Release extension version 0.3.40 (#310)

Co-authored-by: GitHub Actions <github-actions@github.com>

expressions/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/expressions",
-  "version": "0.3.35",
+  "version": "0.3.40",
   "license": "MIT",
   "type": "module",
   "source": "./src/index.ts",

expressions/src/completion.ts

@@ -2,6 +2,7 @@ import {DescriptionPair} from "./completion/descriptionDictionary.js";
 import {Dictionary, isDictionary} from "./data/dictionary.js";
 import {ExpressionData} from "./data/expressiondata.js";
 import {Evaluator} from "./evaluator.js";
+import {FeatureFlags} from "./features.js";
 import {wellKnownFunctions} from "./funcs.js";
 import {FunctionDefinition, FunctionInfo} from "./funcs/info.js";
 import {Lexer, Token, TokenType} from "./lexer.js";
@@ -26,13 +27,15 @@ export type CompletionItem = {
  * @param context Context available for the expression
  * @param extensionFunctions List of functions available
  * @param functions Optional map of functions to use during evaluation
+ * @param featureFlags Optional feature flags to control which features are enabled
  * @returns Array of completion items
  */
 export function complete(
   input: string,
   context: Dictionary,
   extensionFunctions: FunctionInfo[],
-  functions?: Map<string, FunctionDefinition>
+  functions?: Map<string, FunctionDefinition>,
+  featureFlags?: FeatureFlags
 ): CompletionItem[] {
   // Lex
   const lexer = new Lexer(input);
@@ -63,7 +66,7 @@ export function complete(
     const result = contextKeys(context);
 
     // Merge with functions
-    result.push(...functionItems(extensionFunctions));
+    result.push(...functionItems(extensionFunctions, featureFlags));
 
     return result;
   }
@@ -88,10 +91,15 @@ export function complete(
   return contextKeys(result);
 }
 
-function functionItems(extensionFunctions: FunctionInfo[]): CompletionItem[] {
+function functionItems(extensionFunctions: FunctionInfo[], featureFlags?: FeatureFlags): CompletionItem[] {
   const result: CompletionItem[] = [];
+  const flags = featureFlags ?? new FeatureFlags();
 
   for (const fdef of [...Object.values(wellKnownFunctions), ...extensionFunctions]) {
+    // Filter out case function if feature is disabled
+    if (fdef.name === "case" && !flags.isEnabled("allowCaseFunction")) {
+      continue;
+    }
     result.push({
       label: fdef.name,
       description: fdef.description,

expressions/src/errors.ts

@@ -12,6 +12,7 @@ export enum ErrorType {
   ErrorExceededMaxLength,
   ErrorTooFewParameters,
   ErrorTooManyParameters,
+  ErrorEvenParameters,
   ErrorUnrecognizedContext,
   ErrorUnrecognizedFunction
 }
@@ -42,6 +43,8 @@ function errorDescription(typ: ErrorType): string {
       return "Too few parameters supplied";
     case ErrorType.ErrorTooManyParameters:
       return "Too many parameters supplied";
+    case ErrorType.ErrorEvenParameters:
+      return "Even number of parameters supplied, requires an odd number of parameters";
     case ErrorType.ErrorUnrecognizedContext:
       return "Unrecognized named-value";
     case ErrorType.ErrorUnrecognizedFunction:

expressions/src/features.test.ts

@@ -54,7 +54,7 @@ describe("FeatureFlags", () => {
       expect(flags.getEnabledFeatures()).toEqual([
         "missingInputsQuickfix",
         "blockScalarChompingWarning",
-        "actionScaffoldingSnippets"
+        "allowCaseFunction"
       ]);
     });
   });

expressions/src/features.ts

@@ -30,11 +30,10 @@ export interface ExperimentalFeatures {
   blockScalarChompingWarning?: boolean;
 
   /**
-   * Enable action scaffolding snippets in action.yml files.
-   * Offers Node.js, Composite, and Docker action scaffolds.
+   * Enable the case() function in expressions.
    * @default false
    */
-  actionScaffoldingSnippets?: boolean;
+  allowCaseFunction?: boolean;
 }
 
 /**
@@ -49,7 +48,7 @@ export type ExperimentalFeatureKey = Exclude<keyof ExperimentalFeatures, "all">;
 const allFeatureKeys: ExperimentalFeatureKey[] = [
   "missingInputsQuickfix",
   "blockScalarChompingWarning",
-  "actionScaffoldingSnippets"
+  "allowCaseFunction"
 ];
 
 export class FeatureFlags {

expressions/src/funcs.ts

@@ -1,4 +1,5 @@
 import {ErrorType, ExpressionError} from "./errors.js";
+import {caseFunc} from "./funcs/case.js";
 import {contains} from "./funcs/contains.js";
 import {endswith} from "./funcs/endswith.js";
 import {format} from "./funcs/format.js";
@@ -16,6 +17,7 @@ export type ParseContext = {
 };
 
 export const wellKnownFunctions: {[name: string]: FunctionDefinition} = {
+  case: caseFunc,
   contains: contains,
   endswith: endswith,
   format: format,
@@ -53,4 +55,9 @@ export function validateFunction(context: ParseContext, identifier: Token, argCo
   if (argCount > f.maxArgs) {
     throw new ExpressionError(ErrorType.ErrorTooManyParameters, identifier);
   }
+
+  // case function requires an odd number of arguments
+  if (name === "case" && argCount % 2 === 0) {
+    throw new ExpressionError(ErrorType.ErrorEvenParameters, identifier);
+  }
 }

expressions/src/funcs/case.ts

@@ -0,0 +1,29 @@
+import {ExpressionData, Kind} from "../data/index.js";
+import {FunctionDefinition} from "./info.js";
+
+export const caseFunc: FunctionDefinition = {
+  name: "case",
+  description:
+    "`case( pred1, val1, pred2, val2, ..., default )`\n\nEvaluates predicates in order and returns the value corresponding to the first predicate that evaluates to `true`. If no predicate matches, it returns the last argument as the default value.",
+  minArgs: 3,
+  maxArgs: Number.MAX_SAFE_INTEGER,
+  call: (...args: ExpressionData[]): ExpressionData => {
+    // Evaluate predicate-result pairs
+    for (let i = 0; i < args.length - 1; i += 2) {
+      const predicate = args[i];
+
+      // Predicate must be a boolean
+      if (predicate.kind !== Kind.Boolean) {
+        throw new Error("case predicate must evaluate to a boolean value");
+      }
+
+      // If predicate is true, return the corresponding result
+      if (predicate.value) {
+        return args[i + 1];
+      }
+    }
+
+    // No predicate matched, return default (last argument)
+    return args[args.length - 1];
+  }
+};

expressions/testdata/case.json

@@ -0,0 +1,157 @@
+{
+  "case": [
+    {
+      "expr": "case(true, 'first', 'default')",
+      "result": { "kind": "String", "value": "first" }
+    },
+    {
+      "expr": "case(false, 'first', 'default')",
+      "result": { "kind": "String", "value": "default" }
+    },
+    {
+      "expr": "case(true, 'first', false, 'second', 'default')",
+      "result": { "kind": "String", "value": "first" }
+    },
+    {
+      "expr": "case(false, 'first', true, 'second', 'default')",
+      "result": { "kind": "String", "value": "second" }
+    },
+    {
+      "expr": "case(false, 'first', false, 'second', 'default')",
+      "result": { "kind": "String", "value": "default" }
+    },
+    {
+      "expr": "case(1 == 1, 'equal', 'not equal')",
+      "result": { "kind": "String", "value": "equal" }
+    },
+    {
+      "expr": "case(1 == 2, 'equal', 'not equal')",
+      "result": { "kind": "String", "value": "not equal" }
+    },
+    {
+      "expr": "case(github.ref == 'refs/heads/main', 'main', github.event_name == 'pull_request', 'pr', 'other')",
+      "contexts": {
+        "github": {
+          "ref": "refs/heads/main",
+          "event_name": "push"
+        }
+      },
+      "result": { "kind": "String", "value": "main" }
+    },
+    {
+      "expr": "case(github.ref == 'refs/heads/main', 'main', github.event_name == 'pull_request', 'pr', 'other')",
+      "contexts": {
+        "github": {
+          "ref": "refs/heads/develop",
+          "event_name": "pull_request"
+        }
+      },
+      "result": { "kind": "String", "value": "pr" }
+    },
+    {
+      "expr": "case(github.ref == 'refs/heads/main', 'main', github.event_name == 'pull_request', 'pr', 'other')",
+      "contexts": {
+        "github": {
+          "ref": "refs/heads/develop",
+          "event_name": "push"
+        }
+      },
+      "result": { "kind": "String", "value": "other" }
+    },
+    {
+      "expr": "case(true, 123, 456)",
+      "result": { "kind": "Number", "value": 123 }
+    },
+    {
+      "expr": "case(false, 123, 456)",
+      "result": { "kind": "Number", "value": 456 }
+    },
+    {
+      "expr": "case(github.event == 'pull_request', 0, 1)",
+      "contexts": {
+        "github": {
+          "event": "pull_request"
+        }
+      },
+      "result": { "kind": "Number", "value": 0 }
+    },
+    {
+      "expr": "case(false, 0, 1)",
+      "result": { "kind": "Number", "value": 1 }
+    },
+    {
+      "expr": "case(true, false, true)",
+      "result": { "kind": "Boolean", "value": false }
+    },
+    {
+      "expr": "case(false, false, true)",
+      "result": { "kind": "Boolean", "value": true }
+    },
+    {
+      "expr": "case(true, '', 'default')",
+      "result": { "kind": "String", "value": "" }
+    },
+    {
+      "expr": "case(false, 'first', '')",
+      "result": { "kind": "String", "value": "" }
+    },
+    {
+      "expr": "case(true, fromJSON('[1,2,3]'), 'default')",
+      "result": { "kind": "Array", "value": [1, 2, 3] }
+    },
+    {
+      "expr": "case(true, fromJSON('{\"key\":\"value\"}'), 'default')",
+      "result": { "kind": "Object", "value": { "key": "value" } }
+    },
+    {
+      "expr": "case(false, 'first', false, 'second', false, 'third', false, 'fourth', 'default')",
+      "result": { "kind": "String", "value": "default" }
+    },
+    {
+      "expr": "case(false, 'first', false, 'second', true, 'third', false, 'fourth', 'default')",
+      "result": { "kind": "String", "value": "third" }
+    },
+    {
+      "expr": "case('not a boolean', 'first', 'default')",
+      "err": {
+        "kind": "evaluation",
+        "value": "case predicate must evaluate to a boolean value"
+      }
+    },
+    {
+      "expr": "case(1, 'first', 'default')",
+      "err": {
+        "kind": "evaluation",
+        "value": "case predicate must evaluate to a boolean value"
+      }
+    },
+    {
+      "expr": "case(null, 'first', 'default')",
+      "err": {
+        "kind": "evaluation",
+        "value": "case predicate must evaluate to a boolean value"
+      }
+    },
+    {
+      "expr": "case(fromJSON('[]'), 'first', 'default')",
+      "err": {
+        "kind": "evaluation",
+        "value": "case predicate must evaluate to a boolean value"
+      }
+    },
+    {
+      "expr": "case(fromJSON('{}'), 'first', 'default')",
+      "err": {
+        "kind": "evaluation",
+        "value": "case predicate must evaluate to a boolean value"
+      }
+    },
+    {
+      "expr": "case(true, 'first', false, 'second')",
+      "err": {
+        "kind": "parsing",
+        "value": "Even number of parameters supplied, requires an odd number of parameters: 'case'. Located at position 1 within expression: case(true, 'first', false, 'second')"
+      }
+    }
+  ]
+}

languageserver/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/languageserver",
-  "version": "0.3.35",
+  "version": "0.3.40",
   "description": "Language server for GitHub Actions",
   "license": "MIT",
   "type": "module",
@@ -48,8 +48,8 @@
     "actions-languageserver": "./bin/actions-languageserver"
   },
   "dependencies": {
-    "@actions/languageservice": "^0.3.35",
-    "@actions/workflow-parser": "^0.3.35",
+    "@actions/languageservice": "^0.3.40",
+    "@actions/workflow-parser": "^0.3.40",
     "@octokit/rest": "^21.1.1",
     "@octokit/types": "^9.0.0",
     "vscode-languageserver": "^8.0.2",

languageserver/src/connection.ts

@@ -1,8 +1,18 @@
-import {documentLinks, getInlayHints, hover, validate, ValidationConfig} from "@actions/languageservice";
+import {
+  documentLinks,
+  getCodeActions,
+  getInlayHints,
+  hover,
+  validate,
+  ValidationConfig
+} from "@actions/languageservice";
 import {registerLogger, setLogLevel} from "@actions/languageservice/log";
 import {clearCache, clearCacheEntry} from "@actions/languageservice/utils/workflow-cache";
 import {Octokit} from "@octokit/rest";
 import {
+  CodeAction,
+  CodeActionKind,
+  CodeActionParams,
   CompletionItem,
   Connection,
   DocumentLink,
@@ -79,7 +89,10 @@ export function initConnection(connection: Connection) {
         documentLinkProvider: {
           resolveProvider: false
         },
-        inlayHintProvider: true
+        inlayHintProvider: true,
+        codeActionProvider: {
+          codeActionKinds: [CodeActionKind.QuickFix]
+        }
       }
     };
 
@@ -141,7 +154,8 @@ export function initConnection(connection: Connection) {
           getDocument(documents, textDocument),
           client,
           repos.find(repo => textDocument.uri.startsWith(repo.workspaceUri)),
-          cache
+          cache,
+          featureFlags
         )
     );
   });
@@ -177,6 +191,17 @@ export function initConnection(connection: Connection) {
     });
   });
 
+  connection.onCodeAction((params: CodeActionParams): CodeAction[] => {
+    const document = getDocument(documents, params.textDocument);
+    return getCodeActions({
+      uri: params.textDocument.uri,
+      documentContent: document.getText(),
+      diagnostics: params.context.diagnostics,
+      only: params.context.only,
+      featureFlags
+    });
+  });
+
   // Make the text document manager listen on the connection
   // for open, change and close text document events
   documents.listen(connection);

languageserver/src/on-completion.ts

@@ -1,4 +1,5 @@
 import {complete} from "@actions/languageservice/complete";
+import type {FeatureFlags} from "@actions/expressions";
 import {Octokit} from "@octokit/rest";
 import {CompletionItem, Connection, Position} from "vscode-languageserver";
 import {TextDocument} from "vscode-languageserver-textdocument";
@@ -15,11 +16,13 @@ export async function onCompletion(
   document: TextDocument,
   client: Octokit | undefined,
   repoContext: RepositoryContext | undefined,
-  cache: TTLCache
+  cache: TTLCache,
+  featureFlags?: FeatureFlags
 ): Promise<CompletionItem[]> {
   return await complete(document, position, {
     valueProviderConfig: repoContext && valueProviders(client, repoContext, cache),
     contextProviderConfig: repoContext && contextProviders(client, repoContext, cache),
+    featureFlags,
     fileProvider: getFileProvider(client, cache, repoContext?.workspaceUri, async path => {
       return await connection.sendRequest(Requests.ReadFile, {path});
     })

languageservice/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/languageservice",
-  "version": "0.3.35",
+  "version": "0.3.40",
   "description": "Language service for GitHub Actions",
   "license": "MIT",
   "type": "module",
@@ -47,8 +47,8 @@
     "watch": "tsc --build tsconfig.build.json --watch"
   },
   "dependencies": {
-    "@actions/expressions": "^0.3.35",
-    "@actions/workflow-parser": "^0.3.35",
+    "@actions/expressions": "^0.3.40",
+    "@actions/workflow-parser": "^0.3.40",
     "vscode-languageserver-textdocument": "^1.0.7",
     "vscode-languageserver-types": "^3.17.2",
     "vscode-uri": "^3.0.8",

languageservice/src/code-actions/code-actions.ts

@@ -0,0 +1,55 @@
+import {FeatureFlags} from "@actions/expressions";
+import {CodeAction, CodeActionKind, Diagnostic} from "vscode-languageserver-types";
+import {CodeActionContext, CodeActionProvider} from "./types.js";
+import {getQuickfixProviders} from "./quickfix/quickfix-providers.js";
+
+export interface CodeActionParams {
+  uri: string;
+  documentContent: string;
+  diagnostics: Diagnostic[];
+  only?: string[];
+  featureFlags?: FeatureFlags;
+}
+
+export function getCodeActions(params: CodeActionParams): CodeAction[] {
+  const actions: CodeAction[] = [];
+  const context: CodeActionContext = {
+    uri: params.uri,
+    documentContent: params.documentContent,
+    featureFlags: params.featureFlags
+  };
+
+  // Build providers map based on feature flags
+  const providersByKind: Map<string, CodeActionProvider[]> = new Map([
+    [CodeActionKind.QuickFix, getQuickfixProviders(params.featureFlags)]
+    // [CodeActionKind.Refactor, getRefactorProviders(params.featureFlags)],
+    // [CodeActionKind.Source, getSourceProviders(params.featureFlags)],
+    // etc
+  ]);
+
+  // Filter to requested kinds, or use all if none specified
+  const requestedKinds = params.only;
+  const kindsToCheck = requestedKinds
+    ? [...providersByKind.keys()].filter(kind => requestedKinds.some(requested => kind.startsWith(requested)))
+    : [...providersByKind.keys()];
+
+  for (const diagnostic of params.diagnostics) {
+    for (const kind of kindsToCheck) {
+      const providers = providersByKind.get(kind) ?? [];
+      for (const provider of providers) {
+        if (provider.diagnosticCodes.includes(diagnostic.code)) {
+          const action = provider.createCodeAction(context, diagnostic);
+          if (action) {
+            action.kind = kind;
+            action.diagnostics = [diagnostic];
+            actions.push(action);
+          }
+        }
+      }
+    }
+  }
+
+  return actions;
+}
+
+export type {CodeActionContext, CodeActionProvider} from "./types.js";

languageservice/src/code-actions/quickfix/add-missing-inputs.ts

@@ -0,0 +1,245 @@
+import {isMapping} from "@actions/workflow-parser";
+import {MappingToken} from "@actions/workflow-parser/templates/tokens/mapping-token";
+import {ScalarToken} from "@actions/workflow-parser/templates/tokens/scalar-token";
+import {TemplateToken} from "@actions/workflow-parser/templates/tokens/template-token";
+import {CodeAction, Position, TextEdit} from "vscode-languageserver-types";
+import {error} from "../../log.js";
+import {findToken} from "../../utils/find-token.js";
+import {getOrParseWorkflow} from "../../utils/workflow-cache.js";
+import {DiagnosticCode, MissingInputsDiagnosticData} from "../../validate-action-reference.js";
+import {CodeActionContext, CodeActionProvider} from "../types.js";
+
+/**
+ * Information extracted from a step token needed to generate edits
+ */
+interface StepInfo {
+  /** Column where step keys start (1-indexed), e.g., the column of "uses:" */
+  stepKeyColumn: number;
+  /** End line of the step (1-indexed) */
+  stepEndLine: number;
+  /** Detected indent size (spaces per level) */
+  indentSize: number;
+  /** Information about existing with: block, if present */
+  withInfo?: {
+    keyColumn: number;
+    keyEndLine: number;
+    valueEndLine: number;
+    hasChildren: boolean;
+    /** Column of first child input (1-indexed), for indentation detection */
+    firstChildColumn?: number;
+  };
+}
+
+export const addMissingInputsProvider: CodeActionProvider = {
+  diagnosticCodes: [DiagnosticCode.MissingRequiredInputs],
+
+  createCodeAction(context: CodeActionContext, diagnostic): CodeAction | undefined {
+    const data = diagnostic.data as MissingInputsDiagnosticData | undefined;
+    if (!data) {
+      return undefined;
+    }
+
+    // Parse the document to get the step token
+    const stepInfo = getStepInfo(context, diagnostic.range.start);
+    if (!stepInfo) {
+      return undefined;
+    }
+
+    const edits = createInputEdits(data.missingInputs, stepInfo);
+    if (!edits || edits.length === 0) {
+      return undefined;
+    }
+
+    const inputNames = data.missingInputs.map(i => i.name).join(", ");
+
+    return {
+      title: `Add missing input${data.missingInputs.length > 1 ? "s" : ""}: ${inputNames}`,
+      edit: {
+        changes: {
+          [context.uri]: edits
+        }
+      }
+    };
+  }
+};
+
+/**
+ * Parse the document and extract step information needed for generating edits.
+ * Returns undefined if parsing fails or the step token cannot be found.
+ */
+function getStepInfo(context: CodeActionContext, diagnosticPosition: Position): StepInfo | undefined {
+  // Parse the document (uses cache if available from validation)
+  const file = {name: context.uri, content: context.documentContent};
+  const parseResult = getOrParseWorkflow(file, context.uri);
+
+  if (!parseResult.value) {
+    error("Failed to parse workflow for missing inputs quickfix");
+    return undefined;
+  }
+
+  // Find the token at the diagnostic position
+  const {path} = findToken(diagnosticPosition, parseResult.value);
+
+  // Walk up the path to find the step token (regular-step)
+  const stepToken = findStepInPath(path);
+  if (!stepToken) {
+    error("Could not find step token for missing inputs quickfix");
+    return undefined;
+  }
+
+  return extractStepInfo(stepToken);
+}
+
+/**
+ * Find the step token (regular-step) in the token path
+ */
+function findStepInPath(path: TemplateToken[]): MappingToken | undefined {
+  // Walk backwards through path to find the step
+  for (let i = path.length - 1; i >= 0; i--) {
+    if (path[i].definition?.key === "regular-step" && isMapping(path[i])) {
+      return path[i] as MappingToken;
+    }
+  }
+  return undefined;
+}
+
+/**
+ * Extract position and indentation info from a step token
+ */
+function extractStepInfo(stepToken: MappingToken): StepInfo | undefined {
+  if (!stepToken.range) {
+    return undefined;
+  }
+
+  // Get the column of the first key in the step
+  let stepKeyColumn = stepToken.range.start.column;
+  if (stepToken.count > 0) {
+    const firstEntry = stepToken.get(0);
+    if (firstEntry?.key.range) {
+      stepKeyColumn = firstEntry.key.range.start.column;
+    }
+  }
+
+  // Find the with: block if present
+  let withKey: ScalarToken | undefined;
+  let withToken: TemplateToken | undefined;
+  for (const {key, value} of stepToken) {
+    if (key.toString() === "with") {
+      withKey = key;
+      withToken = value;
+      break;
+    }
+  }
+
+  // Calculate indent size
+  let indentSize = 2; // Default
+  let withInfo: StepInfo["withInfo"];
+
+  if (withKey?.range && withToken?.range) {
+    // Has with: block - extract its info
+    const hasChildren = isMapping(withToken) && withToken.count > 0;
+    let firstChildColumn: number | undefined;
+
+    if (hasChildren) {
+      const firstChild = (withToken as MappingToken).get(0);
+      if (firstChild?.key.range) {
+        firstChildColumn = firstChild.key.range.start.column;
+        // Detect indent size from with: children
+        indentSize = firstChildColumn - withKey.range.start.column;
+      }
+    }
+
+    withInfo = {
+      keyColumn: withKey.range.start.column,
+      keyEndLine: withKey.range.end.line,
+      valueEndLine: withToken.range.end.line,
+      hasChildren,
+      firstChildColumn
+    };
+  } else {
+    // No with: block - detect indent size using heuristics
+    // Based on the step key column position, estimate indent size
+    // 2-space indent files typically have step keys at column 7
+    // 4-space indent files typically have step keys at column 15
+    const zeroIndexedCol = stepKeyColumn - 1;
+    if (zeroIndexedCol >= 10) {
+      indentSize = 4;
+    }
+  }
+
+  return {
+    stepKeyColumn,
+    stepEndLine: stepToken.range.end.line,
+    indentSize,
+    withInfo
+  };
+}
+
+/**
+ * Generate text edits to add missing inputs
+ */
+function createInputEdits(missingInputs: MissingInputsDiagnosticData["missingInputs"], stepInfo: StepInfo): TextEdit[] {
+  const formatInputLines = (indent: string) =>
+    missingInputs.map(input => {
+      const value = input.default ?? '""';
+      return `${indent}${input.name}: ${value}`;
+    });
+
+  if (stepInfo.withInfo) {
+    // `with:` exists - add inputs to existing block
+    const withIndent = stepInfo.withInfo.keyColumn - 1; // 0-indexed
+    const inputIndentSize = stepInfo.withInfo.firstChildColumn
+      ? stepInfo.withInfo.firstChildColumn - stepInfo.withInfo.keyColumn
+      : stepInfo.indentSize;
+
+    const inputIndent = " ".repeat(withIndent + inputIndentSize);
+    const inputLines = formatInputLines(inputIndent);
+
+    // Calculate insert position
+    let insertLine: number;
+    if (stepInfo.withInfo.hasChildren) {
+      // Insert after the last child (at end of with: block)
+      // valueEndLine is 1-indexed, we want 0-indexed for Position
+      insertLine = stepInfo.withInfo.valueEndLine - 1;
+    } else {
+      // Empty with: block - insert on the next line after with:
+      // keyEndLine is 1-indexed, convert to 0-indexed and go to next line
+      insertLine = stepInfo.withInfo.keyEndLine;
+    }
+
+    const insertPosition: Position = {
+      line: insertLine,
+      character: 0
+    };
+
+    return [
+      {
+        range: {start: insertPosition, end: insertPosition},
+        newText: inputLines.map(line => line + "\n").join("")
+      }
+    ];
+  } else {
+    // No `with:` key - add `with:` at the same level as other step keys
+    const withKeyIndent = stepInfo.stepKeyColumn - 1; // 0-indexed (columns are 1-based)
+
+    const withIndent = " ".repeat(withKeyIndent);
+    const inputIndent = " ".repeat(withKeyIndent + stepInfo.indentSize);
+    const inputLines = formatInputLines(inputIndent);
+
+    const newText = `${withIndent}with:\n` + inputLines.map(line => `${line}\n`).join("");
+
+    // Insert at end of step
+    // stepEndLine is 1-indexed, we want 0-indexed and insert before the line after
+    const insertPosition: Position = {
+      line: stepInfo.stepEndLine - 1,
+      character: 0
+    };
+
+    return [
+      {
+        range: {start: insertPosition, end: insertPosition},
+        newText
+      }
+    ];
+  }
+}

languageservice/src/code-actions/quickfix/quickfix-providers.ts

@@ -0,0 +1,13 @@
+import {FeatureFlags} from "@actions/expressions";
+import {CodeActionProvider} from "../types.js";
+import {addMissingInputsProvider} from "./add-missing-inputs.js";
+
+export function getQuickfixProviders(featureFlags?: FeatureFlags): CodeActionProvider[] {
+  const providers: CodeActionProvider[] = [];
+
+  if (featureFlags?.isEnabled("missingInputsQuickfix")) {
+    providers.push(addMissingInputsProvider);
+  }
+
+  return providers;
+}

languageservice/src/code-actions/tests/runner.test.ts

@@ -0,0 +1,90 @@
+import * as path from "path";
+import {fileURLToPath} from "url";
+import {loadTestCases, runTestCase} from "./runner.js";
+import {ValidationConfig} from "../../validate.js";
+import {ActionMetadata, ActionReference} from "../../action.js";
+import {clearCache} from "../../utils/workflow-cache.js";
+
+// ESM-compatible __dirname
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+// Mock action metadata provider for tests
+const validationConfig: ValidationConfig = {
+  actionsMetadataProvider: {
+    fetchActionMetadata: (ref: ActionReference): Promise<ActionMetadata | undefined> => {
+      const key = `${ref.owner}/${ref.name}@${ref.ref}`;
+
+      const metadata: Record<string, ActionMetadata> = {
+        "actions/cache@v1": {
+          name: "Cache",
+          description: "Cache dependencies",
+          inputs: {
+            path: {
+              description: "A list of files to cache",
+              required: true
+            },
+            key: {
+              description: "Cache key",
+              required: true
+            },
+            "restore-keys": {
+              description: "Restore keys",
+              required: false
+            }
+          }
+        },
+        "actions/setup-node@v3": {
+          name: "Setup Node",
+          description: "Setup Node.js",
+          inputs: {
+            "node-version": {
+              description: "Node version",
+              required: true,
+              default: "16"
+            }
+          }
+        }
+      };
+
+      return Promise.resolve(metadata[key]);
+    }
+  }
+};
+
+// Point to the source testdata directory
+const testdataDir = path.join(__dirname, "testdata");
+
+beforeEach(() => {
+  clearCache();
+});
+
+describe("code action golden tests", () => {
+  const testCases = loadTestCases(testdataDir);
+
+  if (testCases.length === 0) {
+    it.todo("no test cases found - add .yml files to testdata/");
+    return;
+  }
+
+  for (const testCase of testCases) {
+    it(testCase.name, async () => {
+      const result = await runTestCase(testCase, validationConfig);
+
+      if (!result.passed) {
+        let errorMessage = result.error || "Test failed";
+
+        if (result.expected !== undefined && result.actual !== undefined) {
+          errorMessage += "\n\n";
+          errorMessage += "=== EXPECTED (golden file) ===\n";
+          errorMessage += result.expected;
+          errorMessage += "\n\n";
+          errorMessage += "=== ACTUAL ===\n";
+          errorMessage += result.actual;
+        }
+
+        throw new Error(errorMessage);
+      }
+    });
+  }
+});

languageservice/src/code-actions/tests/runner.ts

@@ -0,0 +1,231 @@
+import * as fs from "fs";
+import * as path from "path";
+import {TextEdit} from "vscode-languageserver-types";
+import {TextDocument} from "vscode-languageserver-textdocument";
+import {FeatureFlags} from "@actions/expressions";
+import {validate, ValidationConfig} from "../../validate.js";
+import {getCodeActions, CodeActionParams} from "../code-actions.js";
+
+// Marker pattern: # want "diagnostic message" fix="code-action-name"
+const MARKER_PATTERN = /#\s*want\s+"([^"]+)"(?:\s+fix="([^"]+)")?/;
+
+export interface TestCase {
+  name: string;
+  inputPath: string;
+  goldenPath: string;
+  input: string;
+  golden: string;
+  markers: Marker[];
+}
+
+export interface Marker {
+  line: number;
+  message: string;
+  fix?: string;
+}
+
+export interface TestResult {
+  name: string;
+  passed: boolean;
+  error?: string;
+  expected?: string;
+  actual?: string;
+}
+
+/**
+ * Parse markers from input file content
+ */
+export function parseMarkers(content: string): Marker[] {
+  const lines = content.split("\n");
+  const markers: Marker[] = [];
+
+  for (let i = 0; i < lines.length; i++) {
+    const match = lines[i].match(MARKER_PATTERN);
+    if (match) {
+      markers.push({
+        line: i,
+        message: match[1],
+        fix: match[2]
+      });
+    }
+  }
+
+  return markers;
+}
+
+/**
+ * Strip markers from content (for processing)
+ */
+export function stripMarkers(content: string): string {
+  return content
+    .split("\n")
+    .map(line => line.replace(MARKER_PATTERN, "").trimEnd())
+    .join("\n");
+}
+
+/**
+ * Load all test cases from a testdata directory
+ */
+export function loadTestCases(testdataDir: string): TestCase[] {
+  const testCases: TestCase[] = [];
+
+  function walkDir(dir: string) {
+    const entries = fs.readdirSync(dir, {withFileTypes: true});
+
+    for (const entry of entries) {
+      const fullPath = path.join(dir, entry.name);
+
+      if (entry.isDirectory()) {
+        walkDir(fullPath);
+      } else if (entry.isFile() && entry.name.endsWith(".yml") && !entry.name.endsWith(".golden.yml")) {
+        const goldenPath = fullPath.replace(".yml", ".golden.yml");
+
+        if (fs.existsSync(goldenPath)) {
+          const input = fs.readFileSync(fullPath, "utf-8");
+          const golden = fs.readFileSync(goldenPath, "utf-8");
+
+          testCases.push({
+            name: path.relative(testdataDir, fullPath),
+            inputPath: fullPath,
+            goldenPath,
+            input,
+            golden,
+            markers: parseMarkers(input)
+          });
+        }
+      }
+    }
+  }
+
+  walkDir(testdataDir);
+  return testCases;
+}
+
+/**
+ * Apply text edits to a document
+ */
+export function applyEdits(content: string, edits: TextEdit[]): string {
+  // Sort edits in reverse order by position to apply from bottom to top
+  const sortedEdits = [...edits].sort((a, b) => {
+    if (b.range.start.line !== a.range.start.line) {
+      return b.range.start.line - a.range.start.line;
+    }
+    return b.range.start.character - a.range.start.character;
+  });
+
+  const lines = content.split("\n");
+
+  for (const edit of sortedEdits) {
+    const startLine = edit.range.start.line;
+    const startChar = edit.range.start.character;
+    const endLine = edit.range.end.line;
+    const endChar = edit.range.end.character;
+
+    const before = lines[startLine].slice(0, startChar);
+    const after = lines[endLine].slice(endChar);
+
+    const newLines = edit.newText.split("\n");
+    newLines[0] = before + newLines[0];
+    newLines[newLines.length - 1] = newLines[newLines.length - 1] + after;
+
+    lines.splice(startLine, endLine - startLine + 1, ...newLines);
+  }
+
+  return lines.join("\n");
+}
+
+/**
+ * Run a single test case
+ */
+export async function runTestCase(testCase: TestCase, validationConfig: ValidationConfig): Promise<TestResult> {
+  const strippedInput = stripMarkers(testCase.input);
+  const document = TextDocument.create("file:///test.yml", "yaml", 1, strippedInput);
+
+  // 1. Validate and get diagnostics
+  const diagnostics = await validate(document, validationConfig);
+
+  // 2.  Verify all expected diagnostics are present
+  const missingDiagnostics: string[] = [];
+  for (const marker of testCase.markers) {
+    const found = diagnostics.find(d => d.range.start.line === marker.line && d.message.includes(marker.message));
+    if (!found) {
+      missingDiagnostics.push(`line ${marker.line}: "${marker.message}"`);
+    }
+  }
+
+  if (missingDiagnostics.length > 0) {
+    return {
+      name: testCase.name,
+      passed: false,
+      error: `Missing expected diagnostics:\n  ${missingDiagnostics.join(
+        "\n  "
+      )}\n\nActual diagnostics:\n  ${diagnostics.map(d => `line ${d.range.start.line}: "${d.message}"`).join("\n  ")}`
+    };
+  }
+
+  // 3.  Collect all edits from all matching code actions
+  const allEdits: TextEdit[] = [];
+
+  for (const marker of testCase.markers) {
+    if (!marker.fix) {
+      continue;
+    }
+
+    const diagnostic = diagnostics.find(d => d.range.start.line === marker.line && d.message.includes(marker.message));
+
+    if (!diagnostic) {
+      continue; // Already reported above
+    }
+
+    const params: CodeActionParams = {
+      uri: document.uri,
+      documentContent: strippedInput,
+      diagnostics: [diagnostic],
+      featureFlags: new FeatureFlags({all: true})
+    };
+
+    const actions = getCodeActions(params);
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- marker.fix is checked at the start of the loop
+    const matchingAction = actions.find(a => a.title.toLowerCase().includes(marker.fix!.toLowerCase()));
+
+    if (!matchingAction) {
+      return {
+        name: testCase.name,
+        passed: false,
+        error: `Code action "${marker.fix}" not found for diagnostic on line ${marker.line}.\nAvailable actions: ${
+          actions.map(a => a.title).join(", ") || "(none)"
+        }`
+      };
+    }
+
+    if (!matchingAction.edit?.changes) {
+      return {
+        name: testCase.name,
+        passed: false,
+        error: `Code action "${marker.fix}" has no edits`
+      };
+    }
+
+    const edits = matchingAction.edit.changes[document.uri] || [];
+    allEdits.push(...edits);
+  }
+
+  // 4. Apply all edits and compare to golden file
+  const actualOutput = applyEdits(strippedInput, allEdits);
+  const expectedOutput = testCase.golden;
+
+  if (actualOutput.trim() !== expectedOutput.trim()) {
+    return {
+      name: testCase.name,
+      passed: false,
+      error: "Output does not match golden file",
+      expected: expectedOutput,
+      actual: actualOutput
+    };
+  }
+
+  return {
+    name: testCase.name,
+    passed: true
+  };
+}

languageservice/src/code-actions/tests/testdata/quickfix/existing-with-key-without-inputs.golden.yml

@@ -0,0 +1,9 @@
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/cache@v1
+        with:
+          path: ""
+          key: ""

languageservice/src/code-actions/tests/testdata/quickfix/existing-with-key-without-inputs.yml

@@ -0,0 +1,7 @@
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/cache@v1
+        with: # want "Missing required inputs: `path`, `key`" fix="Add missing inputs: path, key"

languageservice/src/code-actions/tests/testdata/quickfix/existing-with-key.golden.yml

@@ -0,0 +1,10 @@
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/cache@v1
+        with:
+          restore-keys: ${{ runner.os }}-
+          path: ""
+          key: ""

languageservice/src/code-actions/tests/testdata/quickfix/existing-with-key.yml

@@ -0,0 +1,8 @@
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/cache@v1
+        with: # want "Missing required inputs: `path`, `key`" fix="Add missing inputs: path, key"
+          restore-keys: ${{ runner.os }}-

languageservice/src/code-actions/tests/testdata/quickfix/four-space-indent.golden.yml

@@ -0,0 +1,9 @@
+on: push
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/cache@v1
+              with:
+                  path: ""
+                  key: ""

languageservice/src/code-actions/tests/testdata/quickfix/four-space-indent.yml

@@ -0,0 +1,6 @@
+on: push
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/cache@v1 # want "Missing required inputs: `path`, `key`" fix="Add missing inputs: path, key"

languageservice/src/code-actions/tests/testdata/quickfix/no-with-key.golden.yml

@@ -0,0 +1,9 @@
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/cache@v1
+        with:
+          path: ""
+          key: ""

languageservice/src/code-actions/tests/testdata/quickfix/no-with-key.yml

@@ -0,0 +1,6 @@
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/cache@v1 # want "Missing required inputs: `path`, `key`" fix="Add missing inputs: path, key"

languageservice/src/code-actions/types.ts

@@ -0,0 +1,23 @@
+import {FeatureFlags} from "@actions/expressions";
+import {CodeAction, Diagnostic} from "vscode-languageserver-types";
+
+export interface CodeActionContext {
+  uri: string;
+  documentContent: string;
+  featureFlags?: FeatureFlags;
+}
+
+/**
+ * A provider that can produce a code action for a given diagnostic
+ */
+export interface CodeActionProvider {
+  /**
+   * The diagnostic codes this provider handles
+   */
+  diagnosticCodes: (string | number | undefined)[];
+
+  /**
+   * Create a code action for the diagnostic, if applicable
+   */
+  createCodeAction(context: CodeActionContext, diagnostic: Diagnostic): CodeAction | undefined;
+}

languageservice/src/complete-action.test.ts

@@ -1,17 +1,11 @@
-import {FeatureFlags} from "@actions/expressions";
 import {TextDocument} from "vscode-languageserver-textdocument";
-import {complete, CompletionConfig} from "./complete";
+import {complete} from "./complete";
 import {clearCache} from "./utils/workflow-cache";
 
 beforeEach(() => {
   clearCache();
 });
 
-// Config to enable action scaffolding snippets
-const scaffoldingConfig: CompletionConfig = {
-  featureFlags: new FeatureFlags({actionScaffoldingSnippets: true})
-};
-
 describe("complete action files", () => {
   function createActionDocument(
     content: string,
@@ -265,8 +259,8 @@ runs:
       const usingCompletion = completions.find(c => c.label === "using");
       expect(usingCompletion).toBeDefined();
 
-      // It should have a sortText that makes it sort first
-      expect(usingCompletion?.sortText).toBe("0_using");
+      // It should have a sortText that makes it sort after snippets
+      expect(usingCompletion?.sortText).toBe("9_using");
     });
 
     it("completes step keys inside composite action steps", async () => {
@@ -403,7 +397,7 @@ runs:
   describe("action scaffolding snippets", () => {
     it("offers full scaffolding snippets in empty file", async () => {
       const [doc, position] = createActionDocument(`|`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
       const labels = completions.map(c => c.label);
 
       expect(labels).toContain("Node.js Action");
@@ -419,7 +413,7 @@ runs:
     it("offers full scaffolding snippets when no name or description exists", async () => {
       const [doc, position] = createActionDocument(`author: me
 |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
 
       const nodeSnippet = completions.find(c => c.label === "Node.js Action");
       expect(nodeSnippet).toBeDefined();
@@ -430,7 +424,7 @@ runs:
     it("offers runs-only snippets when name exists", async () => {
       const [doc, position] = createActionDocument(`name: My Action
 |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
 
       const nodeSnippet = completions.find(c => c.label === "Node.js Action");
       expect(nodeSnippet).toBeDefined();
@@ -442,7 +436,7 @@ runs:
     it("offers runs-only snippets when description exists", async () => {
       const [doc, position] = createActionDocument(`description: Does something
 |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
 
       const compositeSnippet = completions.find(c => c.label === "Composite Action");
       expect(compositeSnippet).toBeDefined();
@@ -457,7 +451,7 @@ description: Test
 runs:
   using: composite
   |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
       const labels = completions.map(c => c.label);
 
       expect(labels).not.toContain("Node.js Action");
@@ -470,7 +464,7 @@ runs:
 description: Test
 runs:
   |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
       const labels = completions.map(c => c.label);
 
       expect(labels).toContain("Node.js Action");
@@ -484,7 +478,7 @@ description: Test
 runs:
   steps: []
 |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
       const labels = completions.map(c => c.label);
 
       expect(labels).not.toContain("Node.js Action");
@@ -499,7 +493,7 @@ runs:
   using: composite
   steps:
     - |`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
       const labels = completions.map(c => c.label);
 
       expect(labels).not.toContain("Node.js Action");
@@ -509,7 +503,7 @@ runs:
 
     it("Node.js snippet contains expected content", async () => {
       const [doc, position] = createActionDocument(`|`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
 
       const nodeSnippet = completions.find(c => c.label === "Node.js Action");
       const text = (nodeSnippet?.textEdit as {newText: string})?.newText;
@@ -522,7 +516,7 @@ runs:
 
     it("Composite snippet contains expected content", async () => {
       const [doc, position] = createActionDocument(`|`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
 
       const compositeSnippet = completions.find(c => c.label === "Composite Action");
       const text = (compositeSnippet?.textEdit as {newText: string})?.newText;
@@ -534,7 +528,7 @@ runs:
 
     it("Docker snippet contains expected content", async () => {
       const [doc, position] = createActionDocument(`|`);
-      const completions = await complete(doc, position, scaffoldingConfig);
+      const completions = await complete(doc, position);
 
       const dockerSnippet = completions.find(c => c.label === "Docker Action");
       const text = (dockerSnippet?.textEdit as {newText: string})?.newText;
@@ -544,14 +538,30 @@ runs:
       expect(text).toContain("entrypoint:");
     });
 
-    it("does not offer snippets when feature flag is disabled", async () => {
+    it("replaces typed text when selecting scaffolding snippet", async () => {
+      // User typed "compo" and then triggered completion
+      const [doc, position] = createActionDocument(`compo|`);
+      const completions = await complete(doc, position);
+
+      const compositeSnippet = completions.find(c => c.label === "Composite Action");
+      expect(compositeSnippet).toBeDefined();
+
+      // The textEdit should replace "compo", not insert after it
+      const textEdit = compositeSnippet?.textEdit as {range: {start: {character: number}; end: {character: number}}};
+      expect(textEdit.range.start.character).toBe(0); // Start of "compo"
+      expect(textEdit.range.end.character).toBe(5); // End of "compo"
+    });
+
+    it("handles empty file with no typed text", async () => {
       const [doc, position] = createActionDocument(`|`);
       const completions = await complete(doc, position);
-      const labels = completions.map(c => c.label);
 
-      expect(labels).not.toContain("Node.js Action");
-      expect(labels).not.toContain("Composite Action");
-      expect(labels).not.toContain("Docker Action");
+      const compositeSnippet = completions.find(c => c.label === "Composite Action");
+      const textEdit = compositeSnippet?.textEdit as {range: {start: {character: number}; end: {character: number}}};
+
+      // Zero-length range is fine when there's nothing to replace
+      expect(textEdit.range.start.character).toBe(0);
+      expect(textEdit.range.end.character).toBe(0);
     });
   });
 });

languageservice/src/complete-action.ts

@@ -1,7 +1,7 @@
 import {TemplateToken} from "@actions/workflow-parser/templates/tokens/index";
 import {MappingToken} from "@actions/workflow-parser/templates/tokens/mapping-token";
 import {Position} from "vscode-languageserver-textdocument";
-import {CompletionItem, CompletionItemKind, InsertTextFormat, TextEdit} from "vscode-languageserver-types";
+import {CompletionItem, CompletionItemKind, InsertTextFormat, Range, TextEdit} from "vscode-languageserver-types";
 import {Value} from "./value-providers/config.js";
 
 /**
@@ -53,9 +53,6 @@ runs:
   #   const greeting = \\\`Hello \\\${name}\\\`;
   #   console.log(greeting);
   #   fs.appendFileSync(process.env.GITHUB_OUTPUT, \\\`greeting=\\\${greeting}\\\\n\\\`);
-  #
-  # For JavaScript actions with @actions/toolkit, see:
-  # https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-javascript-action
 `;
 
 const ACTION_SNIPPET_NODEJS_RUNS = `inputs:
@@ -83,12 +80,12 @@ runs:
 `;
 
 const ACTION_SNIPPET_NODEJS_USING = `# For more on JavaScript actions (including @actions/toolkit), see:
-  # https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-javascript-action
-  using: node24
-  main: index.js
-  # Sample index.js (vanilla JS, no build required):
-  #
-  #   console.log('Hello World');
+# https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-javascript-action
+using: node24
+main: index.js
+# Sample index.js (vanilla JS, no build required):
+#
+#   console.log('Hello World');
 `;
 
 const ACTION_SNIPPET_COMPOSITE_FULL = `name: '\${1:Action Name}'
@@ -115,9 +112,9 @@ runs:
       env:
         INPUT_NAME: \\\${{ inputs.name }}
       run: |
-        GREETING="Hello $INPUT_NAME"
-        echo "$GREETING"
-        echo "greeting=$GREETING" >> $GITHUB_OUTPUT
+        GREETING="Hello \\$INPUT_NAME"
+        echo "\\$GREETING"
+        echo "greeting=\\$GREETING" >> \\$GITHUB_OUTPUT
 `;
 
 const ACTION_SNIPPET_COMPOSITE_RUNS = `inputs:
@@ -141,17 +138,17 @@ runs:
       env:
         INPUT_NAME: \\\${{ inputs.name }}
       run: |
-        GREETING="Hello $INPUT_NAME"
-        echo "$GREETING"
-        echo "greeting=$GREETING" >> $GITHUB_OUTPUT
+        GREETING="Hello \\$INPUT_NAME"
+        echo "\\$GREETING"
+        echo "greeting=\\$GREETING" >> \\$GITHUB_OUTPUT
 `;
 
 const ACTION_SNIPPET_COMPOSITE_USING = `# For more on composite actions, see:
-  # https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-composite-action
-  using: composite
-  steps:
-    - shell: bash
-      run: echo "Hello World"
+# https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-composite-action
+using: composite
+steps:
+  - shell: bash
+    run: echo "Hello World"
 `;
 
 const ACTION_SNIPPET_DOCKER_FULL = `name: '\${1:Action Name}'
@@ -179,9 +176,9 @@ runs:
   args:
     - -c
     - |
-      GREETING="Hello $INPUT_NAME"
-      echo "$GREETING"
-      echo "greeting=$GREETING" >> $GITHUB_OUTPUT
+      GREETING="Hello \\$INPUT_NAME"
+      echo "\\$GREETING"
+      echo "greeting=\\$GREETING" >> \\$GITHUB_OUTPUT
 `;
 
 const ACTION_SNIPPET_DOCKER_RUNS = `inputs:
@@ -206,20 +203,20 @@ runs:
   args:
     - -c
     - |
-      GREETING="Hello $INPUT_NAME"
-      echo "$GREETING"
-      echo "greeting=$GREETING" >> $GITHUB_OUTPUT
+      GREETING="Hello \\$INPUT_NAME"
+      echo "\\$GREETING"
+      echo "greeting=\\$GREETING" >> \\$GITHUB_OUTPUT
 `;
 
 const ACTION_SNIPPET_DOCKER_USING = `# For more on Docker actions, see:
-  # https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-docker-container-action
-  using: docker
-  # 'docker://image:tag' uses pre-built image, 'Dockerfile' builds locally
-  image: '\${1:docker://alpine:3.20}'
-  entrypoint: '\${2:sh}'
-  args:
-    - -c
-    - echo "Hello World"
+# https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-docker-container-action
+using: docker
+# 'docker://image:tag' uses pre-built image, 'Dockerfile' builds locally
+image: '\${1:docker://alpine:3.20}'
+entrypoint: '\${2:sh}'
+args:
+  - -c
+  - echo "Hello World"
 `;
 
 /**
@@ -282,7 +279,7 @@ export function filterActionRunsCompletions(values: Value[], path: TemplateToken
     // No using value set - show all keys but prioritize "using"
     return values.map(v => {
       if (v.label.toLowerCase() === "using") {
-        return {...v, sortText: "0_using"}; // Sort first
+        return {...v, sortText: "9_using"}; // Sort after snippets (0_, 1_, 2_)
       }
       return v;
     });
@@ -320,7 +317,8 @@ export function filterActionRunsCompletions(values: Value[], path: TemplateToken
 export function getActionScaffoldingSnippets(
   root: TemplateToken | undefined,
   path: TemplateToken[],
-  position: Position
+  position: Position,
+  replaceRange?: Range
 ): CompletionItem[] {
   // Get the runs mapping from the root, if it exists
   let runsMapping: MappingToken | undefined;
@@ -351,24 +349,27 @@ export function getActionScaffoldingSnippets(
     return [
       createSnippetCompletion(
         "Node.js Action",
-        "Scaffold a Node.js action",
+        "Scaffold a Node.js action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-javascript-action)",
         ACTION_SNIPPET_NODEJS_USING,
         position,
-        "1_nodejs"
+        "0_nodejs",
+        replaceRange
       ),
       createSnippetCompletion(
         "Composite Action",
-        "Scaffold a composite action",
+        "Scaffold a composite action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-composite-action)",
         ACTION_SNIPPET_COMPOSITE_USING,
         position,
-        "2_composite"
+        "1_composite",
+        replaceRange
       ),
       createSnippetCompletion(
         "Docker Action",
-        "Scaffold a Docker action",
+        "Scaffold a Docker action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-docker-container-action)",
         ACTION_SNIPPET_DOCKER_USING,
         position,
-        "3_docker"
+        "2_docker",
+        replaceRange
       )
     ];
   }
@@ -396,24 +397,27 @@ export function getActionScaffoldingSnippets(
     return [
       createSnippetCompletion(
         "Node.js Action",
-        "Scaffold a Node.js action",
+        "Scaffold a Node.js action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-javascript-action)",
         ACTION_SNIPPET_NODEJS_RUNS,
         position,
-        "1_nodejs"
+        "1_nodejs",
+        replaceRange
       ),
       createSnippetCompletion(
         "Composite Action",
-        "Scaffold a composite action",
+        "Scaffold a composite action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-composite-action)",
         ACTION_SNIPPET_COMPOSITE_RUNS,
         position,
-        "2_composite"
+        "2_composite",
+        replaceRange
       ),
       createSnippetCompletion(
         "Docker Action",
-        "Scaffold a Docker action",
+        "Scaffold a Docker action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-docker-container-action)",
         ACTION_SNIPPET_DOCKER_RUNS,
         position,
-        "3_docker"
+        "3_docker",
+        replaceRange
       )
     ];
   }
@@ -422,24 +426,27 @@ export function getActionScaffoldingSnippets(
   return [
     createSnippetCompletion(
       "Node.js Action",
-      "Scaffold a complete Node.js action",
+      "Scaffold a complete Node.js action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-javascript-action)",
       ACTION_SNIPPET_NODEJS_FULL,
       position,
-      "1_nodejs"
+      "1_nodejs",
+      replaceRange
     ),
     createSnippetCompletion(
       "Composite Action",
-      "Scaffold a complete composite action",
+      "Scaffold a complete composite action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-composite-action)",
       ACTION_SNIPPET_COMPOSITE_FULL,
       position,
-      "2_composite"
+      "2_composite",
+      replaceRange
     ),
     createSnippetCompletion(
       "Docker Action",
-      "Scaffold a complete Docker action",
+      "Scaffold a complete Docker action\n\n[Documentation](https://docs.github.com/en/actions/sharing-automations/creating-actions/creating-a-docker-container-action)",
       ACTION_SNIPPET_DOCKER_FULL,
       position,
-      "3_docker"
+      "3_docker",
+      replaceRange
     )
   ];
 }
@@ -452,10 +459,15 @@ function createSnippetCompletion(
   description: string,
   snippetText: string,
   position: Position,
-  sortText: string
+  sortText: string,
+  replaceRange?: Range
 ): CompletionItem {
+  // Use replace if we have a range, otherwise insert at position
+  const textEdit = replaceRange ? TextEdit.replace(replaceRange, snippetText) : TextEdit.insert(position, snippetText);
+
   return {
     label,
+    labelDetails: {description: "snippet"},
     kind: CompletionItemKind.Snippet,
     documentation: {
       kind: "markdown",
@@ -463,6 +475,6 @@ function createSnippetCompletion(
     },
     insertTextFormat: InsertTextFormat.Snippet,
     sortText,
-    textEdit: TextEdit.insert(position, snippetText)
+    textEdit
   };
 }

languageservice/src/complete.expressions.test.ts

@@ -1,5 +1,5 @@
 /* eslint-disable @typescript-eslint/no-non-null-assertion */
-import {data, DescriptionDictionary} from "@actions/expressions";
+import {data, DescriptionDictionary, FeatureFlags} from "@actions/expressions";
 import {CompletionItem, CompletionItemKind} from "vscode-languageserver-types";
 import {complete, getExpressionInput} from "./complete.js";
 import {ContextProviderConfig} from "./context-providers/config.js";
@@ -68,12 +68,16 @@ describe("expressions", () => {
   describe("top-level auto-complete", () => {
     it("single region", async () => {
       const input = "run-name: ${{ | }}";
-      const result = await complete(...getPositionFromCursor(input));
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
 
       expect(result.map(x => x.label)).toEqual([
         "github",
         "inputs",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",
@@ -108,12 +112,16 @@ describe("expressions", () => {
 
     it("single region with existing input", async () => {
       const input = "run-name: ${{ g| }}";
-      const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
 
       expect(result.map(x => x.label)).toEqual([
         "github",
         "inputs",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",
@@ -126,12 +134,16 @@ describe("expressions", () => {
 
     it("single region with existing condition", async () => {
       const input = "run-name: ${{ g| == 'test' }}";
-      const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
 
       expect(result.map(x => x.label)).toEqual([
         "github",
         "inputs",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",
@@ -144,12 +156,16 @@ describe("expressions", () => {
 
     it("multiple regions with partial function", async () => {
       const input = "run-name: Run a ${{ inputs.test }} one-line script ${{ from|('test') == inputs.name }}";
-      const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
 
       expect(result.map(x => x.label)).toEqual([
         "github",
         "inputs",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",
@@ -162,12 +178,16 @@ describe("expressions", () => {
 
     it("multiple regions - first region", async () => {
       const input = "run-name: test-${{ git| == 1 }}-${{ github.event }}";
-      const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
 
       expect(result.map(x => x.label)).toEqual([
         "github",
         "inputs",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",
@@ -180,12 +200,16 @@ describe("expressions", () => {
 
     it("multiple regions", async () => {
       const input = "run-name: test-${{ github }}-${{ | }}";
-      const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
 
       expect(result.map(x => x.label)).toEqual([
         "github",
         "inputs",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",
@@ -1126,7 +1150,10 @@ jobs:
         run: echo hi
 `;
 
-      const result = await complete(...getPositionFromCursor(input), {contextProviderConfig});
+      const result = await complete(...getPositionFromCursor(input), {
+        contextProviderConfig,
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
       expect(result.map(x => x.label)).toEqual([
         "env",
         "github",
@@ -1139,6 +1166,7 @@ jobs:
         "steps",
         "strategy",
         "vars",
+        "case",
         "contains",
         "endsWith",
         "format",

languageservice/src/complete.test.ts

@@ -6,6 +6,7 @@ import {getPositionFromCursor} from "./test-utils/cursor-position.js";
 import {TestLogger} from "./test-utils/logger.js";
 import {clearCache} from "./utils/workflow-cache.js";
 import {ValueProviderConfig, ValueProviderKind} from "./value-providers/config.js";
+import {FeatureFlags} from "@actions/expressions/features";
 
 registerLogger(new TestLogger());
 
@@ -895,4 +896,32 @@ jobs:
       expect(result.some(x => x.label === "macos-latest")).toBe(true);
     });
   });
+
+  describe("expression completions", () => {
+    it("include case function when enabled", async () => {
+      const input = "on: push\njobs:\n  build:\n    runs-on: ${{ c|";
+      const result = await complete(...getPositionFromCursor(input), {
+        featureFlags: new FeatureFlags({allowCaseFunction: true})
+      });
+
+      expect(result).not.toBeUndefined();
+      // Expression completions starting with 'c': case, contains
+      const labels = result.map(x => x.label);
+      expect(labels).toContain("case");
+      expect(labels).toContain("contains");
+    });
+
+    it("exclude case function when disabled", async () => {
+      const input = "on: push\njobs:\n  build:\n    runs-on: ${{ c|";
+      const result = await complete(...getPositionFromCursor(input), {
+        featureFlags: new FeatureFlags({allowCaseFunction: false})
+      });
+
+      expect(result).not.toBeUndefined();
+      // Expression completions starting with 'c': contains
+      const labels = result.map(x => x.label);
+      expect(labels).not.toContain("case");
+      expect(labels).toContain("contains");
+    });
+  });
 });

languageservice/src/complete.ts

@@ -132,7 +132,7 @@ export async function complete(
           Mode.Completion
         );
 
-    return getExpressionCompletionItems(token, context, newPos);
+    return getExpressionCompletionItems(token, context, newPos, config?.featureFlags);
   }
 
   const indentation = guessIndentation(newDoc, 2, true); // Use 2 spaces as default and most common for YAML
@@ -158,12 +158,6 @@ export async function complete(
   const escapeHatches = getEscapeHatchCompletions(token, keyToken, indentString, newPos, schema);
   values.push(...escapeHatches);
 
-  // Get action scaffolding snippets if applicable
-  let actionSnippets: CompletionItem[] = [];
-  if (isAction && config?.featureFlags?.isEnabled("actionScaffoldingSnippets")) {
-    actionSnippets = getActionScaffoldingSnippets(parsedTemplate.value, path, position);
-  }
-
   // Figure out what text to replace when the user picks a completion.
   // For example, if they typed `runs-|` and pick `runs-on`, we need to replace `runs-`.
   let replaceRange: Range | undefined;
@@ -191,6 +185,12 @@ export async function complete(
     }
   }
 
+  // Get action scaffolding snippets if applicable
+  let actionSnippets: CompletionItem[] = [];
+  if (isAction) {
+    actionSnippets = getActionScaffoldingSnippets(parsedTemplate.value, path, position, replaceRange);
+  }
+
   // Convert values to LSP CompletionItems
   const completionItems = values.map(value => {
     const newText = value.insertText || value.label;
@@ -521,7 +521,8 @@ export function getExistingValues(token: TemplateToken | null, parent: TemplateT
 function getExpressionCompletionItems(
   token: TemplateToken,
   context: DescriptionDictionary,
-  pos: Position
+  pos: Position,
+  featureFlags?: FeatureFlags
 ): CompletionItem[] {
   if (!token.range) {
     return [];
@@ -540,7 +541,7 @@ function getExpressionCompletionItems(
   const expressionInput = (getExpressionInput(currentInput, cursorOffset) || "").trim();
 
   try {
-    return completeExpression(expressionInput, context, [], validatorFunctions).map(item =>
+    return completeExpression(expressionInput, context, [], validatorFunctions, featureFlags).map(item =>
       mapExpressionCompletionItem(item, currentInput[cursorOffset])
     );
   } catch (e) {

languageservice/src/index.ts

@@ -6,3 +6,4 @@ export {getInlayHints} from "./inlay-hints.js";
 export {Logger, LogLevel, registerLogger, setLogLevel} from "./log.js";
 export {validate, ValidationConfig, ActionsMetadataProvider} from "./validate.js";
 export {ValueProviderConfig, ValueProviderKind} from "./value-providers/config.js";
+export {getCodeActions, CodeActionParams} from "./code-actions/code-actions.js";

languageservice/src/validate-action-reference.test.ts

@@ -249,7 +249,21 @@ jobs:
             line: 7
           }
         },
-        severity: DiagnosticSeverity.Error
+        severity: DiagnosticSeverity.Error,
+        code: "missing-required-inputs",
+        data: {
+          action: {
+            name: "cache",
+            owner: "actions",
+            ref: "v1"
+          },
+          missingInputs: [
+            {
+              default: undefined,
+              name: "path"
+            }
+          ]
+        }
       }
     ]);
   });
@@ -294,7 +308,25 @@ jobs:
             line: 7
           }
         },
-        severity: DiagnosticSeverity.Error
+        severity: DiagnosticSeverity.Error,
+        code: "missing-required-inputs",
+        data: {
+          action: {
+            name: "cache",
+            owner: "actions",
+            ref: "v1"
+          },
+          missingInputs: [
+            {
+              default: undefined,
+              name: "path"
+            },
+            {
+              default: undefined,
+              name: "key"
+            }
+          ]
+        }
       }
     ]);
   });
@@ -323,7 +355,25 @@ jobs:
             line: 6
           }
         },
-        severity: DiagnosticSeverity.Error
+        severity: DiagnosticSeverity.Error,
+        code: "missing-required-inputs",
+        data: {
+          action: {
+            name: "cache",
+            owner: "actions",
+            ref: "v1"
+          },
+          missingInputs: [
+            {
+              default: undefined,
+              name: "path"
+            },
+            {
+              default: undefined,
+              name: "key"
+            }
+          ]
+        }
       }
     ]);
   });

languageservice/src/validate-action-reference.ts

@@ -4,10 +4,22 @@ import {Step} from "@actions/workflow-parser/model/workflow-template";
 import {ScalarToken} from "@actions/workflow-parser/templates/tokens/scalar-token";
 import {TemplateToken} from "@actions/workflow-parser/templates/tokens/template-token";
 import {Diagnostic, DiagnosticSeverity} from "vscode-languageserver-types";
-import {parseActionReference} from "./action.js";
+import {ActionReference, parseActionReference} from "./action.js";
 import {mapRange} from "./utils/range.js";
 import {ValidationConfig} from "./validate.js";
 
+export const DiagnosticCode = {
+  MissingRequiredInputs: "missing-required-inputs"
+} as const;
+
+export interface MissingInputsDiagnosticData {
+  action: ActionReference;
+  missingInputs: Array<{
+    name: string;
+    default?: string;
+  }>;
+}
+
 /**
  * Validates action references in workflow steps, checking for valid inputs and required inputs.
  */
@@ -94,10 +106,22 @@ export async function validateActionReference(
       missingRequiredInputs.length === 1
         ? `Missing required input \`${missingRequiredInputs[0][0]}\``
         : `Missing required inputs: ${missingRequiredInputs.map(input => `\`${input[0]}\``).join(", ")}`;
+
+    // Build minimal diagnostic data - position calculation happens in the quickfix
+    const diagnosticData: MissingInputsDiagnosticData = {
+      action,
+      missingInputs: missingRequiredInputs.map(([name, input]) => ({
+        name,
+        default: input.default
+      }))
+    };
+
     diagnostics.push({
       severity: DiagnosticSeverity.Error,
-      range: mapRange((withKey || stepToken).range), // Highlight the whole step if we don't have a with key
-      message: message
+      range: mapRange((withKey || stepToken).range),
+      message: message,
+      code: DiagnosticCode.MissingRequiredInputs,
+      data: diagnosticData
     });
   }
 }

lerna.json

@@ -6,5 +6,5 @@
     "languageservice",
     "languageserver"
   ],
-  "version": "0.3.35"
+  "version": "0.3.40"
 }

package-lock.json

@@ -136,7 +136,7 @@
     },
     "expressions": {
       "name": "@actions/expressions",
-      "version": "0.3.35",
+      "version": "0.3.40",
       "license": "MIT",
       "devDependencies": {
         "@types/jest": "^29.0.3",
@@ -396,11 +396,11 @@
     },
     "languageserver": {
       "name": "@actions/languageserver",
-      "version": "0.3.35",
+      "version": "0.3.40",
       "license": "MIT",
       "dependencies": {
-        "@actions/languageservice": "^0.3.35",
-        "@actions/workflow-parser": "^0.3.35",
+        "@actions/languageservice": "^0.3.40",
+        "@actions/workflow-parser": "^0.3.40",
         "@octokit/rest": "^21.1.1",
         "@octokit/types": "^9.0.0",
         "vscode-languageserver": "^8.0.2",
@@ -940,11 +940,11 @@
     },
     "languageservice": {
       "name": "@actions/languageservice",
-      "version": "0.3.35",
+      "version": "0.3.40",
       "license": "MIT",
       "dependencies": {
-        "@actions/expressions": "^0.3.35",
-        "@actions/workflow-parser": "^0.3.35",
+        "@actions/expressions": "^0.3.40",
+        "@actions/workflow-parser": "^0.3.40",
         "vscode-languageserver-textdocument": "^1.0.7",
         "vscode-languageserver-types": "^3.17.2",
         "vscode-uri": "^3.0.8",
@@ -13345,10 +13345,10 @@
     },
     "workflow-parser": {
       "name": "@actions/workflow-parser",
-      "version": "0.3.35",
+      "version": "0.3.40",
       "license": "MIT",
       "dependencies": {
-        "@actions/expressions": "^0.3.35",
+        "@actions/expressions": "^0.3.40",
         "cronstrue": "^2.21.0",
         "yaml": "^2.0.0-8"
       },

workflow-parser/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/workflow-parser",
-  "version": "0.3.35",
+  "version": "0.3.40",
   "license": "MIT",
   "type": "module",
   "source": "./src/index.ts",
@@ -48,7 +48,7 @@
     "watch": "tsc --build tsconfig.build.json --watch"
   },
   "dependencies": {
-    "@actions/expressions": "^0.3.35",
+    "@actions/expressions": "^0.3.40",
     "cronstrue": "^2.21.0",
     "yaml": "^2.0.0-8"
   },