Update ESM migration plan with findings and workarounds

Add detailed plan for migrating to moduleResolution node16/nodenext with
file extensions in imports.

This plan addresses:
- #154 - Upgrade moduleResolution from node to node16/nodenext
- #110 - Published ESM code has imports without file extensions
- #64 - expressions: ERR_MODULE_NOT_FOUND attempting to run example demo script
- #146 - Can not import @actions/workflow-parser

The migration will:
1. Upgrade TypeScript to 5.7+
2. Enable rewriteRelativeImportExtensions
3. Add .ts extensions to all relative imports
4. Update JSON imports to use import attributes

Implementation will begin after pending PRs are merged to avoid conflicts.

.github/workflows/buildtest.yml

@@ -12,15 +12,19 @@ jobs:
   build:
     runs-on: ubuntu-latest
 
+    strategy:
+      matrix:
+        node-version: [18.x, 20.x, 22.x]
+
     steps:
     - uses: actions/checkout@v4
-    - name: Use Node.js 16.15
+    - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v4
       with:
-        node-version: 16.15
+        node-version: ${{ matrix.node-version }}
         cache: 'npm'
         registry-url: 'https://npm.pkg.github.com'
-    - run: npm ci
+    - run: npm ci --engine-strict
       env:
         NODE_AUTH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     - run: npm run format-check -ws
@@ -33,10 +37,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Use Node.js 16.15
+    - name: Use Node.js 22.x
       uses: actions/setup-node@v4
       with:
-        node-version: 16.15
+        node-version: 22.x
         cache: 'npm'
         registry-url: 'https://npm.pkg.github.com'
     - run: npm ci

.github/workflows/release.yml

@@ -69,7 +69,7 @@ jobs:
 
       - uses: actions/setup-node@v4
         with:
-          node-version: 16.x
+          node-version: 22.x
           cache: "npm"
           scope: '@actions'
 

docs/esm-migration-plan.md

@@ -0,0 +1,388 @@
+# ESM Migration Plan: Add File Extensions to Imports
+
+## Overview
+
+This document outlines the plan to migrate from TypeScript's deprecated `"moduleResolution": "node"` (node10) to `"moduleResolution": "node16"` or `"nodenext"`. This change is necessary because the published ESM packages have extensionless imports that don't work correctly in modern ESM environments.
+
+## Issues Fixed
+
+This migration will resolve the following issues:
+
+- **#154** - Upgrade `moduleResolution` from `node` to `node16` or `nodenext` in tsconfig
+- **#110** - Published ESM code has imports without file extensions
+- **#64** - expressions: ERR_MODULE_NOT_FOUND attempting to run example demo script  
+- **#146** - Can not import `@actions/workflow-parser`
+
+## Problem Statement
+
+### Current State
+
+All packages use `"moduleResolution": "node"`:
+
+| Package | moduleResolution | TypeScript |
+|---------|------------------|------------|
+| expressions | `"node"` | ^4.7.4 |
+| workflow-parser | `"node"` | ^4.8.4 |
+| languageservice | `"node"` | ^4.8.4 |
+| languageserver | `"node"` | ^4.8.4 |
+| browser-playground | `"Node16"` ✅ | ^4.9.4 |
+
+This causes TypeScript to emit code like:
+```javascript
+// Published to npm - INVALID ESM
+export { Expr } from "./ast";  // Missing .js extension!
+```
+
+### Why This Fails
+
+ESM in Node.js 12+ **requires** explicit file extensions. When users try to import these packages:
+
+```javascript
+// User's code
+import { Expr } from "@actions/expressions";
+```
+
+Node.js fails with:
+```
+Error [ERR_MODULE_NOT_FOUND]: Cannot find module '.../node_modules/@actions/expressions/dist/ast'
+```
+
+## Migration Strategy
+
+### Option A: TypeScript 5.7+ with `rewriteRelativeImportExtensions` (Recommended)
+
+TypeScript 5.7 introduced a new compiler option that automatically rewrites `.ts` extensions to `.js` in output:
+
+```jsonc
+{
+  "compilerOptions": {
+    "moduleResolution": "node16",  // or "nodenext"
+    "rewriteRelativeImportExtensions": true
+  }
+}
+```
+
+**Source code:**
+```typescript
+import { Expr } from "./ast.ts";
+```
+
+**Compiled output:**
+```javascript
+export { Expr } from "./ast.js";
+```
+
+**Pros:**
+- Source uses `.ts` extensions (matches actual files)
+- Works with Deno (which requires `.ts` extensions)
+- TypeScript automatically transforms to `.js`
+- Modern, forward-looking approach
+
+**Cons:**
+- Requires TypeScript 5.7+
+- Relatively new feature
+- **BUG:** See "Known Issues" section below
+
+### Option B: Manual `.js` Extensions
+
+Use `.js` extensions in source TypeScript files:
+
+```typescript
+import { Expr } from "./ast.js";  // Points to .ts file, but use .js extension
+```
+
+**Pros:**
+- Works with TypeScript 4.7+ (with node16 moduleResolution)
+- Well-established pattern
+- No post-processing needed
+
+**Cons:**
+- Confusing - `.js` files don't exist at write time
+- Doesn't work with Deno out of the box
+
+### Recommendation
+
+**Use Option A** with workarounds for known issues (see below).
+
+---
+
+## Known Issues and Workarounds (December 2025)
+
+### 1. TypeScript Version Conflicts in Monorepo
+
+**Problem:** The root `node_modules/typescript` was version 4.9.5 (pulled in by `ts-node` and `tsutils` dependencies), while workspace packages specified `^5.8.3`.
+
+**Symptoms:** 
+- `npx tsc --version` showed 4.9.5
+- `require('typescript').version` in ts-jest showed 5.8.3
+- Confusing build failures
+
+**Solution:** Add npm overrides in root `package.json`:
+```json
+{
+  "overrides": {
+    "typescript": "5.8.3"
+  }
+}
+```
+
+### 2. ts-jest Compatibility with TypeScript 5.9+
+
+**Problem:** ts-jest 29.4.6 uses `typescript.JSDocParsingMode.ParseAll` which doesn't exist in TypeScript's ES module exports.
+
+**Error:**
+```
+TypeError: Cannot read properties of undefined (reading 'ParseAll')
+at Object.<anonymous> (node_modules/ts-jest/dist/compiler/ts-compiler.js:43:123)
+```
+
+**Root Cause:** ts-jest accesses `typescript_1.default.JSDocParsingMode.ParseAll` but TypeScript has no default export in ESM.
+
+**Solution:** 
+- Use ts-jest 29.0.3 (older version that doesn't use this API)
+- OR wait for ts-jest fix
+- **Stay on TypeScript 5.8.3, not 5.9+**
+
+### 3. TypeScript `rewriteRelativeImportExtensions` Bug with .d.ts Files
+
+**Problem:** TypeScript's `rewriteRelativeImportExtensions: true` correctly rewrites `.ts` → `.js` in `.js` output files, but **incorrectly keeps `.ts` extensions in `.d.ts` declaration files**.
+
+**Example:**
+- Source: `export { Expr } from "./ast.ts";`
+- Output `index.js`: `export { Expr } from "./ast.js";` ✅ Correct
+- Output `index.d.ts`: `export { Expr } from "./ast.ts";` ❌ Wrong (should be `.js`)
+
+**Upstream Issue:** https://github.com/microsoft/TypeScript/issues/61037 (marked "Help Wanted", in Backlog, NOT FIXED as of Dec 2025)
+
+**Workaround:** Post-process `.d.ts` files with a script. Create `script/fix-dts-extensions.cjs`:
+
+```javascript
+#!/usr/bin/env node
+/**
+ * Post-build script to fix TypeScript's rewriteRelativeImportExtensions bug
+ * where .d.ts files get .ts extensions instead of .js extensions.
+ * See: https://github.com/microsoft/TypeScript/issues/61037
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+function fixDtsFile(filePath) {
+    let content = fs.readFileSync(filePath, 'utf8');
+    const original = content;
+    
+    // Replace .ts extensions in import/export statements with .js
+    content = content.replace(/(from\s+["'])([^"']+)\.ts(["'])/g, '$1$2.js$3');
+    content = content.replace(/(import\s*\(\s*["'])([^"']+)\.ts(["']\s*\))/g, '$1$2.js$3');
+    content = content.replace(/(export\s+\*\s+from\s+["'])([^"']+)\.ts(["'])/g, '$1$2.js$3');
+    
+    if (content !== original) {
+        fs.writeFileSync(filePath, content, 'utf8');
+        console.log(`Fixed: ${filePath}`);
+        return true;
+    }
+    return false;
+}
+
+function walkDir(dir, callback) {
+    const files = fs.readdirSync(dir);
+    for (const file of files) {
+        const filePath = path.join(dir, file);
+        const stat = fs.statSync(filePath);
+        if (stat.isDirectory()) {
+            walkDir(filePath, callback);
+        } else if (file.endsWith('.d.ts')) {
+            callback(filePath);
+        }
+    }
+}
+
+function main() {
+    const args = process.argv.slice(2);
+    if (args.length === 0) {
+        console.error('Usage: fix-dts-extensions.cjs <dist-dir> [<dist-dir2> ...]');
+        process.exit(1);
+    }
+    
+    let fixedCount = 0;
+    for (const dir of args) {
+        if (!fs.existsSync(dir)) {
+            console.warn(`Directory not found: ${dir}`);
+            continue;
+        }
+        walkDir(dir, (filePath) => {
+            if (fixDtsFile(filePath)) {
+                fixedCount++;
+            }
+        });
+    }
+    console.log(`Fixed ${fixedCount} .d.ts file(s)`);
+}
+
+main();
+```
+
+**Note:** Use `.cjs` extension since root `package.json` has `"type": "module"`.
+
+**Usage in package.json build scripts:**
+```json
+{
+  "scripts": {
+    "build": "tsc --build tsconfig.build.json && node ../script/fix-dts-extensions.cjs dist"
+  }
+}
+```
+
+### 4. languageserver Tests Hang
+
+**Problem:** The languageserver tests hang indefinitely when running with the ESM configuration.
+
+**Status:** Not fully diagnosed. Tests pass on main branch but hang on ESM branch.
+
+**Possible causes:**
+- Jest ESM module resolution issues
+- Cross-package source mappings in jest.config.js
+- vscode-languageserver ESM compatibility issues
+- Specific test file causing hang (needs isolation testing)
+
+**Investigation needed:**
+- Run individual test files to isolate the hanging test
+- Check if vscode-languageserver has ESM compatibility issues
+- Review jest configuration for problematic mappings
+- Try running with `--detectOpenHandles` flag
+
+---
+
+## Required Configuration Changes
+
+### tsconfig.json (each package)
+
+```json
+{
+  "compilerOptions": {
+    "module": "node16",
+    "moduleResolution": "node16",
+    "rewriteRelativeImportExtensions": true,
+    "lib": ["ES2022"],
+    "target": "ES2022"
+  }
+}
+```
+
+### jest.config.js (each package)
+
+```javascript
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+export default {
+  preset: "ts-jest/presets/default-esm",
+  moduleNameMapper: {
+    "^(\\.{1,2}/.*)\\.js$": "$1",
+    "^(\\.{1,2}/.*)\\.ts$": "$1",
+  },
+  transform: {
+    "^.+\\.tsx?$": [
+      "ts-jest",
+      {
+        useESM: true,
+        isolatedModules: true,
+      },
+    ],
+  },
+  moduleFileExtensions: ["ts", "js"],
+};
+```
+
+### Root package.json
+
+```json
+{
+  "overrides": {
+    "typescript": "5.8.3"
+  }
+}
+```
+
+### Each workspace package.json
+
+```json
+{
+  "devDependencies": {
+    "typescript": "^5.8.3",
+    "ts-jest": "^29.0.3"
+  }
+}
+```
+
+---
+
+## Test Results (December 2025 Attempt)
+
+| Package | Tests | Status |
+|---------|-------|--------|
+| expressions | 1068 | ✅ Pass |
+| workflow-parser | 292 | ✅ Pass |
+| languageservice | 452 | ✅ Pass |
+| languageserver | 6 files | ❌ Hangs (needs investigation) |
+
+---
+
+## Implementation Steps
+
+### Phase 1: Prerequisites
+- [ ] Merge all pending PRs to avoid conflicts
+- [ ] Ensure clean main branch state
+
+### Phase 2: TypeScript & Dependencies
+- [ ] Add `"overrides": { "typescript": "5.8.3" }` to root package.json
+- [ ] Update all workspace packages to TypeScript ^5.8.3
+- [ ] Downgrade ts-jest to ^29.0.3 in all packages
+- [ ] Run `npm install` to apply changes
+
+### Phase 3: tsconfig Updates
+- [ ] Update tsconfig.json in each package with node16 settings
+- [ ] Add `rewriteRelativeImportExtensions: true`
+
+### Phase 4: Add .ts Extensions to Imports
+- [ ] Update all relative imports in source files to use `.ts` extensions
+- [ ] This was already done in PR #243
+
+### Phase 5: Create Fix Script
+- [ ] Add `script/fix-dts-extensions.cjs` to repository
+- [ ] Update build scripts to run fix after tsc
+
+### Phase 6: Fix languageserver Tests
+- [ ] Investigate why tests hang
+- [ ] Isolate problematic test file
+- [ ] Apply fix or workaround
+
+### Phase 7: Verification
+- [ ] Run `npm run build` in all packages
+- [ ] Run `npm test` in all packages
+- [ ] Test importing published packages in Node.js ESM mode
+- [ ] Verify browser-playground still works
+
+### Phase 8: CI Updates
+- [ ] Update GitHub Actions workflows if needed
+- [ ] Ensure fix-dts-extensions.cjs runs in CI
+
+---
+
+## Summary of Required Changes
+
+1. **Root package.json**: Add TypeScript override
+2. **All packages**: TypeScript 5.8.3, ts-jest 29.0.3
+3. **All tsconfigs**: node16 moduleResolution, rewriteRelativeImportExtensions
+4. **All imports**: Add .ts extensions (already done)
+5. **Build scripts**: Add post-build .d.ts fix
+6. **languageserver**: Debug test hang issue
+
+---
+
+## References
+
+- [TypeScript moduleResolution reference](https://www.typescriptlang.org/docs/handbook/modules/reference.html)
+- [TypeScript 5.7 rewriteRelativeImportExtensions](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-7.html#path-rewriting-for-relative-paths)
+- [TypeScript .d.ts extension bug #61037](https://github.com/microsoft/TypeScript/issues/61037)
+- [Node.js ESM mandatory extensions](https://nodejs.org/api/esm.html#mandatory-file-extensions)
+- [ts-jest ESM support](https://kulshekhar.github.io/ts-jest/docs/guides/esm-support)
+- [Community fork that works](https://github.com/boxbuild-io/actions-languageservices/commit/077fb2b58dfd2cca3d6e3df1fdf9e26e75db24ae)

docs/json-data-files.md

@@ -148,3 +148,50 @@ Only `name`, `description`, and `childParamsGroups` are kept — these are used
 To compare all fields vs stripped, run `npm run update-webhooks -- --all` and diff the `.all.json` files against the regular ones.
 
 See `EVENT_ACTION_FIELDS` and `BODY_PARAM_FIELDS` in `script/webhooks/index.ts` to modify what gets stripped.
+
+## Schema Synchronization
+
+The `workflow-v1.0.json` schema defines which activity types are valid for each workflow trigger event. A test in `workflow-parser/src/schema-sync.test.ts` verifies these stay in sync with `webhooks.json`.
+
+### When the Test Fails
+
+If the schema-sync test fails, you'll see an error like:
+
+```
+Event "pull_request" is missing activity type "new_activity" in workflow-v1.0.json
+```
+
+**To resolve:**
+
+1. Check [Events that trigger workflows](https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows) to verify the activity type is a valid workflow trigger:
+   - Find the event section (e.g., "pull_request")
+   - Look at the "Activity types" table — it lists which types can be used in `on.<event>.types`
+   - If the type is listed there, it's a valid workflow trigger
+   - If the type only appears in webhook docs but NOT in the workflow trigger docs, it's webhook-only
+
+2. If it IS a valid workflow trigger:
+   - Edit `workflow-parser/src/workflow-v1.0.json`
+   - Find the `<event>-activity-type` definition (e.g., `pull-request-activity-type`)
+   - Add the new activity type to `allowed-values`
+   - Update the `description` in `<event>-activity` to list all types
+   - Run `npm test` to regenerate the minified JSON
+
+3. If it is NOT a valid workflow trigger (webhook-only):
+   - Edit `workflow-parser/src/schema-sync.test.ts`
+   - Add the type to `WEBHOOK_ONLY` for that event
+
+### Known Discrepancies
+
+The test tracks several types of known discrepancies:
+
+| Category | Purpose | Example |
+|----------|---------|---------|
+| `WEBHOOK_ONLY` | Types in webhooks that aren't valid workflow triggers | `check_suite.requested` |
+| `SCHEMA_ONLY` | Types valid for workflows but missing from webhooks | `registry_package.updated` |
+| `NAME_MAPPINGS` | Different names for the same concept | `project_column`: webhook uses `edited`, schema uses `updated` |
+
+### Bidirectional Checking
+
+The test checks both directions:
+- **webhooks → schema**: Ensures all webhook activity types are in the schema (or listed in `WEBHOOK_ONLY`)
+- **schema → webhooks**: Ensures the schema doesn't have types that don't exist in webhooks (or listed in `SCHEMA_ONLY` or `NAME_MAPPINGS`)

expressions/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/expressions",
-  "version": "0.3.23",
+  "version": "0.3.25",
   "license": "MIT",
   "type": "module",
   "source": "./src/index.ts",
@@ -44,7 +44,7 @@
     "watch": "tsc --build tsconfig.build.json --watch"
   },
   "engines": {
-    "node": ">= 16.15"
+    "node": ">= 18"
   },
   "files": [
     "dist/**/*"

languageserver/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/languageserver",
-  "version": "0.3.23",
+  "version": "0.3.25",
   "description": "Language server for GitHub Actions",
   "license": "MIT",
   "type": "module",
@@ -43,8 +43,8 @@
     "watch": "tsc --build tsconfig.build.json --watch"
   },
   "dependencies": {
-    "@actions/languageservice": "^0.3.23",
-    "@actions/workflow-parser": "^0.3.23",
+    "@actions/languageservice": "^0.3.25",
+    "@actions/workflow-parser": "^0.3.25",
     "@octokit/rest": "^21.1.1",
     "@octokit/types": "^9.0.0",
     "vscode-languageserver": "^8.0.2",
@@ -52,7 +52,7 @@
     "yaml": "^2.1.3"
   },
   "engines": {
-    "node": ">= 16.15"
+    "node": ">= 18"
   },
   "files": [
     "dist/**/*"

languageserver/src/context-providers.test.ts

@@ -0,0 +1,76 @@
+import {data, DescriptionDictionary} from "@actions/expressions";
+import {WorkflowContext} from "@actions/languageservice/context/workflow-context";
+import {Mode} from "@actions/languageservice/context-providers/default";
+import {contextProviders} from "./context-providers";
+import {RepositoryContext} from "./initializationOptions";
+import {TTLCache} from "./utils/cache";
+
+describe("contextProviders", () => {
+  const mockCache = new TTLCache();
+  const mockRepo: RepositoryContext = {
+    id: 123,
+    owner: "test-owner",
+    name: "test-repo",
+    organizationOwned: true,
+    workspaceUri: "file:///workspace"
+  };
+  const mockWorkflowContext: WorkflowContext = {
+    uri: "test.yaml",
+    template: undefined
+  };
+
+  describe("when client is undefined", () => {
+    it("should return incomplete context for secrets", async () => {
+      const config = contextProviders(undefined, mockRepo, mockCache);
+      const result = await config.getContext("secrets", undefined, mockWorkflowContext, Mode.Validation);
+
+      expect(result).toBeInstanceOf(DescriptionDictionary);
+      expect((result as DescriptionDictionary).complete).toBe(false);
+    });
+
+    it("should return incomplete context for vars", async () => {
+      const config = contextProviders(undefined, mockRepo, mockCache);
+      const result = await config.getContext("vars", undefined, mockWorkflowContext, Mode.Validation);
+
+      expect(result).toBeInstanceOf(DescriptionDictionary);
+      expect((result as DescriptionDictionary).complete).toBe(false);
+    });
+
+    it("should preserve defaultContext and mark as incomplete for secrets", async () => {
+      const config = contextProviders(undefined, mockRepo, mockCache);
+      const defaultContext = new DescriptionDictionary();
+      defaultContext.add("EXISTING_SECRET", new data.StringData("test"));
+
+      const result = await config.getContext("secrets", defaultContext, mockWorkflowContext, Mode.Validation);
+
+      expect(result).toBe(defaultContext);
+      expect((result as DescriptionDictionary).complete).toBe(false);
+      expect((result as DescriptionDictionary).get("EXISTING_SECRET")).toBeDefined();
+    });
+
+    it("should return undefined for other contexts like steps", async () => {
+      const config = contextProviders(undefined, mockRepo, mockCache);
+      const result = await config.getContext("steps", undefined, mockWorkflowContext, Mode.Validation);
+
+      expect(result).toBeUndefined();
+    });
+  });
+
+  describe("when both client and repo are undefined", () => {
+    it("should return incomplete context for secrets", async () => {
+      const config = contextProviders(undefined, undefined, mockCache);
+      const result = await config.getContext("secrets", undefined, mockWorkflowContext, Mode.Validation);
+
+      expect(result).toBeInstanceOf(DescriptionDictionary);
+      expect((result as DescriptionDictionary).complete).toBe(false);
+    });
+
+    it("should return incomplete context for vars", async () => {
+      const config = contextProviders(undefined, undefined, mockCache);
+      const result = await config.getContext("vars", undefined, mockWorkflowContext, Mode.Validation);
+
+      expect(result).toBeInstanceOf(DescriptionDictionary);
+      expect((result as DescriptionDictionary).complete).toBe(false);
+    });
+  });
+});

languageserver/src/context-providers.ts

@@ -15,7 +15,18 @@ export function contextProviders(
   cache: TTLCache
 ): ContextProviderConfig {
   if (!repo || !client) {
-    return {getContext: () => Promise.resolve(undefined)};
+    // When GitHub client/repo is unavailable, return an incomplete dictionary
+    // to avoid false "Context access might be invalid" warnings
+    return {
+      getContext: (name: string, defaultContext: DescriptionDictionary | undefined) => {
+        if (name === "secrets" || name === "vars") {
+          const context = defaultContext || new DescriptionDictionary();
+          context.complete = false;
+          return Promise.resolve(context);
+        }
+        return Promise.resolve(undefined);
+      }
+    };
   }
 
   const getContext = async (

languageserver/src/context-providers/secrets.ts

@@ -49,7 +49,7 @@ export async function getSecrets(
           if (isString(x.value)) {
             environmentName = x.value.value;
           } else {
-            // this means we have a dynamic enviornment, in those situations we
+            // this means we have a dynamic environment, in those situations we
             // want to make sure we skip doing secret validation
             secretsContext.complete = false;
           }

languageserver/src/context-providers/steps.test.ts

@@ -1,4 +1,4 @@
-import {data, DescriptionDictionary} from "@actions/expressions";
+import {data, DescriptionDictionary, isDescriptionDictionary} from "@actions/expressions";
 import {getStepsContext as getDefaultStepsContext} from "@actions/languageservice/context-providers/steps";
 import {Octokit} from "@octokit/rest";
 import fetchMock from "fetch-mock";
@@ -63,6 +63,43 @@ it("returns default context when job is undefined", async () => {
   expect(stepsContext).toEqual(defaultContext);
 });
 
+it("outputs is an incomplete dictionary to allow dynamic outputs", async () => {
+  const mock = fetchMock
+    .sandbox()
+    .getOnce("https://api.github.com/repos/actions/cache/contents/action.yml?ref=v3", actionMetadata);
+
+  const workflowContext = await createWorkflowContext(workflow, "build");
+  const defaultContext = getDefaultStepsContext(workflowContext);
+
+  const stepsContext = await getStepsContext(
+    new Octokit({
+      request: {
+        fetch: mock
+      }
+    }),
+    new TTLCache(),
+    defaultContext,
+    workflowContext
+  );
+
+  // Get the step context
+  const stepContext = stepsContext?.get("cache-primes");
+  expect(stepContext).toBeDefined();
+  expect(isDescriptionDictionary(stepContext!)).toBe(true);
+
+  // Get the outputs - should be a dictionary, not null
+  const outputs = (stepContext as DescriptionDictionary).get("outputs");
+  expect(outputs).toBeDefined();
+  expect(isDescriptionDictionary(outputs!)).toBe(true);
+
+  // Outputs should be marked incomplete to allow dynamic outputs
+  const outputsDict = outputs as DescriptionDictionary;
+  expect(outputsDict.complete).toBe(false);
+
+  // Known outputs from action.yml should be present
+  expect(outputsDict.get("cache-hit")).toBeDefined();
+});
+
 it("adds action outputs", async () => {
   const mock = fetchMock
     .sandbox()
@@ -83,17 +120,22 @@ it("adds action outputs", async () => {
   );
   expect(stepsContext).toBeDefined();
 
+  // Create expected outputs dict with complete = false
+  // (actions can have dynamic outputs beyond what's declared in action.yml)
+  const expectedOutputs = new DescriptionDictionary({
+    key: "cache-hit",
+    value: new data.StringData("A boolean value to indicate an exact match was found for the primary key"),
+    description: "A boolean value to indicate an exact match was found for the primary key"
+  });
+  expectedOutputs.complete = false;
+
   expect(stepsContext).toEqual(
     new DescriptionDictionary({
       key: "cache-primes",
       value: new DescriptionDictionary(
         {
           key: "outputs",
-          value: new DescriptionDictionary({
-            key: "cache-hit",
-            value: new data.StringData("A boolean value to indicate an exact match was found for the primary key"),
-            description: "A boolean value to indicate an exact match was found for the primary key"
-          })
+          value: expectedOutputs
         },
         {
           key: "conclusion",

languageserver/src/context-providers/steps.ts

@@ -58,6 +58,8 @@ export async function getStepsContext(
             continue;
           }
           const outputsDict = new DescriptionDictionary();
+          // Actions can have dynamic outputs beyond what's declared in action.yml
+          outputsDict.complete = false;
           for (const [key, value] of Object.entries(outputs)) {
             outputsDict.add(key, new data.StringData(value.description), value.description);
           }

languageserver/src/context-providers/variables.ts

@@ -26,6 +26,8 @@ export async function getVariables(
     return secretsContext;
   }
 
+  const variablesContext = defaultContext || new DescriptionDictionary();
+
   let environmentName: string | undefined;
   if (workflowContext?.job?.environment) {
     if (isString(workflowContext.job.environment)) {
@@ -35,14 +37,19 @@ export async function getVariables(
         if (isString(x.key) && x.key.value === "name") {
           if (isString(x.value)) {
             environmentName = x.value.value;
+          } else {
+            // this means we have a dynamic environment, in those situations we want to skip validation
+            variablesContext.complete = false;
           }
           break;
         }
       }
+    } else {
+      // if the expression is something like environment: ${{ ... }} then we want to skip validation
+      variablesContext.complete = false;
     }
   }
 
-  const variablesContext = defaultContext || new DescriptionDictionary();
   try {
     const variables = await getRemoteVariables(octokit, cache, repo, environmentName);
 

languageservice/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/languageservice",
-  "version": "0.3.23",
+  "version": "0.3.25",
   "description": "Language service for GitHub Actions",
   "license": "MIT",
   "type": "module",
@@ -47,15 +47,15 @@
     "watch": "tsc --build tsconfig.build.json --watch"
   },
   "dependencies": {
-    "@actions/expressions": "^0.3.23",
-    "@actions/workflow-parser": "^0.3.23",
+    "@actions/expressions": "^0.3.25",
+    "@actions/workflow-parser": "^0.3.25",
     "vscode-languageserver-textdocument": "^1.0.7",
     "vscode-languageserver-types": "^3.17.2",
     "vscode-uri": "^3.0.8",
     "yaml": "^2.1.1"
   },
   "engines": {
-    "node": ">= 16.15"
+    "node": ">= 18"
   },
   "files": [
     "dist/**/*"

languageservice/src/complete.expressions.test.ts

@@ -299,7 +299,16 @@ jobs:
         "on: push\njobs:\n  build:\n    runs-on: ubuntu-latest\n    environment:\n      url: ${{ runner.| }}\n    steps:\n      - run: echo";
       const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
 
-      expect(result.map(x => x.label)).toEqual(["arch", "name", "os", "temp", "tool_cache"]);
+      expect(result.map(x => x.label)).toEqual([
+        "arch",
+        "debug",
+        "environment",
+        "name",
+        "os",
+        "temp",
+        "tool_cache",
+        "workspace"
+      ]);
     });
 
     describe("job if", () => {
@@ -861,7 +870,7 @@ jobs:
   });
 
   describe("strategy context", () => {
-    it("strategy is not suggested when outside of a matrix job", async () => {
+    it("strategy is suggested even when no strategy defined", async () => {
       const input = `
 on: push
 
@@ -875,7 +884,7 @@ jobs:
 
       const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
 
-      expect(result.map(x => x.label)).not.toContain("strategy");
+      expect(result.map(x => x.label)).toContain("strategy");
     });
 
     it("strategy is suggested within a matrix job", async () => {
@@ -922,7 +931,7 @@ jobs:
   });
 
   describe("matrix context", () => {
-    it("matrix is not suggested when outside of a matrix job", async () => {
+    it("matrix is suggested even when no strategy defined", async () => {
       const input = `
 on: push
 
@@ -936,7 +945,7 @@ jobs:
 
       const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
 
-      expect(result.map(x => x.label)).not.toContain("strategy");
+      expect(result.map(x => x.label)).toContain("matrix");
     });
 
     it("matrix is suggested within a matrix job", async () => {
@@ -1123,10 +1132,12 @@ jobs:
         "github",
         "inputs",
         "job",
+        "matrix",
         "needs",
         "runner",
         "secrets",
         "steps",
+        "strategy",
         "vars",
         "contains",
         "endsWith",

languageservice/src/complete.multiline-if.test.ts

@@ -0,0 +1,169 @@
+import {complete} from "./complete";
+import {TextDocument} from "vscode-languageserver-textdocument";
+import {clearCache} from "./utils/workflow-cache";
+import {getPositionFromCursor} from "./test-utils/cursor-position";
+
+beforeEach(() => {
+  clearCache();
+});
+
+describe("Issue #81 - multi-line if expression completion", () => {
+  it("should complete in block scalar if with | (exact position)", async () => {
+    // Exact reproduction from issue - cursor after "github." in block scalar
+    const input = `on: push
+
+jobs:
+  build:
+    if: |
+      github.
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    const doc = TextDocument.create("file:///test.yaml", "yaml", 1, input);
+    // Line 5 (0-indexed) = "      github.", character 13 = after the dot
+    const pos = {line: 5, character: 13};
+
+    const result = await complete(doc, pos, {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+    expect(result.map(x => x.label)).toContain("actor");
+  });
+
+  it("should complete in block scalar if with > (exact position)", async () => {
+    const input = `on: push
+
+jobs:
+  build:
+    if: >
+      github.
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    const doc = TextDocument.create("file:///test.yaml", "yaml", 1, input);
+    const pos = {line: 5, character: 13};
+
+    const result = await complete(doc, pos, {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+  });
+
+  it("should complete in block scalar with multiple lines", async () => {
+    const input = `on: push
+jobs:
+  build:
+    if: |
+      github.event_name == 'push' &&
+      github.|
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    // Skip 1 to skip the `|` block scalar indicator (same character as cursor marker)
+    const result = await complete(...getPositionFromCursor(input, 1), {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+  });
+
+  it("should complete step if in block scalar", async () => {
+    const input = `on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo
+      if: |
+        github.
+`;
+
+    const doc = TextDocument.create("file:///test.yaml", "yaml", 1, input);
+    // Line 7 = "        github.", character 15 = after the dot (8 spaces + 7 chars)
+    const pos = {line: 7, character: 15};
+
+    const result = await complete(doc, pos, {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+  });
+
+  it("should complete in block scalar with ${{ expression markers", async () => {
+    // This case works because transform() skips lines with ${{
+    // Note: Using explicit position because | appears in multiple places (block scalar, ||, cursor)
+    const input = `on: push
+jobs:
+  build:
+    if: |
+      \${{
+        github.ref == 'refs/heads/main' ||
+        github.
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    const doc = TextDocument.create("file:///test.yaml", "yaml", 1, input);
+    // Line 6 = "        github." = 8 spaces + 7 chars = 15 chars, cursor after dot is at char 15
+    const pos = {line: 6, character: 15};
+
+    const result = await complete(doc, pos, {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("ref");
+    expect(result.map(x => x.label)).toContain("ref_name");
+  });
+});
+
+describe("Edge cases for getOffsetInContent", () => {
+  it("should complete in single-line if (not block scalar)", async () => {
+    const input = `on: push
+jobs:
+  build:
+    if: github.|
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    const result = await complete(...getPositionFromCursor(input), {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+  });
+
+  it("should complete on third content line of block scalar", async () => {
+    const input = `on: push
+jobs:
+  build:
+    if: |
+      github.event_name == 'push' &&
+      github.ref == 'refs/heads/main' &&
+      github.|
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    const result = await complete(...getPositionFromCursor(input, 1), {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+  });
+
+  it("should complete when block scalar has empty first line", async () => {
+    const input = `on: push
+jobs:
+  build:
+    if: |
+
+      github.|
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`;
+
+    const result = await complete(...getPositionFromCursor(input, 1), {});
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(result.map(x => x.label)).toContain("event");
+  });
+});

languageservice/src/complete.ts

@@ -5,6 +5,7 @@ import {ErrorPolicy} from "@actions/workflow-parser/model/convert";
 import {OPEN_EXPRESSION} from "@actions/workflow-parser/templates/template-constants";
 import {TemplateToken} from "@actions/workflow-parser/templates/tokens/index";
 import {MappingToken} from "@actions/workflow-parser/templates/tokens/mapping-token";
+import {TokenRange} from "@actions/workflow-parser/templates/tokens/token-range";
 import {TokenType} from "@actions/workflow-parser/templates/tokens/types";
 import {File} from "@actions/workflow-parser/workflows/file";
 import {FileProvider} from "@actions/workflow-parser/workflows/file-provider";
@@ -19,7 +20,6 @@ import {isPotentiallyExpression} from "./utils/expression-detection";
 import {findToken} from "./utils/find-token";
 import {guessIndentation} from "./utils/indentation-guesser";
 import {mapRange} from "./utils/range";
-import {getRelCharOffset} from "./utils/rel-char-pos";
 import {isPlaceholder, transform} from "./utils/transform";
 import {fetchOrConvertWorkflowTemplate, fetchOrParseWorkflow} from "./utils/workflow-cache";
 import {Value, ValueProviderConfig} from "./value-providers/config";
@@ -238,12 +238,12 @@ function getExpressionCompletionItems(
     currentInput = stringToken.source || stringToken.value;
   }
 
-  const relCharOffset = getRelCharOffset(token.range, currentInput, pos);
-  const expressionInput = (getExpressionInput(currentInput, relCharOffset) || "").trim();
+  const cursorOffset = getOffsetInContent(token.range, currentInput, pos);
+  const expressionInput = (getExpressionInput(currentInput, cursorOffset) || "").trim();
 
   try {
     return completeExpression(expressionInput, context, [], validatorFunctions).map(item =>
-      mapExpressionCompletionItem(item, currentInput[relCharOffset])
+      mapExpressionCompletionItem(item, currentInput[cursorOffset])
     );
   } catch (e) {
     error(`Error while completing expression: '${(e as Error)?.message || "<no details>"}'`);
@@ -274,3 +274,50 @@ function mapExpressionCompletionItem(item: ExpressionCompletionItem, charAfterPo
     kind: item.function ? CompletionItemKind.Function : CompletionItemKind.Variable
   };
 }
+
+/**
+ * Converts a document position to an offset within the token's content string.
+ */
+function getOffsetInContent(tokenRange: TokenRange, currentInput: string, pos: Position): number {
+  const range = mapRange(tokenRange);
+
+  if (range.start.line === range.end.line) {
+    // Single-line example:
+    //   if: github.ref == 'main'
+    //       ^8      ^15 (cursor)
+    // currentInput = "github.ref == 'main'"
+    // offset = 15 - 8 = 7
+    return pos.character - range.start.character;
+  }
+
+  // Multi-line example:
+  //   if: |                         <- line 3 (range.start.line)
+  //     first line                  <- line 4, content line 0
+  //     second line                 <- line 5, content line 1
+  //     github.                     <- line 6, content line 2, cursor at index 11
+  //            ^11 (cursor)
+  //
+  // currentInput = "    first line\n    second line\n    github."
+  //                 ^0              ^15              ^32        ^43
+
+  // Line index within content.
+  // From the example:
+  // lineIndexWithinContent = pos.line - range.start.line - 1
+  //                        = 6 - 3 - 1 = 2
+  const lineIndexWithinContent = pos.line - range.start.line - 1;
+
+  // Length of content before current line.
+  // From the example:
+  // lengthOfContentBeforeCurrentLine => 14 + 1 = 15 (after first iteration)
+  //                                  => 31 + 1 = 32 (after second iteration)
+  let lengthOfContentBeforeCurrentLine = 0;
+  for (let i = 0; i < lineIndexWithinContent; i++) {
+    lengthOfContentBeforeCurrentLine = currentInput.indexOf("\n", lengthOfContentBeforeCurrentLine) + 1;
+  }
+
+  // Final offset within content.
+  // From the example:
+  // finalOffset = lengthOfContentBeforeCurrentLine + pos.character
+  //             = 32 + 11 = 43
+  return lengthOfContentBeforeCurrentLine + pos.character;
+}

languageservice/src/context-providers/default.test.ts

@@ -0,0 +1,97 @@
+import {DescriptionDictionary} from "@actions/expressions";
+import {WorkflowContext} from "../context/workflow-context";
+import {getContext, Mode} from "./default";
+
+describe("getContext", () => {
+  const emptyWorkflowContext: WorkflowContext = {
+    uri: "test.yaml",
+    template: undefined
+  };
+
+  describe("when no contextProviderConfig is provided", () => {
+    it("should mark secrets context as incomplete", async () => {
+      const result = await getContext(["secrets"], undefined, emptyWorkflowContext, Mode.Validation);
+
+      const secretsContext = result.get("secrets") as DescriptionDictionary;
+      expect(secretsContext).toBeDefined();
+      expect(secretsContext.complete).toBe(false);
+    });
+
+    it("should mark vars context as incomplete", async () => {
+      const result = await getContext(["vars"], undefined, emptyWorkflowContext, Mode.Validation);
+
+      const varsContext = result.get("vars") as DescriptionDictionary;
+      expect(varsContext).toBeDefined();
+      expect(varsContext.complete).toBe(false);
+    });
+
+    it("should not mark other contexts as incomplete", async () => {
+      const result = await getContext(["env", "github"], undefined, emptyWorkflowContext, Mode.Validation);
+
+      const envContext = result.get("env") as DescriptionDictionary;
+      const githubContext = result.get("github") as DescriptionDictionary;
+
+      // These contexts are derived from the workflow file, so they can be complete
+      expect(envContext).toBeDefined();
+      expect(envContext.complete).toBe(true);
+      expect(githubContext).toBeDefined();
+      expect(githubContext.complete).toBe(true);
+    });
+  });
+
+  describe("when contextProviderConfig returns a value", () => {
+    it("should use the provided context for secrets", async () => {
+      const providedContext = new DescriptionDictionary();
+      providedContext.complete = true; // Provider fetched from API, so it's complete
+
+      const config = {
+        getContext: () => Promise.resolve(providedContext)
+      };
+
+      const result = await getContext(["secrets"], config, emptyWorkflowContext, Mode.Validation);
+
+      const secretsContext = result.get("secrets");
+      expect(secretsContext).toBe(providedContext);
+      expect((secretsContext as DescriptionDictionary).complete).toBe(true);
+    });
+
+    it("should use the provided context for vars", async () => {
+      const providedContext = new DescriptionDictionary();
+      providedContext.complete = true;
+
+      const config = {
+        getContext: () => Promise.resolve(providedContext)
+      };
+
+      const result = await getContext(["vars"], config, emptyWorkflowContext, Mode.Validation);
+
+      const varsContext = result.get("vars");
+      expect(varsContext).toBe(providedContext);
+      expect((varsContext as DescriptionDictionary).complete).toBe(true);
+    });
+  });
+
+  describe("when contextProviderConfig returns undefined", () => {
+    it("should mark secrets as incomplete", async () => {
+      const config = {
+        getContext: () => Promise.resolve(undefined)
+      };
+
+      const result = await getContext(["secrets"], config, emptyWorkflowContext, Mode.Validation);
+
+      const secretsContext = result.get("secrets") as DescriptionDictionary;
+      expect(secretsContext.complete).toBe(false);
+    });
+
+    it("should mark vars as incomplete", async () => {
+      const config = {
+        getContext: () => Promise.resolve(undefined)
+      };
+
+      const result = await getContext(["vars"], config, emptyWorkflowContext, Mode.Validation);
+
+      const varsContext = result.get("vars") as DescriptionDictionary;
+      expect(varsContext.complete).toBe(false);
+    });
+  });
+});

languageservice/src/context-providers/default.ts

@@ -32,15 +32,24 @@ export async function getContext(
 ): Promise<DescriptionDictionary> {
   const context = new DescriptionDictionary();
 
-  const filteredNames = filterContextNames(names, workflowContext);
-  for (const contextName of filteredNames) {
+  // All context names are valid - strategy and matrix are always available
+  // (with default values when no strategy block is defined)
+  for (const contextName of names) {
     let value = getDefaultContext(contextName, workflowContext, mode) || new DescriptionDictionary();
     if (value.kind === Kind.Null) {
       context.add(contextName, value);
       continue;
     }
 
-    value = (await config?.getContext(contextName, value, workflowContext, mode)) || value;
+    const remoteValue = await config?.getContext(contextName, value, workflowContext, mode);
+    if (remoteValue) {
+      value = remoteValue;
+    } else if (contextName === "secrets" || contextName === "vars") {
+      // Without a context provider to fetch remote secrets/vars, we can't know
+      // what values exist, so mark the context as incomplete to avoid false
+      // "Context access might be invalid" warnings
+      value.complete = false;
+    }
 
     context.add(contextName, value, getDescription(RootContext, contextName));
   }
@@ -74,11 +83,14 @@ function getDefaultContext(name: string, workflowContext: WorkflowContext, mode:
 
     case "runner":
       return objectToDictionary({
-        os: "Linux",
         arch: "X64",
+        debug: "1",
+        environment: "github-hosted",
         name: "GitHub Actions 2",
+        os: "Linux",
+        temp: "/home/runner/work/_temp",
         tool_cache: "/opt/hostedtoolcache",
-        temp: "/home/runner/work/_temp"
+        workspace: "/home/runner/work/repo"
       });
 
     case "secrets":
@@ -103,18 +115,3 @@ function objectToDictionary(object: {[key: string]: string}): DescriptionDiction
 
   return dictionary;
 }
-
-function filterContextNames(contextNames: string[], workflowContext: WorkflowContext): string[] {
-  return contextNames.filter(name => {
-    switch (name) {
-      case "matrix":
-      case "strategy":
-        return hasStrategy(workflowContext);
-    }
-    return true;
-  });
-}
-
-function hasStrategy(workflowContext: WorkflowContext): boolean {
-  return workflowContext.job?.strategy !== undefined || workflowContext.reusableWorkflowJob?.strategy !== undefined;
-}

languageservice/src/context-providers/descriptions.json

@@ -239,7 +239,13 @@
       "description": "The path to the directory containing preinstalled tools for GitHub-hosted runners. For more information, see \"[About GitHub-hosted runners](https://docs.github.com/actions/reference/specifications-for-github-hosted-runners/#supported-software).\""
     },
     "debug": {
-      "description": "This is set only if [debug logging](https://docs.github.com/actions/monitoring-and-troubleshooting-workflows/enabling-debug-logging) is enabled, and always has the value of `1`. It can be useful as an indicator to enable additional debugging or verbose logging in your own job steps."
+      "description": "This is set only if [`ACTIONS_STEP_DEBUG`](https://docs.github.com/actions/monitoring-and-troubleshooting-workflows/enabling-debug-logging) is enabled, and always has the value of `\"1\"`. It can be useful as an indicator to enable additional debugging or verbose logging in your own job steps."
+    },
+    "environment": {
+      "description": "The environment of the runner executing the job. Possible values are `github-hosted` for GitHub-hosted runners, or `self-hosted` for self-hosted runners."
+    },
+    "workspace": {
+      "description": "The runner-specific working directory path for the job."
     }
   },
   "strategy": {

languageservice/src/context-providers/matrix.test.ts

@@ -64,7 +64,7 @@ describe("matrix context", () => {
       expect(workflowContext.job).toBeUndefined();
 
       const context = getMatrixContext(workflowContext, Mode.Validation);
-      expect(context).toEqual(new DescriptionDictionary());
+      expect(context).toEqual(new data.Null());
     });
 
     it("strategy not defined", () => {
@@ -73,7 +73,7 @@ describe("matrix context", () => {
       expect(workflowContext.job!.strategy).toBeUndefined();
 
       const context = getMatrixContext(workflowContext, Mode.Validation);
-      expect(context).toEqual(new DescriptionDictionary());
+      expect(context).toEqual(new data.Null());
     });
 
     it("strategy is not a mapping token", () => {
@@ -81,7 +81,7 @@ describe("matrix context", () => {
       expect(workflowContext.job!.strategy).toBeDefined();
 
       const context = getMatrixContext(workflowContext, Mode.Validation);
-      expect(context).toEqual(new DescriptionDictionary());
+      expect(context).toEqual(new data.Null());
     });
 
     it("matrix is not defined", () => {

languageservice/src/context-providers/matrix.ts

@@ -10,7 +10,8 @@ export function getMatrixContext(workflowContext: WorkflowContext, mode: Mode):
   // https://docs.github.com/en/actions/learn-github-actions/contexts#matrix-context
   const strategy = workflowContext.job?.strategy ?? workflowContext.reusableWorkflowJob?.strategy;
   if (!strategy || !isMapping(strategy)) {
-    return new DescriptionDictionary();
+    // No strategy defined - matrix is null at runtime (not empty object)
+    return new data.Null();
   }
 
   const matrix = strategy.find("matrix");

languageservice/src/context-providers/steps.test.ts

@@ -0,0 +1,78 @@
+/* eslint-disable @typescript-eslint/no-non-null-assertion */
+import {DescriptionDictionary, isDescriptionDictionary} from "@actions/expressions";
+import {WorkflowContext} from "../context/workflow-context";
+import {getStepsContext} from "./steps";
+
+function createWorkflowContext(stepIds: string[], currentStepId?: string): WorkflowContext {
+  return {
+    job: {
+      steps: stepIds.map(id => ({id}))
+    },
+    step: currentStepId ? {id: currentStepId} : undefined
+  } as WorkflowContext;
+}
+
+describe("steps context", () => {
+  it("returns empty dictionary when no job", () => {
+    const workflowContext = {} as WorkflowContext;
+    const context = getStepsContext(workflowContext);
+    expect(context.pairs().length).toBe(0);
+  });
+
+  it("returns empty dictionary when no steps", () => {
+    const workflowContext = {job: {}} as WorkflowContext;
+    const context = getStepsContext(workflowContext);
+    expect(context.pairs().length).toBe(0);
+  });
+
+  it("includes steps with user-defined ids", () => {
+    const workflowContext = createWorkflowContext(["step-a", "step-b"]);
+    const context = getStepsContext(workflowContext);
+
+    expect(context.get("step-a")).toBeDefined();
+    expect(context.get("step-b")).toBeDefined();
+  });
+
+  it("excludes generated step ids (starting with __)", () => {
+    const workflowContext = createWorkflowContext(["step-a", "__generated"]);
+    const context = getStepsContext(workflowContext);
+
+    expect(context.get("step-a")).toBeDefined();
+    expect(context.get("__generated")).toBeUndefined();
+  });
+
+  it("excludes current step and later steps", () => {
+    const workflowContext = createWorkflowContext(["step-a", "step-b", "step-c"], "step-b");
+    const context = getStepsContext(workflowContext);
+
+    expect(context.get("step-a")).toBeDefined();
+    expect(context.get("step-b")).toBeUndefined();
+    expect(context.get("step-c")).toBeUndefined();
+  });
+
+  describe("step outputs", () => {
+    it("outputs is a dictionary, not null", () => {
+      const workflowContext = createWorkflowContext(["step-a"]);
+      const context = getStepsContext(workflowContext);
+
+      const stepContext = context.get("step-a");
+      expect(stepContext).toBeDefined();
+      expect(isDescriptionDictionary(stepContext!)).toBe(true);
+
+      const outputs = (stepContext as DescriptionDictionary).get("outputs");
+      expect(outputs).toBeDefined();
+      expect(isDescriptionDictionary(outputs!)).toBe(true);
+    });
+
+    it("outputs is marked incomplete to allow dynamic outputs", () => {
+      const workflowContext = createWorkflowContext(["step-a"]);
+      const context = getStepsContext(workflowContext);
+
+      const stepContext = context.get("step-a") as DescriptionDictionary;
+      const outputs = stepContext.get("outputs") as DescriptionDictionary;
+
+      // Outputs should be incomplete since we can't know what outputs a step will produce
+      expect(outputs.complete).toBe(false);
+    });
+  });
+});

languageservice/src/context-providers/steps.ts

@@ -31,7 +31,10 @@ function stepContext(): DescriptionDictionary {
   // https://docs.github.com/en/actions/learn-github-actions/contexts#steps-context
   const d = new DescriptionDictionary();
 
-  d.add("outputs", new data.Null(), getDescription("steps", "outputs"));
+  // Step outputs are dynamic - actions can generate outputs based on their inputs
+  const outputs = new DescriptionDictionary();
+  outputs.complete = false;
+  d.add("outputs", outputs, getDescription("steps", "outputs"));
 
   // Can be "success", "failure", "cancelled", or "skipped"
   d.add("conclusion", new data.Null(), getDescription("steps", "conclusion"));

languageservice/src/context-providers/strategy.test.ts

@@ -0,0 +1,126 @@
+import {data} from "@actions/expressions";
+import {Job} from "@actions/workflow-parser/model/workflow-template";
+import {BooleanToken} from "@actions/workflow-parser/templates/tokens/boolean-token";
+import {MappingToken} from "@actions/workflow-parser/templates/tokens/mapping-token";
+import {NumberToken} from "@actions/workflow-parser/templates/tokens/number-token";
+import {StringToken} from "@actions/workflow-parser/templates/tokens/string-token";
+import {TemplateToken} from "@actions/workflow-parser/templates/tokens/template-token";
+import {WorkflowContext} from "../context/workflow-context";
+import {getStrategyContext} from "./strategy";
+
+function stringToToken(value: string) {
+  return new StringToken(undefined, undefined, value, undefined);
+}
+
+function boolToToken(value: boolean) {
+  return new BooleanToken(undefined, undefined, value, undefined);
+}
+
+function numberToToken(value: number) {
+  return new NumberToken(undefined, undefined, value, undefined);
+}
+
+function contextFromStrategy(strategy?: TemplateToken) {
+  return {
+    job: {
+      strategy: strategy
+    }
+  } as WorkflowContext;
+}
+
+describe("strategy context", () => {
+  describe("no strategy defined", () => {
+    it("returns defaults when job is undefined", () => {
+      const workflowContext = {} as WorkflowContext;
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(true));
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(1));
+    });
+
+    it("returns defaults when strategy is undefined", () => {
+      const job = {} as Job;
+      const workflowContext = {job} as WorkflowContext;
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(true));
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(1));
+    });
+
+    it("returns defaults when strategy is not a mapping", () => {
+      const workflowContext = contextFromStrategy(stringToToken("hello"));
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(true));
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(1));
+    });
+  });
+
+  describe("strategy defined with partial properties", () => {
+    it("uses specified fail-fast, defaults for others", () => {
+      const strategy = new MappingToken(undefined, undefined, undefined);
+      strategy.add(stringToToken("fail-fast"), boolToToken(false));
+      const workflowContext = contextFromStrategy(strategy);
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(false));
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(1));
+    });
+
+    it("uses specified max-parallel, defaults for others", () => {
+      const strategy = new MappingToken(undefined, undefined, undefined);
+      strategy.add(stringToToken("max-parallel"), numberToToken(5));
+      const workflowContext = contextFromStrategy(strategy);
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(true));
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(5));
+    });
+
+    it("only has matrix defined, all strategy properties use defaults", () => {
+      const strategy = new MappingToken(undefined, undefined, undefined);
+      const matrix = new MappingToken(undefined, undefined, undefined);
+      strategy.add(stringToToken("matrix"), matrix);
+      const workflowContext = contextFromStrategy(strategy);
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(true));
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(1));
+    });
+  });
+
+  describe("strategy with all properties defined", () => {
+    it("uses all specified values", () => {
+      const strategy = new MappingToken(undefined, undefined, undefined);
+      strategy.add(stringToToken("fail-fast"), boolToToken(false));
+      strategy.add(stringToToken("max-parallel"), numberToToken(3));
+      const workflowContext = contextFromStrategy(strategy);
+
+      const context = getStrategyContext(workflowContext);
+
+      expect(context.get("fail-fast")).toEqual(new data.BooleanData(false));
+      // job-index and job-total are runtime values, not specified in YAML
+      expect(context.get("job-index")).toEqual(new data.NumberData(0));
+      expect(context.get("job-total")).toEqual(new data.NumberData(1));
+      expect(context.get("max-parallel")).toEqual(new data.NumberData(3));
+    });
+  });
+});

languageservice/src/context-providers/strategy.ts

@@ -3,15 +3,24 @@ import {isMapping, isScalar, isString} from "@actions/workflow-parser";
 import {WorkflowContext} from "../context/workflow-context";
 import {scalarToData} from "../utils/scalar-to-data";
 
+// Default strategy values when no strategy block is defined
+const DEFAULT_STRATEGY = {
+  "fail-fast": new data.BooleanData(true),
+  "job-index": new data.NumberData(0),
+  "job-total": new data.NumberData(1),
+  "max-parallel": new data.NumberData(1)
+};
+
 export function getStrategyContext(workflowContext: WorkflowContext): DescriptionDictionary {
   // https://docs.github.com/en/actions/learn-github-actions/contexts#strategy-context
   const keys = ["fail-fast", "job-index", "job-total", "max-parallel"];
 
   const strategy = workflowContext.job?.strategy ?? workflowContext.reusableWorkflowJob?.strategy;
   if (!strategy || !isMapping(strategy)) {
+    // No strategy defined - return defaults that match runtime behavior
     return new DescriptionDictionary(
       ...keys.map(key => {
-        return {key, value: new data.Null()};
+        return {key, value: DEFAULT_STRATEGY[key as keyof typeof DEFAULT_STRATEGY]};
       })
     );
   }
@@ -31,7 +40,8 @@ export function getStrategyContext(workflowContext: WorkflowContext): Descriptio
 
   for (const key of keys) {
     if (!strategyContext.get(key)) {
-      strategyContext.add(key, new data.Null());
+      // Use default value for missing properties
+      strategyContext.add(key, DEFAULT_STRATEGY[key as keyof typeof DEFAULT_STRATEGY]);
     }
   }
 

languageservice/src/utils/rel-char-pos.ts

@@ -1,15 +0,0 @@
-import {TokenRange} from "@actions/workflow-parser/templates/tokens/token-range";
-import {Position} from "vscode-languageserver-textdocument";
-import {mapRange} from "./range";
-
-export function getRelCharOffset(tokenRange: TokenRange, currentInput: string, pos: Position): number {
-  const range = mapRange(tokenRange);
-  if (range.start.line !== range.end.line) {
-    const lines = currentInput.split("\n");
-    const lineDiff = pos.line - range.start.line - 1;
-    const linesBeforeCusor = lines.slice(0, lineDiff);
-    return linesBeforeCusor.join("\n").length + pos.character + 1;
-  } else {
-    return pos.character - range.start.character;
-  }
-}

languageservice/src/validate.concurrency.test.ts

@@ -0,0 +1,245 @@
+import {DiagnosticSeverity} from "vscode-languageserver-types";
+import {validate} from "./validate";
+import {createDocument} from "./test-utils/document";
+import {clearCache} from "./utils/workflow-cache";
+
+beforeEach(() => {
+  clearCache();
+});
+
+describe("validate concurrency deadlock", () => {
+  describe("should error on matching concurrency groups", () => {
+    it("simple string match", async () => {
+      const input = `
+on: push
+concurrency: test
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: test
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(2);
+
+      // Workflow-level warning
+      expect(concurrencyErrors[0]).toMatchObject({
+        message: "Concurrency group 'test' is also used by job 'job1'. This will cause a deadlock.",
+        severity: DiagnosticSeverity.Error
+      });
+
+      // Job-level warning
+      expect(concurrencyErrors[1]).toMatchObject({
+        message: "Concurrency group 'test' is also defined at the workflow level. This will cause a deadlock.",
+        severity: DiagnosticSeverity.Error
+      });
+    });
+
+    it("workflow mapping form, job string form", async () => {
+      const input = `
+on: push
+concurrency:
+  group: my-group
+  cancel-in-progress: true
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    concurrency: my-group
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(2);
+      expect(concurrencyErrors[0].message).toContain("my-group");
+      expect(concurrencyErrors[0].message).toContain("deploy");
+    });
+
+    it("workflow string form, job mapping form", async () => {
+      const input = `
+on: push
+concurrency: deploy-group
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    concurrency:
+      group: deploy-group
+      cancel-in-progress: true
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(2);
+      expect(concurrencyErrors[0].message).toContain("deploy-group");
+    });
+
+    it("both mapping forms", async () => {
+      const input = `
+on: push
+concurrency:
+  group: shared
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency:
+      group: shared
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(2);
+    });
+
+    it("multiple jobs with matching concurrency", async () => {
+      const input = `
+on: push
+concurrency: shared
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: shared
+    steps:
+      - run: echo hi
+  job2:
+    runs-on: ubuntu-latest
+    concurrency: shared
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      // Should have 2 warnings per job (workflow + job) = 4 total, but workflow is only warned once per match
+      // Actually: 1 workflow warning per matching job + 1 job warning per matching job = 4 total
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(4);
+    });
+  });
+
+  describe("should not warn", () => {
+    it("different concurrency groups", async () => {
+      const input = `
+on: push
+concurrency: workflow-group
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: job-group
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+
+    it("workflow concurrency is an expression", async () => {
+      const input = `
+on: push
+concurrency: \${{ github.ref }}
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: test
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+
+    it("job concurrency is an expression", async () => {
+      const input = `
+on: push
+concurrency: test
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: \${{ github.ref }}
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+
+    it("no workflow-level concurrency", async () => {
+      const input = `
+on: push
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: test
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+
+    it("no job-level concurrency", async () => {
+      const input = `
+on: push
+concurrency: test
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+
+    it("case sensitive - different case is different group", async () => {
+      const input = `
+on: push
+concurrency: Test
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: test
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+
+    it("workflow concurrency group in mapping is an expression", async () => {
+      const input = `
+on: push
+concurrency:
+  group: \${{ github.ref }}
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    concurrency: test
+    steps:
+      - run: echo hi`;
+
+      const result = await validate(createDocument("wf.yaml", input));
+
+      const concurrencyErrors = result.filter(d => d.message.includes("deadlock"));
+      expect(concurrencyErrors).toHaveLength(0);
+    });
+  });
+});

languageservice/src/validate.expressions.test.ts

@@ -681,7 +681,8 @@ jobs:
 
       const result = await validate(createDocument("wf.yaml", input));
 
-      expect(result).not.toEqual([]);
+      // Strategy context is always available with default values
+      expect(result).toEqual([]);
     });
 
     it("invalid strategy property", async () => {
@@ -996,22 +997,8 @@ jobs:
 
       const result = await validate(createDocument("wf.yaml", input));
 
-      expect(result).toEqual([
-        {
-          message: "Context access might be invalid: matrix",
-          range: {
-            end: {
-              character: 36,
-              line: 8
-            },
-            start: {
-              character: 18,
-              line: 8
-            }
-          },
-          severity: DiagnosticSeverity.Warning
-        }
-      ]);
+      // Matrix is null when no strategy is defined, accessing properties on null is valid
+      expect(result).toEqual([]);
     });
 
     it("basic matrix", async () => {
@@ -1609,6 +1596,48 @@ jobs:
         expect(result).toEqual([]);
       });
 
+      it("allows runner.environment context", async () => {
+        const input = `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - if: runner.environment == 'github-hosted'
+        run: echo hello`;
+
+        const result = await validate(createDocument("wf.yaml", input));
+        expect(result).toEqual([]);
+      });
+
+      it("allows runner.debug context", async () => {
+        const input = `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - if: runner.debug == '1'
+        run: echo hello`;
+
+        const result = await validate(createDocument("wf.yaml", input));
+        expect(result).toEqual([]);
+      });
+
+      it("allows runner.workspace context", async () => {
+        const input = `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - if: runner.workspace != ''
+        run: echo hello`;
+
+        const result = await validate(createDocument("wf.yaml", input));
+        expect(result).toEqual([]);
+      });
+
       it("allows env context", async () => {
         const input = `
 on: push

languageservice/src/validate.incomplete-context.test.ts

@@ -0,0 +1,152 @@
+/**
+ * Test validation behavior when no context providers are configured.
+ *
+ * When contextProviderConfig is not provided (or returns incomplete data),
+ * we should skip validation for secrets/vars rather than showing false
+ * positive "Context access might be invalid" warnings.
+ *
+ * This is important for offline/disconnected scenarios where API calls
+ * to fetch secrets/vars are not possible.
+ */
+
+import {validate} from "./validate";
+import {createDocument} from "./test-utils/document";
+import {clearCache} from "./utils/workflow-cache";
+
+beforeEach(() => {
+  clearCache();
+});
+
+describe("validation without context providers", () => {
+  describe("secrets context", () => {
+    it("should not warn on secrets.GITHUB_TOKEN", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "test"
+        env:
+          GH_TOKEN: \${{ secrets.GITHUB_TOKEN }}
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+
+    it("should not warn on custom secrets when no provider configured", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "test"
+        env:
+          API_KEY: \${{ secrets.MY_API_KEY }}
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+
+    it("should not warn on secrets with environment", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    environment: production
+    steps:
+      - run: echo "test"
+        env:
+          API_KEY: \${{ secrets.API_KEY }}
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+  });
+
+  describe("vars context", () => {
+    it("should not warn on vars when no provider configured", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "\${{ vars.ENVIRONMENT }}"
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+
+    it("should not warn on vars with environment", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    environment: production
+    steps:
+      - run: echo "\${{ vars.API_URL }}"
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+
+    it("should not warn on vars with fallback pattern", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "\${{ vars.OPTIONAL_VAR || 'default-value' }}"
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+  });
+
+  describe("combined secrets and vars", () => {
+    it("should not warn on workflow using both secrets and vars", async () => {
+      const doc = createDocument(
+        "wf.yaml",
+        `
+on: push
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    environment: production
+    steps:
+      - run: |
+          echo "Deploying to \${{ vars.API_URL }}"
+          echo "Using region \${{ vars.AWS_REGION }}"
+        env:
+          API_KEY: \${{ secrets.API_KEY }}
+          AWS_SECRET: \${{ secrets.AWS_SECRET_ACCESS_KEY }}
+`
+      );
+      const result = await validate(doc);
+      expect(result).toEqual([]);
+    });
+  });
+});

languageservice/src/validate.test.ts

@@ -385,4 +385,31 @@ jobs:
       expect(result).toEqual([]);
     });
   });
+
+  describe("workflow_dispatch", () => {
+    it("allows empty string in choice options", async () => {
+      const result = await validate(
+        createDocument(
+          "wf.yaml",
+          `on:
+  workflow_dispatch:
+    inputs:
+      plugin-name:
+        description: Specific plugin to build
+        type: choice
+        options:
+          - ''
+          - foo
+          - bar
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo`
+        )
+      );
+
+      expect(result).toEqual([]);
+    });
+  });
 });

languageservice/src/validate.ts

@@ -1,6 +1,6 @@
 import {Lexer, Parser, data} from "@actions/expressions";
 import {Expr, FunctionCall, Literal, Logical} from "@actions/expressions/ast";
-import {ParseWorkflowResult, WorkflowTemplate, isBasicExpression, isString} from "@actions/workflow-parser";
+import {ParseWorkflowResult, WorkflowTemplate, isBasicExpression, isMapping, isString} from "@actions/workflow-parser";
 import {ErrorPolicy} from "@actions/workflow-parser/model/convert";
 import {getCronDescription, hasCronIntervalLessThan5Minutes} from "@actions/workflow-parser/model/converter/cron";
 import {ensureStatusFunction} from "@actions/workflow-parser/model/converter/if-condition";
@@ -209,6 +209,9 @@ async function additionalValidations(
       }
     }
   }
+
+  // Validate concurrency deadlock between workflow and job levels
+  validateConcurrencyDeadlock(diagnostics, template);
 }
 
 function invalidValue(diagnostics: Diagnostic[], token: StringToken, kind: ValueProviderKind) {
@@ -712,3 +715,71 @@ async function validateExpression(
     );
   }
 }
+
+/**
+ * Validates that workflow-level and job-level concurrency groups don't match,
+ * which would cause a deadlock at runtime.
+ */
+function validateConcurrencyDeadlock(diagnostics: Diagnostic[], template: WorkflowTemplate): void {
+  const workflowGroup = getStaticConcurrencyGroup(template.concurrency);
+  if (!workflowGroup) {
+    return; // No workflow-level concurrency or it's an expression
+  }
+
+  for (const job of template.jobs || []) {
+    if (!job.concurrency) {
+      continue;
+    }
+
+    const jobGroup = getStaticConcurrencyGroup(job.concurrency);
+    if (!jobGroup) {
+      continue; // Job concurrency is an expression
+    }
+
+    if (workflowGroup.value === jobGroup.value) {
+      // Error on workflow-level concurrency
+      if (template.concurrency.range) {
+        diagnostics.push({
+          message: `Concurrency group '${workflowGroup.value}' is also used by job '${job.id.value}'. This will cause a deadlock.`,
+          range: mapRange(template.concurrency.range),
+          severity: DiagnosticSeverity.Error
+        });
+      }
+
+      // Error on job-level concurrency
+      if (job.concurrency.range) {
+        diagnostics.push({
+          message: `Concurrency group '${jobGroup.value}' is also defined at the workflow level. This will cause a deadlock.`,
+          range: mapRange(job.concurrency.range),
+          severity: DiagnosticSeverity.Error
+        });
+      }
+    }
+  }
+}
+
+/**
+ * Extracts the static concurrency group name from a concurrency token.
+ * Returns undefined if the token is an expression or doesn't have a static group.
+ */
+function getStaticConcurrencyGroup(token: TemplateToken | undefined): StringToken | undefined {
+  if (!token || token.isExpression) {
+    return undefined;
+  }
+
+  // Simple string form: concurrency: "test"
+  if (isString(token)) {
+    return token;
+  }
+
+  // Mapping form: concurrency: { group: "test", cancel-in-progress: true }
+  if (isMapping(token)) {
+    for (const pair of token) {
+      if (isString(pair.key) && pair.key.value === "group" && isString(pair.value) && !pair.value.isExpression) {
+        return pair.value;
+      }
+    }
+  }
+
+  return undefined;
+}

languageservice/src/validate.yaml-anchors.test.ts

@@ -0,0 +1,202 @@
+import {validate} from "./validate";
+import {createDocument} from "./test-utils/document";
+import {clearCache} from "./utils/workflow-cache";
+
+beforeEach(() => {
+  clearCache();
+});
+
+describe("YAML anchors and aliases", () => {
+  it("should handle anchors and aliases in env", async () => {
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    env: &env
+      ENV1: env1
+      ENV2: env2
+    steps:
+      - run: exit 0
+  job2:
+    runs-on: ubuntu-latest
+    env: *env
+    steps:
+      - run: exit 0
+`
+    );
+    const result = await validate(doc);
+    expect(result).toEqual([]);
+  });
+
+  it("should handle multiple aliases to the same anchor", async () => {
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+env: &shared
+  SHARED: true
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    env: *shared
+    steps:
+      - run: exit 0
+  job2:
+    runs-on: ubuntu-latest
+    env: *shared
+    steps:
+      - run: exit 0
+  job3:
+    runs-on: ubuntu-latest
+    env: *shared
+    steps:
+      - run: exit 0
+`
+    );
+    const result = await validate(doc);
+    expect(result).toEqual([]);
+  });
+
+  it("should handle anchors in matrix strategy", async () => {
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include: &matrix-include
+          - os: ubuntu-latest
+            node: 18
+          - os: windows-latest
+            node: 20
+    steps:
+      - run: exit 0
+  test2:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include: *matrix-include
+    steps:
+      - run: exit 0
+`
+    );
+    const result = await validate(doc);
+    expect(result).toEqual([]);
+  });
+
+  it("should handle anchors in steps", async () => {
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - &checkout
+        uses: actions/checkout@v4
+      - run: npm test
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - *checkout
+      - run: npm run deploy
+`
+    );
+    const result = await validate(doc);
+    expect(result).toEqual([]);
+  });
+
+  it("should handle scalar anchors", async () => {
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  build:
+    runs-on: &runner ubuntu-latest
+    steps:
+      - run: exit 0
+  test:
+    runs-on: *runner
+    steps:
+      - run: exit 0
+`
+    );
+    const result = await validate(doc);
+    expect(result).toEqual([]);
+  });
+
+  it("should work without anchors (control test)", async () => {
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  job1:
+    runs-on: ubuntu-latest
+    env:
+      ENV1: env1
+      ENV2: env2
+    steps:
+      - run: exit 0
+  job2:
+    runs-on: ubuntu-latest
+    env:
+      ENV1: env1
+      ENV2: env2
+    steps:
+      - run: exit 0
+`
+    );
+    const result = await validate(doc);
+    expect(result).toEqual([]);
+  });
+
+  it("should handle circular aliases without hanging", async () => {
+    // This is an invalid use case (alias referencing parent) but should not hang
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    env: &myenv
+      FOO: bar
+      nested: *myenv
+    steps:
+      - run: exit 0
+`
+    );
+    // Should complete without hanging - circular portion is silently ignored
+    // which may cause downstream validation errors, but that's acceptable
+    const result = await validate(doc);
+    expect(result).toBeDefined();
+  });
+
+  it("should handle undefined alias references", async () => {
+    // Reference to non-existent anchor - yaml library should report error
+    const doc = createDocument(
+      "wf.yaml",
+      `
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    env: *nonexistent
+    steps:
+      - run: exit 0
+`
+    );
+    const result = await validate(doc);
+    expect(result).toBeDefined();
+    expect(result.length).toBeGreaterThan(0);
+  });
+});

lerna.json

@@ -6,5 +6,5 @@
     "languageservice",
     "languageserver"
   ],
-  "version": "0.3.23"
+  "version": "0.3.25"
 }

package-lock.json

@@ -135,7 +135,7 @@
     },
     "expressions": {
       "name": "@actions/expressions",
-      "version": "0.3.23",
+      "version": "0.3.25",
       "license": "MIT",
       "devDependencies": {
         "@types/jest": "^29.0.3",
@@ -151,7 +151,7 @@
         "typescript": "^4.7.4"
       },
       "engines": {
-        "node": ">= 16.15"
+        "node": ">= 18"
       }
     },
     "expressions/node_modules/@eslint/eslintrc": {
@@ -395,11 +395,11 @@
     },
     "languageserver": {
       "name": "@actions/languageserver",
-      "version": "0.3.23",
+      "version": "0.3.25",
       "license": "MIT",
       "dependencies": {
-        "@actions/languageservice": "^0.3.23",
-        "@actions/workflow-parser": "^0.3.23",
+        "@actions/languageservice": "^0.3.25",
+        "@actions/workflow-parser": "^0.3.25",
         "@octokit/rest": "^21.1.1",
         "@octokit/types": "^9.0.0",
         "vscode-languageserver": "^8.0.2",
@@ -421,7 +421,7 @@
         "typescript": "^4.8.4"
       },
       "engines": {
-        "node": ">= 16.15"
+        "node": ">= 18"
       }
     },
     "languageserver/node_modules/@eslint/eslintrc": {
@@ -921,11 +921,11 @@
     },
     "languageservice": {
       "name": "@actions/languageservice",
-      "version": "0.3.23",
+      "version": "0.3.25",
       "license": "MIT",
       "dependencies": {
-        "@actions/expressions": "^0.3.23",
-        "@actions/workflow-parser": "^0.3.23",
+        "@actions/expressions": "^0.3.25",
+        "@actions/workflow-parser": "^0.3.25",
         "vscode-languageserver-textdocument": "^1.0.7",
         "vscode-languageserver-types": "^3.17.2",
         "vscode-uri": "^3.0.8",
@@ -947,7 +947,7 @@
         "typescript": "^4.8.4"
       },
       "engines": {
-        "node": ">= 16.15"
+        "node": ">= 18"
       }
     },
     "languageservice/node_modules/@eslint/eslintrc": {
@@ -12834,10 +12834,10 @@
     },
     "workflow-parser": {
       "name": "@actions/workflow-parser",
-      "version": "0.3.23",
+      "version": "0.3.25",
       "license": "MIT",
       "dependencies": {
-        "@actions/expressions": "^0.3.23",
+        "@actions/expressions": "^0.3.25",
         "cronstrue": "^2.21.0",
         "yaml": "^2.0.0-8"
       },
@@ -12855,7 +12855,7 @@
         "typescript": "^4.8.4"
       },
       "engines": {
-        "node": ">= 16.15"
+        "node": ">= 18"
       }
     }
   }

script/fix-dts-extensions.cjs

@@ -0,0 +1,69 @@
+#!/usr/bin/env node
+
+/**
+ * Post-build script to fix TypeScript's rewriteRelativeImportExtensions bug
+ * where .d.ts files get .ts extensions instead of .js extensions.
+ * See: https://github.com/microsoft/TypeScript/issues/61037
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+function fixDtsFile(filePath) {
+    let content = fs.readFileSync(filePath, 'utf8');
+    const original = content;
+    
+    // Replace .ts extensions in import/export statements with .js
+    // Matches: from "./foo.ts" or from './foo.ts'
+    content = content.replace(/(from\s+["'])([^"']+)\.ts(["'])/g, '$1$2.js$3');
+    
+    // Matches: import("./foo.ts") or import('./foo.ts')
+    content = content.replace(/(import\s*\(\s*["'])([^"']+)\.ts(["']\s*\))/g, '$1$2.js$3');
+    
+    // Matches: export * from "./foo.ts"
+    content = content.replace(/(export\s+\*\s+from\s+["'])([^"']+)\.ts(["'])/g, '$1$2.js$3');
+    
+    if (content !== original) {
+        fs.writeFileSync(filePath, content, 'utf8');
+        console.log(`Fixed: ${filePath}`);
+        return true;
+    }
+    return false;
+}
+
+function walkDir(dir, callback) {
+    const files = fs.readdirSync(dir);
+    for (const file of files) {
+        const filePath = path.join(dir, file);
+        const stat = fs.statSync(filePath);
+        if (stat.isDirectory()) {
+            walkDir(filePath, callback);
+        } else if (file.endsWith('.d.ts')) {
+            callback(filePath);
+        }
+    }
+}
+
+function main() {
+    const args = process.argv.slice(2);
+    if (args.length === 0) {
+        console.error('Usage: fix-dts-extensions.js <dist-dir> [<dist-dir2> ...]');
+        process.exit(1);
+    }
+    
+    let fixedCount = 0;
+    for (const dir of args) {
+        if (!fs.existsSync(dir)) {
+            console.warn(`Directory not found: ${dir}`);
+            continue;
+        }
+        walkDir(dir, (filePath) => {
+            if (fixDtsFile(filePath)) {
+                fixedCount++;
+            }
+        });
+    }
+    console.log(`Fixed ${fixedCount} .d.ts file(s)`);
+}
+
+main();

workflow-parser/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/workflow-parser",
-  "version": "0.3.23",
+  "version": "0.3.25",
   "license": "MIT",
   "type": "module",
   "source": "./src/index.ts",
@@ -48,12 +48,12 @@
     "watch": "tsc --build tsconfig.build.json --watch"
   },
   "dependencies": {
-    "@actions/expressions": "^0.3.23",
+    "@actions/expressions": "^0.3.25",
     "cronstrue": "^2.21.0",
     "yaml": "^2.0.0-8"
   },
   "engines": {
-    "node": ">= 16.15"
+    "node": ">= 18"
   },
   "files": [
     "dist/**/*"

workflow-parser/src/schema-sync.test.ts

@@ -0,0 +1,183 @@
+import * as fs from "fs";
+
+/**
+ * This test ensures that activity types in workflow-v1.0.json stay in sync with
+ * the webhooks.json file from the languageservice package.
+ *
+ * When this test fails, it means new activity types were added to webhooks.json
+ * that need to be handled. See docs/json-data-files.md for detailed instructions.
+ *
+ * Quick reference for fixing failures:
+ * 1. Check https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows
+ *    Find the event and look at its "Activity types" table to see if the type is a valid workflow trigger.
+ * 2. If the activity type IS a valid workflow trigger:
+ *    → Add it to the corresponding *-activity-type definition in workflow-v1.0.json
+ * 3. If the activity type is webhook-only (not in workflow docs):
+ *    → Add it to the WEBHOOK_ONLY list below
+ * 4. If there's a naming difference between webhook and schema:
+ *    → Add it to the NAME_MAPPINGS list below
+ * 5. If the schema has a type not in webhooks.json:
+ *    → Add it to the SCHEMA_ONLY list below
+ */
+
+describe("schema-sync", () => {
+  // Activity types that exist in webhooks.json but are intentionally NOT
+  // supported as workflow triggers. These will be ignored when checking
+  // webhooks → schema direction.
+  const WEBHOOK_ONLY: Record<string, string[]> = {
+    // check_suite: requested and rerequested are webhook-only, not valid workflow triggers
+    // See: https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows#check_suite
+    check_suite: ["requested", "rerequested"],
+
+    // registry_package: "default" is a webhook concept, not a workflow trigger type
+    registry_package: ["default"]
+  };
+
+  // Activity types that exist in workflow schema but are intentionally NOT
+  // in webhooks.json (schema-only types). These will be ignored when checking
+  // schema → webhooks direction.
+  const SCHEMA_ONLY: Record<string, string[]> = {
+    // registry_package: "updated" is a valid workflow trigger per GitHub docs
+    // but doesn't exist in webhooks.json (webhooks only has "published" and "default")
+    // See: https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows#registry_package
+    registry_package: ["updated"]
+  };
+
+  // Known naming differences between webhooks.json and workflow-v1.0.json.
+  // Key: event name, Value: { webhook: "webhookName", schema: "schemaName" }
+  // These are treated as equivalent when comparing in both directions.
+  const NAME_MAPPINGS: Record<string, Array<{webhook: string; schema: string}>> = {
+    // project_column: webhooks.json uses "edited" but workflow triggers use "updated"
+    // This is a known naming difference - they represent the same action
+    project_column: [{webhook: "edited", schema: "updated"}]
+  };
+
+  it("activity types in workflow-v1.0.json match webhooks.json", () => {
+    // Load webhooks.json (relative path from the test runner CWD which is the package root)
+    const webhooksPath = "../languageservice/src/context-providers/events/webhooks.json";
+    const webhooks = JSON.parse(fs.readFileSync(webhooksPath, "utf-8")) as Record<string, Record<string, unknown>>;
+
+    // Load workflow-v1.0.json
+    const schemaPath = "./src/workflow-v1.0.json";
+    const schema = JSON.parse(fs.readFileSync(schemaPath, "utf-8")) as {
+      definitions: Record<string, {"allowed-values"?: string[]; description?: string}>;
+    };
+
+    const mismatches: string[] = [];
+
+    // Build mapping helpers for each event
+    const getWebhookToSchemaMapping = (eventName: string): Map<string, string> => {
+      const map = new Map<string, string>();
+      for (const mapping of NAME_MAPPINGS[eventName] || []) {
+        map.set(mapping.webhook, mapping.schema);
+      }
+      return map;
+    };
+
+    const getSchemaToWebhookMapping = (eventName: string): Map<string, string> => {
+      const map = new Map<string, string>();
+      for (const mapping of NAME_MAPPINGS[eventName] || []) {
+        map.set(mapping.schema, mapping.webhook);
+      }
+      return map;
+    };
+
+    // Check both directions for each event
+    for (const [eventName, eventData] of Object.entries(webhooks)) {
+      const webhookTypes = Object.keys(eventData);
+      if (webhookTypes.length === 0) continue;
+
+      const schemaTypeName = `${eventName.replace(/_/g, "-")}-activity-type`;
+      const schemaDef = schema.definitions[schemaTypeName];
+
+      // If there's no activity type definition in the schema, this event
+      // doesn't support activity types in workflows (e.g., push, pull)
+      if (!schemaDef || !schemaDef["allowed-values"]) continue;
+
+      const schemaTypes = new Set(schemaDef["allowed-values"]);
+      const webhookOnly = new Set(WEBHOOK_ONLY[eventName] || []);
+      const schemaOnly = new Set(SCHEMA_ONLY[eventName] || []);
+      const webhookToSchema = getWebhookToSchemaMapping(eventName);
+      const schemaToWebhook = getSchemaToWebhookMapping(eventName);
+
+      // Direction 1: webhooks → schema
+      // Check that each webhook type exists in schema (or has a mapping, or is webhook-only)
+      for (const webhookType of webhookTypes) {
+        if (webhookOnly.has(webhookType)) continue;
+
+        const mappedSchemaType = webhookToSchema.get(webhookType);
+        if (mappedSchemaType) {
+          // Has a mapping - check the mapped name exists in schema
+          if (!schemaTypes.has(mappedSchemaType)) {
+            mismatches.push(
+              `Event "${eventName}": webhook type "${webhookType}" maps to "${mappedSchemaType}" but "${mappedSchemaType}" not found in schema`
+            );
+          }
+        } else {
+          // No mapping - check the type exists directly
+          if (!schemaTypes.has(webhookType)) {
+            mismatches.push(
+              `Event "${eventName}": missing activity type "${webhookType}" in workflow-v1.0.json (exists in webhooks.json)`
+            );
+          }
+        }
+      }
+
+      // Direction 2: schema → webhooks
+      // Check that each schema type exists in webhooks (or has a mapping, or is schema-only)
+      const webhookTypesSet = new Set(webhookTypes);
+      for (const schemaType of schemaTypes) {
+        if (schemaOnly.has(schemaType)) continue;
+
+        const mappedWebhookType = schemaToWebhook.get(schemaType);
+        if (mappedWebhookType) {
+          // Has a mapping - check the mapped name exists in webhooks
+          if (!webhookTypesSet.has(mappedWebhookType)) {
+            mismatches.push(
+              `Event "${eventName}": schema type "${schemaType}" maps to "${mappedWebhookType}" but "${mappedWebhookType}" not found in webhooks.json`
+            );
+          }
+        } else {
+          // No mapping - check the type exists directly
+          if (!webhookTypesSet.has(schemaType)) {
+            mismatches.push(
+              `Event "${eventName}": extra activity type "${schemaType}" in workflow-v1.0.json (not in webhooks.json)`
+            );
+          }
+        }
+      }
+
+      // Check that the description mentions all allowed values
+      const activityDefName = `${eventName.replace(/_/g, "-")}-activity`;
+      const activityDef = schema.definitions[activityDefName];
+      if (activityDef?.description) {
+        for (const schemaType of schemaTypes) {
+          if (!activityDef.description.includes(`\`${schemaType}\``)) {
+            mismatches.push(
+              `Event "${eventName}": description in "${activityDefName}" is missing activity type \`${schemaType}\``
+            );
+          }
+        }
+      }
+    }
+
+    if (mismatches.length > 0) {
+      const errorMessage = [
+        "Activity type mismatches found between webhooks.json and workflow-v1.0.json:",
+        "",
+        ...mismatches,
+        "",
+        "To fix these mismatches:",
+        "1. Check GitHub docs: https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows",
+        "2. Verify the activity type is valid for workflow triggers",
+        "3. Update the *-activity-type definition in workflow-parser/src/workflow-v1.0.json",
+        "4. Update the description to list all supported activity types",
+        "5. If there's a naming difference, add it to NAME_MAPPINGS in schema-sync.test.ts",
+        "6. If the type is webhook-only, add it to WEBHOOK_ONLY",
+        "7. If the type is schema-only, add it to SCHEMA_ONLY"
+      ].join("\n");
+
+      throw new Error(errorMessage);
+    }
+  });
+});

workflow-parser/src/workflow-v1.0.json

@@ -856,7 +856,7 @@
       }
     },
     "pull-request-activity": {
-      "description": "The types of pull request activity that trigger the workflow. Supported activity types: `assigned`, `unassigned`, `labeled`, `unlabeled`, `opened`, `edited`, `closed`, `reopened`, `synchronize`, `converted_to_draft`, `ready_for_review`, `locked`, `unlocked`, `review_requested`, `review_request_removed`, `auto_merge_enabled`, `auto_merge_disabled`.",
+      "description": "The types of pull request activity that trigger the workflow. Supported activity types: `assigned`, `unassigned`, `labeled`, `unlabeled`, `opened`, `edited`, `closed`, `reopened`, `synchronize`, `converted_to_draft`, `locked`, `unlocked`, `enqueued`, `dequeued`, `milestoned`, `demilestoned`, `ready_for_review`, `review_requested`, `review_request_removed`, `auto_merge_enabled`, `auto_merge_disabled`.",
       "one-of": [
         "pull-request-activity-type",
         "pull-request-activity-types"
@@ -879,9 +879,13 @@
         "reopened",
         "synchronize",
         "converted_to_draft",
-        "ready_for_review",
         "locked",
         "unlocked",
+        "enqueued",
+        "dequeued",
+        "milestoned",
+        "demilestoned",
+        "ready_for_review",
         "review_requested",
         "review_request_removed",
         "auto_merge_enabled",
@@ -1004,7 +1008,7 @@
       }
     },
     "pull-request-target-activity": {
-      "description": "The types of pull request activity that trigger the workflow. Supported activity types: `assigned`, `unassigned`, `labeled`, `unlabeled`, `opened`, `edited`, `closed`, `reopened`, `synchronize`, `converted_to_draft`, `ready_for_review`, `locked`, `unlocked`, `review_requested`, `review_request_removed`, `auto_merge_enabled`, `auto_merge_disabled`.",
+      "description": "The types of pull request activity that trigger the workflow. Supported activity types: `assigned`, `unassigned`, `labeled`, `unlabeled`, `opened`, `edited`, `closed`, `reopened`, `synchronize`, `converted_to_draft`, `locked`, `unlocked`, `enqueued`, `dequeued`, `milestoned`, `demilestoned`, `ready_for_review`, `review_requested`, `review_request_removed`, `auto_merge_enabled`, `auto_merge_disabled`.",
       "one-of": [
         "pull-request-target-activity-type",
         "pull-request-target-activity-types"
@@ -1027,9 +1031,13 @@
         "reopened",
         "synchronize",
         "converted_to_draft",
-        "ready_for_review",
         "locked",
         "unlocked",
+        "enqueued",
+        "dequeued",
+        "milestoned",
+        "demilestoned",
+        "ready_for_review",
         "review_requested",
         "review_request_removed",
         "auto_merge_enabled",
@@ -1539,7 +1547,7 @@
           },
           "default": "workflow-dispatch-input-default",
           "options": {
-            "type": "sequence-of-non-empty-string",
+            "type": "sequence-of-string",
             "description": "The options of the dropdown list, if the type is a choice."
           }
         }
@@ -2419,6 +2427,11 @@
         "item-type": "non-empty-string"
       }
     },
+    "sequence-of-string": {
+      "sequence": {
+        "item-type": "string"
+      }
+    },
     "boolean-needs-context": {
       "context": [
         "github",

workflow-parser/src/workflows/yaml-object-reader.ts

@@ -1,4 +1,16 @@
-import {isCollection, isDocument, isMap, isPair, isScalar, isSeq, LineCounter, parseDocument, Scalar} from "yaml";
+import {
+  isAlias,
+  isCollection,
+  isDocument,
+  isMap,
+  isPair,
+  isScalar,
+  isSeq,
+  LineCounter,
+  parseDocument,
+  Scalar
+} from "yaml";
+import type {Document} from "yaml";
 import type {LinePos} from "yaml/dist/errors";
 import type {NodeBase} from "yaml/dist/nodes/Node";
 import {ObjectReader} from "../templates/object-reader";
@@ -22,30 +34,31 @@ export type YamlError = {
 export class YamlObjectReader implements ObjectReader {
   private readonly _generator: Generator<ParseEvent>;
   private _current!: IteratorResult<ParseEvent>;
+  private readonly doc: Document;
   private fileId?: number;
   private lineCounter = new LineCounter();
 
   public errors: YamlError[] = [];
 
   constructor(fileId: number | undefined, content: string) {
-    const doc = parseDocument(content, {
+    this.doc = parseDocument(content, {
       lineCounter: this.lineCounter,
       keepSourceTokens: true,
       uniqueKeys: false // Uniqueness is validated by the template reader
     });
-    for (const err of doc.errors) {
+    for (const err of this.doc.errors) {
       this.errors.push({message: err.message, range: rangeFromLinePos(err.linePos)});
     }
-    this._generator = this.getNodes(doc);
+    this._generator = this.getNodes(this.doc, new Set());
     this.fileId = fileId;
   }
 
-  private *getNodes(node: unknown): Generator<ParseEvent, void> {
+  private *getNodes(node: unknown, aliasResolutionStack: Set<unknown>): Generator<ParseEvent, void> {
     let range = this.getRange(node as NodeBase | undefined);
 
     if (isDocument(node)) {
       yield new ParseEvent(EventType.DocumentStart);
-      for (const item of this.getNodes(node.contents)) {
+      for (const item of this.getNodes(node.contents, new Set())) {
         yield item;
       }
       yield new ParseEvent(EventType.DocumentEnd);
@@ -59,7 +72,7 @@ export class YamlObjectReader implements ObjectReader {
       }
 
       for (const item of node.items) {
-        for (const child of this.getNodes(item)) {
+        for (const child of this.getNodes(item, aliasResolutionStack)) {
           yield child;
         }
       }
@@ -74,12 +87,32 @@ export class YamlObjectReader implements ObjectReader {
       yield new ParseEvent(EventType.Literal, YamlObjectReader.getLiteralToken(this.fileId, range, node));
     }
 
+    // Handle YAML aliases - resolve to the anchored value
+    if (isAlias(node)) {
+      const resolved = node.resolve(this.doc);
+      if (resolved) {
+        // Prevent infinite recursion from circular aliases
+        if (aliasResolutionStack.has(resolved)) {
+          // Silently ignore circular reference - the missing content will cause
+          // downstream validation errors which is acceptable for this edge case
+          return;
+        }
+        // Track this node in the alias resolution stack
+        const newStack = new Set(aliasResolutionStack);
+        newStack.add(resolved);
+        // Yield the resolved node's contents
+        yield* this.getNodes(resolved, newStack);
+      }
+      // If unresolved, the yaml library already reports an error
+      return;
+    }
+
     if (isPair(node)) {
       const scalarKey = node.key as Scalar;
       range = this.getRange(scalarKey);
       const key = scalarKey.value as string;
       yield new ParseEvent(EventType.Literal, new StringToken(this.fileId, range, key, undefined));
-      for (const child of this.getNodes(node.value)) {
+      for (const child of this.getNodes(node.value, aliasResolutionStack)) {
         yield child;
       }
     }

workflow-parser/testdata/reader/events-mapping-all.yml

@@ -120,6 +120,8 @@ on:
       - unassigned
       - labeled
       - unlabeled
+      - milestoned
+      - demilestoned
       - opened
       - edited
       - closed
@@ -129,6 +131,8 @@ on:
       - ready_for_review
       - locked
       - unlocked
+      - enqueued
+      - dequeued
       - review_requested
       - review_request_removed
       - auto_merge_enabled
@@ -160,6 +164,8 @@ on:
       - unassigned
       - labeled
       - unlabeled
+      - milestoned
+      - demilestoned
       - opened
       - edited
       - closed
@@ -169,6 +175,8 @@ on:
       - ready_for_review
       - locked
       - unlocked
+      - enqueued
+      - dequeued
       - review_requested
       - review_request_removed
       - auto_merge_enabled
@@ -386,6 +394,8 @@ jobs:
         "unassigned",
         "labeled",
         "unlabeled",
+        "milestoned",
+        "demilestoned",
         "opened",
         "edited",
         "closed",
@@ -395,6 +405,8 @@ jobs:
         "ready_for_review",
         "locked",
         "unlocked",
+        "enqueued",
+        "dequeued",
         "review_requested",
         "review_request_removed",
         "auto_merge_enabled",
@@ -441,6 +453,8 @@ jobs:
         "unassigned",
         "labeled",
         "unlabeled",
+        "milestoned",
+        "demilestoned",
         "opened",
         "edited",
         "closed",
@@ -450,6 +464,8 @@ jobs:
         "ready_for_review",
         "locked",
         "unlocked",
+        "enqueued",
+        "dequeued",
         "review_requested",
         "review_request_removed",
         "auto_merge_enabled",