefixKind.WebSocketReservedBits
+                    : IncomingStreamPrefixKind.PreUpgradedWebSocket;
+            }
+
+            return IncomingStreamPrefixKind.Unknown;
+        }
+
+        internal static string DescribeInitialBytes(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length == 0)
+            {
+                return "no bytes read";
+            }
+
+            var hex = BitConverter.ToString(initialBytes);
+            var ascii = new string(initialBytes.Select(value => value >= 32 && value <= 126 ? (char)value : '.').ToArray());
+            return $"hex={hex}, ascii=\"{ascii}\"";
+        }
+
+        private static bool LooksLikeHttpUpgrade(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length < 4)
+            {
+                return false;
+            }
+
+            return initialBytes[0] == (byte)'G' &&
+                initialBytes[1] == (byte)'E' &&
+                initialBytes[2] == (byte)'T' &&
+                initialBytes[3] == (byte)' ';
+        }
+
+        private static bool LooksLikeHttp2Preface(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length < 4)
+            {
+                return false;
+            }
+
+            return initialBytes[0] == (byte)'P' &&
+                initialBytes[1] == (byte)'R' &&
+                initialBytes[2] == (byte)'I' &&
+                initialBytes[3] == (byte)' ';
+        }
+
+        private static bool LooksLikeTlsClientHello(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length < 3)
+            {
+                return false;
+            }
+
+            return initialBytes[0] == 0x16 &&
+                initialBytes[1] == 0x03 &&
+                initialBytes[2] >= 0x00 &&
+                initialBytes[2] <= 0x04;
+        }
+
+        private static bool LooksLikeWebSocketFramePrefix(byte[] initialBytes, bool requireReservedBitsClear)
+        {
+            if (initialBytes == null || initialBytes.Length < 2)
+            {
+                return false;
+            }
+
+            var firstByte = initialBytes[0];
+            var secondByte = initialBytes[1];
+            var opcode = firstByte & 0x0F;
+            var isMasked = (secondByte & 0x80) != 0;
+
+            if (!isMasked || !IsSupportedWebSocketOpcode(opcode))
+            {
+                return false;
+            }
+
+            return !requireReservedBitsClear || !HasReservedBitsSet(firstByte);
+        }
+
+        private static bool HasReservedBitsSet(byte firstByte)
+        {
+            return (firstByte & 0x70) != 0;
+        }
+
+        private static bool IsSupportedWebSocketOpcode(int opcode)
+        {
+            switch (opcode)
+            {
+                case 0x0:
+                case 0x1:
+                case 0x2:
+                case 0x8:
+                case 0x9:
+                case 0xA:
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
+        private static async Task WriteHttpErrorAsync(
+            NetworkStream stream,
+            HttpStatusCode statusCode,
+            string message,
+            CancellationToken cancellationToken)
+        {
+            var bodyBytes = Encoding.UTF8.GetBytes(message);
+            var responseBytes = Encoding.ASCII.GetBytes(
+                $"HTTP/1.1 {(int)statusCode} {statusCode}\r\n" +
+                "Connection: close\r\n" +
+                "Content-Type: text/plain; charset=utf-8\r\n" +
+                $"Content-Length: {bodyBytes.Length}\r\n" +
+                "Sec-WebSocket-Version: 13\r\n" +
+                "\r\n");
+
+            await stream.WriteAsync(responseBytes, 0, responseBytes.Length, cancellationToken);
+            await stream.WriteAsync(bodyBytes, 0, bodyBytes.Length, cancellationToken);
+            await stream.FlushAsync(cancellationToken);
+        }
+
+        private static async Task CloseWebSocketAsync(WebSocket webSocket)
+        {
+            if (webSocket == null)
+            {
+                return;
+            }
+
+            if (webSocket.State != WebSocketState.Open &&
+                webSocket.State != WebSocketState.CloseReceived)
+            {
+                return;
+            }
+
+            try
+            {
+                using var cts = new CancellationTokenSource(_closeTimeout);
+                await webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cts.Token);
+            }
+            catch (OperationCanceledException)
+            {
+                // Graceful close timed out, abort the connection.
+                webSocket.Abort();
+            }
+            catch (WebSocketException)
+            {
+                // Peer already disconnected.
+            }
+        }
+
+        private sealed class ReplayableStream : Stream
+        {
+            private readonly Stream _innerStream;
+            private readonly byte[] _prefixBytes;
+            private int _prefixOffset;
+
+            public ReplayableStream(Stream innerStream, byte[] prefixBytes)
+            {
+                _innerStream = innerStream ?? throw new ArgumentNullException(nameof(innerStream));
+                _prefixBytes = prefixBytes ?? Array.Empty<byte>();
+            }
+
+            public override bool CanRead => _innerStream.CanRead;
+            public override bool CanSeek => false;
+            public override bool CanWrite => _innerStream.CanWrite;
+            public override long Length => throw new NotSupportedException();
+
+            public override long Position
+            {
+                get => throw new NotSupportedException();
+                set => throw new NotSupportedException();
+            }
+
+            public override void Flush() => _innerStream.Flush();
+
+            public override Task FlushAsync(CancellationToken cancellationToken) => _innerStream.FlushAsync(cancellationToken);
+
+            public override int Read(byte[] buffer, int offset, int count)
+            {
+                if (TryReadPrefix(buffer, offset, count, out var bytesRead))
+                {
+                    return bytesRead;
+                }
+
+                return _innerStream.Read(buffer, offset, count);
+            }
+
+            public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            {
+                if (TryReadPrefix(buffer, offset, count, out var bytesRead))
+                {
+                    return bytesRead;
+                }
+
+                return await _innerStream.ReadAsync(buffer, offset, count, cancellationToken);
+            }
+
+            public override async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+            {
+                if (_prefixOffset < _prefixBytes.Length)
+                {
+                    var bytesToCopy = Math.Min(buffer.Length, _prefixBytes.Length - _prefixOffset);
+                    new ReadOnlySpan<byte>(_prefixBytes, _prefixOffset, bytesToCopy).CopyTo(buffer.Span);
+                    _prefixOffset += bytesToCopy;
+                    return bytesToCopy;
+                }
+
+                return await _innerStream.ReadAsync(buffer, cancellationToken);
+            }
+
+            public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
+
+            public override void SetLength(long value) => throw new NotSupportedException();
+
+            public override void Write(byte[] buffer, int offset, int count) => _innerStream.Write(buffer, offset, count);
+
+            public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken) =>
+                _innerStream.WriteAsync(buffer, offset, count, cancellationToken);
+
+            public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default) =>
+                _innerStream.WriteAsync(buffer, cancellationToken);
+
+            private bool TryReadPrefix(byte[] buffer, int offset, int count, out int bytesRead)
+            {
+                if (_prefixOffset >= _prefixBytes.Length)
+                {
+                    bytesRead = 0;
+                    return false;
+                }
+
+                bytesRead = Math.Min(count, _prefixBytes.Length - _prefixOffset);
+                Array.Copy(_prefixBytes, _prefixOffset, buffer, offset, bytesRead);
+                _prefixOffset += bytesRead;
+                return true;
+            }
+        }
+    }
+}
@@ -77,8 +77,7 @@ namespace GitHub.Runner.Worker

        List<string> StepEnvironmentOverrides { get; }

-        ExecutionContext Root { get; }
-        ExecutionContext Parent { get; }
+        IExecutionContext Root { get; }

        // Initialize
        void InitializeJob(Pipelines.AgentJobRequestMessage message, CancellationToken token);
@@ -251,7 +250,9 @@ namespace GitHub.Runner.Worker
            }
        }

-        public ExecutionContext Root
+        IExecutionContext IExecutionContext.Root => Root;
+
+        private ExecutionContext Root
        {
            get
            {
@@ -266,13 +267,7 @@ namespace GitHub.Runner.Worker
            }
        }

-        public ExecutionContext Parent
-        {
-            get
-            {
-                return _parentExecutionContext;
-            }
-        }
+

        public JobContext JobContext
        {
@@ -856,6 +851,15 @@ namespace GitHub.Runner.Worker
            // Job level annotations
            Global.JobAnnotations = new List<Annotation>();

+            // Track Node.js 20 actions for deprecation warning
+            Global.DeprecatedNode20Actions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+            // Track actions upgraded from Node.js 20 to Node.js 24
+            Global.UpgradedToNode24Actions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+            // Track actions stuck on Node.js 20 due to ARM32 (separate from general deprecation)
+            Global.Arm32Node20Actions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
            // Job Outputs
            JobOutputs = new Dictionary<string, VariableValue>(StringComparer.OrdinalIgnoreCase);

@@ -888,15 +892,12 @@ namespace GitHub.Runner.Worker

            Trace.Info("Initializing Job context");
            var jobContext = new JobContext();
-            if (Global.Variables.GetBoolean(Constants.Runner.Features.AddCheckRunIdToJobContext) ?? false)
+            ExpressionValues.TryGetValue("job", out var jobDictionary);
+            if (jobDictionary != null)
            {
-                ExpressionValues.TryGetValue("job", out var jobDictionary);
-                if (jobDictionary != null)
+                foreach (var pair in jobDictionary.AssertDictionary("job"))
                {
-                    foreach (var pair in jobDictionary.AssertDictionary("job"))
-                    {
-                        jobContext[pair.Key] = pair.Value;
-                    }
+                    jobContext[pair.Key] = pair.Value;
                }
            }
            ExpressionValues["job"] = jobContext;
@@ -965,6 +966,9 @@ namespace GitHub.Runner.Worker
            // Verbosity (from GitHub.Step_Debug).
            Global.WriteDebug = Global.Variables.Step_Debug ?? false;

+            // Debugger enabled flag (from acquire response).
+            Global.Debugger = new Dap.DebuggerConfig(message.EnableDebugger, message.DebuggerTunnel);
+
            // Hook up JobServerQueueThrottling event, we will log warning on server tarpit.
            _jobServerQueue.JobServerQueueThrottling += JobServerQueueThrottling_EventReceived;
        }
@@ -1325,9 +1329,9 @@ namespace GitHub.Runner.Worker
            UpdateGlobalStepsContext();
        }

-        internal IPipelineTemplateEvaluator ToPipelineTemplateEvaluatorInternal(ObjectTemplating.ITraceWriter traceWriter = null)
+        internal IPipelineTemplateEvaluator ToPipelineTemplateEvaluatorInternal(bool allowServiceContainerCommand, ObjectTemplating.ITraceWriter traceWriter = null)
        {
-            return new PipelineTemplateEvaluatorWrapper(HostContext, this, traceWriter);
+            return new PipelineTemplateEvaluatorWrapper(HostContext, this, allowServiceContainerCommand, traceWriter);
        }

        private static void NoOp()
@@ -1415,10 +1419,13 @@ namespace GitHub.Runner.Worker

        public static IPipelineTemplateEvaluator ToPipelineTemplateEvaluator(this IExecutionContext context, ObjectTemplating.ITraceWriter traceWriter = null)
        {
+            var allowServiceContainerCommand = (context.Global.Variables.GetBoolean(Constants.Runner.Features.ServiceContainerCommand) ?? false)
+                || StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_SERVICE_CONTAINER_COMMAND"));
+
            // Create wrapper?
            if ((context.Global.Variables.GetBoolean(Constants.Runner.Features.CompareWorkflowParser) ?? false) || StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_RUNNER_COMPARE_WORKFLOW_PARSER")))
            {
-                return (context as ExecutionContext).ToPipelineTemplateEvaluatorInternal(traceWriter);
+                return (context as ExecutionContext).ToPipelineTemplateEvaluatorInternal(allowServiceContainerCommand, traceWriter);
            }

            // Legacy
@@ -1430,6 +1437,7 @@ namespace GitHub.Runner.Worker
            return new PipelineTemplateEvaluator(traceWriter, schema, context.Global.FileTable)
            {
                MaxErrorMessageLength = int.MaxValue, // Don't truncate error messages otherwise we might not scrub secrets correctly
+                AllowServiceContainerCommand = allowServiceContainerCommand,
            };
        }

@@ -4,6 +4,7 @@ using GitHub.Actions.RunService.WebApi;
 using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Worker.Container;
+using GitHub.Runner.Worker.Dap;
 using Newtonsoft.Json.Linq;
 using Sdk.RSWebApi.Contracts;

@@ -27,9 +28,15 @@ namespace GitHub.Runner.Worker
        public StepsContext StepsContext { get; set; }
        public Variables Variables { get; set; }
        public bool WriteDebug { get; set; }
+        public DebuggerConfig Debugger { get; set; }
        public string InfrastructureFailureCategory { get; set; }
        public JObject ContainerHookState { get; set; }
        public bool HasTemplateEvaluatorMismatch { get; set; }
        public bool HasActionManifestMismatch { get; set; }
+        public bool HasDeprecatedSetOutput { get; set; }
+        public bool HasDeprecatedSaveState { get; set; }
+        public HashSet<string> DeprecatedNode20Actions { get; set; }
+        public HashSet<string> UpgradedToNode24Actions { get; set; }
+        public HashSet<string> Arm32Node20Actions { get; set; }
    }
 }
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -226,6 +227,11 @@ namespace GitHub.Runner.Worker.Handlers
        {
            ArgUtil.NotNull(embeddedSteps, nameof(embeddedSteps));

+            bool emitCompositeMarkers =
+                (ExecutionContext.Global.Variables.GetBoolean(Constants.Runner.Features.EmitCompositeMarkers) ?? false)
+                || StringUtil.ConvertToBoolean(
+                    System.Environment.GetEnvironmentVariable(Constants.Variables.Agent.EmitCompositeMarkers));
+
            foreach (IStep step in embeddedSteps)
            {
                Trace.Info($"Processing embedded step: DisplayName='{step.DisplayName}'");
@@ -297,6 +303,27 @@ namespace GitHub.Runner.Worker.Handlers
                    SetStepConclusion(step, TaskResult.Failed);
                }

+                // Marker ID uses the step's fully qualified context name (ScopeName.ContextName),
+                // which encodes the full composite nesting chain at any depth.
+                var markerId = emitCompositeMarkers ? step.ExecutionContext.GetFullyQualifiedContextName() : null;
+                var stepStopwatch = default(Stopwatch);
+                var endMarkerEmitted = false;
+
+                // Emit start marker after full context setup so display name expressions resolve correctly
+                if (emitCompositeMarkers)
+                {
+                    try
+                    {
+                        step.EvaluateDisplayName(step.ExecutionContext.ExpressionValues, step.ExecutionContext, out _);
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Warning("Caught exception while evaluating embedded step display name. {0}", ex);
+                    }
+                    ExecutionContext.Output($"##[start-action display={EscapeProperty(SanitizeDisplayName(step.DisplayName))};id={EscapeProperty(markerId)}]");
+                    stepStopwatch = Stopwatch.StartNew();
+                }
+
                // Register Callback
                CancellationTokenRegistration? jobCancelRegister = null;
                try
@@ -381,6 +408,14 @@ namespace GitHub.Runner.Worker.Handlers
                        // Condition is false
                        Trace.Info("Skipping step due to condition evaluation.");
                        SetStepConclusion(step, TaskResult.Skipped);
+
+                        if (emitCompositeMarkers)
+                        {
+                            stepStopwatch.Stop();
+                            ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome=skipped;conclusion=skipped;duration_ms=0]");
+                            endMarkerEmitted = true;
+                        }
+
                        continue;
                    }
                    else if (conditionEvaluateError != null)
@@ -389,13 +424,31 @@ namespace GitHub.Runner.Worker.Handlers
                        step.ExecutionContext.Error(conditionEvaluateError);
                        SetStepConclusion(step, TaskResult.Failed);
                        ExecutionContext.Result = TaskResult.Failed;
+
+                        if (emitCompositeMarkers)
+                        {
+                            stepStopwatch.Stop();
+                            ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome=failure;conclusion=failure;duration_ms={stepStopwatch.ElapsedMilliseconds}]");
+                            endMarkerEmitted = true;
+                        }
+
                        break;
                    }
                    else
                    {
                        await RunStepAsync(step);
-                    }

+                        if (emitCompositeMarkers)
+                        {
+                            stepStopwatch.Stop();
+                            // Outcome = raw result before continue-on-error (null when continue-on-error didn't fire)
+                            // Result = final result after continue-on-error
+                            var outcome = (step.ExecutionContext.Outcome ?? step.ExecutionContext.Result ?? TaskResult.Succeeded).ToActionResult().ToString().ToLowerInvariant();
+                            var conclusion = (step.ExecutionContext.Result ?? TaskResult.Succeeded).ToActionResult().ToString().ToLowerInvariant();
+                            ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome={outcome};conclusion={conclusion};duration_ms={stepStopwatch.ElapsedMilliseconds}]");
+                            endMarkerEmitted = true;
+                        }
+                    }
                }
                finally
                {
@@ -404,6 +457,14 @@ namespace GitHub.Runner.Worker.Handlers
                        jobCancelRegister?.Dispose();
                        jobCancelRegister = null;
                    }
+
+                    if (emitCompositeMarkers && !endMarkerEmitted)
+                    {
+                        stepStopwatch.Stop();
+                        var outcome = (step.ExecutionContext.Outcome ?? step.ExecutionContext.Result ?? TaskResult.Failed).ToActionResult().ToString().ToLowerInvariant();
+                        var conclusion = (step.ExecutionContext.Result ?? TaskResult.Failed).ToActionResult().ToString().ToLowerInvariant();
+                        ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome={outcome};conclusion={conclusion};duration_ms={stepStopwatch.ElapsedMilliseconds}]");
+                    }
                }
                // Check failed or cancelled
                if (step.ExecutionContext.Result == TaskResult.Failed || step.ExecutionContext.Result == TaskResult.Canceled)
@@ -470,5 +531,44 @@ namespace GitHub.Runner.Worker.Handlers
            step.ExecutionContext.Result = result;
            step.ExecutionContext.UpdateGlobalStepsContext();
        }
+
+        /// <summary>
+        /// Escapes marker property values so they cannot break the ##[command key=value] format.
+        /// Delegates to ActionCommand.EscapeValue which escapes `;`, `]`, `\r`, `\n`, and `%`.
+        /// </summary>
+        internal static string EscapeProperty(string value)
+        {
+            return ActionCommand.EscapeValue(value);
+        }
+
+        /// <summary>Maximum character length for display names in markers to prevent log bloat.</summary>
+        internal const int MaxDisplayNameLength = 1000;
+
+        /// <summary>
+        /// Normalizes a step display name for safe embedding in a marker property.
+        /// Trims leading whitespace, drops everything after the first newline, and
+        /// truncates to <see cref="MaxDisplayNameLength"/> characters.
+        /// </summary>
+        internal static string SanitizeDisplayName(string displayName)
+        {
+            if (string.IsNullOrEmpty(displayName)) return displayName;
+
+            // Take first line only (FormatStepName in ActionRunner.cs already does this
+            // for most cases, but be defensive for any code path that skips it)
+            var result = displayName.TrimStart(' ', '\t', '\r', '\n');
+            var firstNewLine = result.IndexOfAny(new[] { '\r', '\n' });
+            if (firstNewLine >= 0)
+            {
+                result = result.Substring(0, firstNewLine);
+            }
+
+            // Truncate excessively long names
+            if (result.Length > MaxDisplayNameLength)
+            {
+                result = result.Substring(0, MaxDisplayNameLength);
+            }
+
+            return result;
+        }
    }
 }
@@ -25,6 +25,14 @@ namespace GitHub.Runner.Worker.Handlers

    public sealed class HandlerFactory : RunnerService, IHandlerFactory
    {
+        internal static bool ShouldTrackAsArm32Node20(bool deprecateArm32, string preferredNodeVersion, string finalNodeVersion, string platformWarningMessage)
+        {
+            return deprecateArm32 &&
+                !string.IsNullOrEmpty(platformWarningMessage) &&
+                string.Equals(preferredNodeVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase) &&
+                string.Equals(finalNodeVersion, Constants.Runner.NodeMigration.Node20, StringComparison.OrdinalIgnoreCase);
+        }
+
        public IHandler Create(
            IExecutionContext executionContext,
            Pipelines.ActionStepDefinitionReference action,
@@ -65,6 +73,13 @@ namespace GitHub.Runner.Worker.Handlers
                    nodeData.NodeVersion = Common.Constants.Runner.NodeMigration.Node20;
                }

+                // Read flags early; actionName is also resolved up front for tracking after version is determined
+                bool warnOnNode20 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.WarnOnNode20Flag) ?? false;
+                bool deprecateArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.DeprecateLinuxArm32Flag) ?? false;
+                bool killArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.KillLinuxArm32Flag) ?? false;
+                string node20RemovalDate = executionContext.Global.Variables?.Get(Constants.Runner.NodeMigration.Node20RemovalDateVariable);
+                string actionName = GetActionName(action);
+
                // Check if node20 was explicitly specified in the action
                // We don't modify if node24 was explicitly specified
                if (string.Equals(nodeData.NodeVersion, Constants.Runner.NodeMigration.Node20, StringComparison.InvariantCultureIgnoreCase))
@@ -73,7 +88,15 @@ namespace GitHub.Runner.Worker.Handlers
                    bool requireNode24 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.RequireNode24Flag) ?? false;

                    var (nodeVersion, configWarningMessage) = NodeUtil.DetermineActionsNodeVersion(environment, useNode24ByDefault, requireNode24);
-                    var (finalNodeVersion, platformWarningMessage) = NodeUtil.CheckNodeVersionForLinuxArm32(nodeVersion);
+                    var (finalNodeVersion, platformWarningMessage) = NodeUtil.CheckNodeVersionForLinuxArm32(nodeVersion, deprecateArm32, killArm32, node20RemovalDate);
+
+                    // ARM32 kill switch: fail the step
+                    if (finalNodeVersion == null)
+                    {
+                        executionContext.Error(platformWarningMessage);
+                        throw new InvalidOperationException(platformWarningMessage);
+                    }
+
                    nodeData.NodeVersion = finalNodeVersion;

                    if (!string.IsNullOrEmpty(configWarningMessage))
@@ -86,14 +109,59 @@ namespace GitHub.Runner.Worker.Handlers
                        executionContext.Warning(platformWarningMessage);
                    }

+                    // Track actions based on their final node version
+                    if (!string.IsNullOrEmpty(actionName))
+                    {
+                        if (string.Equals(finalNodeVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase))
+                        {
+                            // Action was upgraded from node20 to node24
+                            executionContext.Global.UpgradedToNode24Actions?.Add(actionName);
+                        }
+                        else if (ShouldTrackAsArm32Node20(deprecateArm32, nodeVersion, finalNodeVersion, platformWarningMessage))
+                        {
+                            // Action is on node20 because ARM32 can't run node24
+                            executionContext.Global.Arm32Node20Actions?.Add(actionName);
+                        }
+                        else if (warnOnNode20)
+                        {
+                            // Action is still running on node20 (general case)
+                            executionContext.Global.DeprecatedNode20Actions?.Add(actionName);
+                        }
+                    }
+
                    // Show information about Node 24 migration in Phase 2
                    if (useNode24ByDefault && !requireNode24 && string.Equals(finalNodeVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase))
                    {
                        string infoMessage = "Node 20 is being deprecated. This workflow is running with Node 24 by default. " +
-                                             "If you need to temporarily use Node 20, you can set the ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true environment variable.";
+                                             "If you need to temporarily use Node 20, you can set the ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true environment variable. " +
+                                             $"For more information see: {Constants.Runner.NodeMigration.Node20DeprecationUrl}";
                        executionContext.Output(infoMessage);
                    }
                }
+                else if (string.Equals(nodeData.NodeVersion, Constants.Runner.NodeMigration.Node24, StringComparison.InvariantCultureIgnoreCase))
+                {
+                    var (finalNodeVersion, platformWarningMessage) = NodeUtil.CheckNodeVersionForLinuxArm32(nodeData.NodeVersion, deprecateArm32, killArm32, node20RemovalDate);
+
+                    // ARM32 kill switch: fail the step
+                    if (finalNodeVersion == null)
+                    {
+                        executionContext.Error(platformWarningMessage);
+                        throw new InvalidOperationException(platformWarningMessage);
+                    }
+
+                    var preferredVersion = nodeData.NodeVersion;
+                    nodeData.NodeVersion = finalNodeVersion;
+
+                    if (!string.IsNullOrEmpty(platformWarningMessage))
+                    {
+                        executionContext.Warning(platformWarningMessage);
+                    }
+
+                    if (!string.IsNullOrEmpty(actionName) && ShouldTrackAsArm32Node20(deprecateArm32, preferredVersion, finalNodeVersion, platformWarningMessage))
+                    {
+                        executionContext.Global.Arm32Node20Actions?.Add(actionName);
+                    }
+                }

                (handler as INodeScriptActionHandler).Data = nodeData;
            }
@@ -129,5 +197,25 @@ namespace GitHub.Runner.Worker.Handlers
            handler.LocalActionContainerSetupSteps = localActionContainerSetupSteps;
            return handler;
        }
+
+        private static string GetActionName(Pipelines.ActionStepDefinitionReference action)
+        {
+            if (action is Pipelines.RepositoryPathReference repoRef)
+            {
+                var pathString = string.Empty;
+                if (!string.IsNullOrEmpty(repoRef.Path))
+                {
+                    pathString = string.IsNullOrEmpty(repoRef.Name)
+                        ? repoRef.Path
+                        : $"/{repoRef.Path}";
+                }
+                var repoString = string.IsNullOrEmpty(repoRef.Ref)
+                    ? $"{repoRef.Name}{pathString}"
+                    : $"{repoRef.Name}{pathString}@{repoRef.Ref}";
+                return string.IsNullOrEmpty(repoString) ? null : repoString;
+            }
+
+            return null;
+        }
    }
 }
@@ -90,6 +90,14 @@ namespace GitHub.Runner.Worker.Handlers
                }
            }

+            // Strip runner-controlled markers from user output to prevent injection
+            if (!String.IsNullOrEmpty(line) &&
+                (line.Contains("##[start-action") || line.Contains("##[end-action")))
+            {
+                line = line.Replace("##[start-action", @"##[\start-action")
+                           .Replace("##[end-action", @"##[\end-action");
+            }
+
            // Problem matchers
            if (_matchers.Length > 0)
            {
@@ -58,13 +58,23 @@ namespace GitHub.Runner.Worker.Handlers

        public Task<string> DetermineNodeRuntimeVersion(IExecutionContext executionContext, string preferredVersion)
        {
-            // Use NodeUtil to check if Node24 is requested but we're on ARM32 Linux
-            var (nodeVersion, warningMessage) = Common.Util.NodeUtil.CheckNodeVersionForLinuxArm32(preferredVersion);
+            bool deprecateArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.DeprecateLinuxArm32Flag) ?? false;
+            bool killArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.KillLinuxArm32Flag) ?? false;
+            string node20RemovalDate = executionContext.Global.Variables?.Get(Constants.Runner.NodeMigration.Node20RemovalDateVariable);
+
+            var (nodeVersion, warningMessage) = Common.Util.NodeUtil.CheckNodeVersionForLinuxArm32(preferredVersion, deprecateArm32, killArm32, node20RemovalDate);
+
+            if (nodeVersion == null)
+            {
+                executionContext.Error(warningMessage);
+                throw new InvalidOperationException(warningMessage);
+            }
+
            if (!string.IsNullOrEmpty(warningMessage))
            {
                executionContext.Warning(warningMessage);
            }
-            
+
            return Task.FromResult(nodeVersion);
        }

@@ -142,8 +152,18 @@ namespace GitHub.Runner.Worker.Handlers

        public async Task<string> DetermineNodeRuntimeVersion(IExecutionContext executionContext, string preferredVersion)
        {
-            // Use NodeUtil to check if Node24 is requested but we're on ARM32 Linux
-            var (nodeExternal, warningMessage) = Common.Util.NodeUtil.CheckNodeVersionForLinuxArm32(preferredVersion);
+            bool deprecateArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.DeprecateLinuxArm32Flag) ?? false;
+            bool killArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.KillLinuxArm32Flag) ?? false;
+            string node20RemovalDate = executionContext.Global.Variables?.Get(Constants.Runner.NodeMigration.Node20RemovalDateVariable);
+
+            var (nodeExternal, warningMessage) = Common.Util.NodeUtil.CheckNodeVersionForLinuxArm32(preferredVersion, deprecateArm32, killArm32, node20RemovalDate);
+
+            if (nodeExternal == null)
+            {
+                executionContext.Error(warningMessage);
+                throw new InvalidOperationException(warningMessage);
+            }
+
            if (!string.IsNullOrEmpty(warningMessage))
            {
                executionContext.Warning(warningMessage);
@@ -273,8 +293,18 @@ namespace GitHub.Runner.Worker.Handlers

        private string CheckPlatformForAlpineContainer(IExecutionContext executionContext, string preferredVersion)
        {
-            // Use NodeUtil to check if Node24 is requested but we're on ARM32 Linux
-            var (nodeExternal, warningMessage) = Common.Util.NodeUtil.CheckNodeVersionForLinuxArm32(preferredVersion);
+            bool deprecateArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.DeprecateLinuxArm32Flag) ?? false;
+            bool killArm32 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.KillLinuxArm32Flag) ?? false;
+            string node20RemovalDate = executionContext.Global.Variables?.Get(Constants.Runner.NodeMigration.Node20RemovalDateVariable);
+
+            var (nodeExternal, warningMessage) = Common.Util.NodeUtil.CheckNodeVersionForLinuxArm32(preferredVersion, deprecateArm32, killArm32, node20RemovalDate);
+
+            if (nodeExternal == null)
+            {
+                executionContext.Error(warningMessage);
+                throw new InvalidOperationException(warningMessage);
+            }
+
            if (!string.IsNullOrEmpty(warningMessage))
            {
                executionContext.Warning(warningMessage);
@@ -0,0 +1,4 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Test")]
+[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]
@@ -82,5 +82,69 @@ namespace GitHub.Runner.Worker
                }
            }
        }
+
+        public string WorkflowRef
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_ref", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_ref"] = value != null ? new StringContextData(value) : null;
+            }
+        }
+
+        public string WorkflowSha
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_sha", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_sha"] = value != null ? new StringContextData(value) : null;
+            }
+        }
+
+        public string WorkflowRepository
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_repository", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_repository"] = value != null ? new StringContextData(value) : null;
+            }
+        }
+
+        public string WorkflowFilePath
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_file_path", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_file_path"] = value != null ? new StringContextData(value) : null;
+            }
+        }
    }
 }
@@ -735,6 +735,39 @@ namespace GitHub.Runner.Worker
                            context.Global.JobTelemetry.Add(new JobTelemetry() { Type = JobTelemetryType.ConnectivityCheck, Message = $"Fail to check service connectivity. {ex.Message}" });
                        }
                    }
+
+                    // Read dates from server variables with hardcoded fallbacks
+                    var node24DefaultDateRaw = context.Global.Variables?.Get(Constants.Runner.NodeMigration.Node24DefaultDateVariable);
+                    var node24DefaultDate = string.IsNullOrEmpty(node24DefaultDateRaw) ? Constants.Runner.NodeMigration.Node24DefaultDate : node24DefaultDateRaw;
+                    var node20RemovalDateRaw = context.Global.Variables?.Get(Constants.Runner.NodeMigration.Node20RemovalDateVariable);
+                    var node20RemovalDate = string.IsNullOrEmpty(node20RemovalDateRaw) ? Constants.Runner.NodeMigration.Node20RemovalDate : node20RemovalDateRaw;
+
+                    // Add deprecation warning annotation for Node.js 20 actions (Phase 1 - actions still running on node20)
+                    if (context.Global.DeprecatedNode20Actions?.Count > 0)
+                    {
+                        var sortedActions = context.Global.DeprecatedNode20Actions.OrderBy(a => a, StringComparer.OrdinalIgnoreCase);
+                        var actionsList = string.Join(", ", sortedActions);
+                        var deprecationMessage = $"Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: {actionsList}. Actions will be forced to run with Node.js 24 by default starting {node24DefaultDate}. Node.js 20 will be removed from the runner on {node20RemovalDate}. Please check if updated versions of these actions are available that support Node.js 24. To opt into Node.js 24 now, set the FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true environment variable on the runner or in your workflow file. Once Node.js 24 becomes the default, you can temporarily opt out by setting ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true. For more information see: {Constants.Runner.NodeMigration.Node20DeprecationUrl}";
+                        context.Warning(deprecationMessage);
+                    }
+
+                    // Add annotation for actions upgraded from Node.js 20 to Node.js 24 (Phase 2/3)
+                    if (context.Global.UpgradedToNode24Actions?.Count > 0)
+                    {
+                        var sortedActions = context.Global.UpgradedToNode24Actions.OrderBy(a => a, StringComparer.OrdinalIgnoreCase);
+                        var actionsList = string.Join(", ", sortedActions);
+                        var upgradeMessage = $"Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: {actionsList}. For more information see: {Constants.Runner.NodeMigration.Node20DeprecationUrl}";
+                        context.Warning(upgradeMessage);
+                    }
+
+                    // Add annotation for ARM32 actions stuck on Node.js 20 (ARM32 can't run node24)
+                    if (context.Global.Arm32Node20Actions?.Count > 0)
+                    {
+                        var sortedActions = context.Global.Arm32Node20Actions.OrderBy(a => a, StringComparer.OrdinalIgnoreCase);
+                        var actionsList = string.Join(", ", sortedActions);
+                        var arm32Message = $"The following actions are running on Node.js 20 because Node.js 24 is not available on Linux ARM32: {actionsList}. Linux ARM32 runners are deprecated and will no longer be supported after {node20RemovalDate}. Please migrate to a supported platform. For more information see: {Constants.Runner.NodeMigration.Node20DeprecationUrl}";
+                        context.Warning(arm32Message);
+                    }
                }
                catch (Exception ex)
                {
@@ -13,6 +13,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Services.Common;
 using GitHub.Services.WebApi;
 using Sdk.RSWebApi.Contracts;
@@ -28,6 +29,7 @@ namespace GitHub.Runner.Worker

    public sealed class JobRunner : RunnerService, IJobRunner
    {
+        private const string DebuggerConnectionTelemetryPrefix = "DebuggerConnectionResult";
        private IJobServerQueue _jobServerQueue;
        private RunnerSettings _runnerSettings;
        private ITempDirectoryManager _tempDirectoryManager;
@@ -112,6 +114,7 @@ namespace GitHub.Runner.Worker

            IExecutionContext jobContext = null;
            CancellationTokenRegistration? runnerShutdownRegistration = null;
+            IDapDebugger dapDebugger = null;
            try
            {
                // Create the job execution context.
@@ -178,6 +181,26 @@ namespace GitHub.Runner.Worker
                _tempDirectoryManager = HostContext.GetService<ITempDirectoryManager>();
                _tempDirectoryManager.InitializeTempDirectory(jobContext);

+                // Setup the debugger
+                if (jobContext.Global.Debugger?.Enabled == true)
+                {
+                    Trace.Info("Debugger enabled for this job run");
+
+                    try
+                    {
+                        dapDebugger = HostContext.GetService<IDapDebugger>();
+                        await dapDebugger.StartAsync(jobContext);
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Error($"Failed to start DAP debugger: {ex.Message}");
+                        AddDebuggerConnectionTelemetry(jobContext, $"Failed: {ex.Message}");
+                        jobContext.Error("Failed to start debugger.");
+                        return await CompleteJobAsync(server, jobContext, message, TaskResult.Failed);
+                    }
+                }
+
+
                // Get the job extension.
                Trace.Info("Getting job extension.");
                IJobExtension jobExtension = HostContext.CreateService<IJobExtension>();
@@ -219,6 +242,33 @@ namespace GitHub.Runner.Worker
                    await Task.WhenAny(_jobServerQueue.JobRecordUpdated.Task, Task.Delay(1000));
                }

+                // Wait for DAP debugger client connection and handshake after "Set up job"
+                // so the job page shows the setup step before we block on the debugger
+                if (dapDebugger != null)
+                {
+                    try
+                    {
+                        await dapDebugger.WaitUntilReadyAsync();
+                        AddDebuggerConnectionTelemetry(jobContext, "Connected");
+                    }
+                    catch (OperationCanceledException) when (jobRequestCancellationToken.IsCancellationRequested)
+                    {
+                        Trace.Info("Job was cancelled before debugger client connected.");
+                        AddDebuggerConnectionTelemetry(jobContext, "Canceled");
+                        jobContext.Error("Job was cancelled before debugger client connected.");
+                        return await CompleteJobAsync(server, jobContext, message, TaskResult.Canceled);
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Error($"DAP debugger failed to become ready: {ex.Message}");
+                        AddDebuggerConnectionTelemetry(jobContext, $"Failed: {ex.Message}");
+
+                        // If debugging was requested but the debugger is not available, fail the job
+                        jobContext.Error("The debugger failed to start or no debugger client connected in time.");
+                        return await CompleteJobAsync(server, jobContext, message, TaskResult.Failed);
+                    }
+                }
+
                // Run all job steps
                Trace.Info("Run all job steps.");
                var stepsRunner = HostContext.GetService<IStepsRunner>();
@@ -259,6 +309,11 @@ namespace GitHub.Runner.Worker
                    runnerShutdownRegistration = null;
                }

+                if (dapDebugger != null)
+                {
+                    await dapDebugger.OnJobCompletedAsync();
+                }
+
                await ShutdownQueue(throwOnFailure: false);
            }
        }
@@ -440,6 +495,15 @@ namespace GitHub.Runner.Worker
            throw new AggregateException(exceptions);
        }

+        private static void AddDebuggerConnectionTelemetry(IExecutionContext jobContext, string result)
+        {
+            jobContext.Global.JobTelemetry.Add(new JobTelemetry
+            {
+                Type = JobTelemetryType.General,
+                Message = $"{DebuggerConnectionTelemetryPrefix}: {result}"
+            });
+        }
+
        private void MaskTelemetrySecrets(List<JobTelemetry> jobTelemetry)
        {
            foreach (var telemetryItem in jobTelemetry)
@@ -1,5 +1,6 @@
-using System;
+using System;
 using System.Collections.Generic;
+using System.Threading;
 using GitHub.Actions.WorkflowParser;
 using GitHub.DistributedTask.Expressions2;
 using GitHub.DistributedTask.ObjectTemplating.Tokens;
@@ -23,6 +24,7 @@ namespace GitHub.Runner.Worker
        public PipelineTemplateEvaluatorWrapper(
            IHostContext hostContext,
            IExecutionContext context,
+            bool allowServiceContainerCommand,
            ObjectTemplating.ITraceWriter traceWriter = null)
        {
            ArgUtil.NotNull(hostContext, nameof(hostContext));
@@ -40,11 +42,14 @@ namespace GitHub.Runner.Worker
            _legacyEvaluator = new PipelineTemplateEvaluator(traceWriter, schema, context.Global.FileTable)
            {
                MaxErrorMessageLength = int.MaxValue, // Don't truncate error messages otherwise we might not scrub secrets correctly
+                AllowServiceContainerCommand = allowServiceContainerCommand,
            };

            // New evaluator
            var newTraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter();
-            _newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, context.Global.FileTable, features: null)
+            var features = WorkflowFeatures.GetDefaults();
+            features.AllowServiceContainerCommand = allowServiceContainerCommand;
+            _newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, context.Global.FileTable, features)
            {
                MaxErrorMessageLength = int.MaxValue, // Don't truncate error messages otherwise we might not scrub secrets correctly
            };
@@ -216,12 +221,19 @@ namespace GitHub.Runner.Worker
            }
        }

-        private TLegacy EvaluateAndCompare<TLegacy, TNew>(
+        internal TLegacy EvaluateAndCompare<TLegacy, TNew>(
            string methodName,
            Func<TLegacy> legacyEvaluator,
            Func<TNew> newEvaluator,
            Func<TLegacy, TNew, bool> resultComparer)
        {
+            // Use the root (job-level) cancellation token to detect cancellation race conditions.
+            // The step-level token only fires on step timeout, not on job cancellation.
+            // Job cancellation mutates JobContext.Status which expression functions read,
+            // so we need the root token to properly detect cancellation between evaluator runs.
+            var rootCancellationToken = _context.Root?.CancellationToken ?? CancellationToken.None;
+            var cancellationRequestedBefore = rootCancellationToken.IsCancellationRequested;
+
            // Legacy evaluator
            var legacyException = default(Exception);
            var legacyResult = default(TLegacy);
@@ -253,14 +265,18 @@ namespace GitHub.Runner.Worker
                    newException = ex;
                }

+                // Capture cancellation state after evaluation
+                var cancellationRequestedAfter = rootCancellationToken.IsCancellationRequested;
+
                // Compare results or exceptions
+                bool hasMismatch = false;
                if (legacyException != null || newException != null)
                {
                    // Either one or both threw exceptions - compare them
                    if (!CompareExceptions(legacyException, newException))
                    {
                        _trace.Info($"{methodName} exception mismatch");
-                        RecordMismatch($"{methodName}");
+                        hasMismatch = true;
                    }
                }
                else
@@ -269,6 +285,20 @@ namespace GitHub.Runner.Worker
                    if (!resultComparer(legacyResult, newResult))
                    {
                        _trace.Info($"{methodName} mismatch");
+                        hasMismatch = true;
+                    }
+                }
+
+                // Only record mismatch if it wasn't caused by a cancellation race condition
+                if (hasMismatch)
+                {
+                    if (!cancellationRequestedBefore && cancellationRequestedAfter)
+                    {
+                        // Cancellation state changed during evaluation window - skip recording
+                        _trace.Info($"{methodName} mismatch skipped due to cancellation race condition");
+                    }
+                    else
+                    {
                        RecordMismatch($"{methodName}");
                    }
                }
@@ -380,6 +410,18 @@ namespace GitHub.Runner.Worker
                return false;
            }

+            if (!string.Equals(legacyResult.Entrypoint, newResult.Entrypoint, StringComparison.Ordinal))
+            {
+                _trace.Info($"CompareJobContainer mismatch - Entrypoint differs (legacy='{legacyResult.Entrypoint}', new='{newResult.Entrypoint}')");
+                return false;
+            }
+
+            if (!string.Equals(legacyResult.Command, newResult.Command, StringComparison.Ordinal))
+            {
+                _trace.Info($"CompareJobContainer mismatch - Command differs (legacy='{legacyResult.Command}', new='{newResult.Command}')");
+                return false;
+            }
+
            if (!CompareDictionaries(legacyResult.Environment, newResult.Environment, "Environment"))
            {
                return false;
@@ -612,6 +654,13 @@ namespace GitHub.Runner.Worker
                return false;
            }

+            // Check for known equivalent error patterns (e.g., JSON parse errors)
+            // where both parsers correctly reject invalid input but with different wording
+            if (IsKnownEquivalentErrorPattern(legacyException, newException))
+            {
+                return true;
+            }
+
            // Compare exception messages recursively (including inner exceptions)
            var legacyMessages = GetExceptionMessages(legacyException);
            var newMessages = GetExceptionMessages(newException);
@@ -634,6 +683,67 @@ namespace GitHub.Runner.Worker
            return true;
        }

+        /// <summary>
+        /// Checks if two exceptions match a known pattern where both parsers correctly reject
+        /// invalid input but with different error messages (e.g., JSON parse errors from fromJSON).
+        /// </summary>
+        private bool IsKnownEquivalentErrorPattern(Exception legacyException, Exception newException)
+        {
+            // fromJSON('') - both parsers fail when parsing empty string as JSON
+            // The error messages differ but both indicate JSON parsing failure.
+            // Legacy throws raw JsonReaderException: "Error reading JToken from JsonReader..."
+            // New wraps it: "Error parsing fromJson" with inner JsonReaderException
+            // Both may be wrapped in TemplateValidationException: "The template is not valid..."
+            if (HasJsonExceptionType(legacyException) && HasJsonExceptionType(newException))
+            {
+                _trace.Info("CompareExceptions - both exceptions are JSON parse errors, treating as matched");
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Checks if the exception chain contains a JSON-related exception type.
+        /// </summary>
+        internal static bool HasJsonExceptionType(Exception ex)
+        {
+            var toProcess = new Queue<Exception>();
+            toProcess.Enqueue(ex);
+            int count = 0;
+
+            while (toProcess.Count > 0 && count < 50)
+            {
+                var current = toProcess.Dequeue();
+                if (current == null) continue;
+
+                count++;
+
+                if (current is Newtonsoft.Json.JsonReaderException ||
+                    current is System.Text.Json.JsonException)
+                {
+                    return true;
+                }
+
+                if (current is AggregateException aggregateEx)
+                {
+                    foreach (var innerEx in aggregateEx.InnerExceptions)
+                    {
+                        if (innerEx != null && count < 50)
+                        {
+                            toProcess.Enqueue(innerEx);
+                        }
+                    }
+                }
+                else if (current.InnerException != null)
+                {
+                    toProcess.Enqueue(current.InnerException);
+                }
+            }
+
+            return false;
+        }
+
        private IList<string> GetExceptionMessages(Exception ex)
        {
            var messages = new List<string>();
@@ -19,10 +19,11 @@
  </ItemGroup>

  <ItemGroup>
-    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
-    <PackageReference Include="System.ServiceProcess.ServiceController" Version="8.0.1" />
-    <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
+    <PackageReference Include="System.ServiceProcess.ServiceController" Version="10.0.3" />
+    <PackageReference Include="System.Threading.Channels" Version="10.0.3" />
    <PackageReference Include="YamlDotNet.Signed" Version="5.3.0" />
+    <PackageReference Include="Microsoft.DevTunnels.Connections" Version="1.3.16" />
  </ItemGroup>

  <ItemGroup>
@@ -10,6 +10,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Runner.Worker.Expressions;

 namespace GitHub.Runner.Worker
@@ -50,6 +51,7 @@ namespace GitHub.Runner.Worker
            jobContext.JobContext.Status = (jobContext.Result ?? TaskResult.Succeeded).ToActionResult();
            var scopeInputs = new Dictionary<string, PipelineContextData>(StringComparer.OrdinalIgnoreCase);
            bool checkPostJobActions = false;
+            var dapDebugger = HostContext.GetService<IDapDebugger>();
            while (jobContext.JobSteps.Count > 0 || !checkPostJobActions)
            {
                if (jobContext.JobSteps.Count == 0 && !checkPostJobActions)
@@ -226,9 +228,14 @@ namespace GitHub.Runner.Worker
                        }
                        else
                        {
+                            // Pause for DAP debugger before step execution
+                            await dapDebugger?.OnStepStartingAsync(step);
+
                            // Run the step
                            await RunStepAsync(step, jobContext.CancellationToken);
                            CompleteStep(step);
+
+                            dapDebugger?.OnStepCompleted(step);
                        }
                    }
                    finally
@@ -255,6 +262,7 @@ namespace GitHub.Runner.Worker

                Trace.Info($"Current state: job state = '{jobContext.Result}'");
            }
+
        }

        private async Task RunStepAsync(IStep step, CancellationToken jobCancellationToken)
@@ -17,10 +17,9 @@ namespace GitHub.DistributedTask.Expressions2
            String expression,
            ITraceWriter trace,
            IEnumerable<INamedValueInfo> namedValues,
-            IEnumerable<IFunctionInfo> functions,
-            Boolean allowCaseFunction = true)
+            IEnumerable<IFunctionInfo> functions)
        {
-            var context = new ParseContext(expression, trace, namedValues, functions, allowCaseFunction);
+            var context = new ParseContext(expression, trace, namedValues, functions);
            context.Trace.Info($"Parsing expression: <{expression}>");
            return CreateTree(context);
        }
@@ -416,12 +415,6 @@ namespace GitHub.DistributedTask.Expressions2
            String name,
            out IFunctionInfo functionInfo)
        {
-            if (String.Equals(name, "case", StringComparison.OrdinalIgnoreCase) && !context.AllowCaseFunction)
-            {
-                functionInfo = null;
-                return false;
-            }
-
            return ExpressionConstants.WellKnownFunctions.TryGetValue(name, out functionInfo) ||
                context.ExtensionFunctions.TryGetValue(name, out functionInfo);
        }
@@ -429,7 +422,6 @@ namespace GitHub.DistributedTask.Expressions2
        private sealed class ParseContext
        {
            public Boolean AllowUnknownKeywords;
-            public Boolean AllowCaseFunction;
            public readonly String Expression;
            public readonly Dictionary<String, IFunctionInfo> ExtensionFunctions = new Dictionary<String, IFunctionInfo>(StringComparer.OrdinalIgnoreCase);
            public readonly Dictionary<String, INamedValueInfo> ExtensionNamedValues = new Dictionary<String, INamedValueInfo>(StringComparer.OrdinalIgnoreCase);
@@ -445,8 +437,7 @@ namespace GitHub.DistributedTask.Expressions2
                ITraceWriter trace,
                IEnumerable<INamedValueInfo> namedValues,
                IEnumerable<IFunctionInfo> functions,
-                Boolean allowUnknownKeywords = false,
-                Boolean allowCaseFunction = true)
+                Boolean allowUnknownKeywords = false)
            {
                Expression = expression ?? String.Empty;
                if (Expression.Length > ExpressionConstants.MaxLength)
@@ -467,7 +458,6 @@ namespace GitHub.DistributedTask.Expressions2

                LexicalAnalyzer = new LexicalAnalyzer(Expression);
                AllowUnknownKeywords = allowUnknownKeywords;
-                AllowCaseFunction = allowCaseFunction;
            }

            private class NoOperationTraceWriter : ITraceWriter
@@ -86,12 +86,6 @@ namespace GitHub.DistributedTask.ObjectTemplating

        internal ITraceWriter TraceWriter { get; set; }

-        /// <summary>
-        /// Gets or sets a value indicating whether the case expression function is allowed.
-        /// Defaults to true. Set to false to disable the case function.
-        /// </summary>
-        internal Boolean AllowCaseFunction { get; set; } = true;
-
        private IDictionary<String, Int32> FileIds
        {
            get
@@ -57,7 +57,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -94,7 +94,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -123,7 +123,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -152,7 +152,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -253,6 +253,20 @@ namespace GitHub.DistributedTask.Pipelines
            set;
        }

+        [DataMember(EmitDefaultValue = false)]
+        public bool EnableDebugger
+        {
+            get;
+            set;
+        }
+
+        [DataMember(EmitDefaultValue = false)]
+        public DebuggerTunnelInfo DebuggerTunnel
+        {
+            get;
+            set;
+        }
+
        /// <summary>
        /// Gets the collection of variables associated with the current context.
        /// </summary>
@@ -0,0 +1,24 @@
+using System.Runtime.Serialization;
+
+namespace GitHub.DistributedTask.Pipelines
+{
+    /// <summary>
+    /// Dev Tunnel information the runner needs to host the debugger tunnel.
+    /// Matches the run-service <c>DebuggerTunnel</c> contract.
+    /// </summary>
+    [DataContract]
+    public sealed class DebuggerTunnelInfo
+    {
+        [DataMember(EmitDefaultValue = false)]
+        public string TunnelId { get; set; }
+
+        [DataMember(EmitDefaultValue = false)]
+        public string ClusterId { get; set; }
+
+        [DataMember(EmitDefaultValue = false)]
+        public string HostToken { get; set; }
+
+        [DataMember(EmitDefaultValue = false)]
+        public ushort Port { get; set; }
+    }
+}
@@ -39,6 +39,24 @@ namespace GitHub.DistributedTask.Pipelines
            set;
        }

+        /// <summary>
+        /// Gets or sets the container entrypoint override.
+        /// </summary>
+        public String Entrypoint
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Gets or sets the container command and args (after the image name).
+        /// </summary>
+        public String Command
+        {
+            get;
+            set;
+        }
+
        /// <summary>
        /// Gets or sets the volumes which are mounted into the container.
        /// </summary>
@@ -47,6 +47,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
        public const String NumberStrategyContext = "number-strategy-context";
        public const String On = "on";
        public const String Options = "options";
+        public const String Entrypoint = "entrypoint";
+        public const String Command = "command";
        public const String Outputs = "outputs";
        public const String OutputsPattern = "needs.*.outputs";
        public const String Password = "password";
@@ -237,7 +237,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
        internal static JobContainer ConvertToJobContainer(
            TemplateContext context,
            TemplateToken value,
-            bool allowExpressions = false)
+            bool allowExpressions = false,
+            bool allowServiceContainerCommand = false)
        {
            var result = new JobContainer();
            if (allowExpressions && value.Traverse().Any(x => x is ExpressionToken))
@@ -280,6 +281,22 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
                        case PipelineTemplateConstants.Options:
                            result.Options = containerPropertyPair.Value.AssertString($"{PipelineTemplateConstants.Container} {propertyName}").Value;
                            break;
+                        case PipelineTemplateConstants.Entrypoint:
+                            if (!allowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{PipelineTemplateConstants.Entrypoint}' is not allowed");
+                                break;
+                            }
+                            result.Entrypoint = containerPropertyPair.Value.AssertString($"{PipelineTemplateConstants.Container} {propertyName}").Value;
+                            break;
+                        case PipelineTemplateConstants.Command:
+                            if (!allowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{PipelineTemplateConstants.Command}' is not allowed");
+                                break;
+                            }
+                            result.Command = containerPropertyPair.Value.AssertString($"{PipelineTemplateConstants.Container} {propertyName}").Value;
+                            break;
                        case PipelineTemplateConstants.Ports:
                            var ports = containerPropertyPair.Value.AssertSequence($"{PipelineTemplateConstants.Container} {propertyName}");
                            var portList = new List<String>(ports.Count);
@@ -326,7 +343,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
        internal static List<KeyValuePair<String, JobContainer>> ConvertToJobServiceContainers(
            TemplateContext context,
            TemplateToken services,
-            bool allowExpressions = false)
+            bool allowExpressions = false,
+            bool allowServiceContainerCommand = false)
        {
            var result = new List<KeyValuePair<String, JobContainer>>();

@@ -340,7 +358,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
            foreach (var servicePair in servicesMapping)
            {
                var networkAlias = servicePair.Key.AssertString("services key").Value;
-                var container = ConvertToJobContainer(context, servicePair.Value);
+                var container = ConvertToJobContainer(context, servicePair.Value, allowExpressions, allowServiceContainerCommand);
                result.Add(new KeyValuePair<String, JobContainer>(networkAlias, container));
            }

@@ -663,7 +681,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
            var node = default(ExpressionNode);
            try
            {
-                node = expressionParser.CreateTree(condition, null, namedValues, functions, allowCaseFunction: context.AllowCaseFunction) as ExpressionNode;
+                node = expressionParser.CreateTree(condition, null, namedValues, functions) as ExpressionNode;
            }
            catch (Exception ex)
            {
@@ -51,6 +51,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating

        public Int32 MaxResultSize { get; set; } = 10 * 1024 * 1024; // 10 mb

+        public bool AllowServiceContainerCommand { get; set; }
+
        public Boolean EvaluateStepContinueOnError(
            TemplateToken token,
            DictionaryContextData contextData,
@@ -357,7 +359,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
                {
                    token = TemplateEvaluator.Evaluate(context, PipelineTemplateConstants.Services, token, 0, null, omitHeader: true);
                    context.Errors.Check();
-                    result = PipelineTemplateConverter.ConvertToJobServiceContainers(context, token);
+                    result = PipelineTemplateConverter.ConvertToJobServiceContainers(context, token, allowServiceContainerCommand: AllowServiceContainerCommand);
                }
                catch (Exception ex) when (!(ex is TemplateValidationException))
                {
@@ -430,6 +430,21 @@
      }
    },

+    "service-container-mapping": {
+      "mapping": {
+        "properties": {
+          "image": "string",
+          "options": "string",
+          "entrypoint": "string",
+          "command": "string",
+          "env": "container-env",
+          "ports": "sequence-of-non-empty-string",
+          "volumes": "sequence-of-non-empty-string",
+          "credentials": "container-registry-credentials"
+        }
+      }
+    },
+
    "services": {
      "context": [
        "github",
@@ -454,7 +469,7 @@
      ],
      "one-of": [
        "string",
-        "container-mapping"
+        "service-container-mapping"
      ]
    },

@@ -2556,6 +2556,25 @@ namespace GitHub.DistributedTask.WebApi
        }
    }

+    [Serializable]
+    public sealed class FailedToDownloadActionException : DistributedTaskException
+    {
+        public FailedToDownloadActionException(String message)
+            : base(message)
+        {
+        }
+
+        public FailedToDownloadActionException(String message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        private FailedToDownloadActionException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+    }
+
    [Serializable]
    public sealed class InvalidActionArchiveException : DistributedTaskException
    {
@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references

 using System;
 using System.Collections.Generic;
@@ -17,10 +17,9 @@ namespace GitHub.Actions.Expressions
            String expression,
            ITraceWriter trace,
            IEnumerable<INamedValueInfo> namedValues,
-            IEnumerable<IFunctionInfo> functions,
-            Boolean allowCaseFunction = true)
+            IEnumerable<IFunctionInfo> functions)
        {
-            var context = new ParseContext(expression, trace, namedValues, functions, allowCaseFunction: allowCaseFunction);
+            var context = new ParseContext(expression, trace, namedValues, functions);
            context.Trace.Info($"Parsing expression: <{expression}>");
            return CreateTree(context);
        }
@@ -322,7 +321,7 @@ namespace GitHub.Actions.Expressions
                    context.Operators.Pop();
                }
                var functionOperands = PopOperands(context, parameterCount);
-                
+
                // Node already exists on the operand stack
                function = (Function)context.Operands.Peek();

@@ -416,12 +415,6 @@ namespace GitHub.Actions.Expressions
            String name,
            out IFunctionInfo functionInfo)
        {
-            if (String.Equals(name, "case", StringComparison.OrdinalIgnoreCase) && !context.AllowCaseFunction)
-            {
-                functionInfo = null;
-                return false;
-            }
-
            return ExpressionConstants.WellKnownFunctions.TryGetValue(name, out functionInfo) ||
                context.ExtensionFunctions.TryGetValue(name, out functionInfo);
        }
@@ -429,7 +422,6 @@ namespace GitHub.Actions.Expressions
        private sealed class ParseContext
        {
            public Boolean AllowUnknownKeywords;
-            public Boolean AllowCaseFunction;
            public readonly String Expression;
            public readonly Dictionary<String, IFunctionInfo> ExtensionFunctions = new Dictionary<String, IFunctionInfo>(StringComparer.OrdinalIgnoreCase);
            public readonly Dictionary<String, INamedValueInfo> ExtensionNamedValues = new Dictionary<String, INamedValueInfo>(StringComparer.OrdinalIgnoreCase);
@@ -445,8 +437,7 @@ namespace GitHub.Actions.Expressions
                ITraceWriter trace,
                IEnumerable<INamedValueInfo> namedValues,
                IEnumerable<IFunctionInfo> functions,
-                Boolean allowUnknownKeywords = false,
-                Boolean allowCaseFunction = true)
+                Boolean allowUnknownKeywords = false)
            {
                Expression = expression ?? String.Empty;
                if (Expression.Length > ExpressionConstants.MaxLength)
@@ -467,7 +458,6 @@ namespace GitHub.Actions.Expressions

                LexicalAnalyzer = new LexicalAnalyzer(Expression);
                AllowUnknownKeywords = allowUnknownKeywords;
-                AllowCaseFunction = allowCaseFunction;
            }

            private class NoOperationTraceWriter : ITraceWriter
@@ -23,14 +23,14 @@
        <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
        <PackageReference Include="Microsoft.AspNet.WebApi.Client" Version="6.0.0" />
        <PackageReference Include="System.Security.Cryptography.Cng" Version="5.0.0" />
-        <PackageReference Include="System.Security.Cryptography.Pkcs" Version="10.0.2" />
-        <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
+        <PackageReference Include="System.Security.Cryptography.Pkcs" Version="10.0.6" />
+        <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
        <PackageReference Include="Minimatch" Version="2.0.0" />
        <PackageReference Include="YamlDotNet.Signed" Version="5.3.0" />
        <PackageReference Include="System.Net.Http" Version="4.3.4" />
        <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
        <PackageReference Include="System.Private.Uri" Version="4.3.2" />
-        <PackageReference Include="System.Formats.Asn1" Version="10.0.2" />
+        <PackageReference Include="System.Formats.Asn1" Version="10.0.6" />
    </ItemGroup>

    <ItemGroup>
@@ -32,7 +32,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                return;
            }

-            var effectiveMax = explicitMax ?? CreatePermissionsFromPolicy(context, permissionsPolicy, includeIdToken: isTrusted, includeModels: context.GetFeatures().AllowModelsPermission);
+            var effectiveMax = explicitMax ?? CreatePermissionsFromPolicy(context, permissionsPolicy, includeIdToken: isTrusted, includeModels: context.GetFeatures().AllowModelsPermission, includeVulnerabilityAlerts: context.GetFeatures().AllowVulnerabilityAlertsPermission);
            
            if (requested.ViolatesMaxPermissions(effectiveMax, out var permissionLevelViolations))
            {
@@ -59,18 +59,19 @@ namespace GitHub.Actions.WorkflowParser.Conversion
            TemplateContext context,
            string permissionsPolicy,
            bool includeIdToken,
-            bool includeModels)
+            bool includeModels,
+            bool includeVulnerabilityAlerts)
        {
            switch (permissionsPolicy)
            {
                case WorkflowConstants.PermissionsPolicy.LimitedRead:
-                    return new Permissions(PermissionLevel.NoAccess, includeIdToken: false, includeAttestations: false, includeModels: false)
+                    return new Permissions(PermissionLevel.NoAccess, includeIdToken: false, includeAttestations: false, includeModels: false, includeVulnerabilityAlerts: false)
                    {
                        Contents = PermissionLevel.Read,
                        Packages = PermissionLevel.Read,
                    };
                case WorkflowConstants.PermissionsPolicy.Write:
-                    return new Permissions(PermissionLevel.Write, includeIdToken: includeIdToken, includeAttestations: true, includeModels: includeModels);
+                    return new Permissions(PermissionLevel.Write, includeIdToken: includeIdToken, includeAttestations: true, includeModels: includeModels, includeVulnerabilityAlerts: includeVulnerabilityAlerts);
                default:
                    throw new ArgumentException($"Unexpected permission policy: '{permissionsPolicy}'");
            }
@@ -62,6 +62,8 @@ namespace GitHub.Actions.WorkflowParser.Conversion
        public const String NumberStrategyContext = "number-strategy-context";
        public const String On = "on";
        public const String Options = "options";
+        public const String Entrypoint = "entrypoint";
+        public const String Command = "command";
        public const String Org = "org";
        public const String Organization = "organization";
        public const String Outputs = "outputs";
@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references

 using System;
 using System.Collections.Generic;
@@ -43,7 +43,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                    {
                        case WorkflowTemplateConstants.On:
                            var inputTypes = ConvertToOnWorkflowDispatchInputTypes(workflowPair.Value);
-                            foreach(var item in inputTypes)
+                            foreach (var item in inputTypes)
                            {
                                result.InputTypes.TryAdd(item.Key, item.Value);
                            }
@@ -432,7 +432,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                context.Error(snapshotToken, $"job {WorkflowTemplateConstants.Snapshot} {WorkflowTemplateConstants.ImageName} is required.");
                return null;
            }
-            
+
            return new Snapshot
            {
                ImageName = imageName,
@@ -445,7 +445,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
        {
            var versionSegments = versionString.Split(".");

-            if (versionSegments.Length != 2 || 
+            if (versionSegments.Length != 2 ||
                !versionSegments[1].Equals("*") ||
                !Int32.TryParse(versionSegments[0], NumberStyles.None, CultureInfo.InvariantCulture, result: out int parsedMajor) ||
                parsedMajor < 0)
@@ -1079,7 +1079,8 @@ namespace GitHub.Actions.WorkflowParser.Conversion
        internal static JobContainer ConvertToJobContainer(
            TemplateContext context,
            TemplateToken value,
-            bool isEarlyValidation = false)
+            bool isEarlyValidation = false,
+            bool isServiceContainer = false)
        {
            var result = new JobContainer();
            if (isEarlyValidation && value.Traverse().Any(x => x is ExpressionToken))
@@ -1089,11 +1090,34 @@ namespace GitHub.Actions.WorkflowParser.Conversion

            if (value is StringToken containerLiteral)
            {
-                if (String.IsNullOrEmpty(containerLiteral.Value))
+                // Trim "docker://"
+                var trimmedImage = containerLiteral.Value;
+                var hasDockerPrefix = containerLiteral.Value.StartsWith(WorkflowTemplateConstants.DockerUriPrefix, StringComparison.Ordinal);
+                if (hasDockerPrefix)
                {
+                    trimmedImage = trimmedImage.Substring(WorkflowTemplateConstants.DockerUriPrefix.Length);
+                }
+
+                // Empty shorthand after trimming "docker://" ?
+                if (String.IsNullOrEmpty(trimmedImage))
+                {
+                    // Error at parse-time for:
+                    //   1. container: 'docker://'
+                    //   2. services.foo: ''
+                    //   3. services.foo: 'docker://'
+                    //
+                    // Do not error for:
+                    //   1. container: ''
+                    if (isEarlyValidation && (hasDockerPrefix || isServiceContainer))
+                    {
+                        context.Error(value, "Container image cannot be empty");
+                    }
+
+                    // Short-circuit
                    return null;
                }

+                // Store original, trimmed further below
                result.Image = containerLiteral.Value;
            }
            else
@@ -1122,6 +1146,22 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                        case WorkflowTemplateConstants.Options:
                            result.Options = containerPropertyPair.Value.AssertString($"{WorkflowTemplateConstants.Container} {propertyName}").Value;
                            break;
+                        case WorkflowTemplateConstants.Entrypoint:
+                            if (!context.GetFeatures().AllowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{WorkflowTemplateConstants.Entrypoint}' is not allowed");
+                                break;
+                            }
+                            result.Entrypoint = containerPropertyPair.Value.AssertString($"{WorkflowTemplateConstants.Container} {propertyName}").Value;
+                            break;
+                        case WorkflowTemplateConstants.Command:
+                            if (!context.GetFeatures().AllowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{WorkflowTemplateConstants.Command}' is not allowed");
+                                break;
+                            }
+                            result.Command = containerPropertyPair.Value.AssertString($"{WorkflowTemplateConstants.Container} {propertyName}").Value;
+                            break;
                        case WorkflowTemplateConstants.Ports:
                            var ports = containerPropertyPair.Value.AssertSequence($"{WorkflowTemplateConstants.Container} {propertyName}");
                            var portList = new List<String>(ports.Count);
@@ -1152,15 +1192,28 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                }
            }

-            if (String.IsNullOrEmpty(result.Image))
+            // Trim "docker://"
+            var hadDockerPrefix = false;
+            if (!String.IsNullOrEmpty(result.Image) && result.Image.StartsWith(WorkflowTemplateConstants.DockerUriPrefix, StringComparison.Ordinal))
            {
-                context.Error(value, "Container image cannot be empty");
-                return null;
+                hadDockerPrefix = true;
+                result.Image = result.Image.Substring(WorkflowTemplateConstants.DockerUriPrefix.Length);
            }

-            if (result.Image.StartsWith(WorkflowTemplateConstants.DockerUriPrefix, StringComparison.Ordinal))
+            if (String.IsNullOrEmpty(result.Image))
            {
-                result.Image = result.Image.Substring(WorkflowTemplateConstants.DockerUriPrefix.Length);
+                // Error at parse-time for:
+                //   1. container: {image: 'docker://'}
+                //   2. services.foo: {image: ''}
+                //   3. services.foo: {image: 'docker://'}
+                //
+                // Do not error for:
+                //   1. container: {image: ''}
+                if (isEarlyValidation && (hadDockerPrefix || isServiceContainer))
+                {
+                    context.Error(value, "Container image cannot be empty");
+                }
+                return null;
            }

            return result;
@@ -1183,7 +1236,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
            foreach (var servicePair in servicesMapping)
            {
                var networkAlias = servicePair.Key.AssertString("services key").Value;
-                var container = ConvertToJobContainer(context, servicePair.Value);
+                var container = ConvertToJobContainer(context, servicePair.Value, isEarlyValidation, isServiceContainer: true);
                result.Add(new KeyValuePair<String, JobContainer>(networkAlias, container));
            }

@@ -1775,7 +1828,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
            var node = default(ExpressionNode);
            try
            {
-                node = expressionParser.CreateTree(condition, null, namedValues, functions, allowCaseFunction: context.AllowCaseFunction) as ExpressionNode;
+                node = expressionParser.CreateTree(condition, null, namedValues, functions) as ExpressionNode;
            }
            catch (Exception ex)
            {
@@ -1824,7 +1877,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                        permissionsStr.AssertUnexpectedValue(permissionsStr.Value);
                        break;
                }
-                return new Permissions(permissionLevel, includeIdToken: true, includeAttestations: true, includeModels: context.GetFeatures().AllowModelsPermission);
+                return new Permissions(permissionLevel, includeIdToken: true, includeAttestations: true, includeModels: context.GetFeatures().AllowModelsPermission, includeVulnerabilityAlerts: context.GetFeatures().AllowVulnerabilityAlertsPermission);
            }

            var mapping = token.AssertMapping("permissions");
@@ -1838,9 +1891,9 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                    case "actions":
                        permissions.Actions = permissionLevel;
                        break;
-					case "artifact-metadata":
-						permissions.ArtifactMetadata = permissionLevel;
-						break;
+                    case "artifact-metadata":
+                        permissions.ArtifactMetadata = permissionLevel;
+                        break;
                    case "attestations":
                        permissions.Attestations = permissionLevel;
                        break;
@@ -1904,6 +1957,23 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                            context.Error(key, $"The permission 'models' is not allowed");
                        }
                        break;
+                    case "vulnerability-alerts":
+                        if (context.GetFeatures().AllowVulnerabilityAlertsPermission)
+                        {
+                            if (permissionLevel == PermissionLevel.Write)
+                            {
+                                permissions.VulnerabilityAlerts = PermissionLevel.Read;
+                            }
+                            else
+                            {
+                                permissions.VulnerabilityAlerts = permissionLevel;
+                            }
+                        }
+                        else
+                        {
+                            context.Error(key, $"The permission 'vulnerability-alerts' is not allowed");
+                        }
+                        break;
                    default:
                        break;
                }
@@ -35,6 +35,24 @@ namespace GitHub.Actions.WorkflowParser
            set;
        }

+        /// <summary>
+        /// Gets or sets the container entrypoint override.
+        /// </summary>
+        public String Entrypoint
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Gets or sets the container command and args (after the image name).
+        /// </summary>
+        public String Command
+        {
+            get;
+            set;
+        }
+
        /// <summary>
        /// Gets or sets the volumes which are mounted into the container.
        /// </summary>
@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references

 using System;
 using System.Collections.Generic;
@@ -113,12 +113,6 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating
        /// </summary>
        internal Boolean StrictJsonParsing { get; set; }

-        /// <summary>
-        /// Gets or sets a value indicating whether the case expression function is allowed.
-        /// Defaults to true. Set to false to disable the case function.
-        /// </summary>
-        internal Boolean AllowCaseFunction { get; set; } = true;
-
        internal ITraceWriter TraceWriter { get; set; }

        private IDictionary<String, Int32> FileIds
@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references

 using System;
 using System.Collections.Generic;
@@ -55,7 +55,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -93,7 +93,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -123,7 +123,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -153,7 +153,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
            var originalBytes = context.Memory.CurrentBytes;
            try
            {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                var options = new EvaluationOptions
                {
                    MaxMemory = context.Memory.MaxBytes,
@@ -289,4 +289,4 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
            return result;
        }
    }
-}
+}
@@ -32,6 +32,7 @@ namespace GitHub.Actions.WorkflowParser
            SecurityEvents = copy.SecurityEvents;
            IdToken = copy.IdToken;
            Models = copy.Models;
+            VulnerabilityAlerts = copy.VulnerabilityAlerts;
        }

        public Permissions(
@@ -61,6 +62,19 @@ namespace GitHub.Actions.WorkflowParser
                : PermissionLevel.NoAccess;
        }

+        public Permissions(
+            PermissionLevel permissionLevel,
+            bool includeIdToken,
+            bool includeAttestations,
+            bool includeModels,
+            bool includeVulnerabilityAlerts)
+            : this(permissionLevel, includeIdToken, includeAttestations, includeModels)
+        {
+            VulnerabilityAlerts = includeVulnerabilityAlerts
+                ? (permissionLevel == PermissionLevel.Write ? PermissionLevel.Read : permissionLevel)
+                : PermissionLevel.NoAccess;
+        }
+
        private static KeyValuePair<string, (PermissionLevel, PermissionLevel)>[] ComparisonKeyMapping(Permissions left, Permissions right)
        {
            return new[]
@@ -81,6 +95,7 @@ namespace GitHub.Actions.WorkflowParser
                new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("security-events", (left.SecurityEvents, right.SecurityEvents)),
                new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("id-token", (left.IdToken, right.IdToken)),
                new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("models", (left.Models, right.Models)),
+                new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("vulnerability-alerts", (left.VulnerabilityAlerts, right.VulnerabilityAlerts)),
            };
        }

@@ -154,6 +169,13 @@ namespace GitHub.Actions.WorkflowParser
            set;
        }

+        [DataMember(Name = "vulnerability-alerts", EmitDefaultValue = false)]
+        public PermissionLevel VulnerabilityAlerts
+        {
+            get;
+            set;
+        }
+
        [DataMember(Name = "packages", EmitDefaultValue = false)]
        public PermissionLevel Packages
        {
@@ -41,6 +41,13 @@ namespace GitHub.Actions.WorkflowParser
        [DataMember(EmitDefaultValue = false)]
        public bool AllowModelsPermission { get; set; }

+        /// <summary>
+        /// Gets or sets a value indicating whether users may use the "vulnerability-alerts" permission.
+        /// Used during parsing only.
+        /// </summary>
+        [DataMember(EmitDefaultValue = false)]
+        public bool AllowVulnerabilityAlertsPermission { get; set; }
+
        /// <summary>
        /// Gets or sets a value indicating whether the expression function fromJson performs strict JSON parsing.
        /// Used during evaluation only.
@@ -48,6 +55,13 @@ namespace GitHub.Actions.WorkflowParser
        [DataMember(EmitDefaultValue = false)]
        public bool StrictJsonParsing { get; set; }

+        /// <summary>
+        /// Gets or sets a value indicating whether service containers may specify "entrypoint" and "command".
+        /// Used during parsing and evaluation.
+        /// </summary>
+        [DataMember(EmitDefaultValue = false)]
+        public bool AllowServiceContainerCommand { get; set; }
+
        /// <summary>
        /// Gets the default workflow features.
        /// </summary>
@@ -60,6 +74,8 @@ namespace GitHub.Actions.WorkflowParser
                Snapshot = false,           // Default to false since this feature is still in an experimental phase
                StrictJsonParsing = false,  // Default to false since this is temporary for telemetry purposes only
                AllowModelsPermission = false, // Default to false since we want this to be disabled for all non-production environments
+                AllowVulnerabilityAlertsPermission = false, // Default to false since we want this to be disabled for all non-production environments
+                AllowServiceContainerCommand = false, // Default to false since this feature is gated by actions_service_container_command
            };
        }

@@ -496,8 +496,8 @@
    "check-suite-activity": {
      "description": "The types of check suite activity that trigger the workflow. Supported activity types: `completed`.",
      "one-of": [
-         "check-suite-activity-type",
-         "check-suite-activity-types"
+        "check-suite-activity-type",
+        "check-suite-activity-types"
      ]
    },
    "check-suite-activity-types": {
@@ -1865,11 +1865,15 @@
          },
          "security-events": {
            "type": "permission-level-any",
-            "description": "Code scanning and Dependabot alerts."
+            "description": "Code scanning alerts."
          },
          "statuses": {
            "type": "permission-level-any",
            "description": "Commit statuses."
+          },
+          "vulnerability-alerts": {
+            "type": "permission-level-read-or-no-access",
+            "description": "Dependabot alerts."
          }
        }
      }
@@ -2589,21 +2593,53 @@
      "mapping": {
        "properties": {
          "image": {
-            "type": "non-empty-string",
-            "description": "Use `jobs.<job_id>.container.image` to define the Docker image to use as the container to run the action. The value can be the Docker Hub image or a registry name."
+            "type": "string",
+            "description": "The Docker image to use as the container. The value can be the Docker Hub image or a registry name."
          },
          "options": {
            "type": "string",
-            "description": "Use `jobs.<job_id>.container.options` to configure additional Docker container resource options."
+            "description": "Additional Docker container resource options."
          },
          "env": "container-env",
          "ports": {
            "type": "sequence-of-non-empty-string",
-            "description": "Use `jobs.<job_id>.container.ports` to set an array of ports to expose on the container."
+            "description": "An array of ports to expose on the container."
          },
          "volumes": {
            "type": "sequence-of-non-empty-string",
-            "description": "Use `jobs.<job_id>.container.volumes` to set an array of volumes for the container to use. You can use volumes to share data between services or other steps in a job. You can specify named Docker volumes, anonymous Docker volumes, or bind mounts on the host."
+            "description": "An array of volumes for the container to use. You can use volumes to share data between services or other steps in a job. You can specify named Docker volumes, anonymous Docker volumes, or bind mounts on the host."
+          },
+          "credentials": "container-registry-credentials"
+        }
+      }
+    },
+    "service-container-mapping": {
+      "mapping": {
+        "properties": {
+          "image": {
+            "type": "string",
+            "description": "The Docker image to use as the container. The value can be the Docker Hub image or a registry name."
+          },
+          "options": {
+            "type": "string",
+            "description": "Additional Docker container resource options."
+          },
+          "entrypoint": {
+            "type": "string",
+            "description": "Override the default ENTRYPOINT in the service container image."
+          },
+          "command": {
+            "type": "string",
+            "description": "Override the default CMD in the service container image."
+          },
+          "env": "container-env",
+          "ports": {
+            "type": "sequence-of-non-empty-string",
+            "description": "An array of ports to expose on the container."
+          },
+          "volumes": {
+            "type": "sequence-of-non-empty-string",
+            "description": "An array of volumes for the container to use. You can use volumes to share data between services or other steps in a job. You can specify named Docker volumes, anonymous Docker volumes, or bind mounts on the host."
          },
          "credentials": "container-registry-credentials"
        }
@@ -2634,12 +2670,12 @@
        "matrix"
      ],
      "one-of": [
-        "non-empty-string",
-        "container-mapping"
+        "string",
+        "service-container-mapping"
      ]
    },
    "container-registry-credentials": {
-      "description": "If the image's container registry requires authentication to pull the image, you can use `jobs.<job_id>.container.credentials` to set a map of the username and password. The credentials are the same values that you would provide to the `docker login` command.",
+      "description": "If the container registry requires authentication to pull the image, set a map of the username and password. The credentials are the same values that you would provide to the `docker login` command.",
      "context": [
        "github",
        "inputs",
@@ -2655,7 +2691,7 @@
      }
    },
    "container-env": {
-      "description": "Use `jobs.<job_id>.container.env` to set a map of variables in the container.",
+      "description": "A map of environment variables to set in the container.",
      "mapping": {
        "loose-key-type": "non-empty-string",
        "loose-value-type": "string-runner-context"
@@ -739,7 +739,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                Assert.True(jobDispatcher.RunOnceJobCompleted.Task.IsCompleted, "JobDispatcher should set task complete token for one time agent.");
                if (jobDispatcher.RunOnceJobCompleted.Task.IsCompleted)
                {
-                    Assert.True(await jobDispatcher.RunOnceJobCompleted.Task, "JobDispatcher should set task complete token to 'TRUE' for one time agent.");
+                    var result = await jobDispatcher.RunOnceJobCompleted.Task;
+                    Assert.Equal(TaskResult.Succeeded, result);
                }
            }
        }
@@ -295,13 +295,13 @@ namespace GitHub.Runner.Common.Tests.Listener
                _messageListener.Setup(x => x.DeleteMessageAsync(It.IsAny<TaskAgentMessage>()))
                    .Returns(Task.CompletedTask);

-                var runOnceJobCompleted = new TaskCompletionSource<bool>();
+                var runOnceJobCompleted = new TaskCompletionSource<TaskResult>();
                _jobDispatcher.Setup(x => x.RunOnceJobCompleted)
                    .Returns(runOnceJobCompleted);
                _jobDispatcher.Setup(x => x.Run(It.IsAny<Pipelines.AgentJobRequestMessage>(), It.IsAny<bool>()))
                    .Callback(() =>
                    {
-                        runOnceJobCompleted.TrySetResult(true);
+                        runOnceJobCompleted.TrySetResult(TaskResult.Succeeded);
                    });
                _jobNotification.Setup(x => x.StartClient(It.IsAny<String>()))
                    .Callback(() =>
@@ -399,13 +399,13 @@ namespace GitHub.Runner.Common.Tests.Listener
                _messageListener.Setup(x => x.DeleteMessageAsync(It.IsAny<TaskAgentMessage>()))
                    .Returns(Task.CompletedTask);

-                var runOnceJobCompleted = new TaskCompletionSource<bool>();
+                var runOnceJobCompleted = new TaskCompletionSource<TaskResult>();
                _jobDispatcher.Setup(x => x.RunOnceJobCompleted)
                    .Returns(runOnceJobCompleted);
                _jobDispatcher.Setup(x => x.Run(It.IsAny<Pipelines.AgentJobRequestMessage>(), It.IsAny<bool>()))
                    .Callback(() =>
                    {
-                        runOnceJobCompleted.TrySetResult(true);
+                        runOnceJobCompleted.TrySetResult(TaskResult.Succeeded);
                    });
                _jobNotification.Setup(x => x.StartClient(It.IsAny<String>()))
                    .Callback(() =>
@@ -733,8 +733,8 @@ namespace GitHub.Runner.Common.Tests.Listener

                _configStore.Setup(x => x.IsServiceConfigured()).Returns(false);

-                var completedTask = new TaskCompletionSource<bool>();
-                completedTask.SetResult(true);
+                var completedTask = new TaskCompletionSource<TaskResult>();
+                completedTask.SetResult(TaskResult.Succeeded);
                _jobDispatcher.Setup(x => x.RunOnceJobCompleted).Returns(completedTask);

                //Act
@@ -834,8 +834,8 @@ namespace GitHub.Runner.Common.Tests.Listener

                _configStore.Setup(x => x.IsServiceConfigured()).Returns(false);

-                var completedTask = new TaskCompletionSource<bool>();
-                completedTask.SetResult(true);
+                var completedTask = new TaskCompletionSource<TaskResult>();
+                completedTask.SetResult(TaskResult.Succeeded);
                _jobDispatcher.Setup(x => x.RunOnceJobCompleted).Returns(completedTask);

                //Act
@@ -954,8 +954,8 @@ namespace GitHub.Runner.Common.Tests.Listener

                _configStore.Setup(x => x.IsServiceConfigured()).Returns(false);

-                var completedTask = new TaskCompletionSource<bool>();
-                completedTask.SetResult(true);
+                var completedTask = new TaskCompletionSource<TaskResult>();
+                completedTask.SetResult(TaskResult.Succeeded);
                _jobDispatcher.Setup(x => x.RunOnceJobCompleted).Returns(completedTask);

                //Act
@@ -228,8 +228,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                                 .Returns(Task.FromResult(new TaskAgent()));


-                    var ex = await Assert.ThrowsAsync<TaskCanceledException>(() => updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains($"failed after {Constants.RunnerDownloadRetryMaxAttempts} download attempts", ex.Message);
+                    var result = await updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                }
            }
            finally
@@ -281,8 +281,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                                 .Returns(Task.FromResult(new TaskAgent()));


-                    var ex = await Assert.ThrowsAsync<Exception>(() => updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains("did not match expected Runner Hash", ex.Message);
+                    var result = await updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                }
            }
            finally
@@ -170,8 +170,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                        DownloadUrl = "https://github.com/actions/runner/notexists"
                    };

-                    var ex = await Assert.ThrowsAsync<TaskCanceledException>(() => updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains($"failed after {Constants.RunnerDownloadRetryMaxAttempts} download attempts", ex.Message);
+                    var result = await updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                }
            }
            finally
@@ -220,8 +220,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                        SHA256Checksum = "badhash"
                    };

-                    var ex = await Assert.ThrowsAsync<Exception>(() => updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains("did not match expected Runner Hash", ex.Message);
+                    var result = await updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                }
            }
            finally
@@ -0,0 +1,86 @@
+using GitHub.DistributedTask.Expressions2;
+using GitHub.DistributedTask.Expressions2.Sdk;
+using GitHub.DistributedTask.ObjectTemplating;
+using System;
+using System.Collections.Generic;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Sdk
+{
+    /// <summary>
+    /// Regression tests for ExpressionParser.CreateTree to verify that
+    /// the case function does not accidentally set allowUnknownKeywords.
+    /// </summary>
+    public sealed class ExpressionParserL0
+    {
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void CreateTree_RejectsUnrecognizedNamedValue()
+        {
+            // Regression: the case function parameter was passed positionally into
+            // the allowUnknownKeywords parameter, causing all named values
+            // to be silently accepted.
+            var parser = new ExpressionParser();
+            var namedValues = new List<INamedValueInfo>
+            {
+                new NamedValueInfo<ContextValueNode>("inputs"),
+            };
+
+            var ex = Assert.Throws<ParseException>(() =>
+                parser.CreateTree("github.event.repository.private", null, namedValues, null));
+
+            Assert.Contains("Unrecognized named-value", ex.Message);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void CreateTree_AcceptsRecognizedNamedValue()
+        {
+            var parser = new ExpressionParser();
+            var namedValues = new List<INamedValueInfo>
+            {
+                new NamedValueInfo<ContextValueNode>("inputs"),
+            };
+
+            var node = parser.CreateTree("inputs.foo", null, namedValues, null);
+
+            Assert.NotNull(node);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void CreateTree_CaseFunctionWorks()
+        {
+            var parser = new ExpressionParser();
+            var namedValues = new List<INamedValueInfo>
+            {
+                new NamedValueInfo<ContextValueNode>("github"),
+            };
+
+            var node = parser.CreateTree("case(github.event_name, 'push', 'Push Event')", null, namedValues, null);
+
+            Assert.NotNull(node);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void CreateTree_CaseFunctionDoesNotAffectUnknownKeywords()
+        {
+            // The key regression test: unrecognized named values must still be rejected.
+            var parser = new ExpressionParser();
+            var namedValues = new List<INamedValueInfo>
+            {
+                new NamedValueInfo<ContextValueNode>("inputs"),
+            };
+
+            var ex = Assert.Throws<ParseException>(() =>
+                parser.CreateTree("github.ref", null, namedValues, null));
+
+            Assert.Contains("Unrecognized named-value", ex.Message);
+        }
+    }
+}
@@ -0,0 +1,126 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.Serialization.Json;
+using System.Text;
+using Xunit;
+using GitHub.DistributedTask.Pipelines;
+
+namespace GitHub.Actions.RunService.WebApi.Tests;
+
+public sealed class AgentJobRequestMessageL0
+{
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyEnableDebuggerDeserialization_WithTrue()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string jsonWithEnabledDebugger = DoubleQuotify("{'EnableDebugger': true}");
+        
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(jsonWithEnabledDebugger));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+        
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.True(recoveredMessage.EnableDebugger, "EnableDebugger should be true when JSON contains 'EnableDebugger': true");
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyEnableDebuggerDeserialization_DefaultToFalse()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string jsonWithoutDebugger = DoubleQuotify("{'messageType': 'PipelineAgentJobRequest'}");
+        
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(jsonWithoutDebugger));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+        
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should default to false when JSON field is absent");
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyEnableDebuggerDeserialization_WithFalse()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string jsonWithDisabledDebugger = DoubleQuotify("{'EnableDebugger': false}");
+        
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(jsonWithDisabledDebugger));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+        
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should be false when JSON contains 'EnableDebugger': false");
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyDebuggerTunnelDeserialization_WithTunnel()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage), new DataContractJsonSerializerSettings
+        {
+            KnownTypes = new[] { typeof(DebuggerTunnelInfo) }
+        });
+        string json = DoubleQuotify(
+            "{'EnableDebugger': true, 'DebuggerTunnel': {'TunnelId': 'tun-123', 'ClusterId': 'use2', 'HostToken': 'tok-abc', 'Port': 4711}}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.True(recoveredMessage.EnableDebugger);
+        Assert.NotNull(recoveredMessage.DebuggerTunnel);
+        Assert.Equal("tun-123", recoveredMessage.DebuggerTunnel.TunnelId);
+        Assert.Equal("use2", recoveredMessage.DebuggerTunnel.ClusterId);
+        Assert.Equal("tok-abc", recoveredMessage.DebuggerTunnel.HostToken);
+        Assert.Equal(4711, recoveredMessage.DebuggerTunnel.Port);
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyDebuggerTunnelDeserialization_WithoutTunnel()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string json = DoubleQuotify("{'EnableDebugger': true}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.True(recoveredMessage.EnableDebugger);
+        Assert.Null(recoveredMessage.DebuggerTunnel);
+    }
+
+    private static string DoubleQuotify(string text)
+    {
+        return text.Replace('\'', '"');
+    }
+}
@@ -2,6 +2,7 @@
 using GitHub.Runner.Listener.Check;
 using GitHub.Runner.Listener.Configuration;
 using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Runner.Worker.Container.ContainerHooks;
 using GitHub.Runner.Worker.Handlers;
 using System;
@@ -457,6 +457,8 @@ namespace GitHub.Runner.Common.Tests.Worker
                new SetEnvCommandExtension(),
                new WarningCommandExtension(),
                new AddMaskCommandExtension(),
+                new SetOutputCommandExtension(),
+                new SaveStateCommandExtension(),
            };
            foreach (var command in commands)
            {
@@ -499,5 +501,53 @@ namespace GitHub.Runner.Common.Tests.Worker
            };
        }

+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SetOutputCommand_EmitsTelemetryOnce()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                _ec.Object.Global.JobTelemetry = new List<JobTelemetry>();
+                var reference = string.Empty;
+                _ec.Setup(x => x.SetOutput(It.IsAny<string>(), It.IsAny<string>(), out reference));
+
+                // First set-output should add telemetry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::set-output name=foo::bar", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+                Assert.Equal(JobTelemetryType.ActionCommand, _ec.Object.Global.JobTelemetry[0].Type);
+                Assert.Equal("DeprecatedCommand: set-output", _ec.Object.Global.JobTelemetry[0].Message);
+                Assert.True(_ec.Object.Global.HasDeprecatedSetOutput);
+
+                // Second set-output should not add another telemetry entry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::set-output name=foo2::bar2", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SaveStateCommand_EmitsTelemetryOnce()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                _ec.Object.Global.JobTelemetry = new List<JobTelemetry>();
+                _ec.Setup(x => x.IsEmbedded).Returns(false);
+                _ec.Setup(x => x.IntraActionState).Returns(new Dictionary<string, string>());
+
+                // First save-state should add telemetry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::save-state name=foo::bar", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+                Assert.Equal(JobTelemetryType.ActionCommand, _ec.Object.Global.JobTelemetry[0].Type);
+                Assert.Equal("DeprecatedCommand: save-state", _ec.Object.Global.JobTelemetry[0].Message);
+                Assert.True(_ec.Object.Global.HasDeprecatedSaveState);
+
+                // Second save-state should not add another telemetry entry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::save-state name=foo2::bar2", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+            }
+        }
+
    }
 }
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.IO;
 using System.IO.Compression;
 using System.Net;
@@ -198,7 +199,8 @@ namespace GitHub.Runner.Common.Tests.Worker
                Func<Task> action = async () => await _actionManager.PrepareActionsAsync(_ec.Object, actions);

                //Assert
-                await Assert.ThrowsAsync<ActionNotFoundException>(action);
+                var ex = await Assert.ThrowsAsync<FailedToDownloadActionException>(action);
+                Assert.IsType<ActionNotFoundException>(ex.InnerException);

                var watermarkFile = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), ActionName, "main.completed");
                Assert.False(File.Exists(watermarkFile));
@@ -468,6 +470,73 @@ runs:
            }
        }

+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_SymlinkCacheIsReentrant()
+        {
+            try
+            {
+                //Arrange
+                Environment.SetEnvironmentVariable(Constants.Variables.Agent.SymlinkCachedActions, "true");
+                Setup();
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "actions/checkout",
+                            Ref = "master",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "actions/checkout",
+                            Ref = "master",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                const string Content = @"
+name: 'Test'
+runs:
+  using: 'node20'
+  main: 'dist/index.js'
+";
+
+                string actionsArchive = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions_archive", "action_checkout");
+                Directory.CreateDirectory(actionsArchive);
+                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", "master-sha"));
+                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", "master-sha", "content"));
+                await File.WriteAllTextAsync(Path.Combine(actionsArchive, "actions_checkout", "master-sha", "content", "action.yml"), Content);
+                Environment.SetEnvironmentVariable(Constants.Variables.Agent.ActionArchiveCacheDirectory, actionsArchive);
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                string destDirectory = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "actions", "checkout", "master");
+                Assert.True(Directory.Exists(destDirectory), "Destination directory does not exist");  
+                var di = new DirectoryInfo(destDirectory);   
+                Assert.NotNull(di.LinkTarget); 
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable(Constants.Variables.Agent.SymlinkCachedActions, null);
+                Teardown();
+            }
+        }
+
 #if OS_LINUX
        [Fact]
        [Trait("Level", "L0")]
@@ -1186,6 +1255,659 @@ runs:
        }
 #endif

+        // =================================================================
+        // Tests for batched action resolution optimization
+        // =================================================================
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_BatchesResolutionAcrossCompositeActions()
+        {
+            // Verifies that when multiple composite actions at the same depth
+            // reference sub-actions, those sub-actions are resolved in a single
+            // batched API call rather than one call per composite.
+            //
+            // Action tree:
+            //   CompositePrestep (composite) → [Node action, CompositePrestep2 (composite)]
+            //   CompositePrestep2 (composite) → [Node action, Docker action]
+            //
+            // Without batching: 3 API calls (depth 0, depth 1 for CompositePrestep, depth 2 for CompositePrestep2)
+            // With batching: still 3 calls at most, but the key is that depth-1
+            //   sub-actions from all composites at depth 0 are batched into 1 call.
+            //   And the same action appearing at multiple depths triggers only 1 resolve.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var resolveCallCount = 0;
+                var resolvedActions = new List<ActionReferenceList>();
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        resolvedActions.Add(actions);
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // The composite tree is:
+                //   depth 0: CompositePrestep
+                //   depth 1: Node@RepositoryActionWithWrapperActionfile_Node + CompositePrestep2
+                //   depth 2: Node@RepositoryActionWithWrapperActionfile_Node + Docker@RepositoryActionWithWrapperActionfile_Docker
+                //
+                // With batching:
+                //   Call 1 (depth 0, resolve): CompositePrestep
+                //   Call 2 (depth 0→1, pre-resolve): Node + CompositePrestep2 in one batch
+                //   Call 3 (depth 1→2, pre-resolve): Docker only (Node already cached from call 2)
+                Assert.Equal(3, resolveCallCount);
+
+                // Call 1: depth 0 resolve — just the top-level composite
+                var call1Keys = resolvedActions[0].Actions.Select(a => $"{a.NameWithOwner}@{a.Ref}").OrderBy(k => k).ToList();
+                Assert.Equal(new[] { "TingluoHuang/runner_L0@CompositePrestep" }, call1Keys);
+
+                // Call 2: depth 0→1 pre-resolve — batch both children of CompositePrestep
+                var call2Keys = resolvedActions[1].Actions.Select(a => $"{a.NameWithOwner}@{a.Ref}").OrderBy(k => k).ToList();
+                Assert.Equal(new[] { "TingluoHuang/runner_L0@CompositePrestep2", "TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Node" }, call2Keys);
+
+                // Call 3: depth 1→2 pre-resolve — only Docker (Node was cached in call 2)
+                var call3Keys = resolvedActions[2].Actions.Select(a => $"{a.NameWithOwner}@{a.Ref}").OrderBy(k => k).ToList();
+                Assert.Equal(new[] { "TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Docker" }, call3Keys);
+
+                // Verify all actions were downloaded
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "CompositePrestep.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "CompositePrestep2.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+
+                // Verify pre-step tracking still works correctly
+                Assert.Equal(1, result.PreStepTracker.Count);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_DeduplicatesResolutionAcrossDepthLevels()
+        {
+            // Verifies that an action appearing at multiple depths in the
+            // composite tree is only resolved once (not re-resolved at each level).
+            //
+            // CompositePrestep uses Node action at depth 1.
+            // CompositePrestep2 (also at depth 1) uses the SAME Node action at depth 2.
+            // The Node action should only be resolved once total.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var allResolvedKeys = new List<string>();
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            allResolvedKeys.Add(key);
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Node appears
+                // at both depth 1 (sub-step of CompositePrestep) and depth 2 (sub-step of
+                // CompositePrestep2). With deduplication it should only be resolved once.
+                var nodeActionKey = "TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Node";
+                var nodeResolveCount = allResolvedKeys.FindAll(k => k == nodeActionKey).Count;
+                Assert.Equal(1, nodeResolveCount);
+
+                // Verify the total number of unique actions resolved matches the tree
+                var uniqueKeys = new HashSet<string>(allResolvedKeys);
+                // Expected unique actions: CompositePrestep, Node, CompositePrestep2, Docker = 4
+                Assert.Equal(4, uniqueKeys.Count);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_MultipleTopLevelActions_BatchesResolution()
+        {
+            // Verifies that multiple independent actions at depth 0 are
+            // resolved in a single API call.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                // Node action has pre+post, needs IActionRunner instances
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var resolveCallCount = 0;
+                var firstCallActionCount = 0;
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        if (resolveCallCount == 1)
+                        {
+                            firstCallActionCount = actions.Actions.Count;
+                        }
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action1",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Node",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action2",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Docker",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // Both actions are at depth 0 — should be resolved in a single batch call
+                Assert.Equal(1, resolveCallCount);
+                Assert.Equal(2, firstCallActionCount);
+
+                // Verify both were downloaded
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+#if OS_LINUX
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_NestedCompositeContainers_BatchedResolution()
+        {
+            // Verifies batching with nested composite actions that reference
+            // container actions (Linux-only since containers require Linux).
+            //
+            // CompositeContainerNested (composite):
+            //   → repositoryactionwithdockerfile (Dockerfile)
+            //   → CompositeContainerNested2 (composite):
+            //       → repositoryactionwithdockerfile (Dockerfile, same as above)
+            //       → notpullorbuildimagesmultipletimes1 (Dockerfile)
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+
+                var resolveCallCount = 0;
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositeContainerNested",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // Tree has 3 depth levels with 5 unique actions.
+                // With batching, should need at most 3 resolve calls (one per depth level).
+                Assert.True(resolveCallCount <= 3, $"Expected at most 3 resolve calls but got {resolveCallCount}");
+
+                // repositoryactionwithdockerfile appears at both depth 1 and depth 2.
+                // Container setup should still work correctly — 2 unique Docker images.
+                Assert.Equal(2, result.ContainerSetupSteps.Count);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+#endif
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_ParallelDownloads_MultipleUniqueActions()
+        {
+            // Verifies that multiple unique top-level actions are downloaded via
+            // DownloadActionsInParallelAsync (the parallel code path), and that
+            // all actions are correctly resolved and downloaded.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                // Node action has pre step, and CompositePrestep recurses into
+                // sub-actions that also need IActionRunner instances
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var resolveCallCount = 0;
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        Interlocked.Increment(ref resolveCallCount);
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action1",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Node",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action2",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Docker",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action3",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // 3 unique actions at depth 0 → triggers DownloadActionsInParallelAsync
+                // (parallel path used when uniqueDownloads.Count > 1)
+                var nodeCompleted = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed");
+                var dockerCompleted = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed");
+                var compositeCompleted = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "CompositePrestep.completed");
+
+                Assert.True(File.Exists(nodeCompleted), $"Expected watermark at {nodeCompleted}");
+                Assert.True(File.Exists(dockerCompleted), $"Expected watermark at {dockerCompleted}");
+                Assert.True(File.Exists(compositeCompleted), $"Expected watermark at {compositeCompleted}");
+
+                // All depth-0 actions resolved in a single batch call.
+                // Composite sub-actions may add 1-2 more calls.
+                Assert.True(resolveCallCount >= 1, "Expected at least 1 resolve call");
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_DownloadsNextLevelActionsBeforeRecursing()
+        {
+            // Verifies that depth-1 actions are downloaded before the depth-2
+            // pre-resolve fires. We detect this by snapshotting watermark state
+            // inside the 3rd ResolveActionDownloadInfoAsync callback (which is
+            // the depth-2 pre-resolve). If pre-download works, depth-1 watermarks
+            // already exist at that point.
+            //
+            // Action tree:
+            //   CompositePrestep (composite) → [Node, CompositePrestep2 (composite)]
+            //   CompositePrestep2 (composite) → [Node, Docker]
+            //
+            // Without pre-download: downloads happen during recursion (serial per depth)
+            // With pre-download: depth 1 actions (Node + CompositePrestep2) are
+            //   downloaded in parallel before recursing, so recursion is a no-op
+            //   for downloads.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                // Track watermark state at the time of each resolve call.
+                // If pre-download works, when the 3rd resolve fires (depth 2
+                // pre-resolve for Docker), the depth-1 actions (Node +
+                // CompositePrestep2) should already have watermarks on disk.
+                var resolveCallCount = 0;
+                var watermarksAtResolve3 = new Dictionary<string, bool>();
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        if (resolveCallCount == 3)
+                        {
+                            // At the time of the 3rd resolve, check if depth-1 actions
+                            // are already downloaded (pre-download should have done this)
+                            var actionsDir2 = _hc.GetDirectory(WellKnownDirectory.Actions);
+                            watermarksAtResolve3["Node"] = File.Exists(Path.Combine(actionsDir2, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed"));
+                            watermarksAtResolve3["CompositePrestep2"] = File.Exists(Path.Combine(actionsDir2, "TingluoHuang/runner_L0", "CompositePrestep2.completed"));
+                        }
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // All actions should be downloaded (watermarks exist)
+                var actionsDir = _hc.GetDirectory(WellKnownDirectory.Actions);
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "CompositePrestep.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "CompositePrestep2.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+
+                // 3 resolve calls total
+                Assert.Equal(3, resolveCallCount);
+
+                // The key assertion: at the time of the 3rd resolve call
+                // (pre-resolve for depth 2), the depth-1 actions should
+                // ALREADY be downloaded thanks to pre-download.
+                // Without pre-download, these watermarks wouldn't exist yet
+                // because depth-1 downloads would only happen during recursion.
+                Assert.True(watermarksAtResolve3["Node"],
+                    "Node action should be pre-downloaded before depth 2 pre-resolve");
+                Assert.True(watermarksAtResolve3["CompositePrestep2"],
+                    "CompositePrestep2 should be pre-downloaded before depth 2 pre-resolve");
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_ParallelDownloadsAtSameDepth()
+        {
+            // Verifies that multiple unique actions at the same depth are
+            // downloaded concurrently (Task.WhenAll) rather than sequentially.
+            // We detect this by checking that all watermarks exist after a
+            // single PrepareActionsAsync call with multiple top-level actions.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action1",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Node",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action2",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Docker",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert - both downloaded (parallel path used when > 1 unique download)
+                var actionsDir = _hc.GetDirectory(WellKnownDirectory.Actions);
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
        [Fact]
        [Trait("Level", "L0")]
        [Trait("Category", "Worker")]
@@ -504,7 +504,7 @@ namespace GitHub.Runner.Common.Tests.Worker
            }
        }

-         [Fact]
+        [Fact]
        [Trait("Level", "L0")]
        [Trait("Category", "Worker")]
        public void Load_Node24Action()
@@ -928,6 +928,58 @@ namespace GitHub.Runner.Common.Tests.Worker
            }
        }

+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Load_ContainerAction_RejectsInvalidExpressionContext()
+        {
+            try
+            {
+                // Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManager();
+                actionManifest.Initialize(_hc);
+
+                // Act & Assert — github is not a valid context for container-runs-env (only inputs is allowed)
+                var ex = Assert.Throws<ArgumentException>(() =>
+                    actionManifest.Load(_ec.Object, Path.Combine(TestUtil.GetTestDataPath(), "dockerfileaction_env_invalid_context.yml")));
+
+                Assert.Contains("Failed to load", ex.Message);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Load_ContainerAction_AcceptsValidExpressionContext()
+        {
+            try
+            {
+                // Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManager();
+                actionManifest.Initialize(_hc);
+
+                // Act — inputs is a valid context for container-runs-env
+                var result = actionManifest.Load(_ec.Object, Path.Combine(TestUtil.GetTestDataPath(), "dockerfileaction_arg_env_expression.yml"));
+
+                // Assert
+                var containerAction = result.Execution as ContainerActionExecutionDataNew;
+                Assert.NotNull(containerAction);
+                Assert.Equal("${{ inputs.entryPoint }}", containerAction.Environment[1].Value.ToString());
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
        private void Setup([CallerMemberName] string name = "")
        {
            _ecTokenSource?.Dispose();
@@ -954,6 +1006,45 @@ namespace GitHub.Runner.Common.Tests.Worker
            _ec.Setup(x => x.AddIssue(It.IsAny<Issue>(), It.IsAny<ExecutionContextLogOptions>())).Callback((Issue issue, ExecutionContextLogOptions logOptions) => { _hc.GetTrace().Info($"[{issue.Type}]{logOptions.LogMessageOverride ?? issue.Message}"); });
        }

+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Evaluate_Default_Input_Case_Function()
+        {
+            try
+            {
+                //Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManager();
+                actionManifest.Initialize(_hc);
+
+                _ec.Object.ExpressionValues["github"] = new LegacyContextData.DictionaryContextData
+                {
+                    { "ref", new LegacyContextData.StringContextData("refs/heads/main") },
+                };
+                _ec.Object.ExpressionValues["strategy"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["matrix"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["steps"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["job"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["runner"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["env"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionFunctions.Add(new LegacyExpressions.FunctionInfo<GitHub.Runner.Worker.Expressions.HashFilesFunction>("hashFiles", 1, 255));
+
+                // Act — evaluate a case() expression as a default input value.
+                // The feature flag is set, so this should succeed.
+                var token = new BasicExpressionToken(null, null, null, "case(true, 'matched', 'default')");
+                var result = actionManifest.EvaluateDefaultInput(_ec.Object, "testInput", token);
+
+                // Assert — case() should evaluate successfully
+                Assert.Equal("matched", result);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
        private void Teardown()
        {
            _hc?.Dispose();
@@ -926,6 +926,58 @@ namespace GitHub.Runner.Common.Tests.Worker
            }
        }

+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Load_ContainerAction_RejectsInvalidExpressionContext()
+        {
+            try
+            {
+                // Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManagerLegacy();
+                actionManifest.Initialize(_hc);
+
+                // Act & Assert — github is not a valid context for container-runs-env (only inputs is allowed)
+                var ex = Assert.Throws<ArgumentException>(() =>
+                    actionManifest.Load(_ec.Object, Path.Combine(TestUtil.GetTestDataPath(), "dockerfileaction_env_invalid_context.yml")));
+
+                Assert.Contains("Failed to load", ex.Message);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Load_ContainerAction_AcceptsValidExpressionContext()
+        {
+            try
+            {
+                // Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManagerLegacy();
+                actionManifest.Initialize(_hc);
+
+                // Act — inputs is a valid context for container-runs-env
+                var result = actionManifest.Load(_ec.Object, Path.Combine(TestUtil.GetTestDataPath(), "dockerfileaction_arg_env_expression.yml"));
+
+                // Assert
+                var containerAction = result.Execution as ContainerActionExecutionData;
+                Assert.NotNull(containerAction);
+                Assert.Equal("${{ inputs.entryPoint }}", containerAction.Environment[1].Value.ToString());
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
        private void Setup([CallerMemberName] string name = "")
        {
            _ecTokenSource?.Dispose();
@@ -0,0 +1,458 @@
+using GitHub.Actions.WorkflowParser;
+using GitHub.DistributedTask.ObjectTemplating.Tokens;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.Pipelines.ObjectTemplating;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Common;
+using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker;
+using LegacyContextData = GitHub.DistributedTask.Pipelines.ContextData;
+using LegacyExpressions = GitHub.DistributedTask.Expressions2;
+using Moq;
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    /// <summary>
+    /// Tests for parser comparison wrapper classes.
+    /// </summary>
+    public sealed class ActionManifestParserComparisonL0
+    {
+        private CancellationTokenSource _ecTokenSource;
+        private Mock<IExecutionContext> _ec;
+        private TestHostContext _hc;
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ConvertToLegacySteps_ProducesCorrectSteps_WithExplicitPropertyMapping()
+        {
+            try
+            {
+                // Arrange - Test that ActionManifestManagerWrapper properly converts new steps to legacy format
+                Setup();
+
+                // Enable comparison feature
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                // Register required services
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var manifestPath = Path.Combine(TestUtil.GetTestDataPath(), "conditional_composite_action.yml");
+
+                // Act - Load through the wrapper (which internally converts)
+                var result = wrapper.Load(_ec.Object, manifestPath);
+
+                // Assert
+                Assert.NotNull(result);
+                Assert.Equal(ActionExecutionType.Composite, result.Execution.ExecutionType);
+
+                var compositeExecution = result.Execution as CompositeActionExecutionData;
+                Assert.NotNull(compositeExecution);
+                Assert.NotNull(compositeExecution.Steps);
+                Assert.Equal(6, compositeExecution.Steps.Count);
+
+                // Verify steps are NOT null (this was the bug - JSON round-trip produced nulls)
+                foreach (var step in compositeExecution.Steps)
+                {
+                    Assert.NotNull(step);
+                    Assert.NotNull(step.Reference);
+                    Assert.IsType<GitHub.DistributedTask.Pipelines.ScriptReference>(step.Reference);
+                }
+
+                // Verify step with condition
+                var successStep = compositeExecution.Steps[2];
+                Assert.Equal("success-conditional", successStep.ContextName);
+                Assert.Equal("success()", successStep.Condition);
+
+                // Verify step with complex condition
+                var lastStep = compositeExecution.Steps[5];
+                Assert.Contains("inputs.exit-code == 1", lastStep.Condition);
+                Assert.Contains("failure()", lastStep.Condition);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_EmptyImage_BothParsersReturnNull()
+        {
+            try
+            {
+                // Arrange - Test that both parsers return null for empty container image at runtime
+                Setup();
+
+                var fileTable = new List<string>();
+
+                // Create legacy evaluator
+                var legacyTraceWriter = new GitHub.DistributedTask.ObjectTemplating.EmptyTraceWriter();
+                var schema = PipelineTemplateSchemaFactory.GetSchema();
+                var legacyEvaluator = new PipelineTemplateEvaluator(legacyTraceWriter, schema, fileTable);
+
+                // Create new evaluator
+                var newTraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter();
+                var newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, fileTable, features: null);
+
+                // Create a token representing an empty container image (simulates expression evaluated to empty string)
+                var emptyImageToken = new StringToken(null, null, null, "");
+
+                var contextData = new DictionaryContextData();
+                var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+
+                // Act - Call both evaluators
+                var legacyResult = legacyEvaluator.EvaluateJobContainer(emptyImageToken, contextData, expressionFunctions);
+
+                // Convert token for new evaluator
+                var newToken = new GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.StringToken(null, null, null, "");
+                var newContextData = new GitHub.Actions.Expressions.Data.DictionaryExpressionData();
+                var newExpressionFunctions = new List<GitHub.Actions.Expressions.IFunctionInfo>();
+
+                var newResult = newEvaluator.EvaluateJobContainer(newToken, newContextData, newExpressionFunctions);
+
+                // Assert - Both should return null for empty image (no container)
+                Assert.Null(legacyResult);
+                Assert.Null(newResult);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void FromJsonEmptyString_BothParsersFail_WithDifferentMessages()
+        {
+            // This test verifies that both parsers fail with different error messages when parsing fromJSON('')
+            // The comparison layer should treat these as semantically equivalent (both are JSON parse errors)
+            try
+            {
+                Setup();
+
+                var fileTable = new List<string>();
+
+                // Create legacy evaluator
+                var legacyTraceWriter = new GitHub.DistributedTask.ObjectTemplating.EmptyTraceWriter();
+                var schema = PipelineTemplateSchemaFactory.GetSchema();
+                var legacyEvaluator = new PipelineTemplateEvaluator(legacyTraceWriter, schema, fileTable);
+
+                // Create new evaluator
+                var newTraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter();
+                var newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, fileTable, features: null);
+
+                // Create expression token for fromJSON('')
+                var legacyToken = new BasicExpressionToken(null, null, null, "fromJson('')");
+                var newToken = new GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.BasicExpressionToken(null, null, null, "fromJson('')");
+
+                var contextData = new DictionaryContextData();
+                var newContextData = new GitHub.Actions.Expressions.Data.DictionaryExpressionData();
+                var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+                var newExpressionFunctions = new List<GitHub.Actions.Expressions.IFunctionInfo>();
+
+                // Act - Both should throw
+                Exception legacyException = null;
+                Exception newException = null;
+
+                try
+                {
+                    legacyEvaluator.EvaluateStepDisplayName(legacyToken, contextData, expressionFunctions);
+                }
+                catch (Exception ex)
+                {
+                    legacyException = ex;
+                }
+
+                try
+                {
+                    newEvaluator.EvaluateStepName(newToken, newContextData, newExpressionFunctions);
+                }
+                catch (Exception ex)
+                {
+                    newException = ex;
+                }
+
+                // Assert - Both threw exceptions
+                Assert.NotNull(legacyException);
+                Assert.NotNull(newException);
+
+                // Verify the error messages are different (which is why we need semantic comparison)
+                Assert.NotEqual(legacyException.Message, newException.Message);
+
+                // Verify both are JSON parse errors (contain JSON-related error indicators)
+                var legacyFullMsg = GetFullExceptionMessage(legacyException);
+                var newFullMsg = GetFullExceptionMessage(newException);
+
+                // At least one should contain indicators of JSON parsing failure
+                var legacyIsJsonError = legacyFullMsg.Contains("JToken") ||
+                                        legacyFullMsg.Contains("JsonReader") ||
+                                        legacyFullMsg.Contains("fromJson");
+                var newIsJsonError = newFullMsg.Contains("JToken") ||
+                                     newFullMsg.Contains("JsonReader") ||
+                                     newFullMsg.Contains("fromJson");
+
+                Assert.True(legacyIsJsonError, $"Legacy exception should be JSON error: {legacyFullMsg}");
+                Assert.True(newIsJsonError, $"New exception should be JSON error: {newFullMsg}");
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateDefaultInput_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                _ec.Object.ExpressionValues["github"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["strategy"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["matrix"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["steps"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["job"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["runner"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["env"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionFunctions.Add(new LegacyExpressions.FunctionInfo<GitHub.Runner.Worker.Expressions.HashFilesFunction>("hashFiles", 1, 255));
+
+                var result = wrapper.EvaluateDefaultInput(_ec.Object, "testInput", new StringToken(null, null, null, "defaultValue"));
+
+                Assert.Equal("defaultValue", result);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateContainerArguments_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var arguments = new SequenceToken(null, null, null);
+                arguments.Add(new StringToken(null, null, null, "arg1"));
+                arguments.Add(new StringToken(null, null, null, "arg2"));
+
+                var evaluateContext = new Dictionary<string, LegacyContextData.PipelineContextData>(StringComparer.OrdinalIgnoreCase);
+
+                var result = wrapper.EvaluateContainerArguments(_ec.Object, arguments, evaluateContext);
+
+                Assert.Equal(2, result.Count);
+                Assert.Equal("arg1", result[0]);
+                Assert.Equal("arg2", result[1]);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateContainerEnvironment_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var environment = new MappingToken(null, null, null);
+                environment.Add(new StringToken(null, null, null, "hello"), new StringToken(null, null, null, "world"));
+
+                var evaluateContext = new Dictionary<string, LegacyContextData.PipelineContextData>(StringComparer.OrdinalIgnoreCase);
+
+                var result = wrapper.EvaluateContainerEnvironment(_ec.Object, environment, evaluateContext);
+
+                Assert.Equal(1, result.Count);
+                Assert.Equal("world", result["hello"]);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateCompositeOutputs_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var outputDef = new MappingToken(null, null, null);
+                outputDef.Add(new StringToken(null, null, null, "description"), new StringToken(null, null, null, "test output"));
+                outputDef.Add(new StringToken(null, null, null, "value"), new StringToken(null, null, null, "value1"));
+
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "output1"), outputDef);
+
+                var evaluateContext = new Dictionary<string, LegacyContextData.PipelineContextData>(StringComparer.OrdinalIgnoreCase);
+
+                var result = wrapper.EvaluateCompositeOutputs(_ec.Object, token, evaluateContext);
+
+                Assert.NotNull(result);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Load_BothParsersRejectInvalidExpressionContext()
+        {
+            try
+            {
+                // Arrange — regression test: both parsers must reject github context
+                // in container-runs-env (only inputs is allowed per schema)
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var manifestPath = Path.Combine(TestUtil.GetTestDataPath(), "dockerfileaction_env_invalid_context.yml");
+
+                // Act & Assert — both parsers should reject, wrapper should throw
+                Assert.Throws<ArgumentException>(() => wrapper.Load(_ec.Object, manifestPath));
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        private string GetFullExceptionMessage(Exception ex)
+        {
+            var messages = new List<string>();
+            var current = ex;
+            while (current != null)
+            {
+                messages.Add(current.Message);
+                current = current.InnerException;
+            }
+            return string.Join(" -> ", messages);
+        }
+
+        private void Setup([CallerMemberName] string name = "")
+        {
+            _ecTokenSource?.Dispose();
+            _ecTokenSource = new CancellationTokenSource();
+
+            _hc = new TestHostContext(this, name);
+
+            var expressionValues = new LegacyContextData.DictionaryContextData();
+            var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+
+            _ec = new Mock<IExecutionContext>();
+            _ec.Setup(x => x.Global)
+                .Returns(new GlobalContext
+                {
+                    FileTable = new List<String>(),
+                    Variables = new Variables(_hc, new Dictionary<string, VariableValue>()),
+                    WriteDebug = true,
+                });
+            _ec.Setup(x => x.CancellationToken).Returns(_ecTokenSource.Token);
+            _ec.Setup(x => x.ExpressionValues).Returns(expressionValues);
+            _ec.Setup(x => x.ExpressionFunctions).Returns(expressionFunctions);
+            _ec.Setup(x => x.Write(It.IsAny<string>(), It.IsAny<string>())).Callback((string tag, string message) => { _hc.GetTrace().Info($"{tag}{message}"); });
+            _ec.Setup(x => x.AddIssue(It.IsAny<Issue>(), It.IsAny<ExecutionContextLogOptions>())).Callback((Issue issue, ExecutionContextLogOptions logOptions) => { _hc.GetTrace().Info($"[{issue.Type}]{logOptions.LogMessageOverride ?? issue.Message}"); });
+        }
+
+        private void Teardown()
+        {
+            _hc?.Dispose();
+        }
+    }
+}
@@ -0,0 +1,813 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Net.Sockets;
+using System.Net.WebSockets;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Moq;
+using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Dap;
+using Newtonsoft.Json;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapDebuggerL0
+    {
+        private const string TimeoutEnvironmentVariable = "ACTIONS_RUNNER_DAP_CONNECTION_TIMEOUT";
+        private const string TunnelConnectTimeoutVariable = "ACTIONS_RUNNER_DAP_TUNNEL_CONNECT_TIMEOUT_SECONDS";
+        private DapDebugger _debugger;
+        private TestWebSocketDapBridge _testWebSocketBridge;
+
+        private sealed class TestWebSocketDapBridge : RunnerService, IWebSocketDapBridge
+        {
+            private readonly WebSocketDapBridge _inner = new WebSocketDapBridge();
+
+            public int ListenPort => _inner.ListenPort;
+
+            public override void Initialize(IHostContext hostContext)
+            {
+                base.Initialize(hostContext);
+                _inner.Initialize(hostContext);
+            }
+
+            public void Start(int listenPort, int targetPort)
+            {
+                _inner.Start(0, targetPort);
+            }
+
+            public Task ShutdownAsync()
+            {
+                return _inner.ShutdownAsync();
+            }
+        }
+
+        private TestHostContext CreateTestContext(bool enableWebSocketBridge = false, [CallerMemberName] string testName = "")
+        {
+            var hc = new TestHostContext(this, testName);
+            _debugger = new DapDebugger();
+            _testWebSocketBridge = null;
+            _debugger.Initialize(hc);
+            _debugger.SkipTunnelRelay = true;
+            _debugger.SkipWebSocketBridge = !enableWebSocketBridge;
+            if (enableWebSocketBridge)
+            {
+                _testWebSocketBridge = new TestWebSocketDapBridge();
+                hc.EnqueueInstance<IWebSocketDapBridge>(_testWebSocketBridge);
+            }
+
+            return hc;
+        }
+
+        private static async Task WithEnvironmentVariableAsync(string name, string value, Func<Task> action)
+        {
+            var originalValue = Environment.GetEnvironmentVariable(name);
+            Environment.SetEnvironmentVariable(name, value);
+            try
+            {
+                await action();
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable(name, originalValue);
+            }
+        }
+
+        private static void WithEnvironmentVariable(string name, string value, Action action)
+        {
+            var originalValue = Environment.GetEnvironmentVariable(name);
+            Environment.SetEnvironmentVariable(name, value);
+            try
+            {
+                action();
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable(name, originalValue);
+            }
+        }
+
+        private static ushort GetFreePort()
+        {
+            using var listener = new TcpListener(IPAddress.Loopback, 0);
+            listener.Start();
+            return (ushort)((IPEndPoint)listener.LocalEndpoint).Port;
+        }
+
+        private static async Task<TcpClient> ConnectClientAsync(int port)
+        {
+            var client = new TcpClient();
+            await client.ConnectAsync(IPAddress.Loopback, port);
+            return client;
+        }
+
+        private static async Task<ClientWebSocket> ConnectWebSocketClientAsync(int port)
+        {
+            var client = new ClientWebSocket();
+            client.Options.Proxy = null;
+            await client.ConnectAsync(new Uri($"ws://127.0.0.1:{port}/"), CancellationToken.None);
+            return client;
+        }
+
+        private static async Task SendRequestAsync(NetworkStream stream, Request request)
+        {
+            var json = JsonConvert.SerializeObject(request);
+            var body = Encoding.UTF8.GetBytes(json);
+            var header = $"Content-Length: {body.Length}\r\n\r\n";
+            var headerBytes = Encoding.ASCII.GetBytes(header);
+
+            await stream.WriteAsync(headerBytes, 0, headerBytes.Length);
+            await stream.WriteAsync(body, 0, body.Length);
+            await stream.FlushAsync();
+        }
+
+        private static async Task SendRequestAsync(WebSocket client, Request request)
+        {
+            var json = JsonConvert.SerializeObject(request);
+            var body = Encoding.UTF8.GetBytes(json);
+
+            await client.SendAsync(new ArraySegment<byte>(body), WebSocketMessageType.Text, endOfMessage: true, CancellationToken.None);
+        }
+
+        /// <summary>
+        /// Reads a single DAP-framed message from a stream with a timeout.
+        /// Parses the Content-Length header, reads exactly that many bytes,
+        /// and returns the JSON body. Fails with a clear error on timeout.
+        /// </summary>
+        private static async Task<string> ReadDapMessageAsync(NetworkStream stream, TimeSpan timeout)
+        {
+            using var cts = new CancellationTokenSource(timeout);
+            var token = cts.Token;
+
+            var headerBuilder = new StringBuilder();
+            var buffer = new byte[1];
+            var contentLength = -1;
+
+            while (true)
+            {
+                var readTask = stream.ReadAsync(buffer, 0, 1, token);
+                var bytesRead = await readTask;
+                if (bytesRead == 0)
+                {
+                    throw new EndOfStreamException("Connection closed while reading DAP headers");
+                }
+
+                headerBuilder.Append((char)buffer[0]);
+                var headers = headerBuilder.ToString();
+                if (headers.EndsWith("\r\n\r\n", StringComparison.Ordinal))
+                {
+                    foreach (var line in headers.Split(new[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries))
+                    {
+                        if (line.StartsWith("Content-Length: ", StringComparison.OrdinalIgnoreCase))
+                        {
+                            contentLength = int.Parse(line.Substring("Content-Length: ".Length).Trim());
+                        }
+                    }
+                    break;
+                }
+            }
+
+            if (contentLength < 0)
+            {
+                throw new InvalidOperationException("No Content-Length header found in DAP message");
+            }
+
+            var body = new byte[contentLength];
+            var totalRead = 0;
+            while (totalRead < contentLength)
+            {
+                var bytesRead = await stream.ReadAsync(body, totalRead, contentLength - totalRead, token);
+                if (bytesRead == 0)
+                {
+                    throw new EndOfStreamException("Connection closed while reading DAP body");
+                }
+                totalRead += bytesRead;
+            }
+
+            return Encoding.UTF8.GetString(body);
+        }
+
+        private static async Task<string> ReadWebSocketDataUntilAsync(WebSocket client, TimeSpan timeout, params string[] expectedFragments)
+        {
+            using var cts = new CancellationTokenSource(timeout);
+            var buffer = new byte[4096];
+            var allMessages = new StringBuilder();
+
+            while (true)
+            {
+                using var messageStream = new MemoryStream();
+                WebSocketReceiveResult result;
+                do
+                {
+                    result = await client.ReceiveAsync(new ArraySegment<byte>(buffer), cts.Token);
+                    if (result.MessageType == WebSocketMessageType.Close)
+                    {
+                        throw new EndOfStreamException("WebSocket closed before expected DAP messages were received.");
+                    }
+
+                    if (result.Count > 0)
+                    {
+                        messageStream.Write(buffer, 0, result.Count);
+                    }
+                }
+                while (!result.EndOfMessage);
+
+                var messageText = Encoding.UTF8.GetString(messageStream.ToArray());
+                allMessages.Append(messageText);
+
+                var text = allMessages.ToString();
+                var containsAllFragments = true;
+                foreach (var fragment in expectedFragments)
+                {
+                    if (!text.Contains(fragment, StringComparison.Ordinal))
+                    {
+                        containsAllFragments = false;
+                        break;
+                    }
+                }
+
+                if (containsAllFragments)
+                {
+                    return text;
+                }
+            }
+        }
+
+        private static Mock<IExecutionContext> CreateJobContextWithTunnel(CancellationToken cancellationToken, ushort port, string jobName = null)
+        {
+            var tunnel = new GitHub.DistributedTask.Pipelines.DebuggerTunnelInfo
+            {
+                TunnelId = "test-tunnel",
+                ClusterId = "test-cluster",
+                HostToken = "test-token",
+                Port = port
+            };
+            var debuggerConfig = new DebuggerConfig(true, tunnel);
+            var jobContext = new Mock<IExecutionContext>();
+            jobContext.Setup(x => x.CancellationToken).Returns(cancellationToken);
+            jobContext.Setup(x => x.Global).Returns(new GlobalContext { Debugger = debuggerConfig });
+            jobContext
+                .Setup(x => x.GetGitHubContext(It.IsAny<string>()))
+                .Returns((string contextName) => string.Equals(contextName, "job", StringComparison.Ordinal) ? jobName : null);
+            return jobContext;
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitializeSucceeds()
+        {
+            using (CreateTestContext())
+            {
+                Assert.NotNull(_debugger);
+                Assert.False(_debugger.IsActive);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAsyncFailsWithoutValidTunnelConfig()
+        {
+            using (CreateTestContext())
+            {
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = new Mock<IExecutionContext>();
+                jobContext.Setup(x => x.CancellationToken).Returns(cts.Token);
+                jobContext.Setup(x => x.Global).Returns(new GlobalContext
+                {
+                    Debugger = new DebuggerConfig(true, null)
+                });
+
+                await Assert.ThrowsAsync<ArgumentException>(() => _debugger.StartAsync(jobContext.Object));
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAsyncUsesPortFromTunnelConfig()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+                using var client = await ConnectClientAsync(port);
+                Assert.True(client.Connected);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAsyncWithWebSocketBridgeAcceptsInitializeOverWebSocket()
+        {
+            using (CreateTestContext(enableWebSocketBridge: true))
+            {
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, GetFreePort());
+                await _debugger.StartAsync(jobContext.Object);
+
+                var bridgePort = _testWebSocketBridge.ListenPort;
+                Assert.NotEqual(0, _debugger.InternalDapPort);
+                Assert.NotEqual(0, bridgePort);
+                Assert.NotEqual(bridgePort, _debugger.InternalDapPort);
+
+                using var client = await ConnectWebSocketClientAsync(bridgePort);
+                await SendRequestAsync(client, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "initialize"
+                });
+
+                var response = await ReadWebSocketDataUntilAsync(
+                    client,
+                    TimeSpan.FromSeconds(5),
+                    "\"type\":\"response\"",
+                    "\"command\":\"initialize\"",
+                    "\"event\":\"initialized\"");
+
+                Assert.Contains("\"success\":true", response);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAsyncWithWebSocketBridgeAcceptsPreUpgradedWebSocketStream()
+        {
+            using (CreateTestContext(enableWebSocketBridge: true))
+            {
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, GetFreePort());
+                await _debugger.StartAsync(jobContext.Object);
+
+                var bridgePort = _testWebSocketBridge.ListenPort;
+                Assert.NotEqual(0, _debugger.InternalDapPort);
+                Assert.NotEqual(0, bridgePort);
+                Assert.NotEqual(bridgePort, _debugger.InternalDapPort);
+
+                using var tcpClient = await ConnectClientAsync(bridgePort);
+                using var webSocket = WebSocket.CreateFromStream(
+                    tcpClient.GetStream(),
+                    isServer: false,
+                    subProtocol: null,
+                    keepAliveInterval: TimeSpan.FromSeconds(30));
+
+                await SendRequestAsync(webSocket, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "initialize"
+                });
+
+                var response = await ReadWebSocketDataUntilAsync(
+                    webSocket,
+                    TimeSpan.FromSeconds(5),
+                    "\"type\":\"response\"",
+                    "\"command\":\"initialize\"",
+                    "\"event\":\"initialized\"");
+
+                Assert.Contains("\"success\":true", response);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTimeoutUsesCustomTimeoutFromEnvironment()
+        {
+            using (CreateTestContext())
+            {
+                WithEnvironmentVariable(TimeoutEnvironmentVariable, "30", () =>
+                {
+                    Assert.Equal(30, _debugger.ResolveTimeout());
+                });
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTimeoutIgnoresInvalidTimeoutFromEnvironment()
+        {
+            using (CreateTestContext())
+            {
+                WithEnvironmentVariable(TimeoutEnvironmentVariable, "not-a-number", () =>
+                {
+                    Assert.Equal(15, _debugger.ResolveTimeout());
+                });
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTimeoutIgnoresZeroTimeoutFromEnvironment()
+        {
+            using (CreateTestContext())
+            {
+                WithEnvironmentVariable(TimeoutEnvironmentVariable, "0", () =>
+                {
+                    Assert.Equal(15, _debugger.ResolveTimeout());
+                });
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAndStopLifecycle()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+                using var client = await ConnectClientAsync(port);
+                Assert.True(client.Connected);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAndStopMultipleTimesDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                foreach (var port in new[] { GetFreePort(), GetFreePort() })
+                {
+                    using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                    var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                    await _debugger.StartAsync(jobContext.Object);
+                    await _debugger.StopAsync();
+                }
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task WaitUntilReadyCompletesAfterClientConnectionAndConfigurationDone()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                await SendRequestAsync(client.GetStream(), new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+
+                await waitTask;
+                Assert.Equal(DapSessionState.Ready, _debugger.State);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartStoresJobContextForThreadsRequest()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
+                await _debugger.StartAsync(jobContext.Object);
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(client.GetStream(), new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "threads"
+                });
+
+                var response = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"command\":\"threads\"", response);
+                Assert.Contains("\"name\":\"Job: ci-job\"", response);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task CancellationUnblocksAndOnJobCompletedTerminates()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                await SendRequestAsync(client.GetStream(), new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+
+                await waitTask;
+                cts.Cancel();
+
+                // In the real runner, JobRunner always calls OnJobCompletedAsync
+                // from a finally block. The cancellation callback only unblocks
+                // pending waits; OnJobCompletedAsync handles state + cleanup.
+                await _debugger.OnJobCompletedAsync();
+                Assert.Equal(DapSessionState.Terminated, _debugger.State);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StopWithoutStartDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnJobCompletedTerminatesSession()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                await SendRequestAsync(client.GetStream(), new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+
+                await waitTask;
+                await _debugger.OnJobCompletedAsync();
+                Assert.Equal(DapSessionState.Terminated, _debugger.State);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task WaitUntilReadyBeforeStartIsNoOp()
+        {
+            using (CreateTestContext())
+            {
+                await _debugger.WaitUntilReadyAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task WaitUntilReadyJobCancellationPropagatesAsOperationCancelledException()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                await Task.Delay(50);
+                cts.Cancel();
+
+                var ex = await Assert.ThrowsAnyAsync<OperationCanceledException>(() => waitTask);
+                Assert.IsNotType<TimeoutException>(ex);
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task InitializeRequestOverSocketPreservesProtocolMetadataWhenSecretsCollide()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.SecretMasker.AddValue("response");
+                hc.SecretMasker.AddValue("initialize");
+                hc.SecretMasker.AddValue("event");
+                hc.SecretMasker.AddValue("initialized");
+
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "initialize"
+                });
+
+                var response = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"type\":\"response\"", response);
+                Assert.Contains("\"command\":\"initialize\"", response);
+                Assert.Contains("\"success\":true", response);
+
+                var initializedEvent = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"type\":\"event\"", initializedEvent);
+                Assert.Contains("\"event\":\"initialized\"", initializedEvent);
+
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task CancellationDuringStepPauseReleasesWait()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                // Complete handshake so session is ready
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+                await waitTask;
+
+                // Simulate a step starting (which pauses)
+                var step = new Mock<IStep>();
+                step.Setup(s => s.DisplayName).Returns("Test Step");
+                step.Setup(s => s.ExecutionContext).Returns((IExecutionContext)null);
+                var stepTask = _debugger.OnStepStartingAsync(step.Object);
+
+                // Give the step time to pause
+                await Task.Delay(50);
+
+                // Cancel the job — should release the step pause
+                cts.Cancel();
+                await stepTask;
+
+                // In the real runner, OnJobCompletedAsync always follows.
+                await _debugger.OnJobCompletedAsync();
+                Assert.Equal(DapSessionState.Terminated, _debugger.State);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StopAsyncSafeAtAnyLifecyclePoint()
+        {
+            using (CreateTestContext())
+            {
+                // StopAsync before start
+                await _debugger.StopAsync();
+
+                // Start then immediate stop (no connection, no WaitUntilReady)
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+                await _debugger.StopAsync();
+
+                // StopAsync after already stopped
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnJobCompletedSendsTerminatedAndExitedEvents()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+
+                // Read the configurationDone response
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                // Complete the job — events are sent via OnJobCompletedAsync
+                await _debugger.OnJobCompletedAsync();
+
+                var msg1 = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var msg2 = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+
+                // Both events should arrive (order may vary)
+                var combined = msg1 + msg2;
+                Assert.Contains("\"event\":\"terminated\"", combined);
+                Assert.Contains("\"event\":\"exited\"", combined);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTunnelConnectTimeoutReturnsDefaultWhenNoVariable()
+        {
+            using (CreateTestContext())
+            {
+                Assert.Equal(30, _debugger.ResolveTunnelConnectTimeout());
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTunnelConnectTimeoutUsesCustomValue()
+        {
+            using (CreateTestContext())
+            {
+                WithEnvironmentVariable(TunnelConnectTimeoutVariable, "60", () =>
+                {
+                    Assert.Equal(60, _debugger.ResolveTunnelConnectTimeout());
+                });
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTunnelConnectTimeoutIgnoresInvalidValue()
+        {
+            using (CreateTestContext())
+            {
+                WithEnvironmentVariable(TunnelConnectTimeoutVariable, "not-a-number", () =>
+                {
+                    Assert.Equal(30, _debugger.ResolveTunnelConnectTimeout());
+                });
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveTunnelConnectTimeoutIgnoresZeroValue()
+        {
+            using (CreateTestContext())
+            {
+                WithEnvironmentVariable(TunnelConnectTimeoutVariable, "0", () =>
+                {
+                    Assert.Equal(30, _debugger.ResolveTunnelConnectTimeout());
+                });
+            }
+        }
+    }
+}
@@ -0,0 +1,233 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using Xunit;
+using GitHub.Runner.Worker.Dap;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapMessagesL0
+    {
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void RequestSerializesCorrectly()
+        {
+            var request = new Request
+            {
+                Seq = 1,
+                Type = "request",
+                Command = "initialize",
+                Arguments = JObject.FromObject(new { clientID = "test-client" })
+            };
+
+            var json = JsonConvert.SerializeObject(request);
+            var deserialized = JsonConvert.DeserializeObject<Request>(json);
+
+            Assert.Equal(1, deserialized.Seq);
+            Assert.Equal("request", deserialized.Type);
+            Assert.Equal("initialize", deserialized.Command);
+            Assert.Equal("test-client", deserialized.Arguments["clientID"].ToString());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResponseSerializesCorrectly()
+        {
+            var response = new Response
+            {
+                Seq = 2,
+                Type = "response",
+                RequestSeq = 1,
+                Success = true,
+                Command = "initialize",
+                Body = new Capabilities { SupportsConfigurationDoneRequest = true }
+            };
+
+            var json = JsonConvert.SerializeObject(response);
+            var deserialized = JsonConvert.DeserializeObject<Response>(json);
+
+            Assert.Equal(2, deserialized.Seq);
+            Assert.Equal("response", deserialized.Type);
+            Assert.Equal(1, deserialized.RequestSeq);
+            Assert.True(deserialized.Success);
+            Assert.Equal("initialize", deserialized.Command);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EventSerializesWithCorrectType()
+        {
+            var evt = new Event
+            {
+                EventType = "stopped",
+                Body = new StoppedEventBody
+                {
+                    Reason = "entry",
+                    Description = "Stopped at entry",
+                    ThreadId = 1,
+                    AllThreadsStopped = true
+                }
+            };
+
+            Assert.Equal("event", evt.Type);
+
+            var json = JsonConvert.SerializeObject(evt);
+            Assert.Contains("\"type\":\"event\"", json);
+            Assert.Contains("\"event\":\"stopped\"", json);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StoppedEventBodyOmitsNullFields()
+        {
+            var body = new StoppedEventBody
+            {
+                Reason = "step"
+            };
+
+            var json = JsonConvert.SerializeObject(body);
+            Assert.Contains("\"reason\":\"step\"", json);
+            Assert.DoesNotContain("\"threadId\"", json);
+            Assert.DoesNotContain("\"allThreadsStopped\"", json);
+            Assert.DoesNotContain("\"description\"", json);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CapabilitiesMvpDefaults()
+        {
+            var caps = new Capabilities
+            {
+                SupportsConfigurationDoneRequest = true,
+                SupportsFunctionBreakpoints = false,
+                SupportsStepBack = false
+            };
+
+            var json = JsonConvert.SerializeObject(caps);
+            var deserialized = JsonConvert.DeserializeObject<Capabilities>(json);
+
+            Assert.True(deserialized.SupportsConfigurationDoneRequest);
+            Assert.False(deserialized.SupportsFunctionBreakpoints);
+            Assert.False(deserialized.SupportsStepBack);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ContinueResponseBodySerialization()
+        {
+            var body = new ContinueResponseBody { AllThreadsContinued = true };
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ContinueResponseBody>(json);
+
+            Assert.True(deserialized.AllThreadsContinued);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ThreadsResponseBodySerialization()
+        {
+            var body = new ThreadsResponseBody
+            {
+                Threads = new List<Thread>
+                {
+                    new Thread { Id = 1, Name = "Job Thread" }
+                }
+            };
+
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ThreadsResponseBody>(json);
+
+            Assert.Single(deserialized.Threads);
+            Assert.Equal(1, deserialized.Threads[0].Id);
+            Assert.Equal("Job Thread", deserialized.Threads[0].Name);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StackFrameSerialization()
+        {
+            var frame = new StackFrame
+            {
+                Id = 1,
+                Name = "Step: Checkout",
+                Line = 1,
+                Column = 1,
+                PresentationHint = "normal"
+            };
+
+            var json = JsonConvert.SerializeObject(frame);
+            var deserialized = JsonConvert.DeserializeObject<StackFrame>(json);
+
+            Assert.Equal(1, deserialized.Id);
+            Assert.Equal("Step: Checkout", deserialized.Name);
+            Assert.Equal("normal", deserialized.PresentationHint);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ExitedEventBodySerialization()
+        {
+            var body = new ExitedEventBody { ExitCode = 130 };
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ExitedEventBody>(json);
+
+            Assert.Equal(130, deserialized.ExitCode);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void DapCommandEnumValues()
+        {
+            Assert.Equal(0, (int)DapCommand.Continue);
+            Assert.Equal(1, (int)DapCommand.Next);
+            Assert.Equal(4, (int)DapCommand.Disconnect);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void RequestDeserializesFromRawJson()
+        {
+            var json = @"{""seq"":5,""type"":""request"",""command"":""continue"",""arguments"":{""threadId"":1}}";
+            var request = JsonConvert.DeserializeObject<Request>(json);
+
+            Assert.Equal(5, request.Seq);
+            Assert.Equal("request", request.Type);
+            Assert.Equal("continue", request.Command);
+            Assert.Equal(1, request.Arguments["threadId"].Value<int>());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ErrorResponseBodySerialization()
+        {
+            var body = new ErrorResponseBody
+            {
+                Error = new Message
+                {
+                    Id = 1,
+                    Format = "Something went wrong",
+                    ShowUser = true
+                }
+            };
+
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ErrorResponseBody>(json);
+
+            Assert.Equal(1, deserialized.Error.Id);
+            Assert.Equal("Something went wrong", deserialized.Error.Format);
+            Assert.True(deserialized.Error.ShowUser);
+        }
+    }
+}
@@ -0,0 +1,237 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.DistributedTask.Expressions2;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.Runner.Common.Tests;
+using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Dap;
+using Moq;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapReplExecutorL0
+    {
+        private TestHostContext _hc;
+        private DapReplExecutor _executor;
+        private List<Event> _sentEvents;
+
+        private TestHostContext CreateTestContext([CallerMemberName] string testName = "")
+        {
+            _hc = new TestHostContext(this, testName);
+            _sentEvents = new List<Event>();
+            _executor = new DapReplExecutor(_hc, (category, text) =>
+            {
+                _sentEvents.Add(new Event
+                {
+                    EventType = "output",
+                    Body = new OutputEventBody
+                    {
+                        Category = category,
+                        Output = text
+                    }
+                });
+            });
+            return _hc;
+        }
+
+        private Mock<IExecutionContext> CreateMockContext(
+            DictionaryContextData exprValues = null,
+            IDictionary<string, IDictionary<string, string>> jobDefaults = null)
+        {
+            var mock = new Mock<IExecutionContext>();
+            mock.Setup(x => x.ExpressionValues).Returns(exprValues ?? new DictionaryContextData());
+            mock.Setup(x => x.ExpressionFunctions).Returns(new List<IFunctionInfo>());
+
+            var global = new GlobalContext
+            {
+                PrependPath = new List<string>(),
+                JobDefaults = jobDefaults
+                    ?? new Dictionary<string, IDictionary<string, string>>(StringComparer.OrdinalIgnoreCase),
+            };
+            mock.Setup(x => x.Global).Returns(global);
+
+            return mock;
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task ExecuteRunCommand_NullContext_ReturnsError()
+        {
+            using (CreateTestContext())
+            {
+                var command = new RunCommand { Script = "echo hello" };
+                var result = await _executor.ExecuteRunCommandAsync(command, null, CancellationToken.None);
+
+                Assert.Equal("error", result.Type);
+                Assert.Contains("No execution context available", result.Result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ExpandExpressions_NoExpressions_ReturnsInput()
+        {
+            using (CreateTestContext())
+            {
+                var context = CreateMockContext();
+                var result = _executor.ExpandExpressions("echo hello", context.Object);
+
+                Assert.Equal("echo hello", result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ExpandExpressions_NullInput_ReturnsEmpty()
+        {
+            using (CreateTestContext())
+            {
+                var context = CreateMockContext();
+                var result = _executor.ExpandExpressions(null, context.Object);
+
+                Assert.Equal(string.Empty, result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ExpandExpressions_EmptyInput_ReturnsEmpty()
+        {
+            using (CreateTestContext())
+            {
+                var context = CreateMockContext();
+                var result = _executor.ExpandExpressions("", context.Object);
+
+                Assert.Equal(string.Empty, result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ExpandExpressions_UnterminatedExpression_KeepsLiteral()
+        {
+            using (CreateTestContext())
+            {
+                var context = CreateMockContext();
+                var result = _executor.ExpandExpressions("echo ${{ github.repo", context.Object);
+
+                Assert.Equal("echo ${{ github.repo", result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveDefaultShell_NoJobDefaults_ReturnsPlatformDefault()
+        {
+            using (CreateTestContext())
+            {
+                var context = CreateMockContext();
+                var result = _executor.ResolveDefaultShell(context.Object);
+
+#if OS_WINDOWS
+                Assert.True(result == "pwsh" || result == "powershell");
+#else
+                Assert.Equal("sh", result);
+#endif
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResolveDefaultShell_WithJobDefault_ReturnsJobDefault()
+        {
+            using (CreateTestContext())
+            {
+                var jobDefaults = new Dictionary<string, IDictionary<string, string>>(StringComparer.OrdinalIgnoreCase)
+                {
+                    ["run"] = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        ["shell"] = "bash"
+                    }
+                };
+                var context = CreateMockContext(jobDefaults: jobDefaults);
+                var result = _executor.ResolveDefaultShell(context.Object);
+
+                Assert.Equal("bash", result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void BuildEnvironment_MergesEnvContextAndReplOverrides()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                var envData = new DictionaryContextData
+                {
+                    ["FOO"] = new StringContextData("bar"),
+                };
+                exprValues["env"] = envData;
+
+                var context = CreateMockContext(exprValues);
+                var replEnv = new Dictionary<string, string> { { "BAZ", "qux" } };
+                var result = _executor.BuildEnvironment(context.Object, replEnv);
+
+                Assert.Equal("bar", result["FOO"]);
+                Assert.Equal("qux", result["BAZ"]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void BuildEnvironment_ReplOverridesWin()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                var envData = new DictionaryContextData
+                {
+                    ["FOO"] = new StringContextData("original"),
+                };
+                exprValues["env"] = envData;
+
+                var context = CreateMockContext(exprValues);
+                var replEnv = new Dictionary<string, string> { { "FOO", "override" } };
+                var result = _executor.BuildEnvironment(context.Object, replEnv);
+
+                Assert.Equal("override", result["FOO"]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void BuildEnvironment_NullReplEnv_ReturnsContextEnvOnly()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                var envData = new DictionaryContextData
+                {
+                    ["FOO"] = new StringContextData("bar"),
+                };
+                exprValues["env"] = envData;
+
+                var context = CreateMockContext(exprValues);
+                var result = _executor.BuildEnvironment(context.Object, null);
+
+                Assert.Equal("bar", result["FOO"]);
+                Assert.False(result.ContainsKey("BAZ"));
+            }
+        }
+    }
+}
@@ -0,0 +1,314 @@
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using GitHub.Runner.Common.Tests;
+using GitHub.Runner.Worker.Dap;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapReplParserL0
+    {
+        #region help command
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_HelpReturnsHelpCommand()
+        {
+            var cmd = DapReplParser.TryParse("help", out var error);
+
+            Assert.Null(error);
+            var help = Assert.IsType<HelpCommand>(cmd);
+            Assert.Null(help.Topic);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_HelpCaseInsensitive()
+        {
+            var cmd = DapReplParser.TryParse("Help", out var error);
+            Assert.Null(error);
+            Assert.IsType<HelpCommand>(cmd);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_HelpWithTopic()
+        {
+            var cmd = DapReplParser.TryParse("help(\"run\")", out var error);
+
+            Assert.Null(error);
+            var help = Assert.IsType<HelpCommand>(cmd);
+            Assert.Equal("run", help.Topic);
+        }
+
+        #endregion
+
+        #region run command — basic
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunSimpleScript()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo hello\")", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("echo hello", run.Script);
+            Assert.Null(run.Shell);
+            Assert.Null(run.Env);
+            Assert.Null(run.WorkingDirectory);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithShell()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo hello\", shell: \"bash\")", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("echo hello", run.Script);
+            Assert.Equal("bash", run.Shell);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithWorkingDirectory()
+        {
+            var cmd = DapReplParser.TryParse("run(\"ls\", working_directory: \"/tmp\")", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("ls", run.Script);
+            Assert.Equal("/tmp", run.WorkingDirectory);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithEnv()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo $FOO\", env: { FOO: \"bar\" })", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("echo $FOO", run.Script);
+            Assert.NotNull(run.Env);
+            Assert.Equal("bar", run.Env["FOO"]);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithMultipleEnvVars()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo\", env: { A: \"1\", B: \"2\" })", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal(2, run.Env.Count);
+            Assert.Equal("1", run.Env["A"]);
+            Assert.Equal("2", run.Env["B"]);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithAllOptions()
+        {
+            var input = "run(\"echo $X\", shell: \"zsh\", env: { X: \"1\" }, working_directory: \"/tmp\")";
+            var cmd = DapReplParser.TryParse(input, out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("echo $X", run.Script);
+            Assert.Equal("zsh", run.Shell);
+            Assert.Equal("1", run.Env["X"]);
+            Assert.Equal("/tmp", run.WorkingDirectory);
+        }
+
+        #endregion
+
+        #region run command — edge cases
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithEscapedQuotes()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo \\\"hello\\\"\")", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("echo \"hello\"", run.Script);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunWithCommaInEnvValue()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo\", env: { CSV: \"a,b,c\" })", out var error);
+
+            Assert.Null(error);
+            var run = Assert.IsType<RunCommand>(cmd);
+            Assert.Equal("a,b,c", run.Env["CSV"]);
+        }
+
+        #endregion
+
+        #region error cases
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunEmptyArgsReturnsError()
+        {
+            var cmd = DapReplParser.TryParse("run()", out var error);
+
+            Assert.NotNull(error);
+            Assert.Null(cmd);
+            Assert.Contains("requires a script argument", error);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunUnquotedArgReturnsError()
+        {
+            var cmd = DapReplParser.TryParse("run(echo hello)", out var error);
+
+            Assert.NotNull(error);
+            Assert.Null(cmd);
+            Assert.Contains("quoted string", error);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunUnknownOptionReturnsError()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo\", timeout: \"10\")", out var error);
+
+            Assert.NotNull(error);
+            Assert.Null(cmd);
+            Assert.Contains("Unknown option", error);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_RunMissingClosingParenReturnsError()
+        {
+            var cmd = DapReplParser.TryParse("run(\"echo\"", out var error);
+
+            Assert.NotNull(error);
+            Assert.Null(cmd);
+        }
+
+        #endregion
+
+        #region non-DSL input falls through
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_ExpressionReturnsNull()
+        {
+            var cmd = DapReplParser.TryParse("github.repository", out var error);
+
+            Assert.Null(error);
+            Assert.Null(cmd);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_WrappedExpressionReturnsNull()
+        {
+            var cmd = DapReplParser.TryParse("${{ github.event_name }}", out var error);
+
+            Assert.Null(error);
+            Assert.Null(cmd);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Parse_EmptyInputReturnsNull()
+        {
+            var cmd = DapReplParser.TryParse("", out var error);
+            Assert.Null(error);
+            Assert.Null(cmd);
+
+            cmd = DapReplParser.TryParse(null, out error);
+            Assert.Null(error);
+            Assert.Null(cmd);
+        }
+
+        #endregion
+
+        #region help text
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetGeneralHelp_ContainsCommands()
+        {
+            var help = DapReplParser.GetGeneralHelp();
+
+            Assert.Contains("help", help);
+            Assert.Contains("run", help);
+            Assert.Contains("expression", help, System.StringComparison.OrdinalIgnoreCase);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetRunHelp_ContainsOptions()
+        {
+            var help = DapReplParser.GetRunHelp();
+
+            Assert.Contains("shell", help);
+            Assert.Contains("env", help);
+            Assert.Contains("working_directory", help);
+        }
+
+        #endregion
+
+        #region internal parser helpers
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SplitArguments_HandlesNestedBraces()
+        {
+            var args = DapReplParser.SplitArguments("\"hello\", env: { A: \"1\", B: \"2\" }", out var error);
+
+            Assert.Null(error);
+            Assert.Equal(2, args.Count);
+            Assert.Equal("\"hello\"", args[0].Trim());
+            Assert.Contains("A:", args[1]);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ParseEnvBlock_HandlesEmptyBlock()
+        {
+            var result = DapReplParser.ParseEnvBlock("{ }", out var error);
+
+            Assert.Null(error);
+            Assert.NotNull(result);
+            Assert.Empty(result);
+        }
+
+        #endregion
+    }
+}
@@ -0,0 +1,728 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Common;
+using GitHub.Runner.Common.Tests;
+using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Dap;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapVariableProviderL0
+    {
+        private TestHostContext _hc;
+        private DapVariableProvider _provider;
+
+        private TestHostContext CreateTestContext([CallerMemberName] string testName = "")
+        {
+            _hc = new TestHostContext(this, testName);
+            _provider = new DapVariableProvider(_hc.SecretMasker);
+            return _hc;
+        }
+
+        private Moq.Mock<GitHub.Runner.Worker.IExecutionContext> CreateMockContext(DictionaryContextData expressionValues)
+        {
+            var mock = new Moq.Mock<GitHub.Runner.Worker.IExecutionContext>();
+            mock.Setup(x => x.ExpressionValues).Returns(expressionValues);
+            return mock;
+        }
+
+        #region GetScopes tests
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetScopes_ReturnsEmptyWhenContextIsNull()
+        {
+            using (CreateTestContext())
+            {
+                var scopes = _provider.GetScopes(null);
+                Assert.Empty(scopes);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetScopes_ReturnsOnlyPopulatedScopes()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "repository", new StringContextData("owner/repo") }
+                };
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "CI", new StringContextData("true") },
+                    { "HOME", new StringContextData("/home/runner") }
+                };
+                // "runner" is not set — should not appear in scopes
+
+                var ctx = CreateMockContext(exprValues);
+                var scopes = _provider.GetScopes(ctx.Object);
+
+                Assert.Equal(2, scopes.Count);
+                Assert.Equal("github", scopes[0].Name);
+                Assert.Equal("env", scopes[1].Name);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetScopes_ReportsNamedVariableCount()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "A", new StringContextData("1") },
+                    { "B", new StringContextData("2") },
+                    { "C", new StringContextData("3") }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var scopes = _provider.GetScopes(ctx.Object);
+
+                Assert.Single(scopes);
+                Assert.Equal(3, scopes[0].NamedVariables);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetScopes_SecretsGetSpecialPresentationHint()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["secrets"] = new DictionaryContextData
+                {
+                    { "MY_SECRET", new StringContextData("super-secret") }
+                };
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "CI", new StringContextData("true") }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var scopes = _provider.GetScopes(ctx.Object);
+
+                var envScope = scopes.Find(s => s.Name == "env");
+                var secretsScope = scopes.Find(s => s.Name == "secrets");
+
+                Assert.NotNull(envScope);
+                Assert.Null(envScope.PresentationHint);
+
+                Assert.NotNull(secretsScope);
+                Assert.Equal("registers", secretsScope.PresentationHint);
+            }
+        }
+
+        #endregion
+
+        #region GetVariables — basic types
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_ReturnsEmptyWhenContextIsNull()
+        {
+            using (CreateTestContext())
+            {
+                var variables = _provider.GetVariables(null, 1);
+                Assert.Empty(variables);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_ReturnsStringVariables()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "CI", new StringContextData("true") },
+                    { "HOME", new StringContextData("/home/runner") }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                // "env" is at ScopeNames index 1 → variablesReference = 2
+                var variables = _provider.GetVariables(ctx.Object, 2);
+
+                Assert.Equal(2, variables.Count);
+
+                var ciVar = variables.Find(v => v.Name == "CI");
+                Assert.NotNull(ciVar);
+                Assert.Equal("true", ciVar.Value);
+                Assert.Equal("string", ciVar.Type);
+                Assert.Equal(0, ciVar.VariablesReference);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_ReturnsBooleanVariables()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "event_name", new StringContextData("push") },
+                };
+                // Use a nested dict with boolean to test
+                var jobDict = new DictionaryContextData();
+                // BooleanContextData is a valid PipelineContextData type
+                // but job context typically has strings. Use env scope instead.
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "flag", new BooleanContextData(true) }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                // "env" is at index 1 → ref 2
+                var variables = _provider.GetVariables(ctx.Object, 2);
+
+                var flagVar = variables.Find(v => v.Name == "flag");
+                Assert.NotNull(flagVar);
+                Assert.Equal("true", flagVar.Value);
+                Assert.Equal("boolean", flagVar.Type);
+                Assert.Equal(0, flagVar.VariablesReference);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_ReturnsNumberVariables()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "count", new NumberContextData(42) }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 2);
+
+                var countVar = variables.Find(v => v.Name == "count");
+                Assert.NotNull(countVar);
+                Assert.Equal("42", countVar.Value);
+                Assert.Equal("number", countVar.Type);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_HandlesNullValues()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                var dict = new DictionaryContextData();
+                dict["present"] = new StringContextData("yes");
+                dict["missing"] = null;
+                exprValues["env"] = dict;
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 2);
+
+                var nullVar = variables.Find(v => v.Name == "missing");
+                Assert.NotNull(nullVar);
+                Assert.Equal("null", nullVar.Value);
+                Assert.Equal("null", nullVar.Type);
+                Assert.Equal(0, nullVar.VariablesReference);
+            }
+        }
+
+        #endregion
+
+        #region GetVariables — nested expansion
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_NestedDictionaryIsExpandable()
+        {
+            using (CreateTestContext())
+            {
+                var innerDict = new DictionaryContextData
+                {
+                    { "name", new StringContextData("push") },
+                    { "ref", new StringContextData("refs/heads/main") }
+                };
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "event", innerDict }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                // "github" is at index 0 → ref 1
+                var variables = _provider.GetVariables(ctx.Object, 1);
+
+                var eventVar = variables.Find(v => v.Name == "event");
+                Assert.NotNull(eventVar);
+                Assert.Equal("object", eventVar.Type);
+                Assert.True(eventVar.VariablesReference > 0, "Nested dict should have a non-zero variablesReference");
+                Assert.Equal(2, eventVar.NamedVariables);
+
+                // Now expand it
+                var children = _provider.GetVariables(ctx.Object, eventVar.VariablesReference);
+                Assert.Equal(2, children.Count);
+
+                var nameVar = children.Find(v => v.Name == "name");
+                Assert.NotNull(nameVar);
+                Assert.Equal("push", nameVar.Value);
+                Assert.Equal("${{ github.event.name }}", nameVar.EvaluateName);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_NestedArrayIsExpandable()
+        {
+            using (CreateTestContext())
+            {
+                var array = new ArrayContextData();
+                array.Add(new StringContextData("item0"));
+                array.Add(new StringContextData("item1"));
+
+                var exprValues = new DictionaryContextData();
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "list", array }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 2);
+
+                var listVar = variables.Find(v => v.Name == "list");
+                Assert.NotNull(listVar);
+                Assert.Equal("array", listVar.Type);
+                Assert.True(listVar.VariablesReference > 0);
+                Assert.Equal(2, listVar.IndexedVariables);
+
+                // Expand the array
+                var items = _provider.GetVariables(ctx.Object, listVar.VariablesReference);
+                Assert.Equal(2, items.Count);
+                Assert.Equal("[0]", items[0].Name);
+                Assert.Equal("item0", items[0].Value);
+                Assert.Equal("[1]", items[1].Name);
+                Assert.Equal("item1", items[1].Value);
+            }
+        }
+
+        #endregion
+
+        #region Secret masking
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_SecretsScopeValuesAreRedacted()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["secrets"] = new DictionaryContextData
+                {
+                    { "MY_TOKEN", new StringContextData("ghp_abc123secret") },
+                    { "DB_PASSWORD", new StringContextData("p@ssword!") }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                // "secrets" is at index 5 → ref 6
+                var variables = _provider.GetVariables(ctx.Object, 6);
+
+                Assert.Equal(2, variables.Count);
+                foreach (var v in variables)
+                {
+                    Assert.Equal("***", v.Value);
+                    Assert.Equal("string", v.Type);
+                }
+
+                // Keys should still be visible
+                Assert.Contains(variables, v => v.Name == "MY_TOKEN");
+                Assert.Contains(variables, v => v.Name == "DB_PASSWORD");
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_NonSecretScopeValuesMaskedBySecretMasker()
+        {
+            using (var hc = CreateTestContext())
+            {
+                // Register a known secret value with the masker
+                hc.SecretMasker.AddValue("super-secret-token");
+
+                var exprValues = new DictionaryContextData();
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "SAFE", new StringContextData("hello world") },
+                    { "LEAKED", new StringContextData("prefix-super-secret-token-suffix") }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 2);
+
+                var safeVar = variables.Find(v => v.Name == "SAFE");
+                Assert.NotNull(safeVar);
+                Assert.Equal("hello world", safeVar.Value);
+
+                var leakedVar = variables.Find(v => v.Name == "LEAKED");
+                Assert.NotNull(leakedVar);
+                Assert.DoesNotContain("super-secret-token", leakedVar.Value);
+                Assert.Contains("***", leakedVar.Value);
+            }
+        }
+
+        #endregion
+
+        #region Reset
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Reset_InvalidatesNestedReferences()
+        {
+            using (CreateTestContext())
+            {
+                var innerDict = new DictionaryContextData
+                {
+                    { "name", new StringContextData("push") }
+                };
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "event", innerDict }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 1);
+                var eventVar = variables.Find(v => v.Name == "event");
+                Assert.True(eventVar.VariablesReference > 0);
+
+                var savedRef = eventVar.VariablesReference;
+
+                // Reset should clear all dynamic references
+                _provider.Reset();
+
+                var children = _provider.GetVariables(ctx.Object, savedRef);
+                Assert.Empty(children);
+            }
+        }
+
+        #endregion
+
+        #region EvaluateName
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_SetsEvaluateNameWithDotPath()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "repository", new StringContextData("owner/repo") }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 1);
+
+                var repoVar = variables.Find(v => v.Name == "repository");
+                Assert.NotNull(repoVar);
+                Assert.Equal("${{ github.repository }}", repoVar.EvaluateName);
+            }
+        }
+
+        #endregion
+
+        #region EvaluateExpression
+
+        /// <summary>
+        /// Creates a mock execution context with Global set up so that
+        /// ToPipelineTemplateEvaluator() works for real expression evaluation.
+        /// </summary>
+        private Moq.Mock<IExecutionContext> CreateEvaluatableContext(
+            TestHostContext hc,
+            DictionaryContextData expressionValues)
+        {
+            var mock = new Moq.Mock<IExecutionContext>();
+            mock.Setup(x => x.ExpressionValues).Returns(expressionValues);
+            mock.Setup(x => x.ExpressionFunctions)
+                .Returns(new List<GitHub.DistributedTask.Expressions2.IFunctionInfo>());
+            mock.Setup(x => x.Global).Returns(new GlobalContext
+            {
+                FileTable = new List<string>(),
+                Variables = new Variables(hc, new Dictionary<string, VariableValue>()),
+            });
+            // ToPipelineTemplateEvaluator uses ToTemplateTraceWriter which calls
+            // context.Write — provide a no-op so it doesn't NRE.
+            mock.Setup(x => x.Write(Moq.It.IsAny<string>(), Moq.It.IsAny<string>()));
+            return mock;
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateExpression_ReturnsValueForSimpleExpression()
+        {
+            using (var hc = CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "repository", new StringContextData("owner/repo") }
+                };
+
+                var ctx = CreateEvaluatableContext(hc, exprValues);
+                var result = _provider.EvaluateExpression("github.repository", ctx.Object);
+
+                Assert.Equal("owner/repo", result.Result);
+                Assert.Equal("string", result.Type);
+                Assert.Equal(0, result.VariablesReference);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateExpression_StripsWrapperSyntax()
+        {
+            using (var hc = CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData
+                {
+                    { "event_name", new StringContextData("push") }
+                };
+
+                var ctx = CreateEvaluatableContext(hc, exprValues);
+                var result = _provider.EvaluateExpression("${{ github.event_name }}", ctx.Object);
+
+                Assert.Equal("push", result.Result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateExpression_MasksSecretInResult()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.SecretMasker.AddValue("super-secret");
+
+                var exprValues = new DictionaryContextData();
+                exprValues["env"] = new DictionaryContextData
+                {
+                    { "TOKEN", new StringContextData("super-secret") }
+                };
+
+                var ctx = CreateEvaluatableContext(hc, exprValues);
+                var result = _provider.EvaluateExpression("env.TOKEN", ctx.Object);
+
+                Assert.DoesNotContain("super-secret", result.Result);
+                Assert.Contains("***", result.Result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateExpression_ReturnsErrorForInvalidExpression()
+        {
+            using (var hc = CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["github"] = new DictionaryContextData();
+
+                var ctx = CreateEvaluatableContext(hc, exprValues);
+                // An invalid expression syntax should not throw — it should
+                // return an error result.
+                var result = _provider.EvaluateExpression("!!!invalid[[", ctx.Object);
+
+                Assert.Contains("error", result.Result, StringComparison.OrdinalIgnoreCase);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateExpression_ReturnsMessageWhenNoContext()
+        {
+            using (CreateTestContext())
+            {
+                var result = _provider.EvaluateExpression("github.repository", null);
+
+                Assert.Contains("no execution context", result.Result, StringComparison.OrdinalIgnoreCase);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateExpression_ReturnsEmptyForEmptyExpression()
+        {
+            using (var hc = CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                var ctx = CreateEvaluatableContext(hc, exprValues);
+                var result = _provider.EvaluateExpression("", ctx.Object);
+
+                Assert.Equal(string.Empty, result.Result);
+            }
+        }
+
+        #endregion
+
+        #region InferResultType
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InferResultType_ClassifiesCorrectly()
+        {
+            using (CreateTestContext())
+            {
+                Assert.Equal("null", DapVariableProvider.InferResultType(null));
+                Assert.Equal("null", DapVariableProvider.InferResultType("null"));
+                Assert.Equal("boolean", DapVariableProvider.InferResultType("true"));
+                Assert.Equal("boolean", DapVariableProvider.InferResultType("false"));
+                Assert.Equal("number", DapVariableProvider.InferResultType("42"));
+                Assert.Equal("number", DapVariableProvider.InferResultType("3.14"));
+                Assert.Equal("object", DapVariableProvider.InferResultType("{\"key\":\"val\"}"));
+                Assert.Equal("object", DapVariableProvider.InferResultType("[1,2,3]"));
+                Assert.Equal("string", DapVariableProvider.InferResultType("hello world"));
+                Assert.Equal("string", DapVariableProvider.InferResultType("owner/repo"));
+            }
+        }
+
+        #endregion
+
+        #region Non-string secret type redaction
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_SecretsScopeRedactsNumberContextData()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["secrets"] = new DictionaryContextData
+                {
+                    { "NUMERIC_SECRET", new NumberContextData(12345) }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 6);
+
+                Assert.Single(variables);
+                Assert.Equal("NUMERIC_SECRET", variables[0].Name);
+                Assert.Equal("***", variables[0].Value);
+                Assert.Equal("string", variables[0].Type);
+                Assert.Equal(0, variables[0].VariablesReference);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_SecretsScopeRedactsBooleanContextData()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["secrets"] = new DictionaryContextData
+                {
+                    { "BOOL_SECRET", new BooleanContextData(true) }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 6);
+
+                Assert.Single(variables);
+                Assert.Equal("BOOL_SECRET", variables[0].Name);
+                Assert.Equal("***", variables[0].Value);
+                Assert.Equal("string", variables[0].Type);
+                Assert.Equal(0, variables[0].VariablesReference);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_SecretsScopeRedactsNestedDictionary()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                exprValues["secrets"] = new DictionaryContextData
+                {
+                    { "NESTED_SECRET", new DictionaryContextData
+                        {
+                            { "inner_key", new StringContextData("inner_value") }
+                        }
+                    }
+                };
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 6);
+
+                Assert.Single(variables);
+                Assert.Equal("NESTED_SECRET", variables[0].Name);
+                Assert.Equal("***", variables[0].Value);
+                Assert.Equal("string", variables[0].Type);
+                // Nested container should NOT be drillable under secrets
+                Assert.Equal(0, variables[0].VariablesReference);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void GetVariables_SecretsScopeRedactsNullValue()
+        {
+            using (CreateTestContext())
+            {
+                var exprValues = new DictionaryContextData();
+                var secrets = new DictionaryContextData();
+                secrets["NULL_SECRET"] = null;
+                exprValues["secrets"] = secrets;
+
+                var ctx = CreateMockContext(exprValues);
+                var variables = _provider.GetVariables(ctx.Object, 6);
+
+                Assert.Single(variables);
+                Assert.Equal("NULL_SECRET", variables[0].Name);
+                Assert.Equal("***", variables[0].Value);
+                Assert.Equal(0, variables[0].VariablesReference);
+            }
+        }
+
+        #endregion
+    }
+}
@@ -1203,19 +1203,19 @@ namespace GitHub.Runner.Common.Tests.Worker
            }
        }

-        // TODO: this test can be deleted when `AddCheckRunIdToJobContext` is fully rolled out
+        // AddCheckRunIdToJobContext is now permanently enabled server-side (hardcoded to "true"
+        // in acquirejobhandler.go). The runner always copies ContextData["job"] entries, so the
+        // flag-disabled test is no longer applicable. Replaced with a test that verifies
+        // check_run_id is always hydrated regardless of the flag value.
        [Fact]
        [Trait("Level", "L0")]
        [Trait("Category", "Worker")]
-        public void InitializeJob_HydratesJobContextWithCheckRunId_FeatureFlagDisabled()
+        public void InitializeJob_HydratesJobContextWithCheckRunId_AlwaysCopied()
        {
            using (TestHostContext hc = CreateTestContext())
            {
-                // Arrange: Create a job request message and make sure the feature flag is disabled
-                var variables = new Dictionary<string, VariableValue>()
-                {
-                    [Constants.Runner.Features.AddCheckRunIdToJobContext] = new VariableValue("false"),
-                };
+                // Arrange: No feature flag set at all
+                var variables = new Dictionary<string, VariableValue>();
                var jobRequest = new Pipelines.AgentJobRequestMessage(new TaskOrchestrationPlanReference(), new TimelineReference(), Guid.NewGuid(), "some job name", "some job name", null, null, null, variables, new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
                var pagingLogger = new Moq.Mock<IPagingLogger>();
                var jobServerQueue = new Moq.Mock<IJobServerQueue>();
@@ -1233,9 +1233,80 @@ namespace GitHub.Runner.Common.Tests.Worker
                // Act
                ec.InitializeJob(jobRequest, CancellationToken.None);

-                // Assert
+                // Assert: check_run_id is always copied regardless of flag
                Assert.NotNull(ec.JobContext);
-                Assert.Null(ec.JobContext.CheckRunId); // with the feature flag disabled we should not have added a CheckRunId to the JobContext
+                Assert.Equal(123456, ec.JobContext.CheckRunId);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitializeJob_HydratesJobContextWithWorkflowIdentity()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange
+                var variables = new Dictionary<string, VariableValue>();
+                var jobRequest = new Pipelines.AgentJobRequestMessage(new TaskOrchestrationPlanReference(), new TimelineReference(), Guid.NewGuid(), "some job name", "some job name", null, null, null, variables, new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
+                var pagingLogger = new Moq.Mock<IPagingLogger>();
+                var jobServerQueue = new Moq.Mock<IJobServerQueue>();
+                hc.EnqueueInstance(pagingLogger.Object);
+                hc.SetSingleton(jobServerQueue.Object);
+                var ec = new Runner.Worker.ExecutionContext();
+                ec.Initialize(hc);
+
+                // Arrange: Server sends all 4 workflow identity fields
+                var jobContext = new Pipelines.ContextData.DictionaryContextData();
+                jobContext["workflow_ref"] = new StringContextData("my-org/my-repo/.github/workflows/reusable.yml@refs/heads/main");
+                jobContext["workflow_sha"] = new StringContextData("abc123def456");
+                jobContext["workflow_repository"] = new StringContextData("my-org/my-repo");
+                jobContext["workflow_file_path"] = new StringContextData(".github/workflows/reusable.yml");
+                jobRequest.ContextData["job"] = jobContext;
+                jobRequest.ContextData["github"] = new Pipelines.ContextData.DictionaryContextData();
+
+                // Act
+                ec.InitializeJob(jobRequest, CancellationToken.None);
+
+                // Assert: all properties hydrated from server
+                Assert.NotNull(ec.JobContext);
+                Assert.Equal("my-org/my-repo/.github/workflows/reusable.yml@refs/heads/main", ec.JobContext.WorkflowRef);
+                Assert.Equal("abc123def456", ec.JobContext.WorkflowSha);
+                Assert.Equal("my-org/my-repo", ec.JobContext.WorkflowRepository);
+                Assert.Equal(".github/workflows/reusable.yml", ec.JobContext.WorkflowFilePath);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitializeJob_WorkflowIdentityNotSet_WhenServerSendsNoData()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange: Server sends no workflow identity in job context
+                var variables = new Dictionary<string, VariableValue>();
+                var jobRequest = new Pipelines.AgentJobRequestMessage(new TaskOrchestrationPlanReference(), new TimelineReference(), Guid.NewGuid(), "some job name", "some job name", null, null, null, variables, new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
+                var pagingLogger = new Moq.Mock<IPagingLogger>();
+                var jobServerQueue = new Moq.Mock<IJobServerQueue>();
+                hc.EnqueueInstance(pagingLogger.Object);
+                hc.SetSingleton(jobServerQueue.Object);
+                var ec = new Runner.Worker.ExecutionContext();
+                ec.Initialize(hc);
+
+                // Arrange: empty job context
+                jobRequest.ContextData["job"] = new Pipelines.ContextData.DictionaryContextData();
+                jobRequest.ContextData["github"] = new Pipelines.ContextData.DictionaryContextData();
+
+                // Act
+                ec.InitializeJob(jobRequest, CancellationToken.None);
+
+                // Assert: no workflow identity
+                Assert.NotNull(ec.JobContext);
+                Assert.Null(ec.JobContext.WorkflowRef);
+                Assert.Null(ec.JobContext.WorkflowSha);
+                Assert.Null(ec.JobContext.WorkflowRepository);
+                Assert.Null(ec.JobContext.WorkflowFilePath);
            }
        }

--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Salman Chishti	6fb19df797	Merge branch 'main' into dependabot/nuget/src/Runner.Sdk/main/System.Text.Encoding.CodePages-10.0.6	2026-04-21 17:34:12 +01:00
Salman Chishti	00af8379a2	Add vulnerability-alerts permission (#4350 )	2026-04-21 17:31:10 +01:00
dependabot[bot]	727509bed2	Bump System.Text.Encoding.CodePages from 10.0.3 to 10.0.6 --- updated-dependencies: - dependency-name: System.Text.Encoding.CodePages dependency-version: 10.0.6 dependency-type: direct:production update-type: version-update:semver-patch ... Signed-off-by: dependabot[bot] <support@github.com>	2026-04-21 16:09:16 +00:00
dependabot[bot]	6692e6a590	Bump System.Formats.Asn1 and System.Security.Cryptography.Pkcs (#4362 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-04-21 16:06:40 +00:00
dependabot[bot]	cacb25d2ed	Bump @typescript-eslint/parser from 8.58.1 to 8.59.0 in /src/Misc/expressionFunc/hashFiles (#4360 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-04-21 15:15:02 +01:00
github-actions[bot]	c6ca9f6edb	Update dotnet sdk to latest version @8.0.420 (#4356 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-04-20 17:06:35 +00:00
Copilot	fad1253513	Bump Docker version to 29.4.0 (#4352 ) Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: luketomlinson <19689611+luketomlinson@users.noreply.github.com>	2026-04-20 10:45:12 -04:00
github-actions[bot]	45debbd528	chore: update Node versions (#4355 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-04-20 12:44:20 +00:00
Francesco Renzi	43e5211996	Add WS bridge over DAP TCP server (#4328 ) Co-authored-by: Tingluo Huang <tingluohuang@github.com>	2026-04-17 09:18:01 -04:00
Salman Chishti	4a587ada27	feat: add `job.workflow_*` typed accessors to JobContext (#4335 )	2026-04-10 19:39:33 +01:00
Copilot	182a433782	Bump System.Formats.Asn1, Cryptography.Pkcs, ProtectedData, ServiceController, CodePages, Threading.Channels, @actions/glob, @typescript-eslint/parser, lint-staged, picomatch (#4333 ) Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-04-10 12:40:28 +01:00
Salman Chishti	8d35e710da	fix: only show changed versions in node upgrade PR description (#4332 )	2026-04-10 11:34:08 +01:00
dependabot[bot]	2bcc65e864	Bump typescript from 5.9.3 to 6.0.2 in /src/Misc/expressionFunc/hashFiles (#4329 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-04-10 09:01:34 +01:00
dependabot[bot]	1ba5fdfd88	Bump actions/github-script from 8 to 9 (#4331 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-04-10 08:54:56 +01:00
dependabot[bot]	580116c18b	Bump @typescript-eslint/eslint-plugin from 8.57.2 to 8.58.1 in /src/Misc/expressionFunc/hashFiles (#4327 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-04-08 07:44:38 +00:00
github-actions[bot]	c9a1751d87	Update Docker to v29.3.1 and Buildx to v0.33.0 (#4324 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-04-08 08:40:32 +01:00
Francesco Renzi	7711dc53e2	Add devtunnel connection for debugger jobs (#4317 )	2026-04-07 12:51:33 +00:00
dependabot[bot]	df507886cb	Bump brace-expansion in /src/Misc/expressionFunc/hashFiles (#4318 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-04-01 13:19:42 +01:00
Tingluo Huang	5c6dd47e76	Add support for Bearer token in action archive downloads (#4321 )	2026-03-31 17:51:01 -04:00
Stefan Penner	7ff994b932	Batch and deduplicate action resolution across composite depths (#4296 ) Co-authored-by: Stefan Penner <spenner@linkedin.com> Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>	2026-03-31 13:28:43 -04:00
github-actions[bot]	b9275b59cf	chore: update Node versions (#4319 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-03-30 12:58:17 +00:00
eric sciple	f0c228635e	Remove AllowCaseFunction feature flag (#4316 )	2026-03-27 11:45:42 -05:00
dependabot[bot]	9728019b24	Bump @typescript-eslint/eslint-plugin from 8.57.1 to 8.57.2 in /src/Misc/expressionFunc/hashFiles (#4310 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-03-24 10:40:31 +00:00
Francesco Renzi	e17e7aabbf	Add DAP server (#4298 ) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Tingluo Huang <tingluohuang@github.com>	2026-03-23 14:02:15 +00:00
dependabot[bot]	4259ffb6dc	Bump flatted from 3.2.7 to 3.4.2 in /src/Misc/expressionFunc/hashFiles (#4307 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-03-20 01:02:30 +00:00
Salman Chishti	4e8e1ff020	prep new runner release 2.333.0 (#4306 )	2026-03-18 16:51:00 +00:00
dependabot[bot]	b6cca8fb99	Bump @typescript-eslint/eslint-plugin from 8.54.0 to 8.57.1 in /src/Misc/expressionFunc/hashFiles (#4304 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-03-18 16:26:33 +00:00
Salman Chishti	18d0789c74	Node 24 enforcement + Linux ARM32 deprecation support (#4303 )	2026-03-17 18:58:34 +00:00
github-actions[bot]	c985a9ff03	Update dotnet sdk to latest version @8.0.419 (#4301 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Tingluo Huang <tingluohuang@github.com>	2026-03-16 13:48:09 +00:00
Tingluo Huang	45ed15ddf3	Report infra_error for action download failures. (#4294 )	2026-03-16 13:31:57 +00:00
Nikola Jokic	c5dcf59d26	Exit with specified exit code when runner is outdated (#4285 ) Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>	2026-03-13 14:16:31 -04:00
dependabot[bot]	c7f6c49ba0	Bump @typescript-eslint/eslint-plugin from 8.47.0 to 8.54.0 in /src/Misc/expressionFunc/hashFiles (#4230 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-03-11 10:21:47 +00:00
eric sciple	40dd583def	Fix cancellation token race during parser comparison (#4280 )	2026-03-09 16:10:08 +00:00
github-actions[bot]	68f2e9adb7	chore: update Node versions (#4287 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-03-09 13:02:32 +00:00
github-actions[bot]	2b98d42113	Update Docker to v29.3.0 and Buildx to v0.32.1 (#4286 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-03-09 00:37:54 +00:00
dependabot[bot]	ce8ce410b0	Bump @stylistic/eslint-plugin from 5.9.0 to 5.10.0 in /src/Misc/expressionFunc/hashFiles (#4281 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-03-07 22:13:23 +00:00
dependabot[bot]	5310e90af2	Bump actions/attest-build-provenance from 3 to 4 (#4266 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-03-07 01:59:22 +00:00
dependabot[bot]	98323280e8	Bump docker/setup-buildx-action from 3 to 4 (#4282 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-03-07 01:49:28 +00:00
dependabot[bot]	5ef3270368	Bump docker/build-push-action from 6 to 7 (#4283 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-03-07 01:44:58 +00:00
eric sciple	1138dd80f7	Fix positional arg bug in ExpressionParser.CreateTree (#4279 )	2026-03-05 14:56:28 -06:00
dependabot[bot]	99910ca83e	Bump docker/login-action from 3 to 4 (#4278 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-03-05 15:45:49 +00:00
dependabot[bot]	bcd04cfbf0	Bump actions/upload-artifact from 6 to 7 (#4270 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-03-05 14:55:48 +00:00
eric sciple	20111cbfda	Support `entrypoint` and `command` for service containers (#4276 )	2026-03-04 23:36:45 +00:00
Max Horstmann	8f01257663	Devcontainer: bump base image Ubuntu version (#4277 )	2026-03-04 20:17:25 +00:00
eric sciple	8a73bccebb	Fix parser comparison mismatches (#4273 )	2026-03-03 05:38:16 +00:00
Tingluo Huang	a9a07a6553	Avoid throw in SelfUpdaters. (#4274 )	2026-03-02 22:44:14 -05:00
github-actions[bot]	60a9422599	chore: update Node versions (#4272 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-03-02 13:51:11 +00:00
dependabot[bot]	985a06fcca	Bump actions/download-artifact from 7 to 8 (#4269 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-02-27 09:18:13 +00:00
eric sciple	ae09a9d7b5	Fix composite post-step marker display names (#4267 )	2026-02-26 08:36:55 -06:00
Tingluo Huang	7650fc432e	Log inner exception message. (#4265 )	2026-02-25 15:44:27 -05:00
Salman Chishti	bc00800857	Bump runner version to 2.332.0 and update release notes (#4264 )	2026-02-25 13:36:47 +00:00
dependabot[bot]	86e23605d6	Bump @stylistic/eslint-plugin from 3.1.0 to 5.9.0 in /src/Misc/expressionFunc/hashFiles (#4257 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-02-25 12:02:23 +00:00
dependabot[bot]	0fb7482206	Bump minimatch in /src/Misc/expressionFunc/hashFiles (#4261 ) Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-02-25 11:56:32 +00:00
Pavel Iakovenko	052dfbdd68	Symlink actions cache (#4260 )	2026-02-24 12:19:46 -05:00
eric sciple	ecb5f298fa	Composite Action Step Markers (#4243 )	2026-02-23 15:00:12 +00:00
Salman Chishti	a2b220990b	Update Node.js 20 deprecation date to June 2nd, 2026 (#4258 ) Co-authored-by: Salman <salmanmkc@gmail.com>	2026-02-21 19:19:46 +00:00
Salman Chishti	9426c35fda	Add Node.js 20 deprecation warning annotation (Phase 1) (#4242 )	2026-02-19 17:05:32 +00:00
Tingluo Huang	72189aabf8	Try to infer runner is on hosted/ghes when githuburl is empty. (#4254 )	2026-02-18 12:00:37 -05:00
Tingluo Huang	e012ab630b	Fix link to SECURITY.md in README (#4253 )	2026-02-17 14:09:05 -05:00
github-actions[bot]	a798a45826	Update dotnet sdk to latest version @8.0.418 (#4250 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Salman Chishti <salmanmkc@GitHub.com>	2026-02-16 11:34:26 +00:00
github-actions[bot]	9efea31a89	chore: update Node versions (#4249 ) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>	2026-02-16 11:29:25 +00:00
Zach Renner	6680090084	Remove unnecessary connection test during some registration flows (#4244 )	2026-02-12 08:46:48 -05:00
eric sciple	15cb558d8f	Fix parser comparison mismatches (#4220 )	2026-02-11 09:44:01 -06:00
eric sciple	d5a8a936c1	Add telemetry tracking for deprecated set-output and save-state commands (#4221 )	2026-02-10 12:28:42 -06:00
Tingluo Huang	cdb77c6804	Support return job result as exitcode in hosted runner. (#4233 )	2026-02-10 09:31:10 -05:00
Nikola Jokic	a4a19b152e	Bump hook to 0.8.1 (#4222 )	2026-02-10 01:07:20 +00:00
Tingluo Huang	1b5486aa8f	Validate work dir during runner start up. (#4227 )	2026-02-09 08:42:07 -05:00
Takuma Ishikawa	4214709d1b	Add support for libssl3 and libssl3t64 for newer Debian/Ubuntu versions (#4213 )	2026-02-08 16:03:41 -05:00