Add JobExecutionViewRenderer for DAP execution view

The DAP debugger serves a synthesized YAML document as the job's
`source`. That document is a 1:1 representation of how the runner
sees the job — not the workflow file — so pre and post action steps
appear as their own 'lines' that the user can pause on (and
eventually breakpoint, set in a follow-up PR).

This commit adds the core rendering algorithm: given a list of
phase-tagged entries (`JobExecutionViewEntry`), produce the
phase-keyed YAML plus a parallel array of 1-based line numbers
pointing at each entry's `- step:` key. The line numbers are what
later powers the DAP `stackTrace` handler.

Why hand-emit the skeleton instead of serializing a DTO?
Per-entry line offsets must be tracked at emission time. Using a
generic YAML serializer would force a second pass to scan the
output for `- step:` lines, which is fragile and breaks the moment
indentation conventions shift. Scalar values still go through the
library (via YamlScalarFormatter from #PR1a), so we don't carry
quoting rules.

Example output for a typical job (build, build, post step):

    # Job: build
    # Runner execution plan — read-only.

    setup:
      - step: Setup job

    main:
      - step: Run actions/checkout@v6
        uses: actions/checkout@v6
        if: success()
      - step: Cache Primes
        id: cache-primes
        uses: actions/cache@v5
        if: success()
        with:
          path: prime-numbers
          key: ${{ runner.os }}-primes

    post:
      - step: Post Cache Primes
        action: actions/cache@v5

    cleanup:
      - step: Complete job

This is part 2 of 5 splitting the previously-monolithic foundation
for review tractability. The wiring that turns runner state into
these entries lives in the next PRs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.devcontainer/devcontainer.json

@@ -4,7 +4,7 @@
   "features": {
     "ghcr.io/devcontainers/features/docker-in-docker:2": {},
     "ghcr.io/devcontainers/features/dotnet": {
-      "version": "8.0.419"
+      "version": "8.0.421"
     },
     "ghcr.io/devcontainers/features/node:1": {
       "version": "20"

.github/workflows/build.yml

@@ -99,7 +99,7 @@ jobs:
 
     - name: Get latest runner version
       id: latest_runner
-      uses: actions/github-script@v8
+      uses: actions/github-script@v9
       with:
         github-token: ${{secrets.GITHUB_TOKEN}}
         script: |

.github/workflows/docker-publish.yml

@@ -26,7 +26,7 @@ jobs:
 
       - name: Compute image version
         id: image
-        uses: actions/github-script@v8
+        uses: actions/github-script@v9
         with:
           script: |
             const fs = require('fs');

.github/workflows/node-upgrade.yml

@@ -159,18 +159,36 @@ jobs:
           git config --global user.name "github-actions[bot]"
           git config --global user.email "<41898282+github-actions[bot]@users.noreply.github.com>"
 
+          # Build version summary for commit message and PR body (only include changed versions)
+          COMMIT_VERSIONS=""
+          PR_VERSION_LINES=""
+
+          if [ "${{ steps.node-versions.outputs.needs_update20 }}" == "true" ]; then
+            COMMIT_VERSIONS="20: $NODE20_VERSION"
+            PR_VERSION_LINES="- Node 20: ${{ steps.node-versions.outputs.current_node20 }} → $NODE20_VERSION"
+          fi
+
+          if [ "${{ steps.node-versions.outputs.needs_update24 }}" == "true" ]; then
+            if [ -n "$COMMIT_VERSIONS" ]; then
+              COMMIT_VERSIONS="$COMMIT_VERSIONS, 24: $NODE24_VERSION"
+            else
+              COMMIT_VERSIONS="24: $NODE24_VERSION"
+            fi
+            PR_VERSION_LINES="${PR_VERSION_LINES:+$PR_VERSION_LINES
+          }- Node 24: ${{ steps.node-versions.outputs.current_node24 }} → $NODE24_VERSION"
+          fi
+
           # Create branch and commit changes
           branch_name="chore/update-node"
           git checkout -b "$branch_name"
-          git commit -a -m "chore: update Node versions (20: $NODE20_VERSION, 24: $NODE24_VERSION)"
+          git commit -a -m "chore: update Node versions ($COMMIT_VERSIONS)"
           git push --force origin "$branch_name"
 
           # Create PR body using here-doc for proper formatting
           cat > pr_body.txt << EOF
           Automated Node.js version update:
 
-          - Node 20: ${{ steps.node-versions.outputs.current_node20 }} → $NODE20_VERSION
-          - Node 24: ${{ steps.node-versions.outputs.current_node24 }} → $NODE24_VERSION
+          $PR_VERSION_LINES
 
           This update ensures we're using the latest stable Node.js versions for security and performance improvements.
 

.github/workflows/release.yml

@@ -16,7 +16,7 @@ jobs:
     # Make sure ./releaseVersion match ./src/runnerversion
     # Query GitHub release ensure version is not used
     - name: Check version
-      uses: actions/github-script@v8
+      uses: actions/github-script@v9
       with:
         github-token: ${{secrets.GITHUB_TOKEN}}
         script: |
@@ -171,7 +171,7 @@ jobs:
     # Create ReleaseNote file
     - name: Create ReleaseNote
       id: releaseNote
-      uses: actions/github-script@v8
+      uses: actions/github-script@v9
       with:
         github-token: ${{secrets.GITHUB_TOKEN}}
         script: |
@@ -300,7 +300,7 @@ jobs:
 
       - name: Compute image version
         id: image
-        uses: actions/github-script@v8
+        uses: actions/github-script@v9
         with:
           script: |
             const fs = require('fs');

docs/start/envlinux.md

@@ -25,11 +25,11 @@ The `installdependencies.sh` script should install all required dependencies on
 
 Debian based OS (Debian, Ubuntu, Linux Mint)
 
-- liblttng-ust1 or liblttng-ust0
+- liblttng-ust1t64, liblttng-ust1 or liblttng-ust0
 - libkrb5-3
 - zlib1g
 - libssl3t64, libssl3, libssl1.1, libssl1.0.2 or libssl1.0.0
-- libicu76, libicu75, ..., libicu66, libicu65, libicu63, libicu60, libicu57, libicu55, or libicu52
+- libicu80, libicu79, ..., libicu66, libicu65, libicu63, libicu60, libicu57, libicu55, or libicu52
 
 Fedora based OS (Fedora, Red Hat Enterprise Linux, CentOS, Oracle Linux 7)
 

images/Dockerfile

@@ -5,8 +5,8 @@ ARG TARGETOS
 ARG TARGETARCH
 ARG RUNNER_VERSION
 ARG RUNNER_CONTAINER_HOOKS_VERSION=0.7.0
-ARG DOCKER_VERSION=29.3.0
-ARG BUILDX_VERSION=0.32.1
+ARG DOCKER_VERSION=29.5.0
+ARG BUILDX_VERSION=0.34.0
 
 RUN apt update -y && apt install curl unzip -y
 

releaseNote.md

@@ -1,33 +1,36 @@
 ## What's Changed
-* Log inner exception message. by @TingluoHuang in https://github.com/actions/runner/pull/4265
-* Fix composite post-step marker display names by @ericsciple in https://github.com/actions/runner/pull/4267
-* Bump actions/download-artifact from 7 to 8 by @dependabot[bot] in https://github.com/actions/runner/pull/4269
-* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4272
-* Avoid throw in SelfUpdaters. by @TingluoHuang in https://github.com/actions/runner/pull/4274
-* Fix parser comparison mismatches by @ericsciple in https://github.com/actions/runner/pull/4273
-* Devcontainer: bump base image Ubuntu version by @MaxHorstmann in https://github.com/actions/runner/pull/4277
-* Support `entrypoint` and `command` for service containers by @ericsciple in https://github.com/actions/runner/pull/4276
-* Bump actions/upload-artifact from 6 to 7 by @dependabot[bot] in https://github.com/actions/runner/pull/4270
-* Bump docker/login-action from 3 to 4 by @dependabot[bot] in https://github.com/actions/runner/pull/4278
-* Fix positional arg bug in ExpressionParser.CreateTree by @ericsciple in https://github.com/actions/runner/pull/4279
-* Bump docker/build-push-action from 6 to 7 by @dependabot[bot] in https://github.com/actions/runner/pull/4283
-* Bump docker/setup-buildx-action from 3 to 4 by @dependabot[bot] in https://github.com/actions/runner/pull/4282
-* Bump actions/attest-build-provenance from 3 to 4 by @dependabot[bot] in https://github.com/actions/runner/pull/4266
-* Bump @stylistic/eslint-plugin from 5.9.0 to 5.10.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4281
-* Update Docker to v29.3.0 and Buildx to v0.32.1 by @github-actions[bot] in https://github.com/actions/runner/pull/4286
-* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4287
-* Fix cancellation token race during parser comparison by @ericsciple in https://github.com/actions/runner/pull/4280
-* Bump @typescript-eslint/eslint-plugin from 8.47.0 to 8.54.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4230
-* Exit with specified exit code when runner is outdated by @nikola-jokic in https://github.com/actions/runner/pull/4285
-* Report infra_error for action download failures. by @TingluoHuang in https://github.com/actions/runner/pull/4294
-* Update dotnet sdk to latest version @8.0.419 by @github-actions[bot] in https://github.com/actions/runner/pull/4301
-* Node 24 enforcement + Linux ARM32 deprecation support by @salmanmkc in https://github.com/actions/runner/pull/4303
-* Bump @typescript-eslint/eslint-plugin from 8.54.0 to 8.57.1 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4304
+* Bump flatted from 3.2.7 to 3.4.2 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4307
+* Add DAP server by @rentziass in https://github.com/actions/runner/pull/4298
+* Bump @typescript-eslint/eslint-plugin from 8.57.1 to 8.57.2 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4310
+* Remove AllowCaseFunction feature flag by @ericsciple in https://github.com/actions/runner/pull/4316
+* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4319
+* Batch and deduplicate action resolution across composite depths by @stefanpenner in https://github.com/actions/runner/pull/4296
+* Add support for Bearer token in action archive downloads by @TingluoHuang in https://github.com/actions/runner/pull/4321
+* Bump brace-expansion in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4318
+* Add devtunnel connection for debugger jobs by @rentziass in https://github.com/actions/runner/pull/4317
+* Update Docker to v29.3.1 and Buildx to v0.33.0 by @github-actions[bot] in https://github.com/actions/runner/pull/4324
+* Bump @typescript-eslint/eslint-plugin from 8.57.2 to 8.58.1 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4327
+* Bump actions/github-script from 8 to 9 by @dependabot[bot] in https://github.com/actions/runner/pull/4331
+* Bump typescript from 5.9.3 to 6.0.2 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4329
+* fix: only show changed versions in node upgrade PR description by @salmanmkc in https://github.com/actions/runner/pull/4332
+* Bump System.Formats.Asn1, Cryptography.Pkcs, ProtectedData, ServiceController, CodePages, Threading.Channels, @actions/glob, @typescript-eslint/parser, lint-staged, picomatch by @Copilot in https://github.com/actions/runner/pull/4333
+* feat: add `job.workflow_*` typed accessors to JobContext by @salmanmkc in https://github.com/actions/runner/pull/4335
+* Add WS bridge over DAP TCP server by @rentziass in https://github.com/actions/runner/pull/4328
+* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4355
+* Bump Docker version to 29.4.0 by @Copilot in https://github.com/actions/runner/pull/4352
+* Update dotnet sdk to latest version @8.0.420 by @github-actions[bot] in https://github.com/actions/runner/pull/4356
+* Bump @typescript-eslint/parser from 8.58.1 to 8.59.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4360
+* Bump System.Formats.Asn1 and System.Security.Cryptography.Pkcs by @dependabot[bot] in https://github.com/actions/runner/pull/4362
+* Add vulnerability-alerts permission by @salmanmkc in https://github.com/actions/runner/pull/4350
+* Bump @typescript-eslint/eslint-plugin from 8.58.1 to 8.59.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4359
+* Bump System.ServiceProcess.ServiceController from 10.0.3 to 10.0.6 by @dependabot[bot] in https://github.com/actions/runner/pull/4358
+* Bump typescript from 6.0.2 to 6.0.3 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4353
+* Bump Microsoft.DevTunnels.Connections from 1.3.16 to 1.3.39 by @dependabot[bot] in https://github.com/actions/runner/pull/4339
 
 ## New Contributors
-* @MaxHorstmann made their first contribution in https://github.com/actions/runner/pull/4277
+* @stefanpenner made their first contribution in https://github.com/actions/runner/pull/4296
 
-**Full Changelog**: https://github.com/actions/runner/compare/v2.332.0...v2.333.0
+**Full Changelog**: https://github.com/actions/runner/compare/v2.333.1...v2.334.0
 
 _Note: Actions Runner follows a progressive release policy, so the latest release might not be available to your enterprise, organization, or repository yet.
 To confirm which version of the Actions Runner you should expect, please view the download instructions for your enterprise, organization, or repository.

src/Misc/expressionFunc/hashFiles/package.json

@@ -32,20 +32,20 @@
   "author": "GitHub Actions",
   "license": "MIT",
   "dependencies": {
-    "@actions/glob": "^0.4.0"
+    "@actions/glob": "^0.7.0"
   },
   "devDependencies": {
     "@stylistic/eslint-plugin": "^5.10.0",
     "@types/node": "^22.0.0",
-    "@typescript-eslint/eslint-plugin": "^8.57.2",
-    "@typescript-eslint/parser": "^8.0.0",
+    "@typescript-eslint/eslint-plugin": "^8.59.0",
+    "@typescript-eslint/parser": "^8.59.0",
     "@vercel/ncc": "^0.38.3",
     "eslint": "^8.47.0",
     "eslint-plugin-github": "^4.10.2",
     "eslint-plugin-prettier": "^5.0.0",
     "husky": "^9.1.7",
-    "lint-staged": "^15.5.0",
+    "lint-staged": "^16.4.0",
     "prettier": "^3.0.3",
-    "typescript": "^5.9.3"
+    "typescript": "^6.0.3"
   }
 }

src/Misc/externals.sh

@@ -6,8 +6,8 @@ NODE_URL=https://nodejs.org/dist
 NODE_ALPINE_URL=https://github.com/actions/alpine_nodejs/releases/download
 # When you update Node versions you must also create a new release of alpine_nodejs at that updated version.
 # Follow the instructions here: https://github.com/actions/alpine_nodejs?tab=readme-ov-file#getting-started
-NODE20_VERSION="20.20.1"
-NODE24_VERSION="24.14.0"
+NODE20_VERSION="20.20.2"
+NODE24_VERSION="24.15.0"
 
 get_abs_path() {
   # exploits the fact that pwd will print abs path when no args

src/Misc/layoutbin/installdependencies.sh

@@ -94,7 +94,7 @@ then
             fi
         }
 
-        apt_get_with_fallbacks liblttng-ust1 liblttng-ust0
+        apt_get_with_fallbacks liblttng-ust1t64 liblttng-ust1 liblttng-ust0
         if [ $? -ne 0 ]
         then
             echo "'$apt_get' failed with exit code '$?'"
@@ -110,7 +110,7 @@ then
             exit 1
         fi
 
-        apt_get_with_fallbacks libicu76 libicu75 libicu74 libicu73 libicu72 libicu71 libicu70 libicu69 libicu68 libicu67 libicu66 libicu65 libicu63 libicu60 libicu57 libicu55 libicu52
+        apt_get_with_fallbacks libicu80 libicu79 libicu78 libicu77 libicu76 libicu75 libicu74 libicu73 libicu72 libicu71 libicu70 libicu69 libicu68 libicu67 libicu66 libicu65 libicu63 libicu60 libicu57 libicu55 libicu52
         if [ $? -ne 0 ]
         then
             echo "'$apt_get' failed with exit code '$?'"

src/Runner.Common/Constants.cs

@@ -177,6 +177,9 @@ namespace GitHub.Runner.Common
                 public static readonly string SetOrchestrationIdEnvForActions = "actions_set_orchestration_id_env_for_actions";
                 public static readonly string SendJobLevelAnnotations = "actions_send_job_level_annotations";
                 public static readonly string EmitCompositeMarkers = "actions_runner_emit_composite_markers";
+                public static readonly string BatchActionResolution = "actions_batch_action_resolution";
+                public static readonly string UseBearerTokenForCodeload = "actions_use_bearer_token_for_codeload";
+                public static readonly string OverrideDebuggerWelcomeMessage = "actions_runner_override_debugger_welcome_message";
             }
 
             // Node version migration related constants

src/Runner.Common/Runner.Common.csproj

@@ -17,9 +17,9 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
-    <PackageReference Include="System.Text.Encoding.CodePages" Version="8.0.0" />
-    <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="10.0.3" />
+    <PackageReference Include="System.Threading.Channels" Version="10.0.3" />
   </ItemGroup>
 
   <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">

src/Runner.Common/Tracing.cs

@@ -12,6 +12,13 @@ namespace GitHub.Runner.Common
         private ISecretMasker _secretMasker;
         private TraceSource _traceSource;
 
+        /// <summary>
+        /// The underlying <see cref="System.Diagnostics.TraceSource"/> for this instance.
+        /// Useful when third-party libraries require a <see cref="System.Diagnostics.TraceSource"/>
+        /// to route their diagnostics into the runner's log infrastructure.
+        /// </summary>
+        public TraceSource Source => _traceSource;
+
         public Tracing(string name, ISecretMasker secretMasker, SourceSwitch sourceSwitch, HostTraceListener traceListener, StdoutTraceListener stdoutTraceListener = null)
         {
             ArgUtil.NotNull(secretMasker, nameof(secretMasker));

src/Runner.Listener/Runner.Listener.csproj

@@ -22,8 +22,8 @@
     <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="System.IO.FileSystem.AccessControl" Version="5.0.0" />
-    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
-    <PackageReference Include="System.ServiceProcess.ServiceController" Version="8.0.1" />
+    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
+    <PackageReference Include="System.ServiceProcess.ServiceController" Version="10.0.7" />
   </ItemGroup>
 
   <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">

src/Runner.Plugins/Repository/v1.0/RepositoryPlugin.cs

@@ -12,8 +12,6 @@ namespace GitHub.Runner.Plugins.Repository.v1_0
 {
     public class CheckoutTask : IRunnerActionPlugin
     {
-        private readonly Regex _validSha1 = new(@"\b[0-9a-f]{40}\b", RegexOptions.IgnoreCase | RegexOptions.CultureInvariant | RegexOptions.Compiled, TimeSpan.FromSeconds(2));
-
         public async Task RunAsync(RunnerActionPluginExecutionContext executionContext, CancellationToken token)
         {
             string runnerWorkspace = executionContext.GetRunnerContext("workspace");
@@ -99,7 +97,7 @@ namespace GitHub.Runner.Plugins.Repository.v1_0
             {
                 sourceBranch = refInput;
                 sourceVersion = executionContext.GetInput(Pipelines.PipelineConstants.CheckoutTaskInputs.Version);  // version get removed when checkout move to repo in the graph
-                if (string.IsNullOrEmpty(sourceVersion) && RegexUtility.IsMatch(sourceBranch, WellKnownRegularExpressions.SHA1))
+                if (string.IsNullOrEmpty(sourceVersion) && RegexUtility.IsMatch(sourceBranch, WellKnownRegularExpressions.CommitHash))
                 {
                     sourceVersion = sourceBranch;
 

src/Runner.Plugins/Repository/v1.1/RepositoryPlugin.cs

@@ -96,7 +96,7 @@ namespace GitHub.Runner.Plugins.Repository.v1_1
             {
                 sourceBranch = refInput;
                 sourceVersion = executionContext.GetInput(Pipelines.PipelineConstants.CheckoutTaskInputs.Version);  // version get removed when checkout move to repo in the graph
-                if (string.IsNullOrEmpty(sourceVersion) && RegexUtility.IsMatch(sourceBranch, WellKnownRegularExpressions.SHA1))
+                if (string.IsNullOrEmpty(sourceVersion) && RegexUtility.IsMatch(sourceBranch, WellKnownRegularExpressions.CommitHash))
                 {
                     sourceVersion = sourceBranch;
                     // If Ref is a SHA and the repo is self, we need to use github.ref as source branch since it might be refs/pull/*

src/Runner.Sdk/Runner.Sdk.csproj

@@ -15,9 +15,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Text.Encoding.CodePages" Version="8.0.0" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="10.0.3" />
     <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
-    <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="System.Threading.Channels" Version="10.0.3" />
   </ItemGroup>
 
   <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">

src/Runner.Worker/ActionManager.cs

@@ -79,6 +79,13 @@ namespace GitHub.Runner.Worker
                 PreStepTracker = new Dictionary<Guid, IActionRunner>()
             };
             var containerSetupSteps = new List<JobExtensionRunner>();
+            var batchActionResolution = (executionContext.Global.Variables.GetBoolean(Constants.Runner.Features.BatchActionResolution) ?? false)
+                || StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION"));
+            // Stack-local cache: same action (owner/repo@ref) is resolved only once,
+            // even if it appears at multiple depths in a composite tree.
+            var resolvedDownloadInfos = batchActionResolution
+                ? new Dictionary<string, WebApi.ActionDownloadInfo>(StringComparer.Ordinal)
+                : null;
             var depth = 0;
             // We are running at the start of a job
             if (rootStepId == default(Guid))
@@ -105,7 +112,9 @@ namespace GitHub.Runner.Worker
             PrepareActionsState result = new PrepareActionsState();
             try
             {
-                result = await PrepareActionsRecursiveAsync(executionContext, state, actions, depth, rootStepId);
+                result = batchActionResolution
+                    ? await PrepareActionsRecursiveAsync(executionContext, state, actions, resolvedDownloadInfos, depth, rootStepId)
+                    : await PrepareActionsRecursiveLegacyAsync(executionContext, state, actions, depth, rootStepId);
             }
             catch (FailedToResolveActionDownloadInfoException ex)
             {
@@ -169,7 +178,192 @@ namespace GitHub.Runner.Worker
             return new PrepareResult(containerSetupSteps, result.PreStepTracker);
         }
 
-        private async Task<PrepareActionsState> PrepareActionsRecursiveAsync(IExecutionContext executionContext, PrepareActionsState state, IEnumerable<Pipelines.ActionStep> actions, Int32 depth = 0, Guid parentStepId = default(Guid))
+        private async Task<PrepareActionsState> PrepareActionsRecursiveAsync(IExecutionContext executionContext, PrepareActionsState state, IEnumerable<Pipelines.ActionStep> actions, Dictionary<string, WebApi.ActionDownloadInfo> resolvedDownloadInfos, Int32 depth = 0, Guid parentStepId = default(Guid))
+        {
+            ArgUtil.NotNull(executionContext, nameof(executionContext));
+            if (depth > Constants.CompositeActionsMaxDepth)
+            {
+                throw new Exception($"Composite action depth exceeded max depth {Constants.CompositeActionsMaxDepth}");
+            }
+
+            var repositoryActions = new List<Pipelines.ActionStep>();
+
+            foreach (var action in actions)
+            {
+                if (action.Reference.Type == Pipelines.ActionSourceType.ContainerRegistry)
+                {
+                    ArgUtil.NotNull(action, nameof(action));
+                    var containerReference = action.Reference as Pipelines.ContainerRegistryReference;
+                    ArgUtil.NotNull(containerReference, nameof(containerReference));
+                    ArgUtil.NotNullOrEmpty(containerReference.Image, nameof(containerReference.Image));
+
+                    if (!state.ImagesToPull.ContainsKey(containerReference.Image))
+                    {
+                        state.ImagesToPull[containerReference.Image] = new List<Guid>();
+                    }
+
+                    Trace.Info($"Action {action.Name} ({action.Id}) needs to pull image '{containerReference.Image}'");
+                    state.ImagesToPull[containerReference.Image].Add(action.Id);
+                }
+                else if (action.Reference.Type == Pipelines.ActionSourceType.Repository)
+                {
+                    repositoryActions.Add(action);
+                }
+            }
+
+            if (repositoryActions.Count > 0)
+            {
+                // Resolve download info, skipping any actions already cached.
+                await ResolveNewActionsAsync(executionContext, repositoryActions, resolvedDownloadInfos);
+
+                // Download each action.
+                foreach (var action in repositoryActions)
+                {
+                    var lookupKey = GetDownloadInfoLookupKey(action);
+                    if (string.IsNullOrEmpty(lookupKey))
+                    {
+                        continue;
+                    }
+                    if (!resolvedDownloadInfos.TryGetValue(lookupKey, out var downloadInfo))
+                    {
+                        throw new Exception($"Missing download info for {lookupKey}");
+                    }
+                    await DownloadRepositoryActionAsync(executionContext, downloadInfo);
+                }
+
+                // Parse action.yml and collect composite sub-actions for batched
+                // resolution below. Pre/post step registration is deferred until
+                // after recursion so that HasPre/HasPost reflect the full subtree.
+                var nextLevel = new List<(Pipelines.ActionStep action, Guid parentId)>();
+
+                foreach (var action in repositoryActions)
+                {
+                    var setupInfo = PrepareRepositoryActionAsync(executionContext, action);
+                    if (setupInfo != null && setupInfo.Container != null)
+                    {
+                        if (!string.IsNullOrEmpty(setupInfo.Container.Image))
+                        {
+                            if (!state.ImagesToPull.ContainsKey(setupInfo.Container.Image))
+                            {
+                                state.ImagesToPull[setupInfo.Container.Image] = new List<Guid>();
+                            }
+
+                            Trace.Info($"Action {action.Name} ({action.Id}) from repository '{setupInfo.Container.ActionRepository}' needs to pull image '{setupInfo.Container.Image}'");
+                            state.ImagesToPull[setupInfo.Container.Image].Add(action.Id);
+                        }
+                        else
+                        {
+                            ArgUtil.NotNullOrEmpty(setupInfo.Container.ActionRepository, nameof(setupInfo.Container.ActionRepository));
+
+                            if (!state.ImagesToBuild.ContainsKey(setupInfo.Container.ActionRepository))
+                            {
+                                state.ImagesToBuild[setupInfo.Container.ActionRepository] = new List<Guid>();
+                            }
+
+                            Trace.Info($"Action {action.Name} ({action.Id}) from repository '{setupInfo.Container.ActionRepository}' needs to build image '{setupInfo.Container.Dockerfile}'");
+                            state.ImagesToBuild[setupInfo.Container.ActionRepository].Add(action.Id);
+                            state.ImagesToBuildInfo[setupInfo.Container.ActionRepository] = setupInfo.Container;
+                        }
+                    }
+                    else if (setupInfo != null && setupInfo.Steps != null && setupInfo.Steps.Count > 0)
+                    {
+                        foreach (var step in setupInfo.Steps)
+                        {
+                            nextLevel.Add((step, action.Id));
+                        }
+                    }
+                }
+
+                // Resolve all next-level sub-actions in one batch API call,
+                // then recurse per parent (which hits the cache, not the API).
+                if (nextLevel.Count > 0)
+                {
+                    var nextLevelRepoActions = nextLevel
+                        .Where(x => x.action.Reference.Type == Pipelines.ActionSourceType.Repository)
+                        .Select(x => x.action)
+                        .ToList();
+                    await ResolveNewActionsAsync(executionContext, nextLevelRepoActions, resolvedDownloadInfos);
+
+                    foreach (var group in nextLevel.GroupBy(x => x.parentId))
+                    {
+                        var groupActions = group.Select(x => x.action).ToList();
+                        state = await PrepareActionsRecursiveAsync(executionContext, state, groupActions, resolvedDownloadInfos, depth + 1, group.Key);
+                    }
+                }
+
+                // Register pre/post steps after recursion so that HasPre/HasPost
+                // are correct (they depend on _cachedEmbeddedPreSteps/PostSteps
+                // being populated by the recursive calls above).
+                foreach (var action in repositoryActions)
+                {
+                    var repoAction = action.Reference as Pipelines.RepositoryPathReference;
+                    if (repoAction.RepositoryType != Pipelines.PipelineConstants.SelfAlias)
+                    {
+                        var definition = LoadAction(executionContext, action);
+                        if (definition.Data.Execution.HasPre)
+                        {
+                            Trace.Info($"Add 'pre' execution for {action.Id}");
+                            // Root Step
+                            if (depth < 1)
+                            {
+                                var actionRunner = HostContext.CreateService<IActionRunner>();
+                                actionRunner.Action = action;
+                                actionRunner.Stage = ActionRunStage.Pre;
+                                actionRunner.Condition = definition.Data.Execution.InitCondition;
+                                state.PreStepTracker[action.Id] = actionRunner;
+                            }
+                            // Embedded Step
+                            else
+                            {
+                                if (!_cachedEmbeddedPreSteps.ContainsKey(parentStepId))
+                                {
+                                    _cachedEmbeddedPreSteps[parentStepId] = new List<Pipelines.ActionStep>();
+                                }
+                                // Clone action so we can modify the condition without affecting the original
+                                var clonedAction = action.Clone() as Pipelines.ActionStep;
+                                clonedAction.Condition = definition.Data.Execution.InitCondition;
+                                _cachedEmbeddedPreSteps[parentStepId].Add(clonedAction);
+                            }
+                        }
+
+                        if (definition.Data.Execution.HasPost && depth > 0)
+                        {
+                            if (!_cachedEmbeddedPostSteps.ContainsKey(parentStepId))
+                            {
+                                // If we haven't done so already, add the parent to the post steps
+                                _cachedEmbeddedPostSteps[parentStepId] = new Stack<Pipelines.ActionStep>();
+                            }
+                            // Clone action so we can modify the condition without affecting the original
+                            var clonedAction = action.Clone() as Pipelines.ActionStep;
+                            clonedAction.Condition = definition.Data.Execution.CleanupCondition;
+                            _cachedEmbeddedPostSteps[parentStepId].Push(clonedAction);
+                        }
+                    }
+                    else if (depth > 0)
+                    {
+                        // if we're in a composite action and haven't loaded the local action yet
+                        // we assume it has a post step
+                        if (!_cachedEmbeddedPostSteps.ContainsKey(parentStepId))
+                        {
+                            // If we haven't done so already, add the parent to the post steps
+                            _cachedEmbeddedPostSteps[parentStepId] = new Stack<Pipelines.ActionStep>();
+                        }
+                        // Clone action so we can modify the condition without affecting the original
+                        var clonedAction = action.Clone() as Pipelines.ActionStep;
+                        _cachedEmbeddedPostSteps[parentStepId].Push(clonedAction);
+                    }
+                }
+            }
+
+            return state;
+        }
+
+        /// <summary>
+        /// Legacy (non-batched) action resolution. Each composite resolves its
+        /// sub-actions individually, with no cross-depth deduplication.
+        /// Used when the BatchActionResolution feature flag is disabled.
+        /// </summary>
+        private async Task<PrepareActionsState> PrepareActionsRecursiveLegacyAsync(IExecutionContext executionContext, PrepareActionsState state, IEnumerable<Pipelines.ActionStep> actions, Int32 depth = 0, Guid parentStepId = default(Guid))
         {
             ArgUtil.NotNull(executionContext, nameof(executionContext));
             if (depth > Constants.CompositeActionsMaxDepth)
@@ -255,7 +449,7 @@ namespace GitHub.Runner.Worker
                     }
                     else if (setupInfo != null && setupInfo.Steps != null && setupInfo.Steps.Count > 0)
                     {
-                        state = await PrepareActionsRecursiveAsync(executionContext, state, setupInfo.Steps, depth + 1, action.Id);
+                        state = await PrepareActionsRecursiveLegacyAsync(executionContext, state, setupInfo.Steps, depth + 1, action.Id);
                     }
                     var repoAction = action.Reference as Pipelines.RepositoryPathReference;
                     if (repoAction.RepositoryType != Pipelines.PipelineConstants.SelfAlias)
@@ -686,6 +880,11 @@ namespace GitHub.Runner.Worker
                 return new Dictionary<string, WebApi.ActionDownloadInfo>();
             }
 
+            // Pass lockfile dependencies to Launch when present, so it can
+            // perform ref-scoped policy matching with the original refs.
+            var deps = executionContext.Global.ActionsDependencies;
+            IList<string> dependencies = (deps != null && deps.Count > 0) ? deps : null;
+
             // Resolve download info
             var launchServer = HostContext.GetService<ILaunchServer>();
             var jobServer = HostContext.GetService<IJobServer>();
@@ -697,7 +896,7 @@ namespace GitHub.Runner.Worker
                     if (MessageUtil.IsRunServiceJob(executionContext.Global.Variables.Get(Constants.Variables.System.JobRequestType)))
                     {
                         var displayHelpfulActionsDownloadErrors = executionContext.Global.Variables.GetBoolean(Constants.Runner.Features.DisplayHelpfulActionsDownloadErrors) ?? false;
-                        actionDownloadInfos = await launchServer.ResolveActionsDownloadInfoAsync(executionContext.Global.Plan.PlanId, executionContext.Root.Id, new WebApi.ActionReferenceList { Actions = actionReferences }, executionContext.CancellationToken, displayHelpfulActionsDownloadErrors);
+                        actionDownloadInfos = await launchServer.ResolveActionsDownloadInfoAsync(executionContext.Global.Plan.PlanId, executionContext.Root.Id, new WebApi.ActionReferenceList { Actions = actionReferences, Dependencies = dependencies }, executionContext.CancellationToken, displayHelpfulActionsDownloadErrors);
                     }
                     else
                     {
@@ -762,6 +961,33 @@ namespace GitHub.Runner.Worker
             return actionDownloadInfos.Actions;
         }
 
+        /// <summary>
+        /// Only resolves actions not already in resolvedDownloadInfos.
+        /// Results are cached for reuse at deeper recursion levels.
+        /// </summary>
+        private async Task ResolveNewActionsAsync(IExecutionContext executionContext, List<Pipelines.ActionStep> actions, Dictionary<string, WebApi.ActionDownloadInfo> resolvedDownloadInfos)
+        {
+            var actionsToResolve = new List<Pipelines.ActionStep>();
+            var pendingKeys = new HashSet<string>(StringComparer.Ordinal);
+            foreach (var action in actions)
+            {
+                var lookupKey = GetDownloadInfoLookupKey(action);
+                if (!string.IsNullOrEmpty(lookupKey) && !resolvedDownloadInfos.ContainsKey(lookupKey) && pendingKeys.Add(lookupKey))
+                {
+                    actionsToResolve.Add(action);
+                }
+            }
+
+            if (actionsToResolve.Count > 0)
+            {
+                var downloadInfos = await GetDownloadInfoAsync(executionContext, actionsToResolve);
+                foreach (var kvp in downloadInfos)
+                {
+                    resolvedDownloadInfos[kvp.Key] = kvp.Value;
+                }
+            }
+        }
+
         private async Task DownloadRepositoryActionAsync(IExecutionContext executionContext, WebApi.ActionDownloadInfo downloadInfo)
         {
             Trace.Entering();
@@ -1146,16 +1372,29 @@ namespace GitHub.Runner.Worker
             return $"{repositoryReference.Name}@{repositoryReference.Ref}";
         }
 
-        private AuthenticationHeaderValue CreateAuthHeader(string token)
+        private AuthenticationHeaderValue CreateAuthHeader(IExecutionContext executionContext, string downloadUrl, string token)
         {
             if (string.IsNullOrEmpty(token))
             {
                 return null;
             }
 
-            var base64EncodingToken = Convert.ToBase64String(Encoding.UTF8.GetBytes($"x-access-token:{token}"));
-            HostContext.SecretMasker.AddValue(base64EncodingToken);
-            return new AuthenticationHeaderValue("Basic", base64EncodingToken);
+            if (executionContext.Global.Variables.GetBoolean(Constants.Runner.Features.UseBearerTokenForCodeload) == true &&
+                Uri.TryCreate(downloadUrl, UriKind.Absolute, out var parsedUrl) &&
+                !string.IsNullOrEmpty(parsedUrl?.Host) &&
+                !string.IsNullOrEmpty(parsedUrl?.PathAndQuery) &&
+                (parsedUrl.Host.StartsWith("codeload.", StringComparison.OrdinalIgnoreCase) || parsedUrl.PathAndQuery.StartsWith("/_codeload/", StringComparison.OrdinalIgnoreCase)))
+            {
+                Trace.Info("Using Bearer token for action archive download directly to codeload.");
+                return new AuthenticationHeaderValue("Bearer", token);
+            }
+            else
+            {
+                Trace.Info("Using Basic token for action archive download.");
+                var base64EncodingToken = Convert.ToBase64String(Encoding.UTF8.GetBytes($"x-access-token:{token}"));
+                HostContext.SecretMasker.AddValue(base64EncodingToken);
+                return new AuthenticationHeaderValue("Basic", base64EncodingToken);
+            }
         }
 
         private async Task DownloadRepositoryArchive(IExecutionContext executionContext, string downloadUrl, string downloadAuthToken, string archiveFile)
@@ -1180,7 +1419,7 @@ namespace GitHub.Runner.Worker
                             using (var httpClientHandler = HostContext.CreateHttpClientHandler())
                             using (var httpClient = new HttpClient(httpClientHandler))
                             {
-                                httpClient.DefaultRequestHeaders.Authorization = CreateAuthHeader(downloadAuthToken);
+                                httpClient.DefaultRequestHeaders.Authorization = CreateAuthHeader(executionContext, downloadUrl, downloadAuthToken);
 
                                 httpClient.DefaultRequestHeaders.UserAgent.AddRange(HostContext.UserAgents);
                                 using (var response = await httpClient.GetAsync(downloadUrl))
@@ -1207,6 +1446,11 @@ namespace GitHub.Runner.Worker
                                         // It doesn't make sense to retry in this case, so just stop
                                         throw new ActionNotFoundException(new Uri(downloadUrl), requestId);
                                     }
+                                    else if (response.StatusCode == HttpStatusCode.Forbidden)
+                                    {
+                                        // It doesn't make sense to retry in this case, so just stop
+                                        throw new AccessDeniedException($"Access denied to '{downloadUrl}' ({requestId})");
+                                    }
                                     else
                                     {
                                         // Something else bad happened, let's go to our retry logic
@@ -1230,6 +1474,11 @@ namespace GitHub.Runner.Worker
                             Trace.Info($"The action at '{downloadUrl}' does not exist");
                             throw;
                         }
+                        catch (AccessDeniedException)
+                        {
+                            Trace.Info($"Access denied to '{downloadUrl}'");
+                            throw;
+                        }
                         catch (Exception ex) when (retryCount < 2)
                         {
                             retryCount++;
@@ -1255,7 +1504,7 @@ namespace GitHub.Runner.Worker
                     }
                 }
             }
-            catch (Exception ex) when (!(ex is OperationCanceledException) && !executionContext.CancellationToken.IsCancellationRequested)
+            catch (Exception ex) when (!(ex is AccessDeniedException) && !(ex is OperationCanceledException) && !executionContext.CancellationToken.IsCancellationRequested)
             {
                 Trace.Error($"Failed to download archive '{downloadUrl}' after {retryCount + 1} attempts.");
                 Trace.Error(ex);

src/Runner.Worker/ActionManifestManager.cs

@@ -316,7 +316,6 @@ namespace GitHub.Runner.Worker
                 Schema = _actionManifestSchema,
                 // TODO: Switch to real tracewriter for cutover
                 TraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter(),
-                AllowCaseFunction = false,
             };
 
             // Expression values from execution context

src/Runner.Worker/ActionManifestManagerLegacy.cs

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

src/Runner.Worker/Dap/DapDebugger.cs

@@ -1,7 +1,10 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Net;
+using System.Net.Http.Headers;
 using System.Net.Sockets;
 using System.Text;
 using System.Threading;
@@ -9,6 +12,9 @@ using System.Threading.Tasks;
 using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Sdk;
+using Microsoft.DevTunnels.Connections;
+using Microsoft.DevTunnels.Contracts;
+using Microsoft.DevTunnels.Management;
 using Newtonsoft.Json;
 
 namespace GitHub.Runner.Worker.Dap
@@ -30,10 +36,10 @@ namespace GitHub.Runner.Worker.Dap
     /// </summary>
     public sealed class DapDebugger : RunnerService, IDapDebugger
     {
-        private const int _defaultPort = 4711;
         private const int _defaultTimeoutMinutes = 15;
-        private const string _portEnvironmentVariable = "ACTIONS_RUNNER_DAP_PORT";
         private const string _timeoutEnvironmentVariable = "ACTIONS_RUNNER_DAP_CONNECTION_TIMEOUT";
+        private const int _defaultTunnelConnectTimeoutSeconds = 30;
+        private const string _tunnelConnectTimeoutSeconds = "ACTIONS_RUNNER_DAP_TUNNEL_CONNECT_TIMEOUT_SECONDS";
         private const string _contentLengthHeader = "Content-Length: ";
         private const int _maxMessageSize = 10 * 1024 * 1024; // 10 MB
         private const int _maxHeaderLineLength = 8192; // 8 KB
@@ -57,6 +63,22 @@ namespace GitHub.Runner.Worker.Dap
         private volatile DapSessionState _state = DapSessionState.NotStarted;
         private CancellationTokenRegistration? _cancellationRegistration;
         private bool _isFirstStep = true;
+        private bool _welcomeMessageSent;
+
+        // Dev Tunnel relay host for remote debugging
+        private TunnelRelayTunnelHost _tunnelRelayHost;
+        private IWebSocketDapBridge _webSocketBridge;
+
+        // Cancellation source for the connection loop, cancelled in StopAsync
+        // so AcceptTcpClientAsync unblocks cleanly without relying on listener disposal.
+        private CancellationTokenSource _loopCts;
+
+        // When true, skip tunnel relay startup (unit tests only)
+        internal bool SkipTunnelRelay { get; set; }
+
+        // When true, skip the public websocket bridge and expose the raw DAP
+        // listener directly on the configured tunnel port (unit tests only).
+        internal bool SkipWebSocketBridge { get; set; }
 
         // Synchronization for step execution
         private TaskCompletionSource<DapCommand> _commandTcs;
@@ -92,6 +114,7 @@ namespace GitHub.Runner.Worker.Dap
             _state == DapSessionState.Running;
 
         internal DapSessionState State => _state;
+        internal int InternalDapPort => (_listener?.LocalEndpoint as IPEndPoint)?.Port ?? 0;
 
         public override void Initialize(IHostContext hostContext)
         {
@@ -101,22 +124,48 @@ namespace GitHub.Runner.Worker.Dap
             Trace.Info("DapDebugger initialized");
         }
 
-        public Task StartAsync(IExecutionContext jobContext)
+        public async Task StartAsync(IExecutionContext jobContext)
         {
             ArgUtil.NotNull(jobContext, nameof(jobContext));
-            var port = ResolvePort();
+            var debuggerConfig = jobContext.Global.Debugger;
 
-            Trace.Info($"Starting DAP debugger on port {port}");
+            if (!debuggerConfig.HasValidTunnel)
+            {
+                throw new ArgumentException(
+                    "Debugger requires valid tunnel configuration (tunnelId, clusterId, hostToken, port).");
+            }
+
+            Trace.Info($"Starting DAP debugger on port {debuggerConfig.Tunnel.Port}");
 
             _jobContext = jobContext;
             _readyTcs = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
 
-            _listener = new TcpListener(IPAddress.Loopback, port);
+            var dapPort = SkipWebSocketBridge ? debuggerConfig.Tunnel.Port : 0;
+            _listener = new TcpListener(IPAddress.Loopback, dapPort);
             _listener.Start();
-            Trace.Info($"DAP debugger listening on {_listener.LocalEndpoint}");
+            if (SkipWebSocketBridge)
+            {
+                Trace.Info($"DAP debugger listening on {_listener.LocalEndpoint}");
+            }
+            else
+            {
+                Trace.Info($"Internal DAP debugger listening on {_listener.LocalEndpoint}");
+                _webSocketBridge = HostContext.CreateService<IWebSocketDapBridge>();
+                _webSocketBridge.Start(debuggerConfig.Tunnel.Port, InternalDapPort);
+            }
+
+            // Start Dev Tunnel relay so remote clients reach the local DAP port.
+            // The relay is torn down explicitly in StopAsync (after the DAP session
+            // is closed) so we do NOT pass the job cancellation token here — that
+            // would race with the DAP shutdown and drop the transport mid-protocol.
+            if (!SkipTunnelRelay)
+            {
+                await StartTunnelRelayAsync(debuggerConfig);
+            }
 
             _state = DapSessionState.WaitingForConnection;
-            _connectionLoopTask = ConnectionLoopAsync(jobContext.CancellationToken);
+            _loopCts = CancellationTokenSource.CreateLinkedTokenSource(jobContext.CancellationToken);
+            _connectionLoopTask = ConnectionLoopAsync(_loopCts.Token);
 
             _cancellationRegistration = jobContext.CancellationToken.Register(() =>
             {
@@ -125,8 +174,44 @@ namespace GitHub.Runner.Worker.Dap
                 _commandTcs?.TrySetResult(DapCommand.Disconnect);
             });
 
-            Trace.Info($"DAP debugger started on port {port}");
-            return Task.CompletedTask;
+            Trace.Info($"DAP debugger started on port {debuggerConfig.Tunnel.Port}");
+        }
+
+        private async Task StartTunnelRelayAsync(DebuggerConfig config)
+        {
+            Trace.Info($"Starting Dev Tunnel relay (tunnel={config.Tunnel.TunnelId}, cluster={config.Tunnel.ClusterId})");
+
+            var userAgents = HostContext.UserAgents.ToArray();
+            var httpHandler = HostContext.CreateHttpClientHandler();
+            httpHandler.AllowAutoRedirect = false;
+
+            var managementClient = new TunnelManagementClient(
+                userAgents,
+                () => Task.FromResult<AuthenticationHeaderValue>(new AuthenticationHeaderValue("tunnel", config.Tunnel.HostToken)),
+                tunnelServiceUri: null,
+                httpHandler);
+
+            var tunnel = new Tunnel
+            {
+                TunnelId = config.Tunnel.TunnelId,
+                ClusterId = config.Tunnel.ClusterId,
+                AccessTokens = new Dictionary<string, string>
+                {
+                    [TunnelAccessScopes.Host] = config.Tunnel.HostToken
+                },
+                Ports = new[]
+                {
+                    new TunnelPort { PortNumber = config.Tunnel.Port }
+                },
+            };
+
+            _tunnelRelayHost = new TunnelRelayTunnelHost(managementClient, HostContext.GetTrace("DevTunnelRelay").Source);
+            var tunnelConnectTimeoutSeconds = ResolveTunnelConnectTimeout();
+            using var connectCts = new CancellationTokenSource(TimeSpan.FromSeconds(tunnelConnectTimeoutSeconds));
+            Trace.Info($"Connecting to Dev Tunnel relay (timeout: {tunnelConnectTimeoutSeconds}s)");
+            await _tunnelRelayHost.ConnectAsync(tunnel, connectCts.Token);
+
+            Trace.Info("Dev Tunnel relay started");
         }
 
         public async Task WaitUntilReadyAsync()
@@ -159,6 +244,26 @@ namespace GitHub.Runner.Worker.Dap
         {
             if (_state != DapSessionState.NotStarted)
             {
+                // Pause so the user can inspect final job state before we tear down,
+                // but only if the user was stepping through (not if they hit continue).
+                if (IsActive && _pauseOnNextStep)
+                {
+                    try
+                    {
+                        if (_jobContext != null)
+                        {
+                            Trace.Info("Job completed — pausing for inspection");
+                            SendStoppedEvent("completed", "Job completed — inspect variables before the session ends.");
+
+                            await WaitForCommandAsync(_jobContext.CancellationToken);
+                        }
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Warning($"DAP job-completed pause error: {ex.Message}");
+                    }
+                }
+
                 try
                 {
                     OnJobCompleted();
@@ -168,8 +273,6 @@ namespace GitHub.Runner.Worker.Dap
                     Trace.Warning($"DAP OnJobCompleted error: {ex.Message}");
                 }
             }
-
-            await StopAsync();
         }
 
         public async Task StopAsync()
@@ -180,31 +283,74 @@ namespace GitHub.Runner.Worker.Dap
                 _cancellationRegistration = null;
             }
 
-            if (_state != DapSessionState.NotStarted)
+            try
             {
-                try
+                if (_listener != null || _tunnelRelayHost != null || _connectionLoopTask != null)
                 {
                     Trace.Info("Stopping DAP debugger");
-
-                    CleanupConnection();
-
-                    try { _listener?.Stop(); }
-                    catch { /* best effort */ }
-
-                    if (_connectionLoopTask != null)
-                    {
-                        try
-                        {
-                            await Task.WhenAny(_connectionLoopTask, Task.Delay(5000));
-                        }
-                        catch { /* best effort */ }
-                    }
                 }
-                catch (Exception ex)
+
+                // Tear down Dev Tunnel relay FIRST — it may hold connections to the
+                // local port and must be fully disposed before we release the listener,
+                // otherwise the next worker can't bind the same port.
+                if (_tunnelRelayHost != null)
                 {
-                    Trace.Error("Error stopping DAP debugger");
-                    Trace.Error(ex);
+                    Trace.Info("Stopping Dev Tunnel relay");
+                    var disposeTask = _tunnelRelayHost.DisposeAsync().AsTask();
+                    if (await Task.WhenAny(disposeTask, Task.Delay(10_000)) != disposeTask)
+                    {
+                        Trace.Warning("Dev Tunnel relay dispose timed out after 10s");
+                    }
+                    else
+                    {
+                        Trace.Info("Dev Tunnel relay stopped");
+                    }
+
+                    _tunnelRelayHost = null;
                 }
+
+                if (_webSocketBridge != null)
+                {
+                    Trace.Info("Stopping WebSocket DAP bridge");
+                    var shutdownTask = _webSocketBridge.ShutdownAsync();
+                    if (await Task.WhenAny(shutdownTask, Task.Delay(5_000)) != shutdownTask)
+                    {
+                        Trace.Warning("WebSocket DAP bridge shutdown timed out after 5s");
+                        _ = shutdownTask.ContinueWith(
+                            t => Trace.Error($"WebSocket DAP bridge shutdown faulted: {t.Exception?.GetBaseException().Message}"),
+                            TaskContinuationOptions.OnlyOnFaulted);
+                    }
+                    else
+                    {
+                        Trace.Info("WebSocket DAP bridge stopped");
+                    }
+
+                    _webSocketBridge = null;
+                }
+
+                CleanupConnection();
+
+                // Cancel the connection loop first so AcceptTcpClientAsync unblocks
+                // cleanly, then stop the listener once nothing is using it.
+                try { _loopCts?.Cancel(); }
+                catch { /* best effort */ }
+
+                try { _listener?.Stop(); }
+                catch { /* best effort */ }
+
+                if (_connectionLoopTask != null)
+                {
+                    try
+                    {
+                        await Task.WhenAny(_connectionLoopTask, Task.Delay(5000));
+                    }
+                    catch { /* best effort */ }
+                }
+            }
+            catch (Exception ex)
+            {
+                Trace.Error("Error stopping DAP debugger");
+                Trace.Error(ex);
             }
 
             lock (_stateLock)
@@ -221,6 +367,9 @@ namespace GitHub.Runner.Worker.Dap
             _stream = null;
             _readyTcs = null;
             _connectionLoopTask = null;
+            _loopCts?.Dispose();
+            _loopCts = null;
+            _webSocketBridge = null;
         }
 
         public async Task OnStepStartingAsync(IStep step)
@@ -342,6 +491,11 @@ namespace GitHub.Runner.Worker.Dap
                     });
                     Trace.Info("Sent initialized event");
                 }
+
+                if (request.Command == "configurationDone")
+                {
+                    SendWelcomeMessage();
+                }
             }
             catch (Exception ex)
             {
@@ -360,6 +514,7 @@ namespace GitHub.Runner.Worker.Dap
         internal void HandleClientConnected()
         {
             _isClientConnected = true;
+            _welcomeMessageSent = false;
             Trace.Info("Client connected to debug session");
 
             // If we're paused, re-send the stopped event so the new client
@@ -398,12 +553,7 @@ namespace GitHub.Runner.Worker.Dap
                 try
                 {
                     Trace.Info("Waiting for debug client connection...");
-                    _client = await _listener.AcceptTcpClientAsync();
-
-                    if (cancellationToken.IsCancellationRequested)
-                    {
-                        break;
-                    }
+                    _client = await _listener.AcceptTcpClientAsync(cancellationToken);
 
                     _stream = _client.GetStream();
                     var remoteEndPoint = _client.Client.RemoteEndPoint;
@@ -418,6 +568,10 @@ namespace GitHub.Runner.Worker.Dap
                     HandleClientDisconnected();
                     CleanupConnection();
                 }
+                catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+                {
+                    break;
+                }
                 catch (Exception ex)
                 {
                     CleanupConnection();
@@ -427,6 +581,13 @@ namespace GitHub.Runner.Worker.Dap
                         break;
                     }
 
+                    // If the listener has been stopped, don't retry.
+                    if (_listener == null || !_listener.Server.IsBound)
+                    {
+                        Trace.Info("Listener stopped, exiting connection loop");
+                        break;
+                    }
+
                     Trace.Error("Debugger connection error");
                     Trace.Error(ex);
 
@@ -664,6 +825,34 @@ namespace GitHub.Runner.Worker.Dap
             });
         }
 
+        internal void SendWelcomeMessage()
+        {
+            if (_welcomeMessageSent)
+            {
+                return;
+            }
+            _welcomeMessageSent = true;
+
+            var debuggerConfig = _jobContext?.Global?.Debugger;
+            if (debuggerConfig?.OverrideWelcomeMessage == true)
+            {
+                if (!string.IsNullOrEmpty(debuggerConfig.WelcomeMessage))
+                {
+                    SendOutput("console", debuggerConfig.WelcomeMessage);
+                    Trace.Info("Sent custom welcome message");
+                }
+                else
+                {
+                    Trace.Info("Welcome message suppressed by override");
+                }
+            }
+            else
+            {
+                SendOutput("console", DapReplParser.GetGeneralHelp());
+                Trace.Info("Sent default welcome message");
+            }
+        }
+
         internal async Task OnStepStartingAsync(IStep step, bool isFirstStep)
         {
             bool pauseOnNextStep;
@@ -706,6 +895,9 @@ namespace GitHub.Runner.Worker.Dap
             // Send stopped event to debugger (only if client is connected)
             SendStoppedEvent(reason, description);
 
+            // Emit a banner so the user knows where REPL commands will execute
+            SendExecutionContextBanner();
+
             // Wait for debugger command
             await WaitForCommandAsync(cancellationToken);
         }
@@ -1041,7 +1233,12 @@ namespace GitHub.Runner.Worker.Dap
 
                 case RunCommand run:
                     var context = GetExecutionContextForFrame(frameId);
-                    return await _replExecutor.ExecuteRunCommandAsync(run, context, cancellationToken);
+                    bool isActionStep;
+                    lock (_stateLock)
+                    {
+                        isActionStep = _currentStep is IActionRunner;
+                    }
+                    return await _replExecutor.ExecuteRunCommandAsync(run, context, isActionStep, cancellationToken);
 
                 default:
                     return new EvaluateResponseBody
@@ -1166,6 +1363,13 @@ namespace GitHub.Runner.Worker.Dap
                 _commandTcs = new TaskCompletionSource<DapCommand>(TaskCreationOptions.RunContinuationsAsynchronously);
             }
 
+            // If cancellation already fired before we created the new TCS,
+            // the registration callback targeted the old one. Unblock now.
+            if (cancellationToken.IsCancellationRequested)
+            {
+                _commandTcs.TrySetResult(DapCommand.Disconnect);
+            }
+
             Trace.Info("Waiting for debugger command...");
 
             var command = await _commandTcs.Task;
@@ -1246,6 +1450,40 @@ namespace GitHub.Runner.Worker.Dap
             });
         }
 
+        /// <summary>
+        /// Emits a console output banner telling the user whether REPL
+        /// commands will execute on the host or inside the job container.
+        /// </summary>
+        private void SendExecutionContextBanner()
+        {
+            if (!_isClientConnected)
+            {
+                return;
+            }
+
+            bool isActionStep = _currentStep is IActionRunner;
+            var container = _jobContext?.Global?.Container;
+
+            string target;
+            if (isActionStep && container != null &&
+                (!string.IsNullOrEmpty(container.ContainerId) ||
+                 FeatureManager.IsContainerHooksEnabled(_jobContext?.Global?.Variables)))
+            {
+                var image = container.ContainerImage ?? "container";
+                var shortId = !string.IsNullOrEmpty(container.ContainerId) && container.ContainerId.Length >= 12
+                    ? container.ContainerId.Substring(0, 12)
+                    : container.ContainerId ?? "";
+                var idSuffix = !string.IsNullOrEmpty(shortId) ? $" ({shortId})" : "";
+                target = $"job container: {image}{idSuffix}";
+            }
+            else
+            {
+                target = "runner host";
+            }
+
+            SendOutput("console", $"\nCommands will run on {target}\n");
+        }
+
         private string MaskUserVisibleText(string value)
         {
             if (string.IsNullOrEmpty(value))
@@ -1272,18 +1510,6 @@ namespace GitHub.Runner.Worker.Dap
             };
         }
 
-        internal int ResolvePort()
-        {
-            var portEnv = Environment.GetEnvironmentVariable(_portEnvironmentVariable);
-            if (!string.IsNullOrEmpty(portEnv) && int.TryParse(portEnv, out var customPort) && customPort > 1024 && customPort <= 65535)
-            {
-                Trace.Info($"Using custom DAP port {customPort} from {_portEnvironmentVariable}");
-                return customPort;
-            }
-
-            return _defaultPort;
-        }
-
         internal int ResolveTimeout()
         {
             var timeoutEnv = Environment.GetEnvironmentVariable(_timeoutEnvironmentVariable);
@@ -1295,5 +1521,17 @@ namespace GitHub.Runner.Worker.Dap
 
             return _defaultTimeoutMinutes;
         }
+
+        internal int ResolveTunnelConnectTimeout()
+        {
+            var raw = Environment.GetEnvironmentVariable(_tunnelConnectTimeoutSeconds);
+            if (!string.IsNullOrEmpty(raw) && int.TryParse(raw, out var customTimeout) && customTimeout > 0)
+            {
+                Trace.Info($"Using custom tunnel connect timeout {customTimeout}s from {_tunnelConnectTimeoutSeconds}");
+                return customTimeout;
+            }
+
+            return _defaultTunnelConnectTimeoutSeconds;
+        }
     }
 }

src/Runner.Worker/Dap/DapReplExecutor.cs

@@ -9,6 +9,7 @@ using GitHub.DistributedTask.Pipelines.ContextData;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Container;
 using GitHub.Runner.Worker.Handlers;
 
 namespace GitHub.Runner.Worker.Dap
@@ -43,6 +44,7 @@ namespace GitHub.Runner.Worker.Dap
         public async Task<EvaluateResponseBody> ExecuteRunCommandAsync(
             RunCommand command,
             IExecutionContext context,
+            bool isActionStep,
             CancellationToken cancellationToken)
         {
             if (context == null)
@@ -52,7 +54,7 @@ namespace GitHub.Runner.Worker.Dap
 
             try
             {
-                return await ExecuteScriptAsync(command, context, cancellationToken);
+                return await ExecuteScriptAsync(command, context, isActionStep, cancellationToken);
             }
             catch (Exception ex)
             {
@@ -65,9 +67,17 @@ namespace GitHub.Runner.Worker.Dap
         private async Task<EvaluateResponseBody> ExecuteScriptAsync(
             RunCommand command,
             IExecutionContext context,
+            bool isActionStep,
             CancellationToken cancellationToken)
         {
-            // 1. Resolve shell — same logic as ScriptHandler
+            // 1. Resolve step host — container or host, same as ActionRunner.
+            //    Only action steps (user-defined run:/uses:) execute inside the
+            //    container.  Infrastructure steps (Set up job, Initialize
+            //    containers, Complete job, etc.) always run on the host.
+            var stepHost = CreateStepHost(context, isActionStep);
+            var isContainerStepHost = stepHost is IContainerStepHost;
+
+            // 2. Resolve shell — same logic as ScriptHandler
             string shellCommand;
             string argFormat;
 
@@ -87,9 +97,9 @@ namespace GitHub.Runner.Worker.Dap
                 argFormat = ScriptHandlerHelpers.GetScriptArgumentsFormat(shellCommand);
             }
 
-            _trace.Info("Resolved REPL shell");
+            _trace.Info($"Resolved REPL shell (container={isContainerStepHost})");
 
-            // 2. Expand ${{ }} expressions in the script body, just like
+            // 3. Expand ${{ }} expressions in the script body, just like
             //    ActionRunner evaluates step inputs before ScriptHandler sees them
             var contents = ExpandExpressions(command.Script, context);
             contents = ScriptHandlerHelpers.FixUpScriptContents(shellCommand, contents);
@@ -111,25 +121,47 @@ namespace GitHub.Runner.Worker.Dap
 
             try
             {
-                // 3. Format arguments with script path
-                var resolvedPath = scriptFilePath.Replace("\"", "\\\"");
+                // 4. Resolve script path — translate for container if needed
+                var resolvedPath = stepHost.ResolvePathForStepHost(context, scriptFilePath).Replace("\"", "\\\"");
                 if (string.IsNullOrEmpty(argFormat) || !argFormat.Contains("{0}"))
                 {
                     return ErrorResult($"Invalid shell option '{shellCommand}'. Shell must be a valid built-in (bash, sh, cmd, powershell, pwsh) or a format string containing '{{0}}'");
                 }
                 var arguments = string.Format(argFormat, resolvedPath);
 
-                // 4. Resolve shell command path
+                // 5. Resolve shell command path — for containers, use the shell
+                //    name directly (it will be resolved inside the container);
+                //    for host execution, resolve the full path on the host.
                 string prependPath = string.Join(
                     Path.PathSeparator.ToString(),
                     Enumerable.Reverse(context.Global.PrependPath));
-                var commandPath = WhichUtil.Which(shellCommand, false, _trace, prependPath)
-                    ?? shellCommand;
+                var fileName = isContainerStepHost
+                    ? shellCommand
+                    : WhichUtil.Which(shellCommand, false, _trace, prependPath) ?? shellCommand;
 
-                // 5. Build environment — merge from execution context like a real step
+                // 6. Build environment — merge from execution context like a real step
                 var environment = BuildEnvironment(context, command.Env);
 
-                // 6. Resolve working directory
+                // 7. Handle PrependPath — mirrors Handler.AddPrependPathToEnvironment
+                if (context.Global.PrependPath.Count > 0)
+                {
+                    if (stepHost is IContainerStepHost containerHost)
+                    {
+                        containerHost.PrependPath = prependPath;
+                    }
+                    else
+                    {
+                        string taskEnvPATH;
+                        environment.TryGetValue(Constants.PathVariable, out taskEnvPATH);
+                        string originalPath = context.Global.Variables?.Get(Constants.PathVariable) ?? // Prefer a job variable.
+                            taskEnvPATH ?? // Then a task-environment variable.
+                            System.Environment.GetEnvironmentVariable(Constants.PathVariable) ?? // Then an environment variable.
+                            string.Empty;
+                        environment[Constants.PathVariable] = PathUtil.PrependPath(prependPath, originalPath);
+                    }
+                }
+
+                // 8. Resolve working directory — translate for container
                 var workingDirectory = command.WorkingDirectory;
                 if (string.IsNullOrEmpty(workingDirectory))
                 {
@@ -141,48 +173,60 @@ namespace GitHub.Runner.Worker.Dap
                         : null;
                     workingDirectory = workspace ?? _hostContext.GetDirectory(WellKnownDirectory.Work);
                 }
+                workingDirectory = stepHost.ResolvePathForStepHost(context, workingDirectory);
 
                 _trace.Info("Executing REPL command");
 
                 // Stream execution info to debugger
                 SendOutput("console", $"$ {shellCommand} {command.Script.Substring(0, Math.Min(command.Script.Length, 80))}{(command.Script.Length > 80 ? "..." : "")}\n");
 
-                // 7. Execute via IProcessInvoker (same as DefaultStepHost)
-                int exitCode;
-                using (var processInvoker = _hostContext.CreateService<IProcessInvoker>())
+                // NOTE: When container hooks are enabled, ContainerStepHost routes
+                // execution through IContainerHookManager which does not raise
+                // OutputDataReceived/ErrorDataReceived events. Output will not be
+                // streamed to the debug console in that mode.
+                if (isContainerStepHost && FeatureManager.IsContainerHooksEnabled(context.Global?.Variables))
                 {
-                    processInvoker.OutputDataReceived += (sender, args) =>
-                    {
-                        if (!string.IsNullOrEmpty(args.Data))
-                        {
-                            var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
-                            SendOutput("stdout", masked + "\n");
-                        }
-                    };
-
-                    processInvoker.ErrorDataReceived += (sender, args) =>
-                    {
-                        if (!string.IsNullOrEmpty(args.Data))
-                        {
-                            var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
-                            SendOutput("stderr", masked + "\n");
-                        }
-                    };
-
-                    exitCode = await processInvoker.ExecuteAsync(
-                        workingDirectory: workingDirectory,
-                        fileName: commandPath,
-                        arguments: arguments,
-                        environment: environment,
-                        requireExitCodeZero: false,
-                        outputEncoding: null,
-                        killProcessOnCancel: true,
-                        cancellationToken: cancellationToken);
+                    const string hookWarning = "Container hooks are enabled. REPL output will not be streamed to the debug console for this command.";
+                    _trace.Warning(hookWarning);
+                    SendOutput("stderr", hookWarning + "\n");
                 }
 
+                // 9. Execute via IStepHost — handles docker exec for containers,
+                //    direct process execution for host, and container hooks
+                stepHost.OutputDataReceived += (sender, args) =>
+                {
+                    if (!string.IsNullOrEmpty(args.Data))
+                    {
+                        var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
+                        SendOutput("stdout", masked + "\n");
+                    }
+                };
+
+                stepHost.ErrorDataReceived += (sender, args) =>
+                {
+                    if (!string.IsNullOrEmpty(args.Data))
+                    {
+                        var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
+                        SendOutput("stderr", masked + "\n");
+                    }
+                };
+
+                int exitCode = await stepHost.ExecuteAsync(
+                    context: context,
+                    workingDirectory: workingDirectory,
+                    fileName: fileName,
+                    arguments: arguments,
+                    environment: environment,
+                    requireExitCodeZero: false,
+                    outputEncoding: null,
+                    killProcessOnCancel: true,
+                    inheritConsoleHandler: false,
+                    standardInInput: null,
+                    cancellationToken: cancellationToken);
+
                 _trace.Info($"REPL command exited with code {exitCode}");
 
-                // 8. Return only the exit code summary (output was already streamed)
+                // 10. Return only the exit code summary (output was already streamed)
                 return new EvaluateResponseBody
                 {
                     Result = exitCode == 0 ? $"(exit code: {exitCode})" : $"Process completed with exit code {exitCode}.",
@@ -198,6 +242,43 @@ namespace GitHub.Runner.Worker.Dap
             }
         }
 
+        /// <summary>
+        /// Creates the appropriate <see cref="IStepHost"/> for the current
+        /// execution context, mirroring how <see cref="ActionRunner"/> decides
+        /// between host and container execution.
+        ///
+        /// Only action steps (user-defined run:/uses: steps) run inside the
+        /// job container.  Infrastructure steps like "Set up job", "Initialize
+        /// containers", "Stop containers", and "Complete job" always execute
+        /// on the host regardless of whether a container is configured.
+        /// </summary>
+        internal IStepHost CreateStepHost(IExecutionContext context, bool isActionStep)
+        {
+            if (!isActionStep)
+            {
+                _trace.Info("Creating DefaultStepHost for REPL execution (infrastructure step)");
+                return _hostContext.CreateService<IDefaultStepHost>();
+            }
+
+            var container = context?.Global?.Container;
+            if (container != null)
+            {
+                // Container hooks don't always set ContainerId, but the container
+                // step host handles that internally
+                var hooksEnabled = FeatureManager.IsContainerHooksEnabled(context.Global?.Variables);
+                if (hooksEnabled || !string.IsNullOrEmpty(container.ContainerId))
+                {
+                    _trace.Info("Creating ContainerStepHost for REPL execution");
+                    var containerStepHost = _hostContext.CreateService<IContainerStepHost>();
+                    containerStepHost.Container = container;
+                    return containerStepHost;
+                }
+            }
+
+            _trace.Info("Creating DefaultStepHost for REPL execution");
+            return _hostContext.CreateService<IDefaultStepHost>();
+        }
+
         /// <summary>
         /// Expands <c>${{ }}</c> expressions in the input string using the
         /// runner's template evaluator — the same evaluation path that processes

src/Runner.Worker/Dap/DebuggerConfig.cs

@@ -0,0 +1,48 @@
+using GitHub.DistributedTask.Pipelines;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Consolidated runtime configuration for the job debugger.
+    /// Populated once from the acquire response and owned by <see cref="GlobalContext"/>.
+    /// </summary>
+    public sealed class DebuggerConfig
+    {
+        public DebuggerConfig(bool enabled, DebuggerTunnelInfo tunnel, bool overrideWelcomeMessage = false, string welcomeMessage = null)
+        {
+            Enabled = enabled;
+            Tunnel = tunnel;
+            OverrideWelcomeMessage = overrideWelcomeMessage;
+            WelcomeMessage = welcomeMessage;
+        }
+
+        /// <summary>Whether the debugger is enabled for this job.</summary>
+        public bool Enabled { get; }
+
+        /// <summary>
+        /// Dev Tunnel details for remote debugging.
+        /// Required when <see cref="Enabled"/> is true.
+        /// </summary>
+        public DebuggerTunnelInfo Tunnel { get; }
+
+        /// <summary>
+        /// When true, the runner overrides the default welcome message with
+        /// <see cref="WelcomeMessage"/>. A null or empty <see cref="WelcomeMessage"/>
+        /// suppresses the message entirely. When false, the default help text is shown.
+        /// </summary>
+        public bool OverrideWelcomeMessage { get; }
+
+        /// <summary>
+        /// Optional welcome message content for the debugger console. Only used when
+        /// <see cref="OverrideWelcomeMessage"/> is true.
+        /// </summary>
+        public string WelcomeMessage { get; }
+
+        /// <summary>Whether the tunnel configuration is complete and valid.</summary>
+        public bool HasValidTunnel => Tunnel != null
+            && !string.IsNullOrEmpty(Tunnel.TunnelId)
+            && !string.IsNullOrEmpty(Tunnel.ClusterId)
+            && !string.IsNullOrEmpty(Tunnel.HostToken)
+            && Tunnel.Port >= 1024 && Tunnel.Port <= 65535;
+    }
+}

src/Runner.Worker/Dap/IDapDebugger.cs

@@ -22,5 +22,6 @@ namespace GitHub.Runner.Worker.Dap
         Task OnStepStartingAsync(IStep step);
         void OnStepCompleted(IStep step);
         Task OnJobCompletedAsync();
+        Task StopAsync();
     }
 }

src/Runner.Worker/Dap/IWebSocketDapBridge.cs

@@ -0,0 +1,12 @@
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    [ServiceLocator(Default = typeof(WebSocketDapBridge))]
+    public interface IWebSocketDapBridge : IRunnerService
+    {
+        void Start(int listenPort, int targetPort);
+        Task ShutdownAsync();
+    }
+}

src/Runner.Worker/Dap/JobExecutionViewRenderer.cs

@@ -0,0 +1,336 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Text;
+using GitHub.Runner.Sdk;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Phase a step occupies in the runner's flat execution sequence.
+    /// Setup and Cleanup are NOT modeled here — they are synthetic
+    /// boundaries hard-coded by <see cref="JobExecutionViewRenderer"/>
+    /// and cannot be constructed by callers.
+    /// </summary>
+    internal enum JobExecutionPhase
+    {
+        Pre,
+        Main,
+        Post,
+    }
+
+    /// <summary>
+    /// One step in the rendered execution view. Pure data; no link to
+    /// any worker type. Phase 2 will translate runner step objects
+    /// into instances of this record.
+    /// </summary>
+    internal sealed class JobExecutionViewEntry
+    {
+        public JobExecutionViewEntry(
+            JobExecutionPhase phase,
+            string displayName,
+            string uses = null,
+            string run = null,
+            string sourcePath = null,
+            int sourceLine = 0,
+            string id = null,
+            string @if = null,
+            string continueOnError = null,
+            string timeoutMinutes = null,
+            string envYaml = null,
+            string withYaml = null,
+            string shell = null,
+            string workingDirectory = null)
+        {
+            if (string.IsNullOrWhiteSpace(displayName))
+            {
+                throw new ArgumentException("displayName must not be null or whitespace.", nameof(displayName));
+            }
+            if (sourcePath != null && sourceLine < 1)
+            {
+                throw new ArgumentException(
+                    "sourceLine must be >= 1 when sourcePath is provided.",
+                    nameof(sourceLine));
+            }
+
+            Phase = phase;
+            DisplayName = displayName;
+            Uses = uses;
+            Run = run;
+            SourcePath = sourcePath;
+            SourceLine = sourceLine;
+            Id = id;
+            If = @if;
+            ContinueOnError = continueOnError;
+            TimeoutMinutes = timeoutMinutes;
+            EnvYaml = envYaml;
+            WithYaml = withYaml;
+            Shell = shell;
+            WorkingDirectory = workingDirectory;
+        }
+
+        public JobExecutionPhase Phase { get; }
+        public string DisplayName { get; }
+        public string Uses { get; }
+        public string Run { get; }
+        public string SourcePath { get; }
+        public int SourceLine { get; }
+        public string Id { get; }
+        public string If { get; }
+        public string ContinueOnError { get; }
+        public string TimeoutMinutes { get; }
+        // Pre-serialized YAML fragment, already indented for embedding
+        // under the entry's `env:` key (6-space child indent).
+        public string EnvYaml { get; }
+        public string WithYaml { get; }
+        public string Shell { get; }
+        public string WorkingDirectory { get; }
+    }
+
+    /// <summary>
+    /// Output of <see cref="JobExecutionViewRenderer.Render"/>: the YAML
+    /// document plus a parallel array of 1-based line numbers, one per
+    /// input entry, where each entry's <c>- step:</c> key appears.
+    /// Synthetic Setup/Cleanup boundaries are not tracked here.
+    /// </summary>
+    internal readonly struct RenderResult
+    {
+        public RenderResult(string yaml, IReadOnlyList<int> entryStartLines)
+        {
+            Yaml = yaml;
+            EntryStartLines = entryStartLines;
+        }
+
+        public string Yaml { get; }
+        public IReadOnlyList<int> EntryStartLines { get; }
+    }
+
+    /// <summary>
+    /// Renders a job's execution-view YAML. Pure function; no I/O,
+    /// no logging, no static state. Output format and Setup/Cleanup
+    /// boundaries are fixed; callers cannot influence them.
+    ///
+    /// Output is structured as phase-keyed top-level sections:
+    /// <c>setup:</c>, <c>pre:</c>, <c>main:</c>, <c>post:</c>, <c>cleanup:</c>.
+    /// <c>setup:</c> and <c>cleanup:</c> always render; <c>pre:</c>,
+    /// <c>main:</c>, <c>post:</c> only render when they contain at least
+    /// one entry.
+    /// </summary>
+    internal static class JobExecutionViewRenderer
+    {
+        public static RenderResult Render(string jobId, IReadOnlyList<JobExecutionViewEntry> entries)
+        {
+            if (string.IsNullOrWhiteSpace(jobId))
+            {
+                throw new ArgumentException("jobId must not be null or whitespace.", nameof(jobId));
+            }
+            ArgUtil.NotNull(entries, nameof(entries));
+
+            // Pre-validate non-null entries before any output, so partial
+            // state is never observed by callers.
+            for (int i = 0; i < entries.Count; i++)
+            {
+                if (entries[i] == null)
+                {
+                    throw new ArgumentException($"entries[{i}] is null.", nameof(entries));
+                }
+            }
+
+            var sb = new StringBuilder();
+            var startLines = new int[entries.Count];
+            int newlinesEmitted = 0;
+
+            // Header (3 lines).
+            sb.Append("# Job: ").Append(YamlScalarFormatter.Format(jobId)).Append('\n');
+            sb.Append("# Runner execution plan — read-only.\n");
+            sb.Append('\n');
+            newlinesEmitted += 3;
+
+            // setup: section — always present.
+            sb.Append("setup:\n");
+            sb.Append("  - step: Setup job\n");
+            newlinesEmitted += 2;
+
+            // Render phase sections in fixed order. Each emits a leading
+            // blank line separator before its header.
+            EmitPhaseSection(sb, "pre", JobExecutionPhase.Pre, entries, startLines, ref newlinesEmitted);
+            EmitPhaseSection(sb, "main", JobExecutionPhase.Main, entries, startLines, ref newlinesEmitted);
+            EmitPhaseSection(sb, "post", JobExecutionPhase.Post, entries, startLines, ref newlinesEmitted);
+
+            // cleanup: section — always present, preceded by a blank line.
+            sb.Append('\n');
+            sb.Append("cleanup:\n");
+            sb.Append("  - step: Complete job\n");
+
+            return new RenderResult(sb.ToString(), Array.AsReadOnly(startLines));
+        }
+
+        private static void EmitPhaseSection(
+            StringBuilder sb,
+            string sectionName,
+            JobExecutionPhase phase,
+            IReadOnlyList<JobExecutionViewEntry> entries,
+            int[] startLines,
+            ref int newlinesEmitted)
+        {
+            // Skip the section entirely if no entries belong to this phase.
+            bool any = false;
+            for (int i = 0; i < entries.Count; i++)
+            {
+                if (entries[i].Phase == phase) { any = true; break; }
+            }
+            if (!any)
+            {
+                return;
+            }
+
+            // Blank line separator + section header.
+            sb.Append('\n');
+            sb.Append(sectionName).Append(":\n");
+            newlinesEmitted += 2;
+
+            for (int i = 0; i < entries.Count; i++)
+            {
+                var entry = entries[i];
+                if (entry.Phase != phase)
+                {
+                    continue;
+                }
+
+                // 1-based line of the `- step:` key for this entry.
+                startLines[i] = newlinesEmitted + 1;
+
+                sb.Append("  - step: ").Append(YamlScalarFormatter.Format(entry.DisplayName));
+                sb.Append('\n');
+                newlinesEmitted++;
+
+                switch (phase)
+                {
+                    case JobExecutionPhase.Pre:
+                    case JobExecutionPhase.Post:
+                        if (!string.IsNullOrEmpty(entry.Uses))
+                        {
+                            sb.Append("    action: ").Append(YamlScalarFormatter.Format(entry.Uses)).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        // No source: annotation for pre/post.
+                        break;
+
+                    case JobExecutionPhase.Main:
+                        if (!string.IsNullOrEmpty(entry.Id))
+                        {
+                            sb.Append("    id: ").Append(YamlScalarFormatter.Format(entry.Id)).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (!string.IsNullOrEmpty(entry.Uses))
+                        {
+                            sb.Append("    uses: ").Append(YamlScalarFormatter.Format(entry.Uses)).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (!string.IsNullOrEmpty(entry.Run))
+                        {
+                            if (entry.Run.IndexOf('\n') < 0)
+                            {
+                                sb.Append("    run: ").Append(YamlScalarFormatter.Format(entry.Run)).Append('\n');
+                                newlinesEmitted++;
+                            }
+                            else
+                            {
+                                sb.Append("    run: |\n");
+                                newlinesEmitted++;
+                                newlinesEmitted += AppendIndentedBlock(sb, entry.Run, "      ");
+                            }
+                        }
+                        if (!string.IsNullOrEmpty(entry.If))
+                        {
+                            sb.Append("    if: ").Append(YamlScalarFormatter.Format(entry.If)).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (!string.IsNullOrEmpty(entry.ContinueOnError))
+                        {
+                            sb.Append("    continue-on-error: ").Append(entry.ContinueOnError).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (!string.IsNullOrEmpty(entry.TimeoutMinutes))
+                        {
+                            sb.Append("    timeout-minutes: ").Append(entry.TimeoutMinutes).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (!string.IsNullOrEmpty(entry.EnvYaml))
+                        {
+                            sb.Append("    env:\n");
+                            newlinesEmitted++;
+                            sb.Append(entry.EnvYaml).Append('\n');
+                            newlinesEmitted += CountChar(entry.EnvYaml, '\n') + 1;
+                        }
+                        if (!string.IsNullOrEmpty(entry.WithYaml))
+                        {
+                            sb.Append("    with:\n");
+                            newlinesEmitted++;
+                            sb.Append(entry.WithYaml).Append('\n');
+                            newlinesEmitted += CountChar(entry.WithYaml, '\n') + 1;
+                        }
+                        if (!string.IsNullOrEmpty(entry.Shell))
+                        {
+                            sb.Append("    shell: ").Append(YamlScalarFormatter.Format(entry.Shell)).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (!string.IsNullOrEmpty(entry.WorkingDirectory))
+                        {
+                            sb.Append("    working-directory: ").Append(YamlScalarFormatter.Format(entry.WorkingDirectory)).Append('\n');
+                            newlinesEmitted++;
+                        }
+                        if (entry.SourcePath != null)
+                        {
+                            sb.Append("    source: ")
+                              .Append(entry.SourcePath)
+                              .Append(':')
+                              .Append(entry.SourceLine.ToString(CultureInfo.InvariantCulture))
+                              .Append('\n');
+                            newlinesEmitted++;
+                        }
+                        break;
+                }
+            }
+        }
+
+        private static int AppendIndentedBlock(StringBuilder sb, string text, string indent)
+        {
+            int newlines = 0;
+            int i = 0;
+            while (i < text.Length)
+            {
+                int end = text.IndexOf('\n', i);
+                int lineEnd = end < 0 ? text.Length : end;
+                int trimEnd = lineEnd;
+                if (trimEnd > i && text[trimEnd - 1] == '\r')
+                {
+                    trimEnd--;
+                }
+                if (trimEnd > i)
+                {
+                    sb.Append(indent);
+                    sb.Append(text, i, trimEnd - i);
+                }
+                sb.Append('\n');
+                newlines++;
+                if (end < 0)
+                {
+                    break;
+                }
+                i = end + 1;
+            }
+            return newlines;
+        }
+
+        private static int CountChar(string s, char c)
+        {
+            int n = 0;
+            for (int i = 0; i < s.Length; i++)
+            {
+                if (s[i] == c) n++;
+            }
+            return n;
+        }
+    }
+}

src/Runner.Worker/Dap/WebSocketDapBridge.cs

@@ -0,0 +1,839 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Net.Sockets;
+using System.Net.WebSockets;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    internal sealed class WebSocketDapBridge : RunnerService, IWebSocketDapBridge
+    {
+        internal enum IncomingStreamPrefixKind
+        {
+            Unknown,
+            HttpWebSocketUpgrade,
+            PreUpgradedWebSocket,
+            WebSocketReservedBits,
+            Http2Preface,
+            TlsClientHello,
+        }
+
+        private const int _bufferSize = 32 * 1024;
+        private const int _maxHeaderLineLength = 8 * 1024;
+        private const int _defaultMaxInboundMessageSize = 10 * 1024 * 1024; // 10 MB
+        private static readonly TimeSpan _keepAliveInterval = TimeSpan.FromSeconds(30);
+        private static readonly TimeSpan _closeTimeout = TimeSpan.FromSeconds(5);
+        private static readonly TimeSpan _handshakeTimeout = TimeSpan.FromSeconds(10);
+        private const string _webSocketAcceptMagic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
+        private const int _maxHeaderCount = 64;
+        private static readonly byte[] _headerEndMarker = new byte[] { (byte)'\r', (byte)'\n', (byte)'\r', (byte)'\n' };
+
+        private int _listenPort;
+        private int _targetPort;
+
+        private TcpListener _listener;
+        private CancellationTokenSource _loopCts;
+        private Task _acceptLoopTask;
+
+        public int MaxInboundMessageSize { get; set; } = _defaultMaxInboundMessageSize;
+
+        internal int ListenPort => (_listener?.LocalEndpoint as IPEndPoint)?.Port ?? 0;
+
+        public void Start(int listenPort, int targetPort)
+        {
+            if (_listener != null)
+            {
+                throw new InvalidOperationException("WebSocket DAP bridge already started.");
+            }
+
+            _listenPort = listenPort;
+            _targetPort = targetPort;
+
+            _listener = new TcpListener(IPAddress.Loopback, _listenPort);
+            _listener.Start();
+            _loopCts = new CancellationTokenSource();
+            _acceptLoopTask = AcceptLoopAsync(_loopCts.Token);
+
+            Trace.Info($"WebSocket DAP bridge listening on {_listener.LocalEndpoint} -> 127.0.0.1:{_targetPort}");
+        }
+
+        public async Task ShutdownAsync()
+        {
+            _loopCts?.Cancel();
+
+            try
+            {
+                _listener?.Stop();
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning($"Error stopping listener during shutdown ({ex.GetType().Name})");
+            }
+
+            if (_acceptLoopTask != null)
+            {
+                try
+                {
+                    await _acceptLoopTask;
+                }
+                catch (OperationCanceledException)
+                {
+                    // expected on shutdown
+                }
+            }
+
+            _loopCts?.Dispose();
+            _loopCts = null;
+            _listener = null;
+            _acceptLoopTask = null;
+        }
+
+        private async Task AcceptLoopAsync(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                TcpClient client = null;
+                try
+                {
+                    client = await _listener.AcceptTcpClientAsync(cancellationToken);
+                    client.NoDelay = true;
+                    await HandleClientAsync(client, cancellationToken);
+                }
+                catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+                {
+                    break;
+                }
+                catch (Exception ex)
+                {
+                    client?.Dispose();
+                    Trace.Error($"WebSocket DAP bridge connection error");
+                    Trace.Error(ex);
+                }
+                finally
+                {
+                    client?.Dispose();
+                }
+            }
+
+            Trace.Info("WebSocket DAP bridge accept loop ended");
+        }
+
+        private async Task HandleClientAsync(TcpClient incomingClient, CancellationToken cancellationToken)
+        {
+            using (var incomingStream = incomingClient.GetStream())
+            {
+                Trace.Info($"WebSocket DAP bridge accepted client {incomingClient.Client.RemoteEndPoint}");
+
+                WebSocket webSocket;
+                using (var handshakeCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
+                {
+                    handshakeCts.CancelAfter(_handshakeTimeout);
+                    try
+                    {
+                        webSocket = await AcceptWebSocketAsync(incomingStream, handshakeCts.Token);
+                    }
+                    catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
+                    {
+                        Trace.Warning("WebSocket handshake timed out");
+                        return;
+                    }
+                }
+                if (webSocket == null)
+                {
+                    return;
+                }
+
+                using (webSocket)
+                using (var dapClient = new TcpClient())
+                {
+                    dapClient.NoDelay = true;
+                    await dapClient.ConnectAsync(IPAddress.Loopback, _targetPort, cancellationToken);
+
+                    using (var dapStream = dapClient.GetStream())
+                    using (var sessionCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
+                    {
+                        var proxyToken = sessionCts.Token;
+                        var wsToTcpTask = PumpWebSocketToTcpAsync(webSocket, dapStream, proxyToken);
+                        var tcpToWsTask = PumpTcpToWebSocketAsync(dapStream, webSocket, proxyToken);
+
+                        await Task.WhenAny(wsToTcpTask, tcpToWsTask);
+                        sessionCts.Cancel();
+
+                        await CloseWebSocketAsync(webSocket);
+
+                        try
+                        {
+                            await Task.WhenAll(wsToTcpTask, tcpToWsTask);
+                        }
+                        catch (OperationCanceledException) when (proxyToken.IsCancellationRequested)
+                        {
+                            // expected during shutdown
+                        }
+                        catch (Exception ex)
+                        {
+                            Trace.Warning($"DAP protocol error: {ex}");
+                        }
+                    }
+                }
+            }
+        }
+
+        private async Task<WebSocket> AcceptWebSocketAsync(NetworkStream stream, CancellationToken cancellationToken)
+        {
+            var initialBytes = await ReadInitialBytesAsync(stream, cancellationToken);
+            if (initialBytes == null || initialBytes.Length == 0)
+            {
+                return null;
+            }
+
+            var prefixKind = ClassifyIncomingStreamPrefix(initialBytes);
+            if (prefixKind == IncomingStreamPrefixKind.PreUpgradedWebSocket)
+            {
+                Trace.Info($"Treating incoming tunnel stream as an already-upgraded websocket connection ({DescribeInitialBytes(initialBytes)})");
+                return WebSocket.CreateFromStream(
+                    new ReplayableStream(stream, initialBytes),
+                    isServer: true,
+                    subProtocol: null,
+                    keepAliveInterval: _keepAliveInterval);
+            }
+
+            if (prefixKind != IncomingStreamPrefixKind.HttpWebSocketUpgrade)
+            {
+                Trace.Warning($"Unsupported debugger tunnel stream prefix ({prefixKind}): {DescribeInitialBytes(initialBytes)}");
+                return null;
+            }
+
+            var handshakeStream = new ReplayableStream(stream, initialBytes);
+            var requestLine = await ReadLineAsync(handshakeStream, cancellationToken);
+            if (string.IsNullOrEmpty(requestLine))
+            {
+                return null;
+            }
+
+            var headers = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                if (headers.Count >= _maxHeaderCount)
+                {
+                    Trace.Warning($"Rejected WebSocket request with too many headers (>{_maxHeaderCount})");
+                    await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Too many headers.", cancellationToken);
+                    return null;
+                }
+
+                var line = await ReadLineAsync(handshakeStream, cancellationToken);
+                if (line == null)
+                {
+                    return null;
+                }
+
+                if (line.Length == 0)
+                {
+                    break;
+                }
+
+                var separatorIndex = line.IndexOf(':');
+                if (separatorIndex <= 0)
+                {
+                    await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Invalid HTTP header.", cancellationToken);
+                    return null;
+                }
+
+                var headerName = line.Substring(0, separatorIndex).Trim();
+                var headerValue = line.Substring(separatorIndex + 1).Trim();
+
+                if (headers.TryGetValue(headerName, out var existingValue))
+                {
+                    headers[headerName] = $"{existingValue}, {headerValue}";
+                }
+                else
+                {
+                    headers[headerName] = headerValue;
+                }
+            }
+
+            if (!IsValidWebSocketRequest(requestLine, headers))
+            {
+                var method = requestLine.Split(' ')[0];
+                Trace.Info($"Rejected non-websocket request (method={method})");
+                await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Expected a websocket upgrade request.", cancellationToken);
+                return null;
+            }
+
+            if (!headers.TryGetValue("Sec-WebSocket-Version", out var webSocketVersion) ||
+                !string.Equals(webSocketVersion.Trim(), "13", StringComparison.Ordinal))
+            {
+                Trace.Warning("Rejected WebSocket request with unsupported version");
+                await WriteHttpErrorAsync(stream, (HttpStatusCode)426, "Unsupported WebSocket version. Expected: 13.", cancellationToken);
+                return null;
+            }
+
+            var webSocketKey = headers["Sec-WebSocket-Key"];
+            if (!IsValidWebSocketKey(webSocketKey))
+            {
+                Trace.Warning("Rejected WebSocket request with invalid Sec-WebSocket-Key");
+                await WriteHttpErrorAsync(stream, HttpStatusCode.BadRequest, "Invalid Sec-WebSocket-Key.", cancellationToken);
+                return null;
+            }
+
+            var acceptValue = ComputeAcceptValue(webSocketKey);
+            var responseBytes = Encoding.ASCII.GetBytes(
+                "HTTP/1.1 101 Switching Protocols\r\n" +
+                "Connection: Upgrade\r\n" +
+                "Upgrade: websocket\r\n" +
+                $"Sec-WebSocket-Accept: {acceptValue}\r\n" +
+                "\r\n");
+
+            await handshakeStream.WriteAsync(responseBytes, 0, responseBytes.Length, cancellationToken);
+            await handshakeStream.FlushAsync(cancellationToken);
+
+            Trace.Info("WebSocket DAP bridge completed websocket handshake");
+            return WebSocket.CreateFromStream(handshakeStream, isServer: true, subProtocol: null, keepAliveInterval: _keepAliveInterval);
+        }
+
+        private async Task PumpWebSocketToTcpAsync(WebSocket source, NetworkStream destination, CancellationToken cancellationToken)
+        {
+            var buffer = new byte[_bufferSize];
+
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                using (var messageStream = new MemoryStream())
+                {
+                    WebSocketReceiveResult result;
+                    do
+                    {
+                        result = await source.ReceiveAsync(new ArraySegment<byte>(buffer), cancellationToken);
+                        if (result.MessageType == WebSocketMessageType.Close)
+                        {
+                            return;
+                        }
+
+                        if (result.MessageType != WebSocketMessageType.Binary &&
+                            result.MessageType != WebSocketMessageType.Text)
+                        {
+                            break;
+                        }
+
+                        if (result.Count > 0)
+                        {
+                            if (messageStream.Length + result.Count > MaxInboundMessageSize)
+                            {
+                                Trace.Warning($"WebSocket message exceeds maximum allowed size of {MaxInboundMessageSize} bytes, closing connection");
+                                await source.CloseAsync(
+                                    WebSocketCloseStatus.MessageTooBig,
+                                    $"Message exceeds {MaxInboundMessageSize} byte limit",
+                                    CancellationToken.None);
+                                return;
+                            }
+
+                            messageStream.Write(buffer, 0, result.Count);
+                        }
+                    }
+                    while (!result.EndOfMessage && !cancellationToken.IsCancellationRequested);
+
+                    if (result.MessageType != WebSocketMessageType.Binary &&
+                        result.MessageType != WebSocketMessageType.Text)
+                    {
+                        continue;
+                    }
+
+                    var messageBytes = messageStream.ToArray();
+                    if (messageBytes.Length == 0)
+                    {
+                        continue;
+                    }
+
+                    var contentLengthHeader = Encoding.ASCII.GetBytes($"Content-Length: {messageBytes.Length}\r\n\r\n");
+                    await destination.WriteAsync(contentLengthHeader, 0, contentLengthHeader.Length, cancellationToken);
+                    await destination.WriteAsync(messageBytes, 0, messageBytes.Length, cancellationToken);
+                    await destination.FlushAsync(cancellationToken);
+                }
+            }
+        }
+
+        private static async Task PumpTcpToWebSocketAsync(NetworkStream source, WebSocket destination, CancellationToken cancellationToken)
+        {
+            var readBuffer = new byte[_bufferSize];
+            var dapBuffer = new List<byte>();
+
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                var bytesRead = await source.ReadAsync(readBuffer, 0, readBuffer.Length, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    break;
+                }
+
+                dapBuffer.AddRange(new ArraySegment<byte>(readBuffer, 0, bytesRead));
+
+                while (TryParseDapMessage(dapBuffer, out var messageBody))
+                {
+                    await destination.SendAsync(
+                        new ArraySegment<byte>(messageBody),
+                        WebSocketMessageType.Text,
+                        endOfMessage: true,
+                        cancellationToken);
+                }
+            }
+        }
+
+        private static bool TryParseDapMessage(List<byte> buffer, out byte[] messageBody)
+        {
+            messageBody = null;
+
+            var headerEndIndex = FindSequence(buffer, _headerEndMarker);
+            if (headerEndIndex == -1)
+            {
+                return false;
+            }
+
+            var headerBytes = buffer.GetRange(0, headerEndIndex).ToArray();
+            var headerText = Encoding.ASCII.GetString(headerBytes);
+
+            var contentLength = -1;
+            foreach (var line in headerText.Split(new[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries))
+            {
+                if (line.StartsWith("Content-Length:", StringComparison.OrdinalIgnoreCase))
+                {
+                    var valueStart = line.IndexOf(':') + 1;
+                    if (int.TryParse(line.Substring(valueStart).Trim(), out var parsedLength))
+                    {
+                        contentLength = parsedLength;
+                        break;
+                    }
+                }
+            }
+
+            if (contentLength < 0)
+            {
+                throw new InvalidOperationException("DAP message missing or unparseable Content-Length header; tearing down session.");
+            }
+
+            var messageStart = headerEndIndex + 4;
+            var messageEnd = messageStart + contentLength;
+
+            if (buffer.Count < messageEnd)
+            {
+                return false;
+            }
+
+            messageBody = buffer.GetRange(messageStart, contentLength).ToArray();
+            buffer.RemoveRange(0, messageEnd);
+            return true;
+        }
+
+        private static int FindSequence(List<byte> buffer, byte[] sequence)
+        {
+            if (buffer.Count < sequence.Length)
+            {
+                return -1;
+            }
+
+            for (int i = 0; i <= buffer.Count - sequence.Length; i++)
+            {
+                var match = true;
+                for (int j = 0; j < sequence.Length; j++)
+                {
+                    if (buffer[i + j] != sequence[j])
+                    {
+                        match = false;
+                        break;
+                    }
+                }
+
+                if (match)
+                {
+                    return i;
+                }
+            }
+
+            return -1;
+        }
+
+        private static bool IsValidWebSocketRequest(string requestLine, IDictionary<string, string> headers)
+        {
+            if (string.IsNullOrWhiteSpace(requestLine))
+            {
+                return false;
+            }
+
+            var requestLineParts = requestLine.Split(' ');
+            if (requestLineParts.Length < 3 || !string.Equals(requestLineParts[0], "GET", StringComparison.OrdinalIgnoreCase))
+            {
+                return false;
+            }
+
+            return HeaderContainsToken(headers, "Connection", "Upgrade") &&
+                HeaderContainsToken(headers, "Upgrade", "websocket") &&
+                headers.ContainsKey("Sec-WebSocket-Key");
+        }
+
+        private static bool HeaderContainsToken(IDictionary<string, string> headers, string headerName, string expectedToken)
+        {
+            if (!headers.TryGetValue(headerName, out var headerValue) || string.IsNullOrWhiteSpace(headerValue))
+            {
+                return false;
+            }
+
+            return headerValue
+                .Split(',')
+                .Select(token => token.Trim())
+                .Any(token => string.Equals(token, expectedToken, StringComparison.OrdinalIgnoreCase));
+        }
+
+        private static string ComputeAcceptValue(string webSocketKey)
+        {
+            using (var sha1 = SHA1.Create())
+            {
+                var inputBytes = Encoding.ASCII.GetBytes($"{webSocketKey}{_webSocketAcceptMagic}");
+                var hashBytes = sha1.ComputeHash(inputBytes);
+                return Convert.ToBase64String(hashBytes);
+            }
+        }
+
+        private static bool IsValidWebSocketKey(string key)
+        {
+            if (string.IsNullOrEmpty(key) || key.IndexOfAny(new[] { '\r', '\n' }) >= 0)
+            {
+                return false;
+            }
+
+            try
+            {
+                var decoded = Convert.FromBase64String(key);
+                return decoded.Length == 16;
+            }
+            catch (FormatException)
+            {
+                return false;
+            }
+        }
+
+        private static async Task<string> ReadLineAsync(Stream stream, CancellationToken cancellationToken)
+        {
+            var lineBuilder = new StringBuilder();
+            var buffer = new byte[1];
+            var previousWasCarriageReturn = false;
+
+            while (true)
+            {
+                var bytesRead = await stream.ReadAsync(buffer, 0, 1, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    return lineBuilder.Length > 0 ? lineBuilder.ToString() : null;
+                }
+
+                var currentChar = (char)buffer[0];
+                if (currentChar == '\n' && previousWasCarriageReturn)
+                {
+                    if (lineBuilder.Length > 0 && lineBuilder[lineBuilder.Length - 1] == '\r')
+                    {
+                        lineBuilder.Length--;
+                    }
+
+                    return lineBuilder.ToString();
+                }
+
+                previousWasCarriageReturn = currentChar == '\r';
+                lineBuilder.Append(currentChar);
+
+                if (lineBuilder.Length > _maxHeaderLineLength)
+                {
+                    throw new InvalidDataException($"HTTP header line exceeds maximum length of {_maxHeaderLineLength}");
+                }
+            }
+        }
+
+        private static async Task<byte[]> ReadInitialBytesAsync(NetworkStream stream, CancellationToken cancellationToken)
+        {
+            var buffer = new byte[4];
+            var totalRead = 0;
+
+            while (totalRead < buffer.Length)
+            {
+                var bytesRead = await stream.ReadAsync(buffer, totalRead, buffer.Length - totalRead, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    break;
+                }
+
+                totalRead += bytesRead;
+            }
+
+            if (totalRead == 0)
+            {
+                return Array.Empty<byte>();
+            }
+
+            if (totalRead == buffer.Length)
+            {
+                return buffer;
+            }
+
+            var initialBytes = new byte[totalRead];
+            Array.Copy(buffer, initialBytes, totalRead);
+            return initialBytes;
+        }
+
+        internal static IncomingStreamPrefixKind ClassifyIncomingStreamPrefix(byte[] initialBytes)
+        {
+            if (LooksLikeHttpUpgrade(initialBytes))
+            {
+                return IncomingStreamPrefixKind.HttpWebSocketUpgrade;
+            }
+
+            if (LooksLikeHttp2Preface(initialBytes))
+            {
+                return IncomingStreamPrefixKind.Http2Preface;
+            }
+
+            if (LooksLikeTlsClientHello(initialBytes))
+            {
+                return IncomingStreamPrefixKind.TlsClientHello;
+            }
+
+            if (LooksLikeWebSocketFramePrefix(initialBytes, requireReservedBitsClear: false))
+            {
+                return HasReservedBitsSet(initialBytes[0])
+                    ? IncomingStreamPrefixKind.WebSocketReservedBits
+                    : IncomingStreamPrefixKind.PreUpgradedWebSocket;
+            }
+
+            return IncomingStreamPrefixKind.Unknown;
+        }
+
+        internal static string DescribeInitialBytes(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length == 0)
+            {
+                return "no bytes read";
+            }
+
+            var hex = BitConverter.ToString(initialBytes);
+            var ascii = new string(initialBytes.Select(value => value >= 32 && value <= 126 ? (char)value : '.').ToArray());
+            return $"hex={hex}, ascii=\"{ascii}\"";
+        }
+
+        private static bool LooksLikeHttpUpgrade(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length < 4)
+            {
+                return false;
+            }
+
+            return initialBytes[0] == (byte)'G' &&
+                initialBytes[1] == (byte)'E' &&
+                initialBytes[2] == (byte)'T' &&
+                initialBytes[3] == (byte)' ';
+        }
+
+        private static bool LooksLikeHttp2Preface(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length < 4)
+            {
+                return false;
+            }
+
+            return initialBytes[0] == (byte)'P' &&
+                initialBytes[1] == (byte)'R' &&
+                initialBytes[2] == (byte)'I' &&
+                initialBytes[3] == (byte)' ';
+        }
+
+        private static bool LooksLikeTlsClientHello(byte[] initialBytes)
+        {
+            if (initialBytes == null || initialBytes.Length < 3)
+            {
+                return false;
+            }
+
+            return initialBytes[0] == 0x16 &&
+                initialBytes[1] == 0x03 &&
+                initialBytes[2] >= 0x00 &&
+                initialBytes[2] <= 0x04;
+        }
+
+        private static bool LooksLikeWebSocketFramePrefix(byte[] initialBytes, bool requireReservedBitsClear)
+        {
+            if (initialBytes == null || initialBytes.Length < 2)
+            {
+                return false;
+            }
+
+            var firstByte = initialBytes[0];
+            var secondByte = initialBytes[1];
+            var opcode = firstByte & 0x0F;
+            var isMasked = (secondByte & 0x80) != 0;
+
+            if (!isMasked || !IsSupportedWebSocketOpcode(opcode))
+            {
+                return false;
+            }
+
+            return !requireReservedBitsClear || !HasReservedBitsSet(firstByte);
+        }
+
+        private static bool HasReservedBitsSet(byte firstByte)
+        {
+            return (firstByte & 0x70) != 0;
+        }
+
+        private static bool IsSupportedWebSocketOpcode(int opcode)
+        {
+            switch (opcode)
+            {
+                case 0x0:
+                case 0x1:
+                case 0x2:
+                case 0x8:
+                case 0x9:
+                case 0xA:
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
+        private static async Task WriteHttpErrorAsync(
+            NetworkStream stream,
+            HttpStatusCode statusCode,
+            string message,
+            CancellationToken cancellationToken)
+        {
+            var bodyBytes = Encoding.UTF8.GetBytes(message);
+            var responseBytes = Encoding.ASCII.GetBytes(
+                $"HTTP/1.1 {(int)statusCode} {statusCode}\r\n" +
+                "Connection: close\r\n" +
+                "Content-Type: text/plain; charset=utf-8\r\n" +
+                $"Content-Length: {bodyBytes.Length}\r\n" +
+                "Sec-WebSocket-Version: 13\r\n" +
+                "\r\n");
+
+            await stream.WriteAsync(responseBytes, 0, responseBytes.Length, cancellationToken);
+            await stream.WriteAsync(bodyBytes, 0, bodyBytes.Length, cancellationToken);
+            await stream.FlushAsync(cancellationToken);
+        }
+
+        private static async Task CloseWebSocketAsync(WebSocket webSocket)
+        {
+            if (webSocket == null)
+            {
+                return;
+            }
+
+            if (webSocket.State != WebSocketState.Open &&
+                webSocket.State != WebSocketState.CloseReceived)
+            {
+                return;
+            }
+
+            try
+            {
+                using var cts = new CancellationTokenSource(_closeTimeout);
+                await webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cts.Token);
+            }
+            catch (OperationCanceledException)
+            {
+                // Graceful close timed out, abort the connection.
+                webSocket.Abort();
+            }
+            catch (WebSocketException)
+            {
+                // Peer already disconnected.
+            }
+        }
+
+        private sealed class ReplayableStream : Stream
+        {
+            private readonly Stream _innerStream;
+            private readonly byte[] _prefixBytes;
+            private int _prefixOffset;
+
+            public ReplayableStream(Stream innerStream, byte[] prefixBytes)
+            {
+                _innerStream = innerStream ?? throw new ArgumentNullException(nameof(innerStream));
+                _prefixBytes = prefixBytes ?? Array.Empty<byte>();
+            }
+
+            public override bool CanRead => _innerStream.CanRead;
+            public override bool CanSeek => false;
+            public override bool CanWrite => _innerStream.CanWrite;
+            public override long Length => throw new NotSupportedException();
+
+            public override long Position
+            {
+                get => throw new NotSupportedException();
+                set => throw new NotSupportedException();
+            }
+
+            public override void Flush() => _innerStream.Flush();
+
+            public override Task FlushAsync(CancellationToken cancellationToken) => _innerStream.FlushAsync(cancellationToken);
+
+            public override int Read(byte[] buffer, int offset, int count)
+            {
+                if (TryReadPrefix(buffer, offset, count, out var bytesRead))
+                {
+                    return bytesRead;
+                }
+
+                return _innerStream.Read(buffer, offset, count);
+            }
+
+            public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            {
+                if (TryReadPrefix(buffer, offset, count, out var bytesRead))
+                {
+                    return bytesRead;
+                }
+
+                return await _innerStream.ReadAsync(buffer, offset, count, cancellationToken);
+            }
+
+            public override async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+            {
+                if (_prefixOffset < _prefixBytes.Length)
+                {
+                    var bytesToCopy = Math.Min(buffer.Length, _prefixBytes.Length - _prefixOffset);
+                    new ReadOnlySpan<byte>(_prefixBytes, _prefixOffset, bytesToCopy).CopyTo(buffer.Span);
+                    _prefixOffset += bytesToCopy;
+                    return bytesToCopy;
+                }
+
+                return await _innerStream.ReadAsync(buffer, cancellationToken);
+            }
+
+            public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
+
+            public override void SetLength(long value) => throw new NotSupportedException();
+
+            public override void Write(byte[] buffer, int offset, int count) => _innerStream.Write(buffer, offset, count);
+
+            public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken) =>
+                _innerStream.WriteAsync(buffer, offset, count, cancellationToken);
+
+            public override ValueTask WriteAsync(ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken = default) =>
+                _innerStream.WriteAsync(buffer, cancellationToken);
+
+            private bool TryReadPrefix(byte[] buffer, int offset, int count, out int bytesRead)
+            {
+                if (_prefixOffset >= _prefixBytes.Length)
+                {
+                    bytesRead = 0;
+                    return false;
+                }
+
+                bytesRead = Math.Min(count, _prefixBytes.Length - _prefixOffset);
+                Array.Copy(_prefixBytes, _prefixOffset, buffer, offset, bytesRead);
+                _prefixOffset += bytesRead;
+                return true;
+            }
+        }
+    }
+}

src/Runner.Worker/Dap/YamlScalarFormatter.cs

@@ -0,0 +1,63 @@
+using System;
+using System.Globalization;
+using System.IO;
+using GitHub.Runner.Sdk;
+using YamlDotNet.Core;
+using YamlDotNet.Core.Events;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Formats a single string as a quote-safe YAML scalar by routing it
+    /// through YamlDotNet's <see cref="Emitter"/>. The returned text is
+    /// safe to splice into a hand-emitted YAML document fragment.
+    ///
+    /// Caller responsibility: this only handles the scalar value; it does
+    /// not emit a key, indent, or trailing newline.
+    /// </summary>
+    internal static class YamlScalarFormatter
+    {
+        /// <summary>
+        /// Return <paramref name="value"/> formatted as a YAML scalar:
+        /// plain, single-quoted, or double-quoted as the emitter chooses,
+        /// with no surrounding document markers or trailing newline.
+        /// </summary>
+        public static string Format(string value)
+        {
+            ArgUtil.NotNull(value, nameof(value));
+
+            using var sw = new StringWriter(CultureInfo.InvariantCulture);
+            // Force LF line breaks; YamlDotNet's Emitter calls WriteLine,
+            // which would otherwise produce CRLF on Windows and break
+            // both our document-end stripping below and downstream
+            // consumers that assume a single line-break convention.
+            sw.NewLine = "\n";
+            var emitter = new Emitter(sw);
+            emitter.Emit(new StreamStart());
+            emitter.Emit(new DocumentStart(null, null, true));
+            emitter.Emit(new Scalar(null, null, value, ScalarStyle.Any, true, true));
+            emitter.Emit(new DocumentEnd(true));
+            emitter.Emit(new StreamEnd());
+
+            string raw = sw.ToString();
+            // Strip YAML document markers. Emitter elides these for most
+            // scalars but emits "--- " (with space) for some edge cases
+            // (e.g. empty strings). Defensively handle "---\n" too.
+            if (raw.StartsWith("--- ", StringComparison.Ordinal))
+            {
+                raw = raw.Substring(4);
+            }
+            else if (raw.StartsWith("---\n", StringComparison.Ordinal))
+            {
+                raw = raw.Substring(4);
+            }
+            raw = raw.TrimEnd('\n');
+            const string DocEndMarker = "\n...";
+            if (raw.EndsWith(DocEndMarker, StringComparison.Ordinal))
+            {
+                raw = raw.Substring(0, raw.Length - DocEndMarker.Length);
+            }
+            return raw;
+        }
+    }
+}

src/Runner.Worker/ExecutionContext.cs

@@ -875,6 +875,9 @@ namespace GitHub.Runner.Worker
             // File table
             Global.FileTable = new List<String>(message.FileTable ?? new string[0]);
 
+            // Workflow dependencies (lockfile pins)
+            Global.ActionsDependencies = message.ActionsDependencies;
+
             // What type of job request is running (i.e. Run Service vs. pipelines)
             Global.Variables.Set(Constants.Variables.System.JobRequestType, message.MessageType);
 
@@ -892,15 +895,12 @@ namespace GitHub.Runner.Worker
 
             Trace.Info("Initializing Job context");
             var jobContext = new JobContext();
-            if (Global.Variables.GetBoolean(Constants.Runner.Features.AddCheckRunIdToJobContext) ?? false)
+            ExpressionValues.TryGetValue("job", out var jobDictionary);
+            if (jobDictionary != null)
             {
-                ExpressionValues.TryGetValue("job", out var jobDictionary);
-                if (jobDictionary != null)
+                foreach (var pair in jobDictionary.AssertDictionary("job"))
                 {
-                    foreach (var pair in jobDictionary.AssertDictionary("job"))
-                    {
-                        jobContext[pair.Key] = pair.Value;
-                    }
+                    jobContext[pair.Key] = pair.Value;
                 }
             }
             ExpressionValues["job"] = jobContext;
@@ -970,7 +970,8 @@ namespace GitHub.Runner.Worker
             Global.WriteDebug = Global.Variables.Step_Debug ?? false;
 
             // Debugger enabled flag (from acquire response).
-            Global.EnableDebugger = message.EnableDebugger;
+            var overrideDebuggerWelcomeMessage = Global.Variables.GetBoolean(Constants.Runner.Features.OverrideDebuggerWelcomeMessage) ?? false;
+            Global.Debugger = new Dap.DebuggerConfig(message.EnableDebugger, message.DebuggerTunnel, overrideDebuggerWelcomeMessage, message.DebuggerWelcomeMessage);
 
             // Hook up JobServerQueueThrottling event, we will log warning on server tarpit.
             _jobServerQueue.JobServerQueueThrottling += JobServerQueueThrottling_EventReceived;

src/Runner.Worker/GlobalContext.cs

@@ -4,6 +4,7 @@ using GitHub.Actions.RunService.WebApi;
 using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Worker.Container;
+using GitHub.Runner.Worker.Dap;
 using Newtonsoft.Json.Linq;
 using Sdk.RSWebApi.Contracts;
 
@@ -27,7 +28,7 @@ namespace GitHub.Runner.Worker
         public StepsContext StepsContext { get; set; }
         public Variables Variables { get; set; }
         public bool WriteDebug { get; set; }
-        public bool EnableDebugger { get; set; }
+        public DebuggerConfig Debugger { get; set; }
         public string InfrastructureFailureCategory { get; set; }
         public JObject ContainerHookState { get; set; }
         public bool HasTemplateEvaluatorMismatch { get; set; }
@@ -37,5 +38,6 @@ namespace GitHub.Runner.Worker
         public HashSet<string> DeprecatedNode20Actions { get; set; }
         public HashSet<string> UpgradedToNode24Actions { get; set; }
         public HashSet<string> Arm32Node20Actions { get; set; }
+        public IList<String> ActionsDependencies { get; set; }
     }
 }

src/Runner.Worker/JobContext.cs

@@ -82,5 +82,69 @@ namespace GitHub.Runner.Worker
                 }
             }
         }
+
+        public string WorkflowRef
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_ref", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_ref"] = value != null ? new StringContextData(value) : null;
+            }
+        }
+
+        public string WorkflowSha
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_sha", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_sha"] = value != null ? new StringContextData(value) : null;
+            }
+        }
+
+        public string WorkflowRepository
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_repository", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_repository"] = value != null ? new StringContextData(value) : null;
+            }
+        }
+
+        public string WorkflowFilePath
+        {
+            get
+            {
+                if (this.TryGetValue("workflow_file_path", out var value) && value is StringContextData str)
+                {
+                    return str.Value;
+                }
+                return null;
+            }
+            set
+            {
+                this["workflow_file_path"] = value != null ? new StringContextData(value) : null;
+            }
+        }
     }
 }

src/Runner.Worker/JobExtension.cs

@@ -16,6 +16,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Services.Common;
 using Newtonsoft.Json;
 using Pipelines = GitHub.DistributedTask.Pipelines;
@@ -50,6 +51,7 @@ namespace GitHub.Runner.Worker
         private Task _diskSpaceCheckTask = null;
         private CancellationTokenSource _serviceConnectivityCheckToken = new();
         private Task _serviceConnectivityCheckTask = null;
+        private IDapDebugger _dapDebugger;
 
         // Download all required actions.
         // Make sure all condition inputs are valid.
@@ -67,6 +69,7 @@ namespace GitHub.Runner.Worker
 
             List<IStep> preJobSteps = new();
             List<IStep> jobSteps = new();
+            var initSucceeded = false;
             using (var register = jobContext.CancellationToken.Register(() => { context.CancelToken(); }))
             {
                 try
@@ -77,20 +80,25 @@ namespace GitHub.Runner.Worker
 
                     var setting = HostContext.GetService<IConfigurationStore>().GetSettings();
                     var credFile = HostContext.GetConfigFile(WellKnownConfigFile.Credentials);
-                    if (File.Exists(credFile))
+                    var credData = File.Exists(credFile) ? IOUtil.LoadObject<CredentialData>(credFile) : null;
+                    // self-hosted runner is the only runner type using OAuth, can be identified via clientId
+                    if (credData != null &&
+                        credData.Data.TryGetValue("clientId", out _))
                     {
-                        var credData = IOUtil.LoadObject<CredentialData>(credFile);
-                        if (credData != null &&
-                            credData.Data.TryGetValue("clientId", out var clientId))
+                        context.Output($"Runner name: '{setting.AgentName}'");
+                        // use system variable for group name since self-hosted runners can be renamed
+                        if (message.Variables.TryGetValue("system.runnerGroupName", out VariableValue runnerGroupName))
                         {
-                            // print out HostName for self-hosted runner
-                            context.Output($"Runner name: '{setting.AgentName}'");
-                            if (message.Variables.TryGetValue("system.runnerGroupName", out VariableValue runnerGroupName))
-                            {
-                                context.Output($"Runner group name: '{runnerGroupName.Value}'");
-                            }
-                            context.Output($"Machine name: '{Environment.MachineName}'");
+                            context.Output($"Runner group name: '{runnerGroupName.Value}'");
                         }
+                        // print out machine name for self-hosted runner
+                        context.Output($"Machine name: '{Environment.MachineName}'");
+                    }
+                    // print runner info for lhr runners, skips standard runners (PoolId = 0)
+                    else if (setting.PoolId > 0 && !string.IsNullOrEmpty(setting.PoolName) && !string.IsNullOrEmpty(setting.AgentName))
+                    {
+                        context.Output($"Runner name: '{setting.AgentName}'");
+                        context.Output($"Runner group name: '{setting.PoolName}'");
                     }
 
                     var setupInfoFile = HostContext.GetConfigFile(WellKnownConfigFile.SetupInfo);
@@ -476,6 +484,41 @@ namespace GitHub.Runner.Worker
                     Trace.Info($"Start checking service connectivity in background.");
                     _serviceConnectivityCheckTask = CheckServiceConnectivityAsync(context, _serviceConnectivityCheckToken.Token);
 
+                    // Start the DAP debugger and wait for a client connection inside
+                    // "Set up job" so the step stays in-progress while we wait.
+                    if (jobContext.Global.Debugger?.Enabled == true)
+                    {
+                        Trace.Info("Debugger enabled — starting inside Set up job");
+                        context.Output("Starting debugger…");
+
+                        try
+                        {
+                            _dapDebugger = HostContext.GetService<IDapDebugger>();
+                            await _dapDebugger.StartAsync(jobContext);
+
+                            context.Output("Waiting for debugger client to connect…");
+
+                            await _dapDebugger.WaitUntilReadyAsync();
+                            context.Output("Debugger connected.");
+                            AddDebuggerConnectionTelemetry(jobContext, "Connected");
+                        }
+                        catch (OperationCanceledException) when (jobContext.CancellationToken.IsCancellationRequested)
+                        {
+                            Trace.Info("Job was cancelled before debugger client connected.");
+                            AddDebuggerConnectionTelemetry(jobContext, "Canceled");
+                            context.Error("Job was cancelled before debugger client connected.");
+                            throw;
+                        }
+                        catch (Exception ex)
+                        {
+                            Trace.Error($"DAP debugger failed: {ex.Message}");
+                            AddDebuggerConnectionTelemetry(jobContext, $"Failed: {ex.GetType().Name}");
+                            context.Error("The debugger failed to start or no debugger client connected in time.");
+                            throw;
+                        }
+                    }
+
+                    initSucceeded = true;
                     return steps;
                 }
                 catch (OperationCanceledException ex) when (jobContext.CancellationToken.IsCancellationRequested)
@@ -496,12 +539,36 @@ namespace GitHub.Runner.Worker
                 }
                 finally
                 {
+                    // If InitializeJob failed after the debugger was started,
+                    // tear down the transport here since FinalizeJob won't run.
+                    if (!initSucceeded && _dapDebugger != null)
+                    {
+                        try
+                        {
+                            await _dapDebugger.StopAsync();
+                        }
+                        catch (Exception ex)
+                        {
+                            Trace.Warning($"DAP debugger cleanup during failed init: {ex.Message}");
+                        }
+                        _dapDebugger = null;
+                    }
+
                     context.Debug("Finishing: Set up job");
                     context.Complete();
                 }
             }
         }
 
+        private static void AddDebuggerConnectionTelemetry(IExecutionContext jobContext, string result)
+        {
+            jobContext.Global.JobTelemetry.Add(new JobTelemetry
+            {
+                Type = JobTelemetryType.General,
+                Message = $"DebuggerConnectionResult: {result}"
+            });
+        }
+
         private string GetWorkflowReference(IDictionary<string, VariableValue> variables)
         {
             var reference = "";
@@ -777,6 +844,34 @@ namespace GitHub.Runner.Worker
                 }
                 finally
                 {
+                    // Pause for debugger inspection, then tear down the DAP session.
+                    // OnJobCompletedAsync pauses first, then sends terminated/exited
+                    // events and stops the transport.
+                    if (_dapDebugger != null)
+                    {
+                        context.Output("Job completed — pausing for debugger inspection. Press continue to finish.");
+                        try
+                        {
+                            await _dapDebugger.OnJobCompletedAsync();
+                        }
+                        catch (Exception ex)
+                        {
+                            Trace.Warning($"DAP debugger completion error: {ex.Message}");
+                        }
+                        finally
+                        {
+                            try
+                            {
+                                await _dapDebugger.StopAsync();
+                            }
+                            catch (Exception ex)
+                            {
+                                Trace.Warning($"DAP debugger stop error: {ex.Message}");
+                            }
+                        }
+                        _dapDebugger = null;
+                    }
+
                     context.Debug("Finishing: Complete job");
                     context.Complete();
                 }

src/Runner.Worker/JobRunner.cs

@@ -13,7 +13,6 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
-using GitHub.Runner.Worker.Dap;
 using GitHub.Services.Common;
 using GitHub.Services.WebApi;
 using Sdk.RSWebApi.Contracts;
@@ -29,7 +28,6 @@ namespace GitHub.Runner.Worker
 
     public sealed class JobRunner : RunnerService, IJobRunner
     {
-        private const string DebuggerConnectionTelemetryPrefix = "DebuggerConnectionResult";
         private IJobServerQueue _jobServerQueue;
         private RunnerSettings _runnerSettings;
         private ITempDirectoryManager _tempDirectoryManager;
@@ -114,7 +112,6 @@ namespace GitHub.Runner.Worker
 
             IExecutionContext jobContext = null;
             CancellationTokenRegistration? runnerShutdownRegistration = null;
-            IDapDebugger dapDebugger = null;
             try
             {
                 // Create the job execution context.
@@ -181,25 +178,6 @@ namespace GitHub.Runner.Worker
                 _tempDirectoryManager = HostContext.GetService<ITempDirectoryManager>();
                 _tempDirectoryManager.InitializeTempDirectory(jobContext);
 
-                // Setup the debugger
-                if (jobContext.Global.EnableDebugger)
-                {
-                    Trace.Info("Debugger enabled for this job run");
-
-                    try
-                    {
-                        dapDebugger = HostContext.GetService<IDapDebugger>();
-                        await dapDebugger.StartAsync(jobContext);
-                    }
-                    catch (Exception ex)
-                    {
-                        Trace.Error($"Failed to start DAP debugger: {ex.Message}");
-                        AddDebuggerConnectionTelemetry(jobContext, $"Failed: {ex.Message}");
-                        jobContext.Error("Failed to start debugger.");
-                        return await CompleteJobAsync(server, jobContext, message, TaskResult.Failed);
-                    }
-                }
-
 
                 // Get the job extension.
                 Trace.Info("Getting job extension.");
@@ -242,33 +220,6 @@ namespace GitHub.Runner.Worker
                     await Task.WhenAny(_jobServerQueue.JobRecordUpdated.Task, Task.Delay(1000));
                 }
 
-                // Wait for DAP debugger client connection and handshake after "Set up job"
-                // so the job page shows the setup step before we block on the debugger
-                if (dapDebugger != null)
-                {
-                    try
-                    {
-                        await dapDebugger.WaitUntilReadyAsync();
-                        AddDebuggerConnectionTelemetry(jobContext, "Connected");
-                    }
-                    catch (OperationCanceledException) when (jobRequestCancellationToken.IsCancellationRequested)
-                    {
-                        Trace.Info("Job was cancelled before debugger client connected.");
-                        AddDebuggerConnectionTelemetry(jobContext, "Canceled");
-                        jobContext.Error("Job was cancelled before debugger client connected.");
-                        return await CompleteJobAsync(server, jobContext, message, TaskResult.Canceled);
-                    }
-                    catch (Exception ex)
-                    {
-                        Trace.Error($"DAP debugger failed to become ready: {ex.Message}");
-                        AddDebuggerConnectionTelemetry(jobContext, $"Failed: {ex.Message}");
-
-                        // If debugging was requested but the debugger is not available, fail the job
-                        jobContext.Error("The debugger failed to start or no debugger client connected in time.");
-                        return await CompleteJobAsync(server, jobContext, message, TaskResult.Failed);
-                    }
-                }
-
                 // Run all job steps
                 Trace.Info("Run all job steps.");
                 var stepsRunner = HostContext.GetService<IStepsRunner>();
@@ -309,11 +260,6 @@ namespace GitHub.Runner.Worker
                     runnerShutdownRegistration = null;
                 }
 
-                if (dapDebugger != null)
-                {
-                    await dapDebugger.OnJobCompletedAsync();
-                }
-
                 await ShutdownQueue(throwOnFailure: false);
             }
         }
@@ -495,15 +441,6 @@ namespace GitHub.Runner.Worker
             throw new AggregateException(exceptions);
         }
 
-        private static void AddDebuggerConnectionTelemetry(IExecutionContext jobContext, string result)
-        {
-            jobContext.Global.JobTelemetry.Add(new JobTelemetry
-            {
-                Type = JobTelemetryType.General,
-                Message = $"{DebuggerConnectionTelemetryPrefix}: {result}"
-            });
-        }
-
         private void MaskTelemetrySecrets(List<JobTelemetry> jobTelemetry)
         {
             foreach (var telemetryItem in jobTelemetry)

src/Runner.Worker/Runner.Worker.csproj

@@ -19,10 +19,11 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="8.0.0" />
-    <PackageReference Include="System.ServiceProcess.ServiceController" Version="8.0.1" />
-    <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="System.Security.Cryptography.ProtectedData" Version="10.0.3" />
+    <PackageReference Include="System.ServiceProcess.ServiceController" Version="10.0.3" />
+    <PackageReference Include="System.Threading.Channels" Version="10.0.3" />
     <PackageReference Include="YamlDotNet.Signed" Version="5.3.0" />
+    <PackageReference Include="Microsoft.DevTunnels.Connections" Version="1.3.39" />
   </ItemGroup>
 
   <ItemGroup>

src/Sdk/DTExpressions2/Expressions2/ExpressionParser.cs

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

src/Sdk/DTObjectTemplating/ObjectTemplating/TemplateContext.cs

@@ -86,12 +86,6 @@ namespace GitHub.DistributedTask.ObjectTemplating
 
         internal ITraceWriter TraceWriter { get; set; }
 
-        /// <summary>
-        /// Gets or sets a value indicating whether the case expression function is allowed.
-        /// Defaults to true. Set to false to disable the case function.
-        /// </summary>
-        internal Boolean AllowCaseFunction { get; set; } = true;
-
         private IDictionary<String, Int32> FileIds
         {
             get

src/Sdk/DTObjectTemplating/ObjectTemplating/Tokens/TemplateToken.cs

@@ -57,7 +57,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -94,7 +94,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -123,7 +123,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -152,7 +152,7 @@ namespace GitHub.DistributedTask.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,

src/Sdk/DTPipelines/Pipelines/AgentJobRequestMessage.cs

@@ -260,6 +260,43 @@ namespace GitHub.DistributedTask.Pipelines
             set;
         }
 
+        [DataMember(EmitDefaultValue = false)]
+        public DebuggerTunnelInfo DebuggerTunnel
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Optional welcome message shown in the debugger console when a client connects.
+        /// Only used when the <c>actions_runner_override_debugger_welcome_message</c>
+        /// feature flag is set to <c>true</c> in the job variables. With the flag set,
+        /// a non-empty value is shown as-is and a null or empty value suppresses the
+        /// default welcome message. When the flag is not set, the runner shows its
+        /// built-in help text and this field is ignored.
+        /// </summary>
+        [DataMember(EmitDefaultValue = false)]
+        public string DebuggerWelcomeMessage
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Gets the workflow-level action dependencies (lockfile entries)
+        /// </summary>
+        public IList<String> ActionsDependencies
+        {
+            get
+            {
+                if (m_actionsDependencies == null)
+                {
+                    m_actionsDependencies = new List<String>();
+                }
+                return m_actionsDependencies;
+            }
+        }
+
         /// <summary>
         /// Gets the collection of variables associated with the current context.
         /// </summary>
@@ -434,6 +471,11 @@ namespace GitHub.DistributedTask.Pipelines
                 m_variables = null;
             }
 
+            if (m_actionsDependencies?.Count == 0)
+            {
+                m_actionsDependencies = null;
+            }
+
             // todo: remove after feature-flag DistributedTask.EvaluateContainerOnRunner is enabled everywhere
             if (!string.IsNullOrEmpty(m_jobContainerResourceAlias))
             {
@@ -459,6 +501,9 @@ namespace GitHub.DistributedTask.Pipelines
         [DataMember(Name = "Variables", EmitDefaultValue = false)]
         private IDictionary<String, VariableValue> m_variables;
 
+        [DataMember(Name = "dependencies", EmitDefaultValue = false)]
+        private List<String> m_actionsDependencies;
+
         // todo: remove after feature-flag DistributedTask.EvaluateContainerOnRunner is enabled everywhere
         [DataMember(Name = "JobSidecarContainers", EmitDefaultValue = false)]
         private IDictionary<String, String> m_jobSidecarContainers;

src/Sdk/DTPipelines/Pipelines/DebuggerTunnelInfo.cs

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

src/Sdk/DTPipelines/Pipelines/Expressions/WellKnownRegularExpressions.cs

@@ -8,6 +8,7 @@ namespace GitHub.DistributedTask.Pipelines.Expressions
         public const String Email = nameof(Email);
         public const String IPv4Address = nameof(IPv4Address);
         public const String SHA1 = nameof(SHA1);
+        public const String CommitHash = nameof(CommitHash);
         public const String Url = nameof(Url);
 
         /// <summary>
@@ -24,7 +25,8 @@ namespace GitHub.DistributedTask.Pipelines.Expressions
                 case IPv4Address:
                     return s_validIPv4Address;
                 case SHA1:
-                    return s_validSha1;
+                case CommitHash:
+                    return s_validCommitHash;
                 case Url:
                     return s_validUrl;
                 default:
@@ -46,9 +48,9 @@ namespace GitHub.DistributedTask.Pipelines.Expressions
             )
         );
 
-        // 40 hex characters
-        private static readonly Lazy<Regex> s_validSha1 = new Lazy<Regex>(() => new Regex(
-            @"\b[0-9a-f]{40}\b",
+        // 40 or 64 hex characters (SHA-1 or SHA-256 commit hash)
+        private static readonly Lazy<Regex> s_validCommitHash = new Lazy<Regex>(() => new Regex(
+            @"\b(?:[0-9a-f]{40}|[0-9a-f]{64})\b",
             RegexOptions.IgnoreCase | RegexOptions.CultureInvariant | RegexOptions.Compiled, RegexUtility.GetRegexTimeOut()
             )
         );

src/Sdk/DTPipelines/Pipelines/ObjectTemplating/PipelineTemplateConverter.cs

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

src/Sdk/DTWebApi/WebApi/ActionReferenceList.cs

@@ -12,5 +12,12 @@ namespace GitHub.DistributedTask.WebApi
             get;
             set;
         }
+
+        [DataMember(EmitDefaultValue = false)]
+        public IList<string> Dependencies
+        {
+            get;
+            set;
+        }
     }
 }

src/Sdk/Expressions/ExpressionParser.cs

@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
 
 using System;
 using System.Collections.Generic;
@@ -17,10 +17,9 @@ namespace GitHub.Actions.Expressions
             String expression,
             ITraceWriter trace,
             IEnumerable<INamedValueInfo> namedValues,
-            IEnumerable<IFunctionInfo> functions,
-            Boolean allowCaseFunction = true)
+            IEnumerable<IFunctionInfo> functions)
         {
-            var context = new ParseContext(expression, trace, namedValues, functions, allowCaseFunction: allowCaseFunction);
+            var context = new ParseContext(expression, trace, namedValues, functions);
             context.Trace.Info($"Parsing expression: <{expression}>");
             return CreateTree(context);
         }
@@ -322,7 +321,7 @@ namespace GitHub.Actions.Expressions
                     context.Operators.Pop();
                 }
                 var functionOperands = PopOperands(context, parameterCount);
-                
+
                 // Node already exists on the operand stack
                 function = (Function)context.Operands.Peek();
 
@@ -416,12 +415,6 @@ namespace GitHub.Actions.Expressions
             String name,
             out IFunctionInfo functionInfo)
         {
-            if (String.Equals(name, "case", StringComparison.OrdinalIgnoreCase) && !context.AllowCaseFunction)
-            {
-                functionInfo = null;
-                return false;
-            }
-
             return ExpressionConstants.WellKnownFunctions.TryGetValue(name, out functionInfo) ||
                 context.ExtensionFunctions.TryGetValue(name, out functionInfo);
         }
@@ -429,7 +422,6 @@ namespace GitHub.Actions.Expressions
         private sealed class ParseContext
         {
             public Boolean AllowUnknownKeywords;
-            public Boolean AllowCaseFunction;
             public readonly String Expression;
             public readonly Dictionary<String, IFunctionInfo> ExtensionFunctions = new Dictionary<String, IFunctionInfo>(StringComparer.OrdinalIgnoreCase);
             public readonly Dictionary<String, INamedValueInfo> ExtensionNamedValues = new Dictionary<String, INamedValueInfo>(StringComparer.OrdinalIgnoreCase);
@@ -445,8 +437,7 @@ namespace GitHub.Actions.Expressions
                 ITraceWriter trace,
                 IEnumerable<INamedValueInfo> namedValues,
                 IEnumerable<IFunctionInfo> functions,
-                Boolean allowUnknownKeywords = false,
-                Boolean allowCaseFunction = true)
+                Boolean allowUnknownKeywords = false)
             {
                 Expression = expression ?? String.Empty;
                 if (Expression.Length > ExpressionConstants.MaxLength)
@@ -467,7 +458,6 @@ namespace GitHub.Actions.Expressions
 
                 LexicalAnalyzer = new LexicalAnalyzer(Expression);
                 AllowUnknownKeywords = allowUnknownKeywords;
-                AllowCaseFunction = allowCaseFunction;
             }
 
             private class NoOperationTraceWriter : ITraceWriter

src/Sdk/Sdk.csproj

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

src/Sdk/WebApi/WebApi/LaunchContracts.cs

@@ -22,6 +22,9 @@ namespace GitHub.Services.Launch.Contracts
     {
         [DataMember(EmitDefaultValue = false, Name = "actions")]
         public IList<ActionReferenceRequest> Actions { get; set; }
+
+        [DataMember(EmitDefaultValue = false, Name = "actions_dependencies")]
+        public IList<string> ActionsDependencies { get; set; }
     }
 
     [DataContract]

src/Sdk/WebApi/WebApi/LaunchHttpClient.cs

@@ -97,7 +97,8 @@ namespace GitHub.Services.Launch.Client
         {
             return new ActionReferenceRequestList
             {
-                Actions = actionReferenceList.Actions?.Select(ToGitHubData).ToList()
+                Actions = actionReferenceList.Actions?.Select(ToGitHubData).ToList(),
+                ActionsDependencies = actionReferenceList.Dependencies
             };
         }
 

src/Sdk/WorkflowParser/Conversion/PermissionsHelper.cs

@@ -32,7 +32,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                 return;
             }
 
-            var effectiveMax = explicitMax ?? CreatePermissionsFromPolicy(context, permissionsPolicy, includeIdToken: isTrusted, includeModels: context.GetFeatures().AllowModelsPermission);
+            var effectiveMax = explicitMax ?? CreatePermissionsFromPolicy(context, permissionsPolicy, includeIdToken: isTrusted, includeModels: context.GetFeatures().AllowModelsPermission, includeVulnerabilityAlerts: context.GetFeatures().AllowVulnerabilityAlertsPermission);
             
             if (requested.ViolatesMaxPermissions(effectiveMax, out var permissionLevelViolations))
             {
@@ -59,18 +59,19 @@ namespace GitHub.Actions.WorkflowParser.Conversion
             TemplateContext context,
             string permissionsPolicy,
             bool includeIdToken,
-            bool includeModels)
+            bool includeModels,
+            bool includeVulnerabilityAlerts)
         {
             switch (permissionsPolicy)
             {
                 case WorkflowConstants.PermissionsPolicy.LimitedRead:
-                    return new Permissions(PermissionLevel.NoAccess, includeIdToken: false, includeAttestations: false, includeModels: false)
+                    return new Permissions(PermissionLevel.NoAccess, includeIdToken: false, includeAttestations: false, includeModels: false, includeVulnerabilityAlerts: false)
                     {
                         Contents = PermissionLevel.Read,
                         Packages = PermissionLevel.Read,
                     };
                 case WorkflowConstants.PermissionsPolicy.Write:
-                    return new Permissions(PermissionLevel.Write, includeIdToken: includeIdToken, includeAttestations: true, includeModels: includeModels);
+                    return new Permissions(PermissionLevel.Write, includeIdToken: includeIdToken, includeAttestations: true, includeModels: includeModels, includeVulnerabilityAlerts: includeVulnerabilityAlerts);
                 default:
                     throw new ArgumentException($"Unexpected permission policy: '{permissionsPolicy}'");
             }

src/Sdk/WorkflowParser/Conversion/WorkflowTemplateConverter.cs

@@ -1828,7 +1828,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
             var node = default(ExpressionNode);
             try
             {
-                node = expressionParser.CreateTree(condition, null, namedValues, functions, allowCaseFunction: context.AllowCaseFunction) as ExpressionNode;
+                node = expressionParser.CreateTree(condition, null, namedValues, functions) as ExpressionNode;
             }
             catch (Exception ex)
             {
@@ -1877,7 +1877,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                         permissionsStr.AssertUnexpectedValue(permissionsStr.Value);
                         break;
                 }
-                return new Permissions(permissionLevel, includeIdToken: true, includeAttestations: true, includeModels: context.GetFeatures().AllowModelsPermission);
+                return new Permissions(permissionLevel, includeIdToken: true, includeAttestations: true, includeModels: context.GetFeatures().AllowModelsPermission, includeVulnerabilityAlerts: context.GetFeatures().AllowVulnerabilityAlertsPermission);
             }
 
             var mapping = token.AssertMapping("permissions");
@@ -1957,6 +1957,23 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                             context.Error(key, $"The permission 'models' is not allowed");
                         }
                         break;
+                    case "vulnerability-alerts":
+                        if (context.GetFeatures().AllowVulnerabilityAlertsPermission)
+                        {
+                            if (permissionLevel == PermissionLevel.Write)
+                            {
+                                permissions.VulnerabilityAlerts = PermissionLevel.Read;
+                            }
+                            else
+                            {
+                                permissions.VulnerabilityAlerts = permissionLevel;
+                            }
+                        }
+                        else
+                        {
+                            context.Error(key, $"The permission 'vulnerability-alerts' is not allowed");
+                        }
+                        break;
                     default:
                         break;
                 }

src/Sdk/WorkflowParser/ObjectTemplating/TemplateContext.cs

@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
 
 using System;
 using System.Collections.Generic;
@@ -113,12 +113,6 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating
         /// </summary>
         internal Boolean StrictJsonParsing { get; set; }
 
-        /// <summary>
-        /// Gets or sets a value indicating whether the case expression function is allowed.
-        /// Defaults to true. Set to false to disable the case function.
-        /// </summary>
-        internal Boolean AllowCaseFunction { get; set; } = true;
-
         internal ITraceWriter TraceWriter { get; set; }
 
         private IDictionary<String, Int32> FileIds

src/Sdk/WorkflowParser/ObjectTemplating/Tokens/TemplateToken.cs

@@ -1,4 +1,4 @@
-#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
+#nullable disable // Consider removing in the future to minimize likelihood of NullReferenceException; refer https://learn.microsoft.com/en-us/dotnet/csharp/nullable-references
 
 using System;
 using System.Collections.Generic;
@@ -55,7 +55,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -93,7 +93,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -123,7 +123,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -153,7 +153,7 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
             var originalBytes = context.Memory.CurrentBytes;
             try
             {
-                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions, allowCaseFunction: context.AllowCaseFunction);
+                var tree = new ExpressionParser().CreateTree(expression, null, context.GetExpressionNamedValues(), context.ExpressionFunctions);
                 var options = new EvaluationOptions
                 {
                     MaxMemory = context.Memory.MaxBytes,
@@ -289,4 +289,4 @@ namespace GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens
             return result;
         }
     }
-}
+}

src/Sdk/WorkflowParser/Permissions.cs

@@ -32,6 +32,7 @@ namespace GitHub.Actions.WorkflowParser
             SecurityEvents = copy.SecurityEvents;
             IdToken = copy.IdToken;
             Models = copy.Models;
+            VulnerabilityAlerts = copy.VulnerabilityAlerts;
         }
 
         public Permissions(
@@ -61,6 +62,19 @@ namespace GitHub.Actions.WorkflowParser
                 : PermissionLevel.NoAccess;
         }
 
+        public Permissions(
+            PermissionLevel permissionLevel,
+            bool includeIdToken,
+            bool includeAttestations,
+            bool includeModels,
+            bool includeVulnerabilityAlerts)
+            : this(permissionLevel, includeIdToken, includeAttestations, includeModels)
+        {
+            VulnerabilityAlerts = includeVulnerabilityAlerts
+                ? (permissionLevel == PermissionLevel.Write ? PermissionLevel.Read : permissionLevel)
+                : PermissionLevel.NoAccess;
+        }
+
         private static KeyValuePair<string, (PermissionLevel, PermissionLevel)>[] ComparisonKeyMapping(Permissions left, Permissions right)
         {
             return new[]
@@ -81,6 +95,7 @@ namespace GitHub.Actions.WorkflowParser
                 new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("security-events", (left.SecurityEvents, right.SecurityEvents)),
                 new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("id-token", (left.IdToken, right.IdToken)),
                 new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("models", (left.Models, right.Models)),
+                new KeyValuePair<string, (PermissionLevel, PermissionLevel)>("vulnerability-alerts", (left.VulnerabilityAlerts, right.VulnerabilityAlerts)),
             };
         }
 
@@ -154,6 +169,13 @@ namespace GitHub.Actions.WorkflowParser
             set;
         }
 
+        [DataMember(Name = "vulnerability-alerts", EmitDefaultValue = false)]
+        public PermissionLevel VulnerabilityAlerts
+        {
+            get;
+            set;
+        }
+
         [DataMember(Name = "packages", EmitDefaultValue = false)]
         public PermissionLevel Packages
         {

src/Sdk/WorkflowParser/WorkflowFeatures.cs

@@ -41,6 +41,13 @@ namespace GitHub.Actions.WorkflowParser
         [DataMember(EmitDefaultValue = false)]
         public bool AllowModelsPermission { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether users may use the "vulnerability-alerts" permission.
+        /// Used during parsing only.
+        /// </summary>
+        [DataMember(EmitDefaultValue = false)]
+        public bool AllowVulnerabilityAlertsPermission { get; set; }
+
         /// <summary>
         /// Gets or sets a value indicating whether the expression function fromJson performs strict JSON parsing.
         /// Used during evaluation only.
@@ -67,6 +74,7 @@ namespace GitHub.Actions.WorkflowParser
                 Snapshot = false,           // Default to false since this feature is still in an experimental phase
                 StrictJsonParsing = false,  // Default to false since this is temporary for telemetry purposes only
                 AllowModelsPermission = false, // Default to false since we want this to be disabled for all non-production environments
+                AllowVulnerabilityAlertsPermission = false, // Default to false since we want this to be disabled for all non-production environments
                 AllowServiceContainerCommand = false, // Default to false since this feature is gated by actions_service_container_command
             };
         }

src/Sdk/WorkflowParser/workflow-v1.0.json

@@ -496,8 +496,8 @@
     "check-suite-activity": {
       "description": "The types of check suite activity that trigger the workflow. Supported activity types: `completed`.",
       "one-of": [
-         "check-suite-activity-type",
-         "check-suite-activity-types"
+        "check-suite-activity-type",
+        "check-suite-activity-types"
       ]
     },
     "check-suite-activity-types": {
@@ -1865,11 +1865,15 @@
           },
           "security-events": {
             "type": "permission-level-any",
-            "description": "Code scanning and Dependabot alerts."
+            "description": "Code scanning alerts."
           },
           "statuses": {
             "type": "permission-level-any",
             "description": "Commit statuses."
+          },
+          "vulnerability-alerts": {
+            "type": "permission-level-read-or-no-access",
+            "description": "Dependabot alerts."
           }
         }
       }

src/Test/L0/ConstantGenerationL0.cs

@@ -24,7 +24,10 @@ namespace GitHub.Runner.Common.Tests
                 "osx-arm64"
             };
 
-            Assert.Equal(40, BuildConstants.Source.CommitHash.Length);
+            Assert.True(
+                BuildConstants.Source.CommitHash.Length == 40 || BuildConstants.Source.CommitHash.Length == 64,
+                "CommitHash should be a 40-char SHA-1 or 64-char SHA-256 hex string");
+            Assert.Matches("^[0-9a-f]+$", BuildConstants.Source.CommitHash);
             Assert.True(validPackageNames.Contains(BuildConstants.RunnerPackage.PackageName), $"PackageName should be one of the following '{string.Join(", ", validPackageNames)}', current PackageName is '{BuildConstants.RunnerPackage.PackageName}'");
         }
     }

src/Test/L0/Listener/RunnerL0.cs

@@ -14,7 +14,7 @@ using Pipelines = GitHub.DistributedTask.Pipelines;
 
 namespace GitHub.Runner.Common.Tests.Listener
 {
-    public sealed class RunnerL0
+    public sealed class RunnerL0 : IDisposable
     {
         private Mock<IConfigurationManager> _configurationManager;
         private Mock<IJobNotification> _jobNotification;
@@ -29,6 +29,7 @@ namespace GitHub.Runner.Common.Tests.Listener
         private Mock<ICredentialManager> _credentialManager;
         private Mock<IActionsRunServer> _actionsRunServer;
         private Mock<IRunServer> _runServer;
+        private readonly string _returnJobResultForHosted;
 
         public RunnerL0()
         {
@@ -45,6 +46,14 @@ namespace GitHub.Runner.Common.Tests.Listener
             _credentialManager = new Mock<ICredentialManager>();
             _actionsRunServer = new Mock<IActionsRunServer>();
             _runServer = new Mock<IRunServer>();
+
+            _returnJobResultForHosted = Environment.GetEnvironmentVariable("ACTIONS_RUNNER_RETURN_JOB_RESULT_FOR_HOSTED");
+            Environment.SetEnvironmentVariable("ACTIONS_RUNNER_RETURN_JOB_RESULT_FOR_HOSTED", null);
+        }
+
+        public void Dispose()
+        {
+            Environment.SetEnvironmentVariable("ACTIONS_RUNNER_RETURN_JOB_RESULT_FOR_HOSTED", _returnJobResultForHosted);
         }
 
         private Pipelines.AgentJobRequestMessage CreateJobRequestMessage(string jobName)

src/Test/L0/Sdk/ExpressionParserL0.cs

@@ -1,4 +1,4 @@
-using GitHub.DistributedTask.Expressions2;
+using GitHub.DistributedTask.Expressions2;
 using GitHub.DistributedTask.Expressions2.Sdk;
 using GitHub.DistributedTask.ObjectTemplating;
 using System;
@@ -9,7 +9,7 @@ namespace GitHub.Runner.Common.Tests.Sdk
 {
     /// <summary>
     /// Regression tests for ExpressionParser.CreateTree to verify that
-    /// allowCaseFunction does not accidentally set allowUnknownKeywords.
+    /// the case function does not accidentally set allowUnknownKeywords.
     /// </summary>
     public sealed class ExpressionParserL0
     {
@@ -18,7 +18,7 @@ namespace GitHub.Runner.Common.Tests.Sdk
         [Trait("Category", "Sdk")]
         public void CreateTree_RejectsUnrecognizedNamedValue()
         {
-            // Regression: allowCaseFunction was passed positionally into
+            // Regression: the case function parameter was passed positionally into
             // the allowUnknownKeywords parameter, causing all named values
             // to be silently accepted.
             var parser = new ExpressionParser();
@@ -52,7 +52,7 @@ namespace GitHub.Runner.Common.Tests.Sdk
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Sdk")]
-        public void CreateTree_CaseFunctionWorks_WhenAllowed()
+        public void CreateTree_CaseFunctionWorks()
         {
             var parser = new ExpressionParser();
             var namedValues = new List<INamedValueInfo>
@@ -60,35 +60,17 @@ namespace GitHub.Runner.Common.Tests.Sdk
                 new NamedValueInfo<ContextValueNode>("github"),
             };
 
-            var node = parser.CreateTree("case(github.event_name, 'push', 'Push Event')", null, namedValues, null, allowCaseFunction: true);
+            var node = parser.CreateTree("case(github.event_name, 'push', 'Push Event')", null, namedValues, null);
 
             Assert.NotNull(node);
         }
 
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Sdk")]
-        public void CreateTree_CaseFunctionRejected_WhenDisallowed()
-        {
-            var parser = new ExpressionParser();
-            var namedValues = new List<INamedValueInfo>
-            {
-                new NamedValueInfo<ContextValueNode>("github"),
-            };
-
-            var ex = Assert.Throws<ParseException>(() =>
-                parser.CreateTree("case(github.event_name, 'push', 'Push Event')", null, namedValues, null, allowCaseFunction: false));
-
-            Assert.Contains("Unrecognized function", ex.Message);
-        }
-
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Sdk")]
         public void CreateTree_CaseFunctionDoesNotAffectUnknownKeywords()
         {
-            // The key regression test: with allowCaseFunction=true (default),
-            // unrecognized named values must still be rejected.
+            // The key regression test: unrecognized named values must still be rejected.
             var parser = new ExpressionParser();
             var namedValues = new List<INamedValueInfo>
             {
@@ -96,7 +78,7 @@ namespace GitHub.Runner.Common.Tests.Sdk
             };
 
             var ex = Assert.Throws<ParseException>(() =>
-                parser.CreateTree("github.ref", null, namedValues, null, allowCaseFunction: true));
+                parser.CreateTree("github.ref", null, namedValues, null));
 
             Assert.Contains("Unrecognized named-value", ex.Message);
         }

src/Test/L0/Sdk/RSWebApi/AgentJobRequestMessageL0.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.IO;
 using System.Runtime.Serialization.Json;
 using System.Text;
@@ -17,13 +17,13 @@ public sealed class AgentJobRequestMessageL0
         // Arrange
         var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
         string jsonWithEnabledDebugger = DoubleQuotify("{'EnableDebugger': true}");
-        
+
         // Act
         using var stream = new MemoryStream();
         stream.Write(Encoding.UTF8.GetBytes(jsonWithEnabledDebugger));
         stream.Position = 0;
         var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-        
+
         // Assert
         Assert.NotNull(recoveredMessage);
         Assert.True(recoveredMessage.EnableDebugger, "EnableDebugger should be true when JSON contains 'EnableDebugger': true");
@@ -37,13 +37,13 @@ public sealed class AgentJobRequestMessageL0
         // Arrange
         var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
         string jsonWithoutDebugger = DoubleQuotify("{'messageType': 'PipelineAgentJobRequest'}");
-        
+
         // Act
         using var stream = new MemoryStream();
         stream.Write(Encoding.UTF8.GetBytes(jsonWithoutDebugger));
         stream.Position = 0;
         var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-        
+
         // Assert
         Assert.NotNull(recoveredMessage);
         Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should default to false when JSON field is absent");
@@ -57,18 +57,130 @@ public sealed class AgentJobRequestMessageL0
         // Arrange
         var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
         string jsonWithDisabledDebugger = DoubleQuotify("{'EnableDebugger': false}");
-        
+
         // Act
         using var stream = new MemoryStream();
         stream.Write(Encoding.UTF8.GetBytes(jsonWithDisabledDebugger));
         stream.Position = 0;
         var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-        
+
         // Assert
         Assert.NotNull(recoveredMessage);
         Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should be false when JSON contains 'EnableDebugger': false");
     }
 
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyDebuggerTunnelDeserialization_WithTunnel()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage), new DataContractJsonSerializerSettings
+        {
+            KnownTypes = new[] { typeof(DebuggerTunnelInfo) }
+        });
+        string json = DoubleQuotify(
+            "{'EnableDebugger': true, 'DebuggerTunnel': {'TunnelId': 'tun-123', 'ClusterId': 'use2', 'HostToken': 'tok-abc', 'Port': 4711}}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.True(recoveredMessage.EnableDebugger);
+        Assert.NotNull(recoveredMessage.DebuggerTunnel);
+        Assert.Equal("tun-123", recoveredMessage.DebuggerTunnel.TunnelId);
+        Assert.Equal("use2", recoveredMessage.DebuggerTunnel.ClusterId);
+        Assert.Equal("tok-abc", recoveredMessage.DebuggerTunnel.HostToken);
+        Assert.Equal(4711, recoveredMessage.DebuggerTunnel.Port);
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyDebuggerTunnelDeserialization_WithoutTunnel()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string json = DoubleQuotify("{'EnableDebugger': true}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.True(recoveredMessage.EnableDebugger);
+        Assert.Null(recoveredMessage.DebuggerTunnel);
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyActionsDependenciesDeserialization_WithDependencies()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string json = DoubleQuotify("{'dependencies': ['actions/checkout@v4:sha256-abc123', 'actions/setup-node@v4:sha256-def456']}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.Equal(2, recoveredMessage.ActionsDependencies.Count);
+        Assert.Equal("actions/checkout@v4:sha256-abc123", recoveredMessage.ActionsDependencies[0]);
+        Assert.Equal("actions/setup-node@v4:sha256-def456", recoveredMessage.ActionsDependencies[1]);
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyActionsDependenciesDeserialization_DefaultsToEmpty()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string json = DoubleQuotify("{'messageType': 'PipelineAgentJobRequest'}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.Empty(recoveredMessage.ActionsDependencies);
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyDebuggerWelcomeMessageRoundTrips()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string json = DoubleQuotify("{'DebuggerWelcomeMessage': 'Welcome to debugging!'}");
+
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(json));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.Equal("Welcome to debugging!", recoveredMessage.DebuggerWelcomeMessage);
+    }
+
     private static string DoubleQuotify(string text)
     {
         return text.Replace('\'', '"');

src/Test/L0/Sdk/WellKnownRegularExpressionsL0.cs

@@ -0,0 +1,100 @@
+using GitHub.DistributedTask.Pipelines.Expressions;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Sdk
+{
+    public sealed class WellKnownRegularExpressionsL0
+    {
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void SHA1_Key_Returns_CommitHash_Regex()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.SHA1);
+
+            Assert.NotNull(regex);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void CommitHash_Key_Returns_CommitHash_Regex()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+
+            Assert.NotNull(regex);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void SHA1_And_CommitHash_Return_Same_Regex()
+        {
+            var sha1Regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.SHA1);
+            var commitHashRegex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+
+            Assert.Same(sha1Regex, commitHashRegex);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void Matches_40_Char_Hex()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+
+            Assert.Matches(regex.Value, new string('a', 40));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void Matches_64_Char_Hex()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+
+            Assert.Matches(regex.Value, new string('a', 64));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void Does_Not_Match_63_Char_Hex()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+
+            Assert.DoesNotMatch(regex.Value, new string('a', 63));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void Does_Not_Match_65_Char_Hex()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+
+            Assert.DoesNotMatch(regex.Value, new string('a', 65));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void Matches_Mixed_Case_64_Char()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex(WellKnownRegularExpressions.CommitHash);
+            var value = new string('A', 32) + new string('b', 32);
+
+            Assert.Matches(regex.Value, value);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Sdk")]
+        public void Unknown_Key_Returns_Null()
+        {
+            var regex = WellKnownRegularExpressions.GetRegex("UnknownType");
+
+            Assert.Null(regex);
+        }
+    }
+}

src/Test/L0/Worker/ActionManagerL0.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.IO;
 using System.IO.Compression;
 using System.Net;
@@ -24,6 +25,7 @@ namespace GitHub.Runner.Common.Tests.Worker
     public sealed class ActionManagerL0
     {
         private const string TestDataFolderName = "TestData";
+        private const string Sha256 = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
         private CancellationTokenSource _ecTokenSource;
         private Mock<IConfigurationStore> _configurationStore;
         private Mock<IDockerCommandManager> _dockerManager;
@@ -333,7 +335,7 @@ runs:
                 await File.WriteAllTextAsync(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions-download-artifact", "action.yml"), Content);
 
 #if OS_WINDOWS
-                ZipFile.CreateFromDirectory(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions-download-artifact"), Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "action_cache", "actions_download-artifact", "master-sha.zip"), CompressionLevel.Fastest, true);
+                ZipFile.CreateFromDirectory(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions-download-artifact"), Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "action_cache", "actions_download-artifact", $"{Sha256}.zip"), CompressionLevel.Fastest, true);
 #else
                 string tar = WhichUtil.Which("tar", require: true, trace: _hc.GetTrace());
 
@@ -359,7 +361,7 @@ runs:
 
                     string cwd = Path.GetDirectoryName(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions-download-artifact"));
                     string inputDirectory = Path.GetFileName(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions-download-artifact"));
-                    string archiveFile = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "action_cache", "actions_download-artifact", "master-sha.tar.gz");
+                    string archiveFile = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "action_cache", "actions_download-artifact", $"{Sha256}.tar.gz");
                     int exitCode = await processInvoker.ExecuteAsync(_hc.GetDirectory(WellKnownDirectory.Bin), tar, $"-czf \"{archiveFile}\" -C \"{cwd}\" \"{inputDirectory}\"", null, CancellationToken.None);
                     if (exitCode != 0)
                     {
@@ -367,6 +369,8 @@ runs:
                     }
                 }
 #endif
+                MockResolvedSha("actions/download-artifact", "master", Sha256);
+
                 var actionId = Guid.NewGuid();
                 var actions = new List<Pipelines.ActionStep>
                 {
@@ -515,9 +519,10 @@ runs:
 
                 string actionsArchive = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions_archive", "action_checkout");
                 Directory.CreateDirectory(actionsArchive);
-                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", "master-sha"));
-                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", "master-sha", "content"));
-                await File.WriteAllTextAsync(Path.Combine(actionsArchive, "actions_checkout", "master-sha", "content", "action.yml"), Content);
+                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", Sha256));
+                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", Sha256, "content"));
+                await File.WriteAllTextAsync(Path.Combine(actionsArchive, "actions_checkout", Sha256, "content", "action.yml"), Content);
+                MockResolvedSha("actions/checkout", "master", Sha256);
                 Environment.SetEnvironmentVariable(Constants.Variables.Agent.ActionArchiveCacheDirectory, actionsArchive);
 
                 //Act
@@ -1254,6 +1259,659 @@ runs:
         }
 #endif
 
+        // =================================================================
+        // Tests for batched action resolution optimization
+        // =================================================================
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_BatchesResolutionAcrossCompositeActions()
+        {
+            // Verifies that when multiple composite actions at the same depth
+            // reference sub-actions, those sub-actions are resolved in a single
+            // batched API call rather than one call per composite.
+            //
+            // Action tree:
+            //   CompositePrestep (composite) → [Node action, CompositePrestep2 (composite)]
+            //   CompositePrestep2 (composite) → [Node action, Docker action]
+            //
+            // Without batching: 3 API calls (depth 0, depth 1 for CompositePrestep, depth 2 for CompositePrestep2)
+            // With batching: still 3 calls at most, but the key is that depth-1
+            //   sub-actions from all composites at depth 0 are batched into 1 call.
+            //   And the same action appearing at multiple depths triggers only 1 resolve.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var resolveCallCount = 0;
+                var resolvedActions = new List<ActionReferenceList>();
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        resolvedActions.Add(actions);
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // The composite tree is:
+                //   depth 0: CompositePrestep
+                //   depth 1: Node@RepositoryActionWithWrapperActionfile_Node + CompositePrestep2
+                //   depth 2: Node@RepositoryActionWithWrapperActionfile_Node + Docker@RepositoryActionWithWrapperActionfile_Docker
+                //
+                // With batching:
+                //   Call 1 (depth 0, resolve): CompositePrestep
+                //   Call 2 (depth 0→1, pre-resolve): Node + CompositePrestep2 in one batch
+                //   Call 3 (depth 1→2, pre-resolve): Docker only (Node already cached from call 2)
+                Assert.Equal(3, resolveCallCount);
+
+                // Call 1: depth 0 resolve — just the top-level composite
+                var call1Keys = resolvedActions[0].Actions.Select(a => $"{a.NameWithOwner}@{a.Ref}").OrderBy(k => k).ToList();
+                Assert.Equal(new[] { "TingluoHuang/runner_L0@CompositePrestep" }, call1Keys);
+
+                // Call 2: depth 0→1 pre-resolve — batch both children of CompositePrestep
+                var call2Keys = resolvedActions[1].Actions.Select(a => $"{a.NameWithOwner}@{a.Ref}").OrderBy(k => k).ToList();
+                Assert.Equal(new[] { "TingluoHuang/runner_L0@CompositePrestep2", "TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Node" }, call2Keys);
+
+                // Call 3: depth 1→2 pre-resolve — only Docker (Node was cached in call 2)
+                var call3Keys = resolvedActions[2].Actions.Select(a => $"{a.NameWithOwner}@{a.Ref}").OrderBy(k => k).ToList();
+                Assert.Equal(new[] { "TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Docker" }, call3Keys);
+
+                // Verify all actions were downloaded
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "CompositePrestep.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "CompositePrestep2.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+
+                // Verify pre-step tracking still works correctly
+                Assert.Equal(1, result.PreStepTracker.Count);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_DeduplicatesResolutionAcrossDepthLevels()
+        {
+            // Verifies that an action appearing at multiple depths in the
+            // composite tree is only resolved once (not re-resolved at each level).
+            //
+            // CompositePrestep uses Node action at depth 1.
+            // CompositePrestep2 (also at depth 1) uses the SAME Node action at depth 2.
+            // The Node action should only be resolved once total.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var allResolvedKeys = new List<string>();
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            allResolvedKeys.Add(key);
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Node appears
+                // at both depth 1 (sub-step of CompositePrestep) and depth 2 (sub-step of
+                // CompositePrestep2). With deduplication it should only be resolved once.
+                var nodeActionKey = "TingluoHuang/runner_L0@RepositoryActionWithWrapperActionfile_Node";
+                var nodeResolveCount = allResolvedKeys.FindAll(k => k == nodeActionKey).Count;
+                Assert.Equal(1, nodeResolveCount);
+
+                // Verify the total number of unique actions resolved matches the tree
+                var uniqueKeys = new HashSet<string>(allResolvedKeys);
+                // Expected unique actions: CompositePrestep, Node, CompositePrestep2, Docker = 4
+                Assert.Equal(4, uniqueKeys.Count);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_MultipleTopLevelActions_BatchesResolution()
+        {
+            // Verifies that multiple independent actions at depth 0 are
+            // resolved in a single API call.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                // Node action has pre+post, needs IActionRunner instances
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var resolveCallCount = 0;
+                var firstCallActionCount = 0;
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        if (resolveCallCount == 1)
+                        {
+                            firstCallActionCount = actions.Actions.Count;
+                        }
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action1",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Node",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action2",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Docker",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // Both actions are at depth 0 — should be resolved in a single batch call
+                Assert.Equal(1, resolveCallCount);
+                Assert.Equal(2, firstCallActionCount);
+
+                // Verify both were downloaded
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+#if OS_LINUX
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_NestedCompositeContainers_BatchedResolution()
+        {
+            // Verifies batching with nested composite actions that reference
+            // container actions (Linux-only since containers require Linux).
+            //
+            // CompositeContainerNested (composite):
+            //   → repositoryactionwithdockerfile (Dockerfile)
+            //   → CompositeContainerNested2 (composite):
+            //       → repositoryactionwithdockerfile (Dockerfile, same as above)
+            //       → notpullorbuildimagesmultipletimes1 (Dockerfile)
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+
+                var resolveCallCount = 0;
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositeContainerNested",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // Tree has 3 depth levels with 5 unique actions.
+                // With batching, should need at most 3 resolve calls (one per depth level).
+                Assert.True(resolveCallCount <= 3, $"Expected at most 3 resolve calls but got {resolveCallCount}");
+
+                // repositoryactionwithdockerfile appears at both depth 1 and depth 2.
+                // Container setup should still work correctly — 2 unique Docker images.
+                Assert.Equal(2, result.ContainerSetupSteps.Count);
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+#endif
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_ParallelDownloads_MultipleUniqueActions()
+        {
+            // Verifies that multiple unique top-level actions are downloaded via
+            // DownloadActionsInParallelAsync (the parallel code path), and that
+            // all actions are correctly resolved and downloaded.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                // Node action has pre step, and CompositePrestep recurses into
+                // sub-actions that also need IActionRunner instances
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                var resolveCallCount = 0;
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        Interlocked.Increment(ref resolveCallCount);
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action1",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Node",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action2",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Docker",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action3",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // 3 unique actions at depth 0 → triggers DownloadActionsInParallelAsync
+                // (parallel path used when uniqueDownloads.Count > 1)
+                var nodeCompleted = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed");
+                var dockerCompleted = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed");
+                var compositeCompleted = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "TingluoHuang/runner_L0", "CompositePrestep.completed");
+
+                Assert.True(File.Exists(nodeCompleted), $"Expected watermark at {nodeCompleted}");
+                Assert.True(File.Exists(dockerCompleted), $"Expected watermark at {dockerCompleted}");
+                Assert.True(File.Exists(compositeCompleted), $"Expected watermark at {compositeCompleted}");
+
+                // All depth-0 actions resolved in a single batch call.
+                // Composite sub-actions may add 1-2 more calls.
+                Assert.True(resolveCallCount >= 1, "Expected at least 1 resolve call");
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_DownloadsNextLevelActionsBeforeRecursing()
+        {
+            // Verifies that depth-1 actions are downloaded before the depth-2
+            // pre-resolve fires. We detect this by snapshotting watermark state
+            // inside the 3rd ResolveActionDownloadInfoAsync callback (which is
+            // the depth-2 pre-resolve). If pre-download works, depth-1 watermarks
+            // already exist at that point.
+            //
+            // Action tree:
+            //   CompositePrestep (composite) → [Node, CompositePrestep2 (composite)]
+            //   CompositePrestep2 (composite) → [Node, Docker]
+            //
+            // Without pre-download: downloads happen during recursion (serial per depth)
+            // With pre-download: depth 1 actions (Node + CompositePrestep2) are
+            //   downloaded in parallel before recursing, so recursion is a no-op
+            //   for downloads.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                // Track watermark state at the time of each resolve call.
+                // If pre-download works, when the 3rd resolve fires (depth 2
+                // pre-resolve for Docker), the depth-1 actions (Node +
+                // CompositePrestep2) should already have watermarks on disk.
+                var resolveCallCount = 0;
+                var watermarksAtResolve3 = new Dictionary<string, bool>();
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        resolveCallCount++;
+                        if (resolveCallCount == 3)
+                        {
+                            // At the time of the 3rd resolve, check if depth-1 actions
+                            // are already downloaded (pre-download should have done this)
+                            var actionsDir2 = _hc.GetDirectory(WellKnownDirectory.Actions);
+                            watermarksAtResolve3["Node"] = File.Exists(Path.Combine(actionsDir2, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed"));
+                            watermarksAtResolve3["CompositePrestep2"] = File.Exists(Path.Combine(actionsDir2, "TingluoHuang/runner_L0", "CompositePrestep2.completed"));
+                        }
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "CompositePrestep",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                // All actions should be downloaded (watermarks exist)
+                var actionsDir = _hc.GetDirectory(WellKnownDirectory.Actions);
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "CompositePrestep.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "CompositePrestep2.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+
+                // 3 resolve calls total
+                Assert.Equal(3, resolveCallCount);
+
+                // The key assertion: at the time of the 3rd resolve call
+                // (pre-resolve for depth 2), the depth-1 actions should
+                // ALREADY be downloaded thanks to pre-download.
+                // Without pre-download, these watermarks wouldn't exist yet
+                // because depth-1 downloads would only happen during recursion.
+                Assert.True(watermarksAtResolve3["Node"],
+                    "Node action should be pre-downloaded before depth 2 pre-resolve");
+                Assert.True(watermarksAtResolve3["CompositePrestep2"],
+                    "CompositePrestep2 should be pre-downloaded before depth 2 pre-resolve");
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_ParallelDownloadsAtSameDepth()
+        {
+            // Verifies that multiple unique actions at the same depth are
+            // downloaded concurrently (Task.WhenAll) rather than sequentially.
+            // We detect this by checking that all watermarks exist after a
+            // single PrepareActionsAsync call with multiple top-level actions.
+            Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", "true");
+            try
+            {
+                //Arrange
+                Setup();
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+                _hc.EnqueueInstance<IActionRunner>(new Mock<IActionRunner>().Object);
+
+                _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>()))
+                    .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                    {
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action1",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Node",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action2",
+                        Id = Guid.NewGuid(),
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "TingluoHuang/runner_L0",
+                            Ref = "RepositoryActionWithWrapperActionfile_Docker",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert - both downloaded (parallel path used when > 1 unique download)
+                var actionsDir = _hc.GetDirectory(WellKnownDirectory.Actions);
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Node.completed")));
+                Assert.True(File.Exists(Path.Combine(actionsDir, "TingluoHuang/runner_L0", "RepositoryActionWithWrapperActionfile_Docker.completed")));
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable("ACTIONS_BATCH_ACTION_RESOLUTION", null);
+                Teardown();
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]
@@ -2495,6 +3153,51 @@ runs:
 #endif
         }
 
+        private void MockResolvedSha(string nameWithOwner, string reference, string resolvedSha)
+        {
+            _jobServer.Setup(x => x.ResolveActionDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<Guid>(), It.IsAny<Guid>(), It.Is<ActionReferenceList>(actions => actions.Actions.Any(action => action.NameWithOwner == nameWithOwner && action.Ref == reference)), It.IsAny<CancellationToken>()))
+                .Returns((Guid scopeIdentifier, string hubName, Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken) =>
+                {
+                    var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                    foreach (var action in actions.Actions)
+                    {
+                        var key = $"{action.NameWithOwner}@{action.Ref}";
+                        result.Actions[key] = new ActionDownloadInfo
+                        {
+                            NameWithOwner = action.NameWithOwner,
+                            Ref = action.Ref,
+                            ResolvedNameWithOwner = action.NameWithOwner,
+                            ResolvedSha = resolvedSha,
+                            TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                            ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                        };
+                    }
+
+                    return Task.FromResult(result);
+                });
+
+            _launchServer.Setup(x => x.ResolveActionsDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<Guid>(), It.Is<ActionReferenceList>(actions => actions.Actions.Any(action => action.NameWithOwner == nameWithOwner && action.Ref == reference)), It.IsAny<CancellationToken>(), It.IsAny<bool>()))
+                .Returns((Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken cancellationToken, bool displayHelpfulActionsDownloadErrors) =>
+                {
+                    var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                    foreach (var action in actions.Actions)
+                    {
+                        var key = $"{action.NameWithOwner}@{action.Ref}";
+                        result.Actions[key] = new ActionDownloadInfo
+                        {
+                            NameWithOwner = action.NameWithOwner,
+                            Ref = action.Ref,
+                            ResolvedNameWithOwner = action.NameWithOwner,
+                            ResolvedSha = resolvedSha,
+                            TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                            ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                        };
+                    }
+
+                    return Task.FromResult(result);
+                });
+        }
+
         private void Setup([CallerMemberName] string name = "", bool enableComposite = true)
         {
             _ecTokenSource?.Dispose();
@@ -2629,5 +3332,141 @@ runs:
                 Directory.Delete(_workFolder, recursive: true);
             }
         }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task GetDownloadInfoAsync_PropagatesDependencies_WhenPresent()
+        {
+            try
+            {
+                // Arrange
+                Setup();
+
+                // Set RunServiceJob so we hit the Launch path
+                _ec.Object.Global.Variables.Set(Constants.Variables.System.JobRequestType, "RunnerJobRequest");
+
+                // Populate lockfile dependencies
+                _ec.Object.Global.ActionsDependencies = new List<string>
+                {
+                    "github.com/actions/checkout@v4:sha256-abc123",
+                    "github.com/actions/setup-node@v4:sha256-def456"
+                };
+
+                // Capture the ActionReferenceList passed to Launch
+                ActionReferenceList capturedList = null;
+                _launchServer
+                    .Setup(x => x.ResolveActionsDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>(), It.IsAny<bool>()))
+                    .Callback<Guid, Guid, ActionReferenceList, CancellationToken, bool>((planId, jobId, list, ct, display) => capturedList = list)
+                    .Returns((Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken ct, bool display) =>
+                    {
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionStep = new Pipelines.ActionStep()
+                {
+                    Name = "action",
+                    Id = Guid.NewGuid(),
+                    Reference = new Pipelines.RepositoryPathReference()
+                    {
+                        Name = "actions/checkout",
+                        Ref = "v4",
+                        RepositoryType = "GitHub"
+                    }
+                };
+
+                // Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, new List<Pipelines.JobStep> { actionStep }, default);
+
+                // Assert
+                Assert.NotNull(capturedList);
+                Assert.NotNull(capturedList.Dependencies);
+                Assert.Equal(2, capturedList.Dependencies.Count);
+                Assert.Equal("github.com/actions/checkout@v4:sha256-abc123", capturedList.Dependencies[0]);
+                Assert.Equal("github.com/actions/setup-node@v4:sha256-def456", capturedList.Dependencies[1]);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task GetDownloadInfoAsync_OmitsDependencies_WhenEmpty()
+        {
+            try
+            {
+                // Arrange
+                Setup();
+
+                // Set RunServiceJob so we hit the Launch path
+                _ec.Object.Global.Variables.Set(Constants.Variables.System.JobRequestType, "RunnerJobRequest");
+
+                // No dependencies set (default empty list from GlobalContext)
+
+                // Capture the ActionReferenceList passed to Launch
+                ActionReferenceList capturedList = null;
+                _launchServer
+                    .Setup(x => x.ResolveActionsDownloadInfoAsync(It.IsAny<Guid>(), It.IsAny<Guid>(), It.IsAny<ActionReferenceList>(), It.IsAny<CancellationToken>(), It.IsAny<bool>()))
+                    .Callback<Guid, Guid, ActionReferenceList, CancellationToken, bool>((planId, jobId, list, ct, display) => capturedList = list)
+                    .Returns((Guid planId, Guid jobId, ActionReferenceList actions, CancellationToken ct, bool display) =>
+                    {
+                        var result = new ActionDownloadInfoCollection { Actions = new Dictionary<string, ActionDownloadInfo>() };
+                        foreach (var action in actions.Actions)
+                        {
+                            var key = $"{action.NameWithOwner}@{action.Ref}";
+                            result.Actions[key] = new ActionDownloadInfo
+                            {
+                                NameWithOwner = action.NameWithOwner,
+                                Ref = action.Ref,
+                                ResolvedNameWithOwner = action.NameWithOwner,
+                                ResolvedSha = $"{action.Ref}-sha",
+                                TarballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/tarball/{action.Ref}",
+                                ZipballUrl = $"https://api.github.com/repos/{action.NameWithOwner}/zipball/{action.Ref}",
+                            };
+                        }
+                        return Task.FromResult(result);
+                    });
+
+                var actionStep = new Pipelines.ActionStep()
+                {
+                    Name = "action",
+                    Id = Guid.NewGuid(),
+                    Reference = new Pipelines.RepositoryPathReference()
+                    {
+                        Name = "actions/checkout",
+                        Ref = "v4",
+                        RepositoryType = "GitHub"
+                    }
+                };
+
+                // Act
+                var result = await _actionManager.PrepareActionsAsync(_ec.Object, new List<Pipelines.JobStep> { actionStep }, default);
+
+                // Assert
+                Assert.NotNull(capturedList);
+                Assert.Null(capturedList.Dependencies);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
     }
 }

src/Test/L0/Worker/ActionManifestManagerL0.cs

@@ -504,7 +504,7 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
-         [Fact]
+        [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]
         public void Load_Node24Action()
@@ -1006,6 +1006,45 @@ namespace GitHub.Runner.Common.Tests.Worker
             _ec.Setup(x => x.AddIssue(It.IsAny<Issue>(), It.IsAny<ExecutionContextLogOptions>())).Callback((Issue issue, ExecutionContextLogOptions logOptions) => { _hc.GetTrace().Info($"[{issue.Type}]{logOptions.LogMessageOverride ?? issue.Message}"); });
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Evaluate_Default_Input_Case_Function()
+        {
+            try
+            {
+                //Arrange
+                Setup();
+
+                var actionManifest = new ActionManifestManager();
+                actionManifest.Initialize(_hc);
+
+                _ec.Object.ExpressionValues["github"] = new LegacyContextData.DictionaryContextData
+                {
+                    { "ref", new LegacyContextData.StringContextData("refs/heads/main") },
+                };
+                _ec.Object.ExpressionValues["strategy"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["matrix"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["steps"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["job"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["runner"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["env"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionFunctions.Add(new LegacyExpressions.FunctionInfo<GitHub.Runner.Worker.Expressions.HashFilesFunction>("hashFiles", 1, 255));
+
+                // Act — evaluate a case() expression as a default input value.
+                // The feature flag is set, so this should succeed.
+                var token = new BasicExpressionToken(null, null, null, "case(true, 'matched', 'default')");
+                var result = actionManifest.EvaluateDefaultInput(_ec.Object, "testInput", token);
+
+                // Assert — case() should evaluate successfully
+                Assert.Equal("matched", result);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
         private void Teardown()
         {
             _hc?.Dispose();

src/Test/L0/Worker/DapReplExecutorL0.cs

@@ -5,9 +5,12 @@ using System.Threading;
 using System.Threading.Tasks;
 using GitHub.DistributedTask.Expressions2;
 using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common.Tests;
 using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Container;
 using GitHub.Runner.Worker.Dap;
+using GitHub.Runner.Worker.Handlers;
 using Moq;
 using Xunit;
 
@@ -40,7 +43,8 @@ namespace GitHub.Runner.Common.Tests.Worker
 
         private Mock<IExecutionContext> CreateMockContext(
             DictionaryContextData exprValues = null,
-            IDictionary<string, IDictionary<string, string>> jobDefaults = null)
+            IDictionary<string, IDictionary<string, string>> jobDefaults = null,
+            ContainerInfo container = null)
         {
             var mock = new Mock<IExecutionContext>();
             mock.Setup(x => x.ExpressionValues).Returns(exprValues ?? new DictionaryContextData());
@@ -51,6 +55,7 @@ namespace GitHub.Runner.Common.Tests.Worker
                 PrependPath = new List<string>(),
                 JobDefaults = jobDefaults
                     ?? new Dictionary<string, IDictionary<string, string>>(StringComparer.OrdinalIgnoreCase),
+                Container = container,
             };
             mock.Setup(x => x.Global).Returns(global);
 
@@ -65,7 +70,7 @@ namespace GitHub.Runner.Common.Tests.Worker
             using (CreateTestContext())
             {
                 var command = new RunCommand { Script = "echo hello" };
-                var result = await _executor.ExecuteRunCommandAsync(command, null, CancellationToken.None);
+                var result = await _executor.ExecuteRunCommandAsync(command, null, false, CancellationToken.None);
 
                 Assert.Equal("error", result.Type);
                 Assert.Contains("No execution context available", result.Result);
@@ -233,5 +238,101 @@ namespace GitHub.Runner.Common.Tests.Worker
                 Assert.False(result.ContainsKey("BAZ"));
             }
         }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CreateStepHost_NoContainer_ReturnsDefaultStepHost()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.EnqueueInstance<IDefaultStepHost>(new DefaultStepHost());
+                var context = CreateMockContext();
+                var result = _executor.CreateStepHost(context.Object, isActionStep: true);
+
+                Assert.IsType<DefaultStepHost>(result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CreateStepHost_WithContainer_ActionStep_ReturnsContainerStepHost()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.EnqueueInstance<IContainerStepHost>(new ContainerStepHost());
+                var container = new ContainerInfo { ContainerId = "abc123" };
+                var context = CreateMockContext(container: container);
+                var result = _executor.CreateStepHost(context.Object, isActionStep: true);
+
+                Assert.IsType<ContainerStepHost>(result);
+                var containerHost = (ContainerStepHost)result;
+                Assert.Same(container, containerHost.Container);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CreateStepHost_WithContainer_InfrastructureStep_ReturnsDefaultStepHost()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.EnqueueInstance<IDefaultStepHost>(new DefaultStepHost());
+                var container = new ContainerInfo { ContainerId = "abc123" };
+                var context = CreateMockContext(container: container);
+                var result = _executor.CreateStepHost(context.Object, isActionStep: false);
+
+                Assert.IsType<DefaultStepHost>(result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CreateStepHost_ContainerWithoutId_NoHooks_ReturnsDefaultStepHost()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.EnqueueInstance<IDefaultStepHost>(new DefaultStepHost());
+                // Container exists but hasn't been started yet (no ContainerId)
+                var container = new ContainerInfo();
+                var context = CreateMockContext(container: container);
+                var result = _executor.CreateStepHost(context.Object, isActionStep: true);
+
+                Assert.IsType<DefaultStepHost>(result);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CreateStepHost_ContainerWithoutId_HooksEnabled_ReturnsContainerStepHost()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.EnqueueInstance<IContainerStepHost>(new ContainerStepHost());
+                // Container hooks need both the feature flag and the env var
+                Environment.SetEnvironmentVariable("ACTIONS_RUNNER_CONTAINER_HOOKS", "/some/hook/path");
+                try
+                {
+                    var container = new ContainerInfo();
+                    var context = CreateMockContext(container: container);
+                    context.Object.Global.Variables = new Variables(
+                        hc,
+                        new Dictionary<string, VariableValue>
+                        {
+                            { Constants.Runner.Features.AllowRunnerContainerHooks, new VariableValue("true") }
+                        });
+                    var result = _executor.CreateStepHost(context.Object, isActionStep: true);
+                    Assert.IsAssignableFrom<IContainerStepHost>(result);
+                }
+                finally
+                {
+                    Environment.SetEnvironmentVariable("ACTIONS_RUNNER_CONTAINER_HOOKS", null);
+                }
+            }
+        }
     }
 }

src/Test/L0/Worker/ExecutionContextL0.cs

@@ -1203,19 +1203,19 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
-        // TODO: this test can be deleted when `AddCheckRunIdToJobContext` is fully rolled out
+        // AddCheckRunIdToJobContext is now permanently enabled server-side (hardcoded to "true"
+        // in acquirejobhandler.go). The runner always copies ContextData["job"] entries, so the
+        // flag-disabled test is no longer applicable. Replaced with a test that verifies
+        // check_run_id is always hydrated regardless of the flag value.
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]
-        public void InitializeJob_HydratesJobContextWithCheckRunId_FeatureFlagDisabled()
+        public void InitializeJob_HydratesJobContextWithCheckRunId_AlwaysCopied()
         {
             using (TestHostContext hc = CreateTestContext())
             {
-                // Arrange: Create a job request message and make sure the feature flag is disabled
-                var variables = new Dictionary<string, VariableValue>()
-                {
-                    [Constants.Runner.Features.AddCheckRunIdToJobContext] = new VariableValue("false"),
-                };
+                // Arrange: No feature flag set at all
+                var variables = new Dictionary<string, VariableValue>();
                 var jobRequest = new Pipelines.AgentJobRequestMessage(new TaskOrchestrationPlanReference(), new TimelineReference(), Guid.NewGuid(), "some job name", "some job name", null, null, null, variables, new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
                 var pagingLogger = new Moq.Mock<IPagingLogger>();
                 var jobServerQueue = new Moq.Mock<IJobServerQueue>();
@@ -1233,9 +1233,80 @@ namespace GitHub.Runner.Common.Tests.Worker
                 // Act
                 ec.InitializeJob(jobRequest, CancellationToken.None);
 
-                // Assert
+                // Assert: check_run_id is always copied regardless of flag
                 Assert.NotNull(ec.JobContext);
-                Assert.Null(ec.JobContext.CheckRunId); // with the feature flag disabled we should not have added a CheckRunId to the JobContext
+                Assert.Equal(123456, ec.JobContext.CheckRunId);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitializeJob_HydratesJobContextWithWorkflowIdentity()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange
+                var variables = new Dictionary<string, VariableValue>();
+                var jobRequest = new Pipelines.AgentJobRequestMessage(new TaskOrchestrationPlanReference(), new TimelineReference(), Guid.NewGuid(), "some job name", "some job name", null, null, null, variables, new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
+                var pagingLogger = new Moq.Mock<IPagingLogger>();
+                var jobServerQueue = new Moq.Mock<IJobServerQueue>();
+                hc.EnqueueInstance(pagingLogger.Object);
+                hc.SetSingleton(jobServerQueue.Object);
+                var ec = new Runner.Worker.ExecutionContext();
+                ec.Initialize(hc);
+
+                // Arrange: Server sends all 4 workflow identity fields
+                var jobContext = new Pipelines.ContextData.DictionaryContextData();
+                jobContext["workflow_ref"] = new StringContextData("my-org/my-repo/.github/workflows/reusable.yml@refs/heads/main");
+                jobContext["workflow_sha"] = new StringContextData("abc123def456");
+                jobContext["workflow_repository"] = new StringContextData("my-org/my-repo");
+                jobContext["workflow_file_path"] = new StringContextData(".github/workflows/reusable.yml");
+                jobRequest.ContextData["job"] = jobContext;
+                jobRequest.ContextData["github"] = new Pipelines.ContextData.DictionaryContextData();
+
+                // Act
+                ec.InitializeJob(jobRequest, CancellationToken.None);
+
+                // Assert: all properties hydrated from server
+                Assert.NotNull(ec.JobContext);
+                Assert.Equal("my-org/my-repo/.github/workflows/reusable.yml@refs/heads/main", ec.JobContext.WorkflowRef);
+                Assert.Equal("abc123def456", ec.JobContext.WorkflowSha);
+                Assert.Equal("my-org/my-repo", ec.JobContext.WorkflowRepository);
+                Assert.Equal(".github/workflows/reusable.yml", ec.JobContext.WorkflowFilePath);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitializeJob_WorkflowIdentityNotSet_WhenServerSendsNoData()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange: Server sends no workflow identity in job context
+                var variables = new Dictionary<string, VariableValue>();
+                var jobRequest = new Pipelines.AgentJobRequestMessage(new TaskOrchestrationPlanReference(), new TimelineReference(), Guid.NewGuid(), "some job name", "some job name", null, null, null, variables, new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
+                var pagingLogger = new Moq.Mock<IPagingLogger>();
+                var jobServerQueue = new Moq.Mock<IJobServerQueue>();
+                hc.EnqueueInstance(pagingLogger.Object);
+                hc.SetSingleton(jobServerQueue.Object);
+                var ec = new Runner.Worker.ExecutionContext();
+                ec.Initialize(hc);
+
+                // Arrange: empty job context
+                jobRequest.ContextData["job"] = new Pipelines.ContextData.DictionaryContextData();
+                jobRequest.ContextData["github"] = new Pipelines.ContextData.DictionaryContextData();
+
+                // Act
+                ec.InitializeJob(jobRequest, CancellationToken.None);
+
+                // Assert: no workflow identity
+                Assert.NotNull(ec.JobContext);
+                Assert.Null(ec.JobContext.WorkflowRef);
+                Assert.Null(ec.JobContext.WorkflowSha);
+                Assert.Null(ec.JobContext.WorkflowRepository);
+                Assert.Null(ec.JobContext.WorkflowFilePath);
             }
         }
 

src/Test/L0/Worker/JobContextL0.cs

@@ -34,5 +34,109 @@ namespace GitHub.Runner.Common.Tests.Worker
             ctx.CheckRunId = null;
             Assert.Null(ctx.CheckRunId);
         }
+
+        [Fact]
+        public void WorkflowRef_SetAndGet_WorksCorrectly()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowRef = "owner/repo/.github/workflows/ci.yml@refs/heads/main";
+            Assert.Equal("owner/repo/.github/workflows/ci.yml@refs/heads/main", ctx.WorkflowRef);
+            Assert.True(ctx.TryGetValue("workflow_ref", out var value));
+            Assert.IsType<StringContextData>(value);
+        }
+
+        [Fact]
+        public void WorkflowRef_NotSet_ReturnsNull()
+        {
+            var ctx = new JobContext();
+            Assert.Null(ctx.WorkflowRef);
+        }
+
+        [Fact]
+        public void WorkflowRef_SetNull_ClearsValue()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowRef = "owner/repo/.github/workflows/ci.yml@refs/heads/main";
+            ctx.WorkflowRef = null;
+            Assert.Null(ctx.WorkflowRef);
+        }
+
+        [Fact]
+        public void WorkflowSha_SetAndGet_WorksCorrectly()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowSha = "abc123def456";
+            Assert.Equal("abc123def456", ctx.WorkflowSha);
+            Assert.True(ctx.TryGetValue("workflow_sha", out var value));
+            Assert.IsType<StringContextData>(value);
+        }
+
+        [Fact]
+        public void WorkflowSha_NotSet_ReturnsNull()
+        {
+            var ctx = new JobContext();
+            Assert.Null(ctx.WorkflowSha);
+        }
+
+        [Fact]
+        public void WorkflowSha_SetNull_ClearsValue()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowSha = "abc123def456";
+            ctx.WorkflowSha = null;
+            Assert.Null(ctx.WorkflowSha);
+        }
+
+        [Fact]
+        public void WorkflowRepository_SetAndGet_WorksCorrectly()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowRepository = "owner/repo";
+            Assert.Equal("owner/repo", ctx.WorkflowRepository);
+            Assert.True(ctx.TryGetValue("workflow_repository", out var value));
+            Assert.IsType<StringContextData>(value);
+        }
+
+        [Fact]
+        public void WorkflowRepository_NotSet_ReturnsNull()
+        {
+            var ctx = new JobContext();
+            Assert.Null(ctx.WorkflowRepository);
+        }
+
+        [Fact]
+        public void WorkflowRepository_SetNull_ClearsValue()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowRepository = "owner/repo";
+            ctx.WorkflowRepository = null;
+            Assert.Null(ctx.WorkflowRepository);
+        }
+
+        [Fact]
+        public void WorkflowFilePath_SetAndGet_WorksCorrectly()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowFilePath = ".github/workflows/ci.yml";
+            Assert.Equal(".github/workflows/ci.yml", ctx.WorkflowFilePath);
+            Assert.True(ctx.TryGetValue("workflow_file_path", out var value));
+            Assert.IsType<StringContextData>(value);
+        }
+
+        [Fact]
+        public void WorkflowFilePath_NotSet_ReturnsNull()
+        {
+            var ctx = new JobContext();
+            Assert.Null(ctx.WorkflowFilePath);
+        }
+
+        [Fact]
+        public void WorkflowFilePath_SetNull_ClearsValue()
+        {
+            var ctx = new JobContext();
+            ctx.WorkflowFilePath = ".github/workflows/ci.yml";
+            ctx.WorkflowFilePath = null;
+            Assert.Null(ctx.WorkflowFilePath);
+        }
     }
 }

src/Test/L0/Worker/JobExecutionViewRendererL0.cs

@@ -0,0 +1,598 @@
+using System;
+using System.Collections.Generic;
+using GitHub.Runner.Worker.Dap;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class JobExecutionViewRendererL0
+    {
+        // Verbatim expected YAML for the design doc's "Worked example".
+        // The render output is structured as phase-keyed top-level sections;
+        // there is no per-entry `phase:` field. The setup: and cleanup:
+        // sections always render; pre:/main:/post: render only when
+        // they contain at least one entry. The Main entries surface
+        // user-authored step parameters pre-evaluation (no expression
+        // substitution); Pre/Post entries stay minimal.
+        private const string ExpectedWorkedExampleYaml =
+            "# Job: build\n" +
+            "# Runner execution plan — read-only.\n" +
+            "\n" +
+            "setup:\n" +
+            "  - step: Setup job\n" +
+            "\n" +
+            "pre:\n" +
+            "  - step: Pre actions/checkout@v4\n" +
+            "    action: actions/checkout@v4\n" +
+            "  - step: Pre actions/cache@v5\n" +
+            "    action: actions/cache@v5\n" +
+            "\n" +
+            "main:\n" +
+            "  - step: actions/checkout@v4\n" +
+            "    uses: actions/checkout@v4\n" +
+            "    source: .github/workflows/ci.yml:10\n" +
+            "  - step: Cache Primes\n" +
+            "    id: cache-primes\n" +
+            "    uses: actions/cache@v5\n" +
+            "    with:\n" +
+            "      path: prime-numbers\n" +
+            "      key: ${{ runner.os }}-primes\n" +
+            "    source: .github/workflows/ci.yml:12\n" +
+            "  - step: Run tests\n" +
+            "    id: test\n" +
+            "    run: |\n" +
+            "      echo starting\n" +
+            "      npm test\n" +
+            "    if: ${{ github.event_name == 'push' }}\n" +
+            "    env:\n" +
+            "      NODE_ENV: production\n" +
+            "    shell: bash\n" +
+            "    working-directory: ./api\n" +
+            "    source: .github/workflows/ci.yml:18\n" +
+            "  - step: npm ci\n" +
+            "    run: npm ci\n" +
+            "    source: .github/workflows/ci.yml:28\n" +
+            "\n" +
+            "post:\n" +
+            "  - step: Post actions/cache@v5\n" +
+            "    action: actions/cache@v5\n" +
+            "  - step: Post actions/checkout@v4\n" +
+            "    action: actions/checkout@v4\n" +
+            "\n" +
+            "cleanup:\n" +
+            "  - step: Complete job\n";
+
+        private static List<JobExecutionViewEntry> WorkedExampleEntries()
+        {
+            return new List<JobExecutionViewEntry>
+            {
+                new JobExecutionViewEntry(JobExecutionPhase.Pre, "Pre actions/checkout@v4", uses: "actions/checkout@v4"),
+                new JobExecutionViewEntry(JobExecutionPhase.Pre, "Pre actions/cache@v5", uses: "actions/cache@v5"),
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "actions/checkout@v4", uses: "actions/checkout@v4", sourcePath: ".github/workflows/ci.yml", sourceLine: 10),
+                new JobExecutionViewEntry(
+                    JobExecutionPhase.Main,
+                    "Cache Primes",
+                    uses: "actions/cache@v5",
+                    id: "cache-primes",
+                    withYaml: "      path: prime-numbers\n      key: ${{ runner.os }}-primes",
+                    sourcePath: ".github/workflows/ci.yml",
+                    sourceLine: 12),
+                new JobExecutionViewEntry(
+                    JobExecutionPhase.Main,
+                    "Run tests",
+                    run: "echo starting\nnpm test",
+                    id: "test",
+                    @if: "${{ github.event_name == 'push' }}",
+                    envYaml: "      NODE_ENV: production",
+                    shell: "bash",
+                    workingDirectory: "./api",
+                    sourcePath: ".github/workflows/ci.yml",
+                    sourceLine: 18),
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "npm ci", run: "npm ci", sourcePath: ".github/workflows/ci.yml", sourceLine: 28),
+                new JobExecutionViewEntry(JobExecutionPhase.Post, "Post actions/cache@v5", uses: "actions/cache@v5"),
+                new JobExecutionViewEntry(JobExecutionPhase.Post, "Post actions/checkout@v4", uses: "actions/checkout@v4"),
+            };
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_MatchesDesignDocWorkedExample()
+        {
+            var entries = WorkedExampleEntries();
+
+            var result = JobExecutionViewRenderer.Render("build", entries);
+
+            Assert.Equal(ExpectedWorkedExampleYaml, result.Yaml);
+            Assert.Equal(8, result.EntryStartLines.Count);
+            var lines = result.Yaml.Split('\n');
+            for (int i = 0; i < entries.Count; i++)
+            {
+                Assert.StartsWith("  - step: ", lines[result.EntryStartLines[i] - 1]);
+                Assert.Contains(entries[i].DisplayName, lines[result.EntryStartLines[i] - 1]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_AlwaysEmitsSetupAndCleanup()
+        {
+            var result = JobExecutionViewRenderer.Render("job-1", new List<JobExecutionViewEntry>());
+
+            const string expected =
+                "# Job: job-1\n" +
+                "# Runner execution plan — read-only.\n" +
+                "\n" +
+                "setup:\n" +
+                "  - step: Setup job\n" +
+                "\n" +
+                "cleanup:\n" +
+                "  - step: Complete job\n";
+            Assert.Equal(expected, result.Yaml);
+            Assert.Empty(result.EntryStartLines);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_OmitsEmptyOptionalSections()
+        {
+            // Only a Main entry — pre:/post: must not appear.
+            var result = JobExecutionViewRenderer.Render("j", new[]
+            {
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "echo", run: "echo hello"),
+            });
+
+            Assert.Contains("setup:\n", result.Yaml);
+            Assert.Contains("main:\n", result.Yaml);
+            Assert.Contains("cleanup:\n", result.Yaml);
+            Assert.DoesNotContain("\npre:\n", result.Yaml);
+            Assert.DoesNotContain("\npost:\n", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EmitsPhaseSectionsInFixedOrder()
+        {
+            // Input order [Post, Pre, Main] should still render as setup → pre → main → post → cleanup.
+            var entries = new[]
+            {
+                new JobExecutionViewEntry(JobExecutionPhase.Post, "post-a", uses: "a/b@v1"),
+                new JobExecutionViewEntry(JobExecutionPhase.Pre, "pre-a", uses: "a/b@v1"),
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-a", uses: "a/b@v1"),
+            };
+
+            var result = JobExecutionViewRenderer.Render("j", entries);
+            string yaml = result.Yaml;
+
+            int setupIdx = yaml.IndexOf("setup:\n", StringComparison.Ordinal);
+            int preIdx = yaml.IndexOf("\npre:\n", StringComparison.Ordinal);
+            int mainIdx = yaml.IndexOf("\nmain:\n", StringComparison.Ordinal);
+            int postIdx = yaml.IndexOf("\npost:\n", StringComparison.Ordinal);
+            int cleanupIdx = yaml.IndexOf("\ncleanup:\n", StringComparison.Ordinal);
+            Assert.True(setupIdx >= 0 && preIdx > setupIdx && mainIdx > preIdx && postIdx > mainIdx && cleanupIdx > postIdx,
+                $"section ordering wrong: setup={setupIdx} pre={preIdx} main={mainIdx} post={postIdx} cleanup={cleanupIdx}");
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_StartLinesAlignWithInputOrder()
+        {
+            // Input order is [Pre, Main, Post]; output order is also pre/main/post,
+            // but startLines must be indexed by INPUT position, not by section.
+            var entries = new[]
+            {
+                new JobExecutionViewEntry(JobExecutionPhase.Pre, "pre-x", uses: "x/y@v1"),     // index 0
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-x", uses: "x/y@v1"),    // index 1
+                new JobExecutionViewEntry(JobExecutionPhase.Post, "post-x", uses: "x/y@v1"),    // index 2
+            };
+
+            var result = JobExecutionViewRenderer.Render("j", entries);
+            var lines = result.Yaml.Split('\n');
+
+            Assert.StartsWith("  - step: pre-x", lines[result.EntryStartLines[0] - 1]);
+            Assert.StartsWith("  - step: main-x", lines[result.EntryStartLines[1] - 1]);
+            Assert.StartsWith("  - step: post-x", lines[result.EntryStartLines[2] - 1]);
+            // And input-order ordering of start lines is strictly increasing
+            // when phases are in declaration order matching the section order.
+            Assert.True(result.EntryStartLines[0] < result.EntryStartLines[1]);
+            Assert.True(result.EntryStartLines[1] < result.EntryStartLines[2]);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_StartLinesFollowInputOrderEvenWhenPhasesAreInterleaved()
+        {
+            // Input order is [Main A, Pre B, Main C]: pre section will render
+            // first (Pre B) and main second (Main A then Main C). startLines
+            // must still be indexed by input order.
+            var entries = new[]
+            {
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-a", uses: "a@v1"),  // index 0 — renders in main section
+                new JobExecutionViewEntry(JobExecutionPhase.Pre, "pre-b", uses: "b@v1"),    // index 1 — renders in pre section
+                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-c", uses: "c@v1"),  // index 2 — renders in main section
+            };
+
+            var result = JobExecutionViewRenderer.Render("j", entries);
+            var lines = result.Yaml.Split('\n');
+
+            Assert.StartsWith("  - step: main-a", lines[result.EntryStartLines[0] - 1]);
+            Assert.StartsWith("  - step: pre-b", lines[result.EntryStartLines[1] - 1]);
+            Assert.StartsWith("  - step: main-c", lines[result.EntryStartLines[2] - 1]);
+            // The pre section comes before main: input-index-1 entry's line is
+            // before input-index-0 entry's line.
+            Assert.True(result.EntryStartLines[1] < result.EntryStartLines[0]);
+            Assert.True(result.EntryStartLines[0] < result.EntryStartLines[2]);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EntryStartLinesPointAtStepKeys()
+        {
+            var entries = WorkedExampleEntries();
+            var result = JobExecutionViewRenderer.Render("build", entries);
+            var lines = result.Yaml.Split('\n');
+
+            for (int i = 0; i < result.EntryStartLines.Count; i++)
+            {
+                int oneBased = result.EntryStartLines[i];
+                Assert.True(oneBased >= 1 && oneBased <= lines.Length, $"start line {oneBased} out of range");
+                Assert.StartsWith("  - step: ", lines[oneBased - 1]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EntryStartLinesExcludeSetupAndCleanup()
+        {
+            var entries = WorkedExampleEntries();
+            var result = JobExecutionViewRenderer.Render("build", entries);
+            var lines = result.Yaml.Split('\n');
+
+            int setupLine = -1, cleanupLine = -1;
+            for (int i = 0; i < lines.Length; i++)
+            {
+                if (lines[i] == "  - step: Setup job") setupLine = i + 1;
+                if (lines[i] == "  - step: Complete job") cleanupLine = i + 1;
+            }
+            Assert.True(setupLine > 0 && cleanupLine > 0, "Setup/Cleanup lines must exist");
+            Assert.DoesNotContain(setupLine, result.EntryStartLines);
+            Assert.DoesNotContain(cleanupLine, result.EntryStartLines);
+        }
+
+        [Theory]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        [InlineData("hello")]
+        [InlineData("with: colon")]
+        [InlineData("with#hash")]
+        [InlineData(" leading")]
+        [InlineData("trailing ")]
+        [InlineData("a\"b")]
+        [InlineData("a\\b")]
+        [InlineData("@at")]
+        [InlineData("*star")]
+        public void Render_QuotesSpecialChars(string displayName)
+        {
+            // Round-trip the rendered YAML through YamlDotNet's deserializer
+            // and assert the parsed step's display name matches the input.
+            // This decouples the test from any specific quoting style.
+            var entry = new JobExecutionViewEntry(JobExecutionPhase.Main, displayName);
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+
+            var deserializer = new YamlDotNet.Serialization.DeserializerBuilder().Build();
+            var doc = deserializer.Deserialize<Dictionary<string, List<Dictionary<string, object>>>>(result.Yaml);
+            Assert.NotNull(doc);
+            Assert.True(doc.ContainsKey("main"), "rendered YAML missing top-level 'main' key");
+            var mainSteps = doc["main"];
+            Assert.Single(mainSteps);
+            Assert.Equal(displayName, mainSteps[0]["step"] as string);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EmitsSourceAnnotationForMainStep()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "npm ci",
+                run: "npm ci",
+                sourcePath: ".github/workflows/ci.yml",
+                sourceLine: 42);
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+
+            Assert.Contains("    source: .github/workflows/ci.yml:42\n", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_OmitsSourceAnnotationForPreAndPost()
+        {
+            var pre = new JobExecutionViewEntry(
+                JobExecutionPhase.Pre,
+                "Pre actions/checkout@v4",
+                uses: "actions/checkout@v4",
+                sourcePath: ".github/workflows/ci.yml",
+                sourceLine: 9);
+            var post = new JobExecutionViewEntry(
+                JobExecutionPhase.Post,
+                "Post actions/checkout@v4",
+                uses: "actions/checkout@v4",
+                sourcePath: ".github/workflows/ci.yml",
+                sourceLine: 9);
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { pre, post });
+
+            Assert.DoesNotContain("source:", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EmitsMultilineRunAsBlockScalar()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "multi",
+                run: "echo a\necho b\necho c");
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+
+            Assert.Contains("    run: |\n", result.Yaml);
+            Assert.Contains("      echo a\n", result.Yaml);
+            Assert.Contains("      echo b\n", result.Yaml);
+            Assert.Contains("      echo c\n", result.Yaml);
+            Assert.DoesNotContain("truncated", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EmitsAllUserAuthoredParamsForActionStep()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "Run action",
+                uses: "actions/cache@v5",
+                id: "cache-primes",
+                @if: "${{ github.event_name == 'push' }}",
+                continueOnError: "true",
+                timeoutMinutes: "10",
+                envYaml: "      NODE_ENV: production",
+                withYaml: "      path: prime-numbers\n      key: ${{ runner.os }}-primes",
+                sourcePath: "ci.yml",
+                sourceLine: 5);
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+
+            Assert.Contains("    id: cache-primes\n", result.Yaml);
+            Assert.Contains("    uses: actions/cache@v5\n", result.Yaml);
+            Assert.Contains("    continue-on-error: true\n", result.Yaml);
+            Assert.Contains("    timeout-minutes: 10\n", result.Yaml);
+            Assert.Contains("    env:\n      NODE_ENV: production\n", result.Yaml);
+            Assert.Contains("    with:\n      path: prime-numbers\n      key: ${{ runner.os }}-primes\n", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_EmitsRunStepWithShellAndWorkingDirectory()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "Run tests",
+                run: "echo starting\nnpm test",
+                id: "test",
+                shell: "bash",
+                workingDirectory: "./api");
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+
+            Assert.Contains("    run: |\n      echo starting\n      npm test\n", result.Yaml);
+            Assert.Contains("    shell: bash\n", result.Yaml);
+            Assert.Contains("    working-directory: ./api\n", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_PreservesExpressionsInRenderedYaml()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "Cache",
+                uses: "actions/cache@v5",
+                withYaml: "      key: ${{ runner.os }}-primes");
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+
+            // Expressions render exactly as authored — no evaluation.
+            Assert.Contains("${{ runner.os }}-primes", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_PrePostStepsRemainMinimal()
+        {
+            // Even if a pre/post entry carries user-param fields (it shouldn't
+            // in production, but the renderer must defensively drop them),
+            // only step: + action: render for these phases.
+            var pre = new JobExecutionViewEntry(
+                JobExecutionPhase.Pre,
+                "Pre actions/cache@v5",
+                uses: "actions/cache@v5",
+                id: "should-not-appear",
+                envYaml: "      X: y",
+                withYaml: "      key: nope");
+            var post = new JobExecutionViewEntry(
+                JobExecutionPhase.Post,
+                "Post actions/cache@v5",
+                uses: "actions/cache@v5",
+                id: "should-not-appear",
+                envYaml: "      X: y");
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { pre, post });
+
+            Assert.DoesNotContain("id:", result.Yaml);
+            Assert.DoesNotContain("env:", result.Yaml);
+            Assert.DoesNotContain("with:", result.Yaml);
+            Assert.DoesNotContain("should-not-appear", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_FieldOrderIsStable()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "Everything",
+                uses: "actions/cache@v5",
+                id: "x",
+                @if: "always()",
+                continueOnError: "false",
+                timeoutMinutes: "5",
+                envYaml: "      A: 1",
+                withYaml: "      key: k",
+                sourcePath: "ci.yml",
+                sourceLine: 1);
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+            var y = result.Yaml;
+            int iStep = y.IndexOf("    - step: ", StringComparison.Ordinal) >= 0
+                ? y.IndexOf("- step:", StringComparison.Ordinal) : y.IndexOf("- step:", StringComparison.Ordinal);
+            int iId = y.IndexOf("    id:", StringComparison.Ordinal);
+            int iUses = y.IndexOf("    uses:", StringComparison.Ordinal);
+            int iIf = y.IndexOf("    if:", StringComparison.Ordinal);
+            int iCoe = y.IndexOf("    continue-on-error:", StringComparison.Ordinal);
+            int iTm = y.IndexOf("    timeout-minutes:", StringComparison.Ordinal);
+            int iEnv = y.IndexOf("    env:", StringComparison.Ordinal);
+            int iWith = y.IndexOf("    with:", StringComparison.Ordinal);
+            int iSrc = y.IndexOf("    source:", StringComparison.Ordinal);
+            Assert.True(iId < iUses && iUses < iIf && iIf < iCoe && iCoe < iTm && iTm < iEnv && iEnv < iWith && iWith < iSrc,
+                $"order wrong: id={iId} uses={iUses} if={iIf} coe={iCoe} tm={iTm} env={iEnv} with={iWith} src={iSrc}");
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_OmitsEmptyOptionalFields()
+        {
+            var entry = new JobExecutionViewEntry(
+                JobExecutionPhase.Main,
+                "bare",
+                uses: "a/b@v1");
+
+            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
+            Assert.DoesNotContain("    id:", result.Yaml);
+            Assert.DoesNotContain("    if:", result.Yaml);
+            Assert.DoesNotContain("    continue-on-error:", result.Yaml);
+            Assert.DoesNotContain("    timeout-minutes:", result.Yaml);
+            Assert.DoesNotContain("    env:", result.Yaml);
+            Assert.DoesNotContain("    with:", result.Yaml);
+            Assert.DoesNotContain("    shell:", result.Yaml);
+            Assert.DoesNotContain("    working-directory:", result.Yaml);
+            Assert.DoesNotContain("    source:", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_HandlesEmptyEntries()
+        {
+            var result = JobExecutionViewRenderer.Render("j", new List<JobExecutionViewEntry>());
+
+            Assert.Empty(result.EntryStartLines);
+            Assert.Contains("  - step: Setup job\n", result.Yaml);
+            Assert.Contains("  - step: Complete job\n", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_NoPerEntryPhaseField()
+        {
+            // The phase: <value> per-entry field is gone — the section
+            // header is the phase indicator. Guard against accidental
+            // regressions.
+            var result = JobExecutionViewRenderer.Render("build", WorkedExampleEntries());
+            Assert.DoesNotContain("phase:", result.Yaml);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_ThrowsOnNullJobId()
+        {
+            Assert.Throws<ArgumentException>(
+                () => JobExecutionViewRenderer.Render(null, new List<JobExecutionViewEntry>()));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_ThrowsOnWhitespaceJobId()
+        {
+            Assert.Throws<ArgumentException>(
+                () => JobExecutionViewRenderer.Render("   ", new List<JobExecutionViewEntry>()));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_ThrowsOnNullEntries()
+        {
+            Assert.Throws<ArgumentNullException>(
+                () => JobExecutionViewRenderer.Render("j", null));
+        }
+
+        [Theory]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        [InlineData(null, 1)]
+        [InlineData("", 1)]
+        [InlineData("   ", 1)]
+        public void Entry_Constructor_RejectsBadDisplayName(string displayName, int sourceLine)
+        {
+            Assert.Throws<ArgumentException>(
+                () => new JobExecutionViewEntry(JobExecutionPhase.Main, displayName, sourceLine: sourceLine));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Entry_Constructor_RejectsZeroLineWhenSourcePathSet()
+        {
+            Assert.Throws<ArgumentException>(
+                () => new JobExecutionViewEntry(
+                    JobExecutionPhase.Main,
+                    "ok",
+                    sourcePath: "ci.yml",
+                    sourceLine: 0));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Render_AlwaysUsesLfLineBreaks()
+        {
+            // Regression: YamlDotNet's Emitter calls WriteLine, which on
+            // Windows produces CRLF (the host's Environment.NewLine).
+            // The renderer's hand-emitted skeleton always uses '\n'; this
+            // test asserts the scalar formatter doesn't sneak CRLF in.
+            var entry = new JobExecutionViewEntry(JobExecutionPhase.Main, "with: colon", id: "step-1", uses: "actions/checkout@v4");
+            var result = JobExecutionViewRenderer.Render("job-1", new[] { entry });
+            Assert.DoesNotContain("\r", result.Yaml);
+        }
+    }
+}

src/Test/L0/Worker/JobExtensionL0.cs

@@ -760,5 +760,171 @@ namespace GitHub.Runner.Common.Tests.Worker
             Environment.SetEnvironmentVariable("RUNNER_ENVIRONMENT", null);
             Environment.SetEnvironmentVariable("GITHUB_ACTIONS_IMAGE_GEN_ENABLED", null);
         }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task DebuggerStartedInSetupJobWhenEnabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                var jobExtension = new JobExtension();
+                jobExtension.Initialize(hc);
+
+                // Enable debugger on the message
+                _message.EnableDebugger = true;
+                _message.DebuggerTunnel = new Pipelines.DebuggerTunnelInfo
+                {
+                    TunnelId = "test-tunnel",
+                    ClusterId = "test-cluster",
+                    HostToken = "test-token",
+                    Port = 9229
+                };
+
+                // Re-initialize the execution context so it picks up debugger config
+                _jobEc = new Runner.Worker.ExecutionContext();
+                _jobEc.Initialize(hc);
+                _jobEc.InitializeJob(_message, _tokenSource.Token);
+
+                // Set up mock debugger
+                var mockDebugger = new Mock<IDapDebugger>();
+                mockDebugger.Setup(x => x.StartAsync(It.IsAny<IExecutionContext>())).Returns(Task.CompletedTask);
+                mockDebugger.Setup(x => x.WaitUntilReadyAsync()).Returns(Task.CompletedTask);
+                hc.SetSingleton(mockDebugger.Object);
+
+                _actionManager.Setup(x => x.PrepareActionsAsync(It.IsAny<IExecutionContext>(), It.IsAny<IEnumerable<Pipelines.JobStep>>(), It.IsAny<Guid>()))
+                              .Returns(Task.FromResult(new PrepareResult(new List<JobExtensionRunner>(), new Dictionary<Guid, IActionRunner>())));
+
+                List<IStep> result = await jobExtension.InitializeJob(_jobEc, _message);
+
+                // Verify DAP debugger was started and waited on
+                mockDebugger.Verify(x => x.StartAsync(It.IsAny<IExecutionContext>()), Times.Once);
+                mockDebugger.Verify(x => x.WaitUntilReadyAsync(), Times.Once);
+
+                // Verify steps are still returned correctly
+                Assert.Equal(5, result.Count);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task DebuggerNotStartedInSetupJobWhenDisabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                var jobExtension = new JobExtension();
+                jobExtension.Initialize(hc);
+
+                // Debugger NOT enabled on the message — should not be started
+
+                // Set up mock debugger (should NOT be called)
+                var mockDebugger = new Mock<IDapDebugger>();
+                hc.SetSingleton(mockDebugger.Object);
+
+                _actionManager.Setup(x => x.PrepareActionsAsync(It.IsAny<IExecutionContext>(), It.IsAny<IEnumerable<Pipelines.JobStep>>(), It.IsAny<Guid>()))
+                              .Returns(Task.FromResult(new PrepareResult(new List<JobExtensionRunner>(), new Dictionary<Guid, IActionRunner>())));
+
+                List<IStep> result = await jobExtension.InitializeJob(_jobEc, _message);
+
+                // Verify DAP debugger was NOT started during setup job
+                mockDebugger.Verify(x => x.StartAsync(It.IsAny<IExecutionContext>()), Times.Never);
+                mockDebugger.Verify(x => x.WaitUntilReadyAsync(), Times.Never);
+
+                Assert.Equal(5, result.Count);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task DebuggerCleanedUpInFinalizeJob()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                var jobExtension = new JobExtension();
+                jobExtension.Initialize(hc);
+
+                // Enable debugger on the message
+                _message.EnableDebugger = true;
+                _message.DebuggerTunnel = new Pipelines.DebuggerTunnelInfo
+                {
+                    TunnelId = "test-tunnel",
+                    ClusterId = "test-cluster",
+                    HostToken = "test-token",
+                    Port = 9229
+                };
+
+                // Re-initialize the execution context so it picks up debugger config
+                _jobEc = new Runner.Worker.ExecutionContext();
+                _jobEc.Initialize(hc);
+                _jobEc.InitializeJob(_message, _tokenSource.Token);
+
+                // Set up mock debugger
+                var mockDebugger = new Mock<IDapDebugger>();
+                mockDebugger.Setup(x => x.StartAsync(It.IsAny<IExecutionContext>())).Returns(Task.CompletedTask);
+                mockDebugger.Setup(x => x.WaitUntilReadyAsync()).Returns(Task.CompletedTask);
+                mockDebugger.Setup(x => x.OnJobCompletedAsync()).Returns(Task.CompletedTask);
+                hc.SetSingleton(mockDebugger.Object);
+
+                _actionManager.Setup(x => x.PrepareActionsAsync(It.IsAny<IExecutionContext>(), It.IsAny<IEnumerable<Pipelines.JobStep>>(), It.IsAny<Guid>()))
+                              .Returns(Task.FromResult(new PrepareResult(new List<JobExtensionRunner>(), new Dictionary<Guid, IActionRunner>())));
+
+                // Run InitializeJob to start the debugger
+                await jobExtension.InitializeJob(_jobEc, _message);
+
+                // Run FinalizeJob — should pause (inside OnJobCompletedAsync) then clean up
+                await jobExtension.FinalizeJob(_jobEc, _message, DateTime.UtcNow);
+
+                // Verify OnJobCompletedAsync was called (it handles pause + cleanup)
+                mockDebugger.Verify(x => x.OnJobCompletedAsync(), Times.Once);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task FinalizeJobHandlesDebuggerCleanupException()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                var jobExtension = new JobExtension();
+                jobExtension.Initialize(hc);
+
+                // Enable debugger on the message
+                _message.EnableDebugger = true;
+                _message.DebuggerTunnel = new Pipelines.DebuggerTunnelInfo
+                {
+                    TunnelId = "test-tunnel",
+                    ClusterId = "test-cluster",
+                    HostToken = "test-token",
+                    Port = 9229
+                };
+
+                // Re-initialize the execution context so it picks up debugger config
+                _jobEc = new Runner.Worker.ExecutionContext();
+                _jobEc.Initialize(hc);
+                _jobEc.InitializeJob(_message, _tokenSource.Token);
+
+                // Set up mock debugger — OnJobCompletedAsync throws
+                var mockDebugger = new Mock<IDapDebugger>();
+                mockDebugger.Setup(x => x.StartAsync(It.IsAny<IExecutionContext>())).Returns(Task.CompletedTask);
+                mockDebugger.Setup(x => x.WaitUntilReadyAsync()).Returns(Task.CompletedTask);
+                mockDebugger.Setup(x => x.OnJobCompletedAsync()).ThrowsAsync(new InvalidOperationException("tunnel disposed"));
+                mockDebugger.Setup(x => x.StopAsync()).Returns(Task.CompletedTask);
+                hc.SetSingleton(mockDebugger.Object);
+
+                _actionManager.Setup(x => x.PrepareActionsAsync(It.IsAny<IExecutionContext>(), It.IsAny<IEnumerable<Pipelines.JobStep>>(), It.IsAny<Guid>()))
+                              .Returns(Task.FromResult(new PrepareResult(new List<JobExtensionRunner>(), new Dictionary<Guid, IActionRunner>())));
+
+                await jobExtension.InitializeJob(_jobEc, _message);
+
+                // FinalizeJob should not throw even when OnJobCompletedAsync throws
+                await jobExtension.FinalizeJob(_jobEc, _message, DateTime.UtcNow);
+
+                mockDebugger.Verify(x => x.OnJobCompletedAsync(), Times.Once);
+                mockDebugger.Verify(x => x.StopAsync(), Times.Once);
+            }
+        }
     }
 }

src/Test/L0/Worker/WebSocketDapBridgeL0.cs

@@ -0,0 +1,266 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Net.Sockets;
+using System.Net.WebSockets;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+using GitHub.Runner.Worker.Dap;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class WebSocketDapBridgeL0
+    {
+        private TestHostContext CreateTestContext([CallerMemberName] string testName = "")
+        {
+            return new TestHostContext(this, testName);
+        }
+
+        private static async Task<byte[]> ReadWebSocketMessageAsync(ClientWebSocket client, TimeSpan timeout)
+        {
+            using var cts = new CancellationTokenSource(timeout);
+            using var buffer = new MemoryStream();
+            var receiveBuffer = new byte[1024];
+
+            while (true)
+            {
+                var result = await client.ReceiveAsync(new ArraySegment<byte>(receiveBuffer), cts.Token);
+                if (result.MessageType == WebSocketMessageType.Close)
+                {
+                    throw new EndOfStreamException("WebSocket closed unexpectedly.");
+                }
+
+                if (result.Count > 0)
+                {
+                    buffer.Write(receiveBuffer, 0, result.Count);
+                }
+
+                if (result.EndOfMessage)
+                {
+                    return buffer.ToArray();
+                }
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task BridgeForwardsWebSocketFramesToTcpAndBack()
+        {
+            using var hc = CreateTestContext();
+            using var targetListener = new TcpListener(IPAddress.Loopback, 0);
+            targetListener.Start();
+
+            var targetPort = ((IPEndPoint)targetListener.LocalEndpoint).Port;
+
+            var bridge = new WebSocketDapBridge();
+            bridge.Initialize(hc);
+            bridge.Start(0, targetPort);
+            var bridgePort = bridge.ListenPort;
+
+            try
+            {
+            var echoTask = Task.Run(async () =>
+            {
+                using var targetClient = await targetListener.AcceptTcpClientAsync();
+                using var stream = targetClient.GetStream();
+                
+                var headerBuilder = new StringBuilder();
+                var buffer = new byte[1];
+                var contentLength = -1;
+
+                while (true)
+                {
+                    var bytesRead = await stream.ReadAsync(buffer, 0, 1);
+                    if (bytesRead == 0) break;
+
+                    headerBuilder.Append((char)buffer[0]);
+                    var headers = headerBuilder.ToString();
+                    if (headers.EndsWith("\r\n\r\n", StringComparison.Ordinal))
+                    {
+                        foreach (var line in headers.Split(new[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries))
+                        {
+                            if (line.StartsWith("Content-Length: ", StringComparison.OrdinalIgnoreCase))
+                            {
+                                contentLength = int.Parse(line.Substring("Content-Length: ".Length).Trim());
+                            }
+                        }
+                        break;
+                    }
+                }
+
+                var body = new byte[contentLength];
+                var totalRead = 0;
+                while (totalRead < contentLength)
+                {
+                    var bytesRead = await stream.ReadAsync(body, totalRead, contentLength - totalRead);
+                    if (bytesRead == 0) break;
+                    totalRead += bytesRead;
+                }
+
+                var header = $"Content-Length: {body.Length}\r\n\r\n";
+                var headerBytes = Encoding.ASCII.GetBytes(header);
+                await stream.WriteAsync(headerBytes, 0, headerBytes.Length);
+                await stream.WriteAsync(body, 0, body.Length);
+                await stream.FlushAsync();
+            });
+
+            using var client = new ClientWebSocket();
+            client.Options.Proxy = null;
+            await client.ConnectAsync(new Uri($"ws://127.0.0.1:{bridgePort}/"), CancellationToken.None);
+
+            var dapMessage = "{\"type\":\"request\",\"seq\":1,\"command\":\"initialize\"}";
+            var payload = Encoding.UTF8.GetBytes(dapMessage);
+            await client.SendAsync(new ArraySegment<byte>(payload), WebSocketMessageType.Text, endOfMessage: true, CancellationToken.None);
+
+            var echoed = await ReadWebSocketMessageAsync(client, TimeSpan.FromSeconds(5));
+            Assert.Equal(payload, echoed);
+
+            await echoTask;
+            }
+            finally
+            {
+                await bridge.ShutdownAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task BridgeRejectsNonWebSocketRequests()
+        {
+            using var hc = CreateTestContext();
+
+            var bridge = new WebSocketDapBridge();
+            bridge.Initialize(hc);
+            bridge.Start(0, 0);
+            var bridgePort = bridge.ListenPort;
+
+            try
+            {
+            using var client = new TcpClient();
+            await client.ConnectAsync(IPAddress.Loopback, bridgePort);
+            using var stream = client.GetStream();
+
+            var request = Encoding.ASCII.GetBytes(
+                "GET / HTTP/1.1\r\n" +
+                "Host: localhost\r\n" +
+                "\r\n");
+            await stream.WriteAsync(request, 0, request.Length);
+            await stream.FlushAsync();
+
+            // Read until the server closes the connection (Connection: close).
+            // A single ReadAsync may return a partial response on some platforms.
+            using var ms = new MemoryStream();
+            var responseBuffer = new byte[1024];
+            int bytesRead;
+            while ((bytesRead = await stream.ReadAsync(responseBuffer, 0, responseBuffer.Length)) > 0)
+            {
+                ms.Write(responseBuffer, 0, bytesRead);
+            }
+
+            var response = Encoding.ASCII.GetString(ms.ToArray());
+
+            Assert.Contains("400 BadRequest", response);
+            Assert.Contains("Expected a websocket upgrade request.", response);
+            }
+            finally
+            {
+                await bridge.ShutdownAsync();
+            }
+        }
+
+        [Theory]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        [InlineData(new byte[] { (byte)'G', (byte)'E', (byte)'T', (byte)' ' }, 1)]
+        [InlineData(new byte[] { 0x81, 0x85, 0x00, 0x00 }, 2)]
+        [InlineData(new byte[] { 0xC1, 0x85, 0x00, 0x00 }, 3)]
+        [InlineData(new byte[] { (byte)'P', (byte)'R', (byte)'I', (byte)' ' }, 4)]
+        [InlineData(new byte[] { 0x16, 0x03, 0x03, 0x01 }, 5)]
+        [InlineData(new byte[] { (byte)'B', (byte)'A', (byte)'D', (byte)'!' }, 0)]
+        public void ClassifyIncomingStreamPrefixDetectsExpectedProtocols(byte[] initialBytes, int expectedKind)
+        {
+            var actualKind = WebSocketDapBridge.ClassifyIncomingStreamPrefix(initialBytes);
+            Assert.Equal((WebSocketDapBridge.IncomingStreamPrefixKind)expectedKind, actualKind);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task BridgeRejectsOversizedWebSocketMessage()
+        {
+            using var hc = CreateTestContext();
+            using var targetListener = new TcpListener(IPAddress.Loopback, 0);
+            targetListener.Start();
+
+            var targetPort = ((IPEndPoint)targetListener.LocalEndpoint).Port;
+
+            var bridge = new WebSocketDapBridge();
+            bridge.Initialize(hc);
+            bridge.MaxInboundMessageSize = 64; // artificially small limit for testing
+            bridge.Start(0, targetPort);
+            var bridgePort = bridge.ListenPort;
+
+            try
+            {
+            using var client = new ClientWebSocket();
+            client.Options.Proxy = null;
+            await client.ConnectAsync(new Uri($"ws://127.0.0.1:{bridgePort}/"), CancellationToken.None);
+
+            // Send a message that exceeds the 64-byte limit
+            var oversizedPayload = new byte[128];
+            Array.Fill(oversizedPayload, (byte)'X');
+            await client.SendAsync(
+                new ArraySegment<byte>(oversizedPayload),
+                WebSocketMessageType.Text,
+                endOfMessage: true,
+                CancellationToken.None);
+
+            // The bridge should close the connection with MessageTooBig
+            var receiveBuffer = new byte[256];
+            using var receiveCts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
+            var result = await client.ReceiveAsync(
+                new ArraySegment<byte>(receiveBuffer),
+                receiveCts.Token);
+
+            Assert.Equal(WebSocketMessageType.Close, result.MessageType);
+            Assert.Equal(WebSocketCloseStatus.MessageTooBig, client.CloseStatus);
+            }
+            finally
+            {
+                await bridge.ShutdownAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task BridgeShutdownCompletesWhenPeerDoesNotCloseGracefully()
+        {
+            using var hc = CreateTestContext();
+            using var targetListener = new TcpListener(IPAddress.Loopback, 0);
+            targetListener.Start();
+
+            var targetPort = ((IPEndPoint)targetListener.LocalEndpoint).Port;
+
+            var bridge = new WebSocketDapBridge();
+            bridge.Initialize(hc);
+            bridge.Start(0, targetPort);
+            var bridgePort = bridge.ListenPort;
+
+            // Connect a raw TCP client but never perform WebSocket close handshake
+            using var rawClient = new TcpClient();
+            await rawClient.ConnectAsync(IPAddress.Loopback, bridgePort);
+
+            // Shutdown should complete within a bounded time, not hang
+            var shutdownTask = bridge.ShutdownAsync();
+            var completed = await Task.WhenAny(shutdownTask, Task.Delay(TimeSpan.FromSeconds(15)));
+            Assert.True(completed == shutdownTask, "Bridge shutdown should complete within the timeout, not hang on a non-cooperative peer");
+        }
+    }
+}

src/Test/L0/Worker/YamlScalarFormatterL0.cs

@@ -0,0 +1,119 @@
+using System;
+using System.Collections.Generic;
+using GitHub.Runner.Worker.Dap;
+using Xunit;
+using YamlDotNet.Serialization;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class YamlScalarFormatterL0
+    {
+        private static readonly IDeserializer Deserializer = new DeserializerBuilder().Build();
+
+        // Embed the formatter output inside a minimal YAML mapping and
+        // round-trip through YamlDotNet, asserting the parsed value equals
+        // the original input. Decouples assertions from the emitter's
+        // quoting choices (plain vs single- vs double-quoted).
+        private static void AssertRoundTrips(string value)
+        {
+            string scalar = YamlScalarFormatter.Format(value);
+            string yaml = $"k: {scalar}\n";
+
+            Dictionary<string, object> doc;
+            try
+            {
+                doc = Deserializer.Deserialize<Dictionary<string, object>>(yaml);
+            }
+            catch (Exception ex)
+            {
+                throw new Xunit.Sdk.XunitException(
+                    $"Formatted scalar did not round-trip as valid YAML.\nInput: '{value}'\nFormatted: '{scalar}'\nFull YAML:\n{yaml}\nError: {ex}");
+            }
+            Assert.NotNull(doc);
+            Assert.True(doc.ContainsKey("k"), $"missing key in parsed doc. Formatted: '{scalar}'");
+            Assert.Equal(value, doc["k"] as string);
+        }
+
+        [Theory]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        [InlineData("hello")]
+        [InlineData("with: colon")]
+        [InlineData("with#hash")]
+        [InlineData(" leading")]
+        [InlineData("trailing ")]
+        [InlineData("a\"b")]
+        [InlineData("a\\b")]
+        [InlineData("@at")]
+        [InlineData("*star")]
+        [InlineData("&amp")]
+        [InlineData("?question")]
+        [InlineData("!exclaim")]
+        [InlineData("- dash")]
+        [InlineData("{brace}")]
+        [InlineData("[bracket]")]
+        public void Format_RoundTripsThroughYamlDeserializer(string value)
+        {
+            // The formatter must produce output that, embedded under a key,
+            // parses back to exactly the input. The emitter is free to
+            // pick plain, single-quoted, or double-quoted style.
+            AssertRoundTrips(value);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Format_PlainAscii_NoQuotingNeeded()
+        {
+            // Sanity check that the simple case stays plain.
+            Assert.Equal("hello", YamlScalarFormatter.Format("hello"));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Format_NoTrailingNewline()
+        {
+            Assert.False(YamlScalarFormatter.Format("hello").EndsWith("\n"));
+            Assert.False(YamlScalarFormatter.Format("with: colon").EndsWith("\n"));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Format_NoDocumentMarkers()
+        {
+            // The emitter wraps the scalar in a document; the formatter
+            // must strip both `--- ` (with space) and `---\n` (on its
+            // own line) prefixes plus the `\n...` suffix.
+            Assert.DoesNotContain("---", YamlScalarFormatter.Format("hello"));
+            Assert.DoesNotContain("...", YamlScalarFormatter.Format("hello"));
+            // Empty string is one of the cases where the emitter does
+            // produce a document marker by default.
+            Assert.DoesNotContain("---", YamlScalarFormatter.Format(""));
+            Assert.DoesNotContain("...", YamlScalarFormatter.Format(""));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Format_AlwaysUsesLfLineBreaks()
+        {
+            // Regression: YamlDotNet's Emitter calls WriteLine, which on
+            // Windows produces CRLF (the host's Environment.NewLine).
+            // Format must force LF so the output round-trips regardless
+            // of platform.
+            Assert.DoesNotContain('\r', YamlScalarFormatter.Format("hello"));
+            Assert.DoesNotContain('\r', YamlScalarFormatter.Format("with: colon"));
+            Assert.DoesNotContain('\r', YamlScalarFormatter.Format(""));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Format_NullValue_Throws()
+        {
+            Assert.Throws<ArgumentNullException>(() => YamlScalarFormatter.Format(null));
+        }
+    }
+}

src/dev.sh

@@ -17,7 +17,7 @@ LAYOUT_DIR="$SCRIPT_DIR/../_layout"
 DOWNLOAD_DIR="$SCRIPT_DIR/../_downloads/netcore2x"
 PACKAGE_DIR="$SCRIPT_DIR/../_package"
 DOTNETSDK_ROOT="$SCRIPT_DIR/../_dotnetsdk"
-DOTNETSDK_VERSION="8.0.419"
+DOTNETSDK_VERSION="8.0.421"
 DOTNETSDK_INSTALLDIR="$DOTNETSDK_ROOT/$DOTNETSDK_VERSION"
 RUNNER_VERSION=$(cat runnerversion)
 

src/global.json

@@ -1,5 +1,5 @@
 {
   "sdk": {
-    "version": "8.0.419"
+    "version": "8.0.421"
   }
 }

src/runnerversion

@@ -1 +1 @@
-2.333.0
+2.334.0