Integrate DAP debugger into JobRunner and StepsRunner

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.devcontainer/devcontainer.json

@@ -1,10 +1,10 @@
 {
   "name": "Actions Runner Devcontainer",
-  "image": "mcr.microsoft.com/devcontainers/base:focal",
+  "image": "mcr.microsoft.com/devcontainers/base:noble",
   "features": {
-    "ghcr.io/devcontainers/features/docker-in-docker:1": {},
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {},
     "ghcr.io/devcontainers/features/dotnet": {
-      "version": "8.0.417"
+      "version": "8.0.418"
     },
     "ghcr.io/devcontainers/features/node:1": {
       "version": "20"

.github/workflows/release.yml

@@ -133,37 +133,37 @@ jobs:
 
     # Download runner package tar.gz/zip produced by 'build' job
     - name: Download Artifact (win-x64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-win-x64
         path: ./
     - name: Download Artifact (win-arm64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-win-arm64
         path: ./
     - name: Download Artifact (osx-x64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-osx-x64
         path: ./
     - name: Download Artifact (osx-arm64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-osx-arm64
         path: ./
     - name: Download Artifact (linux-x64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-linux-x64
         path: ./
     - name: Download Artifact (linux-arm)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-linux-arm
         path: ./
     - name: Download Artifact (linux-arm64)
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: runner-packages-linux-arm64
         path: ./

README.md

@@ -32,7 +32,7 @@ We are taking the following steps to better direct requests related to GitHub Ac
 
 2. High Priority bugs can be reported through Community Discussions or you can report these to our support team https://support.github.com/contact/bug-report.
 
-3. Security Issues should be handled as per our [security.md](security.md)
+3. Security Issues should be handled as per our [SECURITY.md](https://github.com/actions/runner?tab=security-ov-file)
 
 We will still provide security updates for this project and fix major breaking changes during this time.
 

docs/start/envlinux.md

@@ -28,8 +28,8 @@ Debian based OS (Debian, Ubuntu, Linux Mint)
 - liblttng-ust1 or liblttng-ust0
 - libkrb5-3
 - zlib1g
-- libssl1.1, libssl1.0.2 or libssl1.0.0
-- libicu63, libicu60, libicu57 or libicu55
+- libssl3t64, libssl3, libssl1.1, libssl1.0.2 or libssl1.0.0
+- libicu76, libicu75, ..., libicu66, libicu65, libicu63, libicu60, libicu57, libicu55, or libicu52
 
 Fedora based OS (Fedora, Red Hat Enterprise Linux, CentOS, Oracle Linux 7)
 

images/Dockerfile

@@ -21,7 +21,7 @@ RUN curl -f -L -o runner-container-hooks.zip https://github.com/actions/runner-c
     && unzip ./runner-container-hooks.zip -d ./k8s \
     && rm runner-container-hooks.zip
 
-RUN curl -f -L -o runner-container-hooks.zip https://github.com/actions/runner-container-hooks/releases/download/v0.8.0/actions-runner-hooks-k8s-0.8.0.zip \
+RUN curl -f -L -o runner-container-hooks.zip https://github.com/actions/runner-container-hooks/releases/download/v0.8.1/actions-runner-hooks-k8s-0.8.1.zip \
     && unzip ./runner-container-hooks.zip -d ./k8s-novolume \
     && rm runner-container-hooks.zip
 

releaseNote.md

@@ -1,27 +1,35 @@
 ## What's Changed
-* Fix owner of /home/runner directory by @nikola-jokic in https://github.com/actions/runner/pull/4132
-* Update Docker to v29.0.2 and Buildx to v0.30.1 by @github-actions[bot] in https://github.com/actions/runner/pull/4135
-* Update workflow around runner docker image. by @TingluoHuang in https://github.com/actions/runner/pull/4133
-* Fix regex for validating runner version format by @TingluoHuang in https://github.com/actions/runner/pull/4136
-* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4144
-* Ensure safe_sleep tries alternative approaches by @TingluoHuang in https://github.com/actions/runner/pull/4146
-* Bump actions/github-script from 7 to 8 by @dependabot[bot] in https://github.com/actions/runner/pull/4137
-* Bump actions/checkout from 5 to 6 by @dependabot[bot] in https://github.com/actions/runner/pull/4130
-* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4149
-* Bump docker image to use ubuntu 24.04 by @TingluoHuang in https://github.com/actions/runner/pull/4018
-* Add support for case function by @AllanGuigou in https://github.com/actions/runner/pull/4147
-* Cleanup feature flag actions_container_action_runner_temp by @ericsciple in https://github.com/actions/runner/pull/4163
-* Bump actions/download-artifact from 6 to 7 by @dependabot[bot] in https://github.com/actions/runner/pull/4155
-* Bump actions/upload-artifact from 5 to 6 by @dependabot[bot] in https://github.com/actions/runner/pull/4157
-* Set ACTIONS_ORCHESTRATION_ID as env to actions. by @TingluoHuang in https://github.com/actions/runner/pull/4178
-* Allow hosted VM report job telemetry via .setup_info file. by @TingluoHuang in https://github.com/actions/runner/pull/4186
-* Bump typescript from 5.9.2 to 5.9.3 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4184
-* Bump Azure.Storage.Blobs from 12.26.0 to 12.27.0 by @dependabot[bot] in https://github.com/actions/runner/pull/4189
+* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4200
+* Update dotnet sdk to latest version @8.0.417 by @github-actions[bot] in https://github.com/actions/runner/pull/4201
+* Bump System.Formats.Asn1 and System.Security.Cryptography.Pkcs by @dependabot[bot] in https://github.com/actions/runner/pull/4202
+* Allow empty container options by @ericsciple in https://github.com/actions/runner/pull/4208
+* Update Docker to v29.1.5 and Buildx to v0.31.0 by @github-actions[bot] in https://github.com/actions/runner/pull/4212
+* Report job level annotations by @TingluoHuang in https://github.com/actions/runner/pull/4216
+* Fix local action display name showing `Run /./` instead of `Run ./` by @ericsciple in https://github.com/actions/runner/pull/4218
+* Update Docker to v29.2.0 and Buildx to v0.31.1 by @github-actions[bot] in https://github.com/actions/runner/pull/4219
+* Add support for libssl3 and libssl3t64 for newer Debian/Ubuntu versions by @nekketsuuu in https://github.com/actions/runner/pull/4213
+* Validate work dir during runner start up. by @TingluoHuang in https://github.com/actions/runner/pull/4227
+* Bump hook to 0.8.1 by @nikola-jokic in https://github.com/actions/runner/pull/4222
+* Support return job result as exitcode in hosted runner. by @TingluoHuang in https://github.com/actions/runner/pull/4233
+* Add telemetry tracking for deprecated set-output and save-state commands by @ericsciple in https://github.com/actions/runner/pull/4221
+* Fix parser comparison mismatches by @ericsciple in https://github.com/actions/runner/pull/4220
+* Remove unnecessary connection test during some registration flows by @zarenner in https://github.com/actions/runner/pull/4244
+* chore: update Node versions by @github-actions[bot] in https://github.com/actions/runner/pull/4249
+* Update dotnet sdk to latest version @8.0.418 by @github-actions[bot] in https://github.com/actions/runner/pull/4250
+* Fix link to SECURITY.md in README by @TingluoHuang in https://github.com/actions/runner/pull/4253
+* Try to infer runner is on hosted/ghes when githuburl is empty. by @TingluoHuang in https://github.com/actions/runner/pull/4254
+* Add Node.js 20 deprecation warning annotation (Phase 1) by @salmanmkc in https://github.com/actions/runner/pull/4242
+* Update Node.js 20 deprecation date to June 2nd, 2026 by @salmanmkc in https://github.com/actions/runner/pull/4258
+* Composite Action Step Markers by @ericsciple in https://github.com/actions/runner/pull/4243
+* Symlink actions cache by @paveliak in https://github.com/actions/runner/pull/4260
+* Bump minimatch in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4261
+* Bump @stylistic/eslint-plugin from 3.1.0 to 5.9.0 in /src/Misc/expressionFunc/hashFiles by @dependabot[bot] in https://github.com/actions/runner/pull/4257
 
 ## New Contributors
-* @AllanGuigou made their first contribution in https://github.com/actions/runner/pull/4147
+* @nekketsuuu made their first contribution in https://github.com/actions/runner/pull/4213
+* @zarenner made their first contribution in https://github.com/actions/runner/pull/4244
 
-**Full Changelog**: https://github.com/actions/runner/compare/v2.330.0...v2.331.0
+**Full Changelog**: https://github.com/actions/runner/compare/v2.331.0...v2.332.0
 
 _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-lock.json

@@ -12,7 +12,7 @@
         "@actions/glob": "^0.4.0"
       },
       "devDependencies": {
-        "@stylistic/eslint-plugin": "^3.1.0",
+        "@stylistic/eslint-plugin": "^5.9.0",
         "@types/node": "^22.0.0",
         "@typescript-eslint/eslint-plugin": "^8.0.0",
         "@typescript-eslint/parser": "^8.0.0",
@@ -75,11 +75,10 @@
       }
     },
     "node_modules/@eslint-community/eslint-utils": {
-      "version": "4.9.0",
-      "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.9.0.tgz",
-      "integrity": "sha512-ayVFHdtZ+hsq1t2Dy24wCmGXGe4q9Gu3smhLYALJrr473ZH27MsnSL+LKUlimp4BWJqMDMLmPpx/Q9R3OAlL4g==",
+      "version": "4.9.1",
+      "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.9.1.tgz",
+      "integrity": "sha512-phrYmNiYppR7znFEdqgfWHXR6NCkZEK7hwWDHZUjit/2/U0r6XvkDl0SYnoM51Hq7FhCGdLDT6zxCCOY1hexsQ==",
       "dev": true,
-      "license": "MIT",
       "dependencies": {
         "eslint-visitor-keys": "^3.4.3"
       },
@@ -229,23 +228,36 @@
       }
     },
     "node_modules/@stylistic/eslint-plugin": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/@stylistic/eslint-plugin/-/eslint-plugin-3.1.0.tgz",
-      "integrity": "sha512-pA6VOrOqk0+S8toJYhQGv2MWpQQR0QpeUo9AhNkC49Y26nxBQ/nH1rta9bUU1rPw2fJ1zZEMV5oCX5AazT7J2g==",
+      "version": "5.9.0",
+      "resolved": "https://registry.npmjs.org/@stylistic/eslint-plugin/-/eslint-plugin-5.9.0.tgz",
+      "integrity": "sha512-FqqSkvDMYJReydrMhlugc71M76yLLQWNfmGq+SIlLa7N3kHp8Qq8i2PyWrVNAfjOyOIY+xv9XaaYwvVW7vroMA==",
       "dev": true,
-      "license": "MIT",
       "dependencies": {
-        "@typescript-eslint/utils": "^8.13.0",
-        "eslint-visitor-keys": "^4.2.0",
-        "espree": "^10.3.0",
+        "@eslint-community/eslint-utils": "^4.9.1",
+        "@typescript-eslint/types": "^8.56.0",
+        "eslint-visitor-keys": "^4.2.1",
+        "espree": "^10.4.0",
         "estraverse": "^5.3.0",
-        "picomatch": "^4.0.2"
+        "picomatch": "^4.0.3"
       },
       "engines": {
         "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
       },
       "peerDependencies": {
-        "eslint": ">=8.40.0"
+        "eslint": "^9.0.0 || ^10.0.0"
+      }
+    },
+    "node_modules/@stylistic/eslint-plugin/node_modules/@typescript-eslint/types": {
+      "version": "8.56.0",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-8.56.0.tgz",
+      "integrity": "sha512-DBsLPs3GsWhX5HylbP9HNG15U0bnwut55Lx12bHB9MpXxQ+R5GC8MwQe+N1UFXxAeQDvEsEDY6ZYwX03K7Z6HQ==",
+      "dev": true,
+      "engines": {
+        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/typescript-eslint"
       }
     },
     "node_modules/@stylistic/eslint-plugin/node_modules/eslint-visitor-keys": {
@@ -524,24 +536,34 @@
         "typescript": ">=4.8.4 <6.0.0"
       }
     },
-    "node_modules/@typescript-eslint/typescript-estree/node_modules/brace-expansion": {
-      "version": "2.0.2",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.2.tgz",
-      "integrity": "sha512-Jt0vHyM+jmUBqojB7E1NIYadt0vI0Qxjxd2TErW94wDz+E2LAm5vKMXXwg6ZZBTHPuUlDgQHKXvjGBdfcF1ZDQ==",
+    "node_modules/@typescript-eslint/typescript-estree/node_modules/balanced-match": {
+      "version": "4.0.4",
+      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-4.0.4.tgz",
+      "integrity": "sha512-BLrgEcRTwX2o6gGxGOCNyMvGSp35YofuYzw9h1IMTRmKqttAZZVU67bdb9Pr2vUHA8+j3i2tJfjO6C6+4myGTA==",
+      "dev": true,
+      "engines": {
+        "node": "18 || 20 || >=22"
+      }
+    },
+    "node_modules/@typescript-eslint/typescript-estree/node_modules/brace-expansion": {
+      "version": "5.0.3",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.3.tgz",
+      "integrity": "sha512-fy6KJm2RawA5RcHkLa1z/ScpBeA762UF9KmZQxwIbDtRJrgLzM10depAiEQ+CXYcoiqW1/m96OAAoke2nE9EeA==",
       "dev": true,
-      "license": "MIT",
       "dependencies": {
-        "balanced-match": "^1.0.0"
+        "balanced-match": "^4.0.2"
+      },
+      "engines": {
+        "node": "18 || 20 || >=22"
       }
     },
     "node_modules/@typescript-eslint/typescript-estree/node_modules/minimatch": {
-      "version": "9.0.5",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.5.tgz",
-      "integrity": "sha512-G6T0ZX48xgozx7587koeX9Ys2NYy6Gmv//P89sEte9V9whIapMNF4idKxnW2QtCcLiTWlb/wfCabAtAFWhhBow==",
+      "version": "9.0.7",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.7.tgz",
+      "integrity": "sha512-MOwgjc8tfrpn5QQEvjijjmDVtMw2oL88ugTevzxQnzRLm6l3fVEF2gzU0kYeYYKD8C66+IdGX6peJ4MyUlUnPg==",
       "dev": true,
-      "license": "ISC",
       "dependencies": {
-        "brace-expansion": "^2.0.1"
+        "brace-expansion": "^5.0.2"
       },
       "engines": {
         "node": ">=16 || 14 >=14.17"
@@ -1769,23 +1791,34 @@
         "url": "https://opencollective.com/typescript-eslint"
       }
     },
-    "node_modules/eslint-plugin-github/node_modules/brace-expansion": {
-      "version": "2.0.2",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.2.tgz",
-      "integrity": "sha512-Jt0vHyM+jmUBqojB7E1NIYadt0vI0Qxjxd2TErW94wDz+E2LAm5vKMXXwg6ZZBTHPuUlDgQHKXvjGBdfcF1ZDQ==",
+    "node_modules/eslint-plugin-github/node_modules/balanced-match": {
+      "version": "4.0.4",
+      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-4.0.4.tgz",
+      "integrity": "sha512-BLrgEcRTwX2o6gGxGOCNyMvGSp35YofuYzw9h1IMTRmKqttAZZVU67bdb9Pr2vUHA8+j3i2tJfjO6C6+4myGTA==",
+      "dev": true,
+      "engines": {
+        "node": "18 || 20 || >=22"
+      }
+    },
+    "node_modules/eslint-plugin-github/node_modules/brace-expansion": {
+      "version": "5.0.3",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.3.tgz",
+      "integrity": "sha512-fy6KJm2RawA5RcHkLa1z/ScpBeA762UF9KmZQxwIbDtRJrgLzM10depAiEQ+CXYcoiqW1/m96OAAoke2nE9EeA==",
       "dev": true,
-      "license": "MIT",
       "dependencies": {
-        "balanced-match": "^1.0.0"
+        "balanced-match": "^4.0.2"
+      },
+      "engines": {
+        "node": "18 || 20 || >=22"
       }
     },
     "node_modules/eslint-plugin-github/node_modules/minimatch": {
-      "version": "9.0.4",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.4.tgz",
-      "integrity": "sha512-KqWh+VchfxcMNRAJjj2tnsSJdNbHsVgnkBhTNrW7AjVo6OvLtxw8zfT9oLw1JSohlFzJ8jCoTgaoXvJ+kHt6fw==",
+      "version": "9.0.7",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.7.tgz",
+      "integrity": "sha512-MOwgjc8tfrpn5QQEvjijjmDVtMw2oL88ugTevzxQnzRLm6l3fVEF2gzU0kYeYYKD8C66+IdGX6peJ4MyUlUnPg==",
       "dev": true,
       "dependencies": {
-        "brace-expansion": "^2.0.1"
+        "brace-expansion": "^5.0.2"
       },
       "engines": {
         "node": ">=16 || 14 >=14.17"
@@ -3300,9 +3333,9 @@
       }
     },
     "node_modules/minimatch": {
-      "version": "3.1.2",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
-      "integrity": "sha512-J7p63hRiAjw1NDEww1W7i37+ByIrOWO5XQQAzZ3VOcL0PNybwpfmV/N05zFAzwQ9USyEcX6t3UO+K5aqBQOIHw==",
+      "version": "3.1.4",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.4.tgz",
+      "integrity": "sha512-twmL+S8+7yIsE9wsqgzU3E8/LumN3M3QELrBZ20OdmQ9jB2JvW5oZtBEmft84k/Gs5CG9mqtWc6Y9vW+JEzGxw==",
       "dependencies": {
         "brace-expansion": "^1.1.7"
       },
@@ -4714,9 +4747,9 @@
       }
     },
     "@eslint-community/eslint-utils": {
-      "version": "4.9.0",
-      "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.9.0.tgz",
-      "integrity": "sha512-ayVFHdtZ+hsq1t2Dy24wCmGXGe4q9Gu3smhLYALJrr473ZH27MsnSL+LKUlimp4BWJqMDMLmPpx/Q9R3OAlL4g==",
+      "version": "4.9.1",
+      "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.9.1.tgz",
+      "integrity": "sha512-phrYmNiYppR7znFEdqgfWHXR6NCkZEK7hwWDHZUjit/2/U0r6XvkDl0SYnoM51Hq7FhCGdLDT6zxCCOY1hexsQ==",
       "dev": true,
       "requires": {
         "eslint-visitor-keys": "^3.4.3"
@@ -4821,18 +4854,25 @@
       }
     },
     "@stylistic/eslint-plugin": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/@stylistic/eslint-plugin/-/eslint-plugin-3.1.0.tgz",
-      "integrity": "sha512-pA6VOrOqk0+S8toJYhQGv2MWpQQR0QpeUo9AhNkC49Y26nxBQ/nH1rta9bUU1rPw2fJ1zZEMV5oCX5AazT7J2g==",
+      "version": "5.9.0",
+      "resolved": "https://registry.npmjs.org/@stylistic/eslint-plugin/-/eslint-plugin-5.9.0.tgz",
+      "integrity": "sha512-FqqSkvDMYJReydrMhlugc71M76yLLQWNfmGq+SIlLa7N3kHp8Qq8i2PyWrVNAfjOyOIY+xv9XaaYwvVW7vroMA==",
       "dev": true,
       "requires": {
-        "@typescript-eslint/utils": "^8.13.0",
-        "eslint-visitor-keys": "^4.2.0",
-        "espree": "^10.3.0",
+        "@eslint-community/eslint-utils": "^4.9.1",
+        "@typescript-eslint/types": "^8.56.0",
+        "eslint-visitor-keys": "^4.2.1",
+        "espree": "^10.4.0",
         "estraverse": "^5.3.0",
-        "picomatch": "^4.0.2"
+        "picomatch": "^4.0.3"
       },
       "dependencies": {
+        "@typescript-eslint/types": {
+          "version": "8.56.0",
+          "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-8.56.0.tgz",
+          "integrity": "sha512-DBsLPs3GsWhX5HylbP9HNG15U0bnwut55Lx12bHB9MpXxQ+R5GC8MwQe+N1UFXxAeQDvEsEDY6ZYwX03K7Z6HQ==",
+          "dev": true
+        },
         "eslint-visitor-keys": {
           "version": "4.2.1",
           "resolved": "https://registry.npmjs.org/eslint-visitor-keys/-/eslint-visitor-keys-4.2.1.tgz",
@@ -4992,22 +5032,28 @@
         "ts-api-utils": "^2.1.0"
       },
       "dependencies": {
+        "balanced-match": {
+          "version": "4.0.4",
+          "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-4.0.4.tgz",
+          "integrity": "sha512-BLrgEcRTwX2o6gGxGOCNyMvGSp35YofuYzw9h1IMTRmKqttAZZVU67bdb9Pr2vUHA8+j3i2tJfjO6C6+4myGTA==",
+          "dev": true
+        },
         "brace-expansion": {
-          "version": "2.0.2",
-          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.2.tgz",
-          "integrity": "sha512-Jt0vHyM+jmUBqojB7E1NIYadt0vI0Qxjxd2TErW94wDz+E2LAm5vKMXXwg6ZZBTHPuUlDgQHKXvjGBdfcF1ZDQ==",
+          "version": "5.0.3",
+          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.3.tgz",
+          "integrity": "sha512-fy6KJm2RawA5RcHkLa1z/ScpBeA762UF9KmZQxwIbDtRJrgLzM10depAiEQ+CXYcoiqW1/m96OAAoke2nE9EeA==",
           "dev": true,
           "requires": {
-            "balanced-match": "^1.0.0"
+            "balanced-match": "^4.0.2"
           }
         },
         "minimatch": {
-          "version": "9.0.5",
-          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.5.tgz",
-          "integrity": "sha512-G6T0ZX48xgozx7587koeX9Ys2NYy6Gmv//P89sEte9V9whIapMNF4idKxnW2QtCcLiTWlb/wfCabAtAFWhhBow==",
+          "version": "9.0.7",
+          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.7.tgz",
+          "integrity": "sha512-MOwgjc8tfrpn5QQEvjijjmDVtMw2oL88ugTevzxQnzRLm6l3fVEF2gzU0kYeYYKD8C66+IdGX6peJ4MyUlUnPg==",
           "dev": true,
           "requires": {
-            "brace-expansion": "^2.0.1"
+            "brace-expansion": "^5.0.2"
           }
         },
         "ts-api-utils": {
@@ -5831,22 +5877,28 @@
             "eslint-visitor-keys": "^3.4.3"
           }
         },
+        "balanced-match": {
+          "version": "4.0.4",
+          "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-4.0.4.tgz",
+          "integrity": "sha512-BLrgEcRTwX2o6gGxGOCNyMvGSp35YofuYzw9h1IMTRmKqttAZZVU67bdb9Pr2vUHA8+j3i2tJfjO6C6+4myGTA==",
+          "dev": true
+        },
         "brace-expansion": {
-          "version": "2.0.2",
-          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.2.tgz",
-          "integrity": "sha512-Jt0vHyM+jmUBqojB7E1NIYadt0vI0Qxjxd2TErW94wDz+E2LAm5vKMXXwg6ZZBTHPuUlDgQHKXvjGBdfcF1ZDQ==",
+          "version": "5.0.3",
+          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.3.tgz",
+          "integrity": "sha512-fy6KJm2RawA5RcHkLa1z/ScpBeA762UF9KmZQxwIbDtRJrgLzM10depAiEQ+CXYcoiqW1/m96OAAoke2nE9EeA==",
           "dev": true,
           "requires": {
-            "balanced-match": "^1.0.0"
+            "balanced-match": "^4.0.2"
           }
         },
         "minimatch": {
-          "version": "9.0.4",
-          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.4.tgz",
-          "integrity": "sha512-KqWh+VchfxcMNRAJjj2tnsSJdNbHsVgnkBhTNrW7AjVo6OvLtxw8zfT9oLw1JSohlFzJ8jCoTgaoXvJ+kHt6fw==",
+          "version": "9.0.7",
+          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.7.tgz",
+          "integrity": "sha512-MOwgjc8tfrpn5QQEvjijjmDVtMw2oL88ugTevzxQnzRLm6l3fVEF2gzU0kYeYYKD8C66+IdGX6peJ4MyUlUnPg==",
           "dev": true,
           "requires": {
-            "brace-expansion": "^2.0.1"
+            "brace-expansion": "^5.0.2"
           }
         }
       }
@@ -6883,9 +6935,9 @@
       "dev": true
     },
     "minimatch": {
-      "version": "3.1.2",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
-      "integrity": "sha512-J7p63hRiAjw1NDEww1W7i37+ByIrOWO5XQQAzZ3VOcL0PNybwpfmV/N05zFAzwQ9USyEcX6t3UO+K5aqBQOIHw==",
+      "version": "3.1.4",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.4.tgz",
+      "integrity": "sha512-twmL+S8+7yIsE9wsqgzU3E8/LumN3M3QELrBZ20OdmQ9jB2JvW5oZtBEmft84k/Gs5CG9mqtWc6Y9vW+JEzGxw==",
       "requires": {
         "brace-expansion": "^1.1.7"
       }

src/Misc/expressionFunc/hashFiles/package.json

@@ -35,7 +35,7 @@
     "@actions/glob": "^0.4.0"
   },
   "devDependencies": {
-    "@stylistic/eslint-plugin": "^3.1.0",
+    "@stylistic/eslint-plugin": "^5.9.0",
     "@types/node": "^22.0.0",
     "@typescript-eslint/eslint-plugin": "^8.0.0",
     "@typescript-eslint/parser": "^8.0.0",

src/Misc/externals.sh

@@ -7,7 +7,7 @@ NODE_ALPINE_URL=https://github.com/actions/alpine_nodejs/releases/download
 # When you update Node versions you must also create a new release of alpine_nodejs at that updated version.
 # Follow the instructions here: https://github.com/actions/alpine_nodejs?tab=readme-ov-file#getting-started
 NODE20_VERSION="20.20.0"
-NODE24_VERSION="24.13.0"
+NODE24_VERSION="24.14.0"
 
 get_abs_path() {
   # exploits the fact that pwd will print abs path when no args

src/Misc/layoutbin/installdependencies.sh

@@ -102,7 +102,7 @@ then
             exit 1
         fi
 
-        apt_get_with_fallbacks libssl1.1$ libssl1.0.2$ libssl1.0.0$
+        apt_get_with_fallbacks libssl3t64$ libssl3$ libssl1.1$ libssl1.0.2$ libssl1.0.0$
         if [ $? -ne 0 ]
         then
             echo "'$apt_get' failed with exit code '$?'"

src/Runner.Common/ActionCommand.cs

@@ -204,6 +204,26 @@ namespace GitHub.Runner.Common
             return unescaped;
         }
 
+        /// <summary>
+        /// Escapes special characters in a value using the standard action command escape mappings.
+        /// Iterates in reverse so that '%' is escaped first to avoid double-encoding.
+        /// </summary>
+        public static string EscapeValue(string value)
+        {
+            if (string.IsNullOrEmpty(value))
+            {
+                return value;
+            }
+
+            string escaped = value;
+            for (int i = _escapeMappings.Length - 1; i >= 0; i--)
+            {
+                escaped = escaped.Replace(_escapeMappings[i].Token, _escapeMappings[i].Replacement);
+            }
+
+            return escaped;
+        }
+
         private static string UnescapeProperty(string escaped)
         {
             if (string.IsNullOrEmpty(escaped))

src/Runner.Common/ConfigurationStore.cs

@@ -75,6 +75,41 @@ namespace GitHub.Runner.Common
                 {
                     return UrlUtil.IsHostedServer(new UriBuilder(GitHubUrl));
                 }
+                else
+                {
+                    // feature flag env in case the new logic is wrong.
+                    if (StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("GITHUB_ACTIONS_RUNNER_FORCE_EMPTY_GITHUB_URL_IS_HOSTED")))
+                    {
+                        return true;
+                    }
+
+                    // GitHubUrl will be empty for jit configured runner
+                    // We will try to infer it from the ServerUrl/ServerUrlV2
+                    if (StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("GITHUB_ACTIONS_RUNNER_FORCE_GHES")))
+                    {
+                        // Allow env to override and force GHES in case the inference logic is wrong.
+                        return false;
+                    }
+
+                    if (!string.IsNullOrEmpty(ServerUrl))
+                    {
+                        // pipelines services
+                        var serverUrl = new UriBuilder(ServerUrl);
+                        return serverUrl.Host.EndsWith(".actions.githubusercontent.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrl.Host.EndsWith(".codedev.ms", StringComparison.OrdinalIgnoreCase);
+                    }
+
+                    if (!string.IsNullOrEmpty(ServerUrlV2))
+                    {
+                        // broker-listener
+                        var serverUrlV2 = new UriBuilder(ServerUrlV2);
+                        return serverUrlV2.Host.EndsWith(".actions.githubusercontent.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".githubapp.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".ghe.com", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".actions.localhost", StringComparison.OrdinalIgnoreCase)
+                                || serverUrlV2.Host.EndsWith(".ghe.localhost", StringComparison.OrdinalIgnoreCase);
+                    }
+                }
 
                 // Default to true since Hosted runners likely don't have this property set.
                 return true;

src/Runner.Common/Constants.cs

@@ -172,8 +172,10 @@ namespace GitHub.Runner.Common
                 public static readonly string SnapshotPreflightHostedRunnerCheck = "actions_snapshot_preflight_hosted_runner_check";
                 public static readonly string SnapshotPreflightImageGenPoolCheck = "actions_snapshot_preflight_image_gen_pool_check";
                 public static readonly string CompareWorkflowParser = "actions_runner_compare_workflow_parser";
+                public static readonly string ServiceContainerCommand = "actions_service_container_command";
                 public static readonly string SetOrchestrationIdEnvForActions = "actions_set_orchestration_id_env_for_actions";
                 public static readonly string SendJobLevelAnnotations = "actions_send_job_level_annotations";
+                public static readonly string EmitCompositeMarkers = "actions_runner_emit_composite_markers";
             }
 
             // Node version migration related constants
@@ -190,6 +192,10 @@ namespace GitHub.Runner.Common
                 // Feature flags for controlling the migration phases
                 public static readonly string UseNode24ByDefaultFlag = "actions.runner.usenode24bydefault";
                 public static readonly string RequireNode24Flag = "actions.runner.requirenode24";
+                public static readonly string WarnOnNode20Flag = "actions.runner.warnonnode20";
+
+                // Blog post URL for Node 20 deprecation
+                public static readonly string Node20DeprecationUrl = "https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/";
             }
 
             public static readonly string InternalTelemetryIssueDataKey = "_internal_telemetry";
@@ -284,6 +290,8 @@ namespace GitHub.Runner.Common
                 public static readonly string ForcedActionsNodeVersion = "ACTIONS_RUNNER_FORCE_ACTIONS_NODE_VERSION";
                 public static readonly string PrintLogToStdout = "ACTIONS_RUNNER_PRINT_LOG_TO_STDOUT";
                 public static readonly string ActionArchiveCacheDirectory = "ACTIONS_RUNNER_ACTION_ARCHIVE_CACHE";
+                public static readonly string SymlinkCachedActions = "ACTIONS_RUNNER_SYMLINK_CACHED_ACTIONS";
+                public static readonly string EmitCompositeMarkers = "ACTIONS_RUNNER_EMIT_COMPOSITE_MARKERS";
             }
 
             public static class System

src/Runner.Listener/Configuration/ConfigurationManager.cs

@@ -178,8 +178,12 @@ namespace GitHub.Runner.Listener.Configuration
                         }
                     }
 
-                    // Validate can connect.
-                    await _runnerServer.ConnectAsync(new Uri(runnerSettings.ServerUrl), creds);
+                    // Validate can connect using the obtained vss credentials.
+                    // In Runner Admin flow there's nothing new to test connection to at this point as registerToken is already validated via GetTenantCredential.
+                    if (!runnerSettings.UseRunnerAdminFlow)
+                    {
+                        await _runnerServer.ConnectAsync(new Uri(runnerSettings.ServerUrl), creds);
+                    }
 
                     _term.WriteLine();
                     _term.WriteSuccessMessage("Connected to GitHub");

src/Runner.Listener/JobDispatcher.cs

@@ -24,7 +24,7 @@ namespace GitHub.Runner.Listener
     public interface IJobDispatcher : IRunnerService
     {
         bool Busy { get; }
-        TaskCompletionSource<bool> RunOnceJobCompleted { get; }
+        TaskCompletionSource<TaskResult> RunOnceJobCompleted { get; }
         void Run(Pipelines.AgentJobRequestMessage message, bool runOnce = false);
         bool Cancel(JobCancelMessage message);
         Task WaitAsync(CancellationToken token);
@@ -56,7 +56,7 @@ namespace GitHub.Runner.Listener
         // timeout limit can be overwritten by environment GITHUB_ACTIONS_RUNNER_CHANNEL_TIMEOUT
         private TimeSpan _channelTimeout;
 
-        private TaskCompletionSource<bool> _runOnceJobCompleted = new();
+        private TaskCompletionSource<TaskResult> _runOnceJobCompleted = new();
 
         public event EventHandler<JobStatusEventArgs> JobStatus;
 
@@ -82,7 +82,7 @@ namespace GitHub.Runner.Listener
             Trace.Info($"Set runner/worker IPC timeout to {_channelTimeout.TotalSeconds} seconds.");
         }
 
-        public TaskCompletionSource<bool> RunOnceJobCompleted => _runOnceJobCompleted;
+        public TaskCompletionSource<TaskResult> RunOnceJobCompleted => _runOnceJobCompleted;
 
         public bool Busy { get; private set; }
 
@@ -340,18 +340,19 @@ namespace GitHub.Runner.Listener
 
         private async Task RunOnceAsync(Pipelines.AgentJobRequestMessage message, string orchestrationId, WorkerDispatcher previousJobDispatch, CancellationToken jobRequestCancellationToken, CancellationToken workerCancelTimeoutKillToken)
         {
+            var jobResult = TaskResult.Succeeded;
             try
             {
-                await RunAsync(message, orchestrationId, previousJobDispatch, jobRequestCancellationToken, workerCancelTimeoutKillToken);
+                jobResult = await RunAsync(message, orchestrationId, previousJobDispatch, jobRequestCancellationToken, workerCancelTimeoutKillToken);
             }
             finally
             {
                 Trace.Info("Fire signal for one time used runner.");
-                _runOnceJobCompleted.TrySetResult(true);
+                _runOnceJobCompleted.TrySetResult(jobResult);
             }
         }
 
-        private async Task RunAsync(Pipelines.AgentJobRequestMessage message, string orchestrationId, WorkerDispatcher previousJobDispatch, CancellationToken jobRequestCancellationToken, CancellationToken workerCancelTimeoutKillToken)
+        private async Task<TaskResult> RunAsync(Pipelines.AgentJobRequestMessage message, string orchestrationId, WorkerDispatcher previousJobDispatch, CancellationToken jobRequestCancellationToken, CancellationToken workerCancelTimeoutKillToken)
         {
             Busy = true;
             try
@@ -399,7 +400,7 @@ namespace GitHub.Runner.Listener
                     {
                         // renew job request task complete means we run out of retry for the first job request renew.
                         Trace.Info($"Unable to renew job request for job {message.JobId} for the first time, stop dispatching job to worker.");
-                        return;
+                        return TaskResult.Abandoned;
                     }
 
                     if (jobRequestCancellationToken.IsCancellationRequested)
@@ -412,7 +413,7 @@ namespace GitHub.Runner.Listener
 
                         // complete job request with result Cancelled
                         await CompleteJobRequestAsync(_poolId, message, systemConnection, lockToken, TaskResult.Canceled);
-                        return;
+                        return TaskResult.Canceled;
                     }
 
                     HostContext.WritePerfCounter($"JobRequestRenewed_{requestId.ToString()}");
@@ -523,7 +524,7 @@ namespace GitHub.Runner.Listener
                             await renewJobRequest;
 
                             // not finish the job request since the job haven't run on worker at all, we will not going to set a result to server.
-                            return;
+                            return TaskResult.Failed;
                         }
 
                         // we get first jobrequest renew succeed and start the worker process with the job message.
@@ -604,7 +605,7 @@ namespace GitHub.Runner.Listener
                                     Trace.Error(detailInfo);
                                 }
 
-                                return;
+                                return TaskResultUtil.TranslateFromReturnCode(returnCode);
                             }
                             else if (completedTask == renewJobRequest)
                             {
@@ -706,6 +707,8 @@ namespace GitHub.Runner.Listener
 
                             // complete job request
                             await CompleteJobRequestAsync(_poolId, message, systemConnection, lockToken, resultOnAbandonOrCancel);
+
+                            return resultOnAbandonOrCancel;
                         }
                         finally
                         {

src/Runner.Listener/Runner.cs

@@ -324,8 +324,11 @@ namespace GitHub.Runner.Listener
                         HostContext.EnableAuthMigration("EnableAuthMigrationByDefault");
                     }
 
+                    // hosted runner only run one job and would like to know the result of the job for telemetry and alerting on failure spike.
+                    var returnJobResultForHosted = StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_RUNNER_RETURN_JOB_RESULT_FOR_HOSTED"));
+
                     // Run the runner interactively or as service
-                    return await ExecuteRunnerAsync(settings, command.RunOnce || settings.Ephemeral);
+                    return await ExecuteRunnerAsync(settings, command.RunOnce || settings.Ephemeral || returnJobResultForHosted, returnJobResultForHosted);
                 }
                 else
                 {
@@ -401,7 +404,7 @@ namespace GitHub.Runner.Listener
         }
 
         //create worker manager, create message listener and start listening to the queue
-        private async Task<int> RunAsync(RunnerSettings settings, bool runOnce = false)
+        private async Task<int> RunAsync(RunnerSettings settings, bool runOnce = false, bool returnRunOnceJobResult = false)
         {
             try
             {
@@ -580,6 +583,21 @@ namespace GitHub.Runner.Listener
                                         Trace.Info($"Ignore any exception after cancel message loop. {ex}");
                                     }
 
+                                    if (returnRunOnceJobResult)
+                                    {
+                                        try
+                                        {
+                                            var jobResult = await jobDispatcher.RunOnceJobCompleted.Task;
+                                            return TaskResultUtil.TranslateToReturnCode(jobResult);
+                                        }
+                                        catch (Exception ex)
+                                        {
+                                            Trace.Error("run once job finished with error.");
+                                            Trace.Error(ex);
+                                            return Constants.Runner.ReturnCode.TerminatedError;
+                                        }
+                                    }
+
                                     return Constants.Runner.ReturnCode.Success;
                                 }
                             }
@@ -866,14 +884,14 @@ namespace GitHub.Runner.Listener
             return Constants.Runner.ReturnCode.Success;
         }
 
-        private async Task<int> ExecuteRunnerAsync(RunnerSettings settings, bool runOnce)
+        private async Task<int> ExecuteRunnerAsync(RunnerSettings settings, bool runOnce, bool returnRunOnceJobResult)
         {
             int returnCode = Constants.Runner.ReturnCode.Success;
             bool restart = false;
             do
             {
                 restart = false;
-                returnCode = await RunAsync(settings, runOnce);
+                returnCode = await RunAsync(settings, runOnce, returnRunOnceJobResult);
 
                 if (returnCode == Constants.Runner.ReturnCode.RunnerConfigurationRefreshed)
                 {

src/Runner.Listener/SelfUpdater.cs

@@ -120,8 +120,10 @@ namespace GitHub.Runner.Listener
             }
             catch (Exception ex)
             {
+                Trace.Error(ex);
+                _terminal.WriteError($"Runner update failed: {ex.Message}");
                 _updateTrace.Enqueue(ex.ToString());
-                throw;
+                return false;
             }
             finally
             {

src/Runner.Listener/SelfUpdaterV2.cs

@@ -120,8 +120,10 @@ namespace GitHub.Runner.Listener
             }
             catch (Exception ex)
             {
+                Trace.Error(ex);
+                _terminal.WriteError($"Runner update failed: {ex.Message}");
                 _updateTrace.Enqueue(ex.ToString());
-                throw;
+                return false;
             }
             finally
             {

src/Runner.Sdk/Util/IOUtil.cs

@@ -93,6 +93,16 @@ namespace GitHub.Runner.Sdk
             }
         }
 
+        public static FileSystemInfo CreateSymbolicLink(string destDirectory, string srcDirectory)
+        {
+            // ensure directory chain exists
+            Directory.CreateDirectory(destDirectory);
+            // delete leaf directory
+            Directory.Delete(destDirectory);
+            // create symlink for the leaf directory
+            return Directory.CreateSymbolicLink(destDirectory, srcDirectory);
+        }
+
         public static void Delete(string path, CancellationToken cancellationToken)
         {
             DeleteDirectory(path, cancellationToken);

src/Runner.Worker/ActionCommandManager.cs

@@ -318,6 +318,17 @@ namespace GitHub.Runner.Worker
                 context.AddIssue(issue, ExecutionContextLogOptions.Default);
             }
 
+            if (!context.Global.HasDeprecatedSetOutput)
+            {
+                context.Global.HasDeprecatedSetOutput = true;
+                var telemetry = new JobTelemetry
+                {
+                    Type = JobTelemetryType.ActionCommand,
+                    Message = "DeprecatedCommand: set-output"
+                };
+                context.Global.JobTelemetry.Add(telemetry);
+            }
+
             if (!command.Properties.TryGetValue(SetOutputCommandProperties.Name, out string outputName) || string.IsNullOrEmpty(outputName))
             {
                 throw new Exception("Required field 'name' is missing in ##[set-output] command.");
@@ -353,6 +364,17 @@ namespace GitHub.Runner.Worker
                 context.AddIssue(issue, ExecutionContextLogOptions.Default);
             }
 
+            if (!context.Global.HasDeprecatedSaveState)
+            {
+                context.Global.HasDeprecatedSaveState = true;
+                var telemetry = new JobTelemetry
+                {
+                    Type = JobTelemetryType.ActionCommand,
+                    Message = "DeprecatedCommand: save-state"
+                };
+                context.Global.JobTelemetry.Add(telemetry);
+            }
+
             if (!command.Properties.TryGetValue(SaveStateCommandProperties.Name, out string stateName) || string.IsNullOrEmpty(stateName))
             {
                 throw new Exception("Required field 'name' is missing in ##[save-state] command.");

src/Runner.Worker/ActionManager.cs

@@ -111,7 +111,7 @@ namespace GitHub.Runner.Worker
             {
                 // Log the error and fail the PrepareActionsAsync Initialization.
                 Trace.Error($"Caught exception from PrepareActionsAsync Initialization: {ex}");
-                executionContext.InfrastructureError(ex.Message, category: "resolve_action");
+                executionContext.InfrastructureError(ex.InnerException?.Message ?? ex.Message, category: "resolve_action");
                 executionContext.Result = TaskResult.Failed;
                 throw;
             }
@@ -773,10 +773,6 @@ namespace GitHub.Runner.Worker
             }
             else
             {
-                // make sure we get a clean folder ready to use.
-                IOUtil.DeleteDirectory(destDirectory, executionContext.CancellationToken);
-                Directory.CreateDirectory(destDirectory);
-
                 if (downloadInfo.PackageDetails != null)
                 {
                     executionContext.Output($"##[group]Download immutable action package '{downloadInfo.NameWithOwner}@{downloadInfo.Ref}'");
@@ -811,6 +807,50 @@ namespace GitHub.Runner.Worker
                 if (!string.IsNullOrEmpty(actionArchiveCacheDir) &&
                     Directory.Exists(actionArchiveCacheDir))
                 {
+                    var symlinkCachedActions = StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable(Constants.Variables.Agent.SymlinkCachedActions));
+                    if (symlinkCachedActions)
+                    {
+                        Trace.Info($"Checking if can symlink '{downloadInfo.ResolvedNameWithOwner}@{downloadInfo.ResolvedSha}'");
+
+                        var cacheDirectory = Path.Combine(actionArchiveCacheDir, downloadInfo.ResolvedNameWithOwner.Replace(Path.DirectorySeparatorChar, '_').Replace(Path.AltDirectorySeparatorChar, '_'), downloadInfo.ResolvedSha);
+                        if (Directory.Exists(cacheDirectory))
+                        {
+                            try
+                            {
+                                Trace.Info($"Found unpacked action directory '{cacheDirectory}' in cache directory '{actionArchiveCacheDir}'");
+
+                                // repository archive from github always contains a nested folder
+                                var nestedDirectories = new DirectoryInfo(cacheDirectory).GetDirectories();
+                                if (nestedDirectories.Length != 1)
+                                {
+                                    throw new InvalidOperationException($"'{cacheDirectory}' contains '{nestedDirectories.Length}' directories");
+                                }
+                                else
+                                {
+                                    executionContext.Debug($"Symlink '{nestedDirectories[0].Name}' to '{destDirectory}'");
+                                    // make sure we get a clean folder ready to use.
+                                    IOUtil.DeleteDirectory(destDirectory, executionContext.CancellationToken);
+                                    IOUtil.CreateSymbolicLink(destDirectory, nestedDirectories[0].FullName);
+                                }
+
+                                executionContext.Debug($"Created symlink from cached directory '{cacheDirectory}' to '{destDirectory}'");
+                                executionContext.Global.JobTelemetry.Add(new JobTelemetry()
+                                {
+                                    Type = JobTelemetryType.General,
+                                    Message = $"Action archive cache usage: {downloadInfo.ResolvedNameWithOwner}@{downloadInfo.ResolvedSha} use cache {useActionArchiveCache} has cache {hasActionArchiveCache} via symlink"
+                                });
+
+                                Trace.Info("Finished getting action repository.");
+                                return;
+                            }
+                            catch (Exception ex)
+                            {
+                                Trace.Error($"Failed to create symlink from cached directory '{cacheDirectory}' to '{destDirectory}'. Error: {ex}");
+                                // Fall through to normal download logic
+                            }
+                        }
+                    }
+
                     hasActionArchiveCache = true;
                     Trace.Info($"Check if action archive '{downloadInfo.ResolvedNameWithOwner}@{downloadInfo.ResolvedSha}' already exists in cache directory '{actionArchiveCacheDir}'");
 #if OS_WINDOWS
@@ -892,6 +932,10 @@ namespace GitHub.Runner.Worker
                 }
 #endif
 
+                // make sure we get a clean folder ready to use.
+                IOUtil.DeleteDirectory(destDirectory, executionContext.CancellationToken);
+                Directory.CreateDirectory(destDirectory);
+
                 // repository archive from github always contains a nested folder
                 var subDirectories = new DirectoryInfo(stagingDirectory).GetDirectories();
                 if (subDirectories.Length != 1)

src/Runner.Worker/ActionManifestManagerWrapper.cs

@@ -84,7 +84,8 @@ namespace GitHub.Runner.Worker
                 "EvaluateContainerEnvironment",
                 () => _legacyManager.EvaluateContainerEnvironment(executionContext, token, extraExpressionValues),
                 () => _newManager.EvaluateContainerEnvironment(executionContext, ConvertToNewToken(token) as GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.MappingToken, ConvertToNewExpressionValues(extraExpressionValues)),
-                (legacyResult, newResult) => {
+                (legacyResult, newResult) =>
+                {
                     var trace = HostContext.GetTrace(nameof(ActionManifestManagerWrapper));
                     return CompareDictionaries(trace, legacyResult, newResult, "ContainerEnvironment");
                 });
@@ -165,9 +166,150 @@ namespace GitHub.Runner.Worker
                 return null;
             }
 
-            // Serialize new steps and deserialize to old steps
-            var json = StringUtil.ConvertToJson(newSteps, Newtonsoft.Json.Formatting.None);
-            return StringUtil.ConvertFromJson<List<GitHub.DistributedTask.Pipelines.ActionStep>>(json);
+            var result = new List<GitHub.DistributedTask.Pipelines.ActionStep>();
+            foreach (var step in newSteps)
+            {
+                var actionStep = new GitHub.DistributedTask.Pipelines.ActionStep
+                {
+                    ContextName = step.Id,
+                };
+
+                if (step is GitHub.Actions.WorkflowParser.RunStep runStep)
+                {
+                    actionStep.Condition = ExtractConditionString(runStep.If);
+                    actionStep.DisplayNameToken = ConvertToLegacyToken<TemplateToken>(runStep.Name);
+                    actionStep.ContinueOnError = ConvertToLegacyToken<TemplateToken>(runStep.ContinueOnError);
+                    actionStep.TimeoutInMinutes = ConvertToLegacyToken<TemplateToken>(runStep.TimeoutMinutes);
+                    actionStep.Environment = ConvertToLegacyToken<TemplateToken>(runStep.Env);
+                    actionStep.Reference = new GitHub.DistributedTask.Pipelines.ScriptReference();
+                    actionStep.Inputs = BuildRunStepInputs(runStep);
+                }
+                else if (step is GitHub.Actions.WorkflowParser.ActionStep usesStep)
+                {
+                    actionStep.Condition = ExtractConditionString(usesStep.If);
+                    actionStep.DisplayNameToken = ConvertToLegacyToken<TemplateToken>(usesStep.Name);
+                    actionStep.ContinueOnError = ConvertToLegacyToken<TemplateToken>(usesStep.ContinueOnError);
+                    actionStep.TimeoutInMinutes = ConvertToLegacyToken<TemplateToken>(usesStep.TimeoutMinutes);
+                    actionStep.Environment = ConvertToLegacyToken<TemplateToken>(usesStep.Env);
+                    actionStep.Reference = ParseActionReference(usesStep.Uses?.Value);
+                    actionStep.Inputs = ConvertToLegacyToken<MappingToken>(usesStep.With);
+                }
+
+                result.Add(actionStep);
+            }
+            return result;
+        }
+
+        private string ExtractConditionString(GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.BasicExpressionToken ifToken)
+        {
+            if (ifToken == null)
+            {
+                return null;
+            }
+
+            // The Expression property is internal, so we use ToString() which formats as "${{ expr }}"
+            // Then strip the delimiters to get just the expression
+            var str = ifToken.ToString();
+            if (str.StartsWith("${{") && str.EndsWith("}}"))
+            {
+                return str.Substring(3, str.Length - 5).Trim();
+            }
+            return str;
+        }
+
+        private MappingToken BuildRunStepInputs(GitHub.Actions.WorkflowParser.RunStep runStep)
+        {
+            var inputs = new MappingToken(null, null, null);
+
+            // script (from run)
+            if (runStep.Run != null)
+            {
+                inputs.Add(
+                    new StringToken(null, null, null, "script"),
+                    ConvertToLegacyToken<TemplateToken>(runStep.Run));
+            }
+
+            // shell
+            if (runStep.Shell != null)
+            {
+                inputs.Add(
+                    new StringToken(null, null, null, "shell"),
+                    ConvertToLegacyToken<TemplateToken>(runStep.Shell));
+            }
+
+            // working-directory
+            if (runStep.WorkingDirectory != null)
+            {
+                inputs.Add(
+                    new StringToken(null, null, null, "workingDirectory"),
+                    ConvertToLegacyToken<TemplateToken>(runStep.WorkingDirectory));
+            }
+
+            return inputs.Count > 0 ? inputs : null;
+        }
+
+        private GitHub.DistributedTask.Pipelines.ActionStepDefinitionReference ParseActionReference(string uses)
+        {
+            if (string.IsNullOrEmpty(uses))
+            {
+                return null;
+            }
+
+            // Docker reference: docker://image:tag
+            if (uses.StartsWith("docker://", StringComparison.OrdinalIgnoreCase))
+            {
+                return new GitHub.DistributedTask.Pipelines.ContainerRegistryReference
+                {
+                    Image = uses.Substring("docker://".Length)
+                };
+            }
+
+            // Local path reference: ./path/to/action
+            if (uses.StartsWith("./") || uses.StartsWith(".\\"))
+            {
+                return new GitHub.DistributedTask.Pipelines.RepositoryPathReference
+                {
+                    RepositoryType = "self",
+                    Path = uses
+                };
+            }
+
+            // Repository reference: owner/repo@ref or owner/repo/path@ref
+            var atIndex = uses.LastIndexOf('@');
+            string refPart = null;
+            string repoPart = uses;
+
+            if (atIndex > 0)
+            {
+                refPart = uses.Substring(atIndex + 1);
+                repoPart = uses.Substring(0, atIndex);
+            }
+
+            // Split by / to get owner/repo and optional path
+            var parts = repoPart.Split('/');
+            string name;
+            string path = null;
+
+            if (parts.Length >= 2)
+            {
+                name = $"{parts[0]}/{parts[1]}";
+                if (parts.Length > 2)
+                {
+                    path = string.Join("/", parts, 2, parts.Length - 2);
+                }
+            }
+            else
+            {
+                name = repoPart;
+            }
+
+            return new GitHub.DistributedTask.Pipelines.RepositoryPathReference
+            {
+                RepositoryType = "GitHub",
+                Name = name,
+                Ref = refPart,
+                Path = path
+            };
         }
 
         private T ConvertToLegacyToken<T>(GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.TemplateToken newToken) where T : TemplateToken
@@ -633,6 +775,14 @@ namespace GitHub.Runner.Worker
                 return false;
             }
 
+            // Check for known equivalent error patterns (e.g., JSON parse errors)
+            // where both parsers correctly reject invalid input but with different wording
+            if (PipelineTemplateEvaluatorWrapper.HasJsonExceptionType(legacyException) && PipelineTemplateEvaluatorWrapper.HasJsonExceptionType(newException))
+            {
+                trace.Info("CompareExceptions - both exceptions are JSON parse errors, treating as matched");
+                return true;
+            }
+
             // Compare exception messages recursively (including inner exceptions)
             var legacyMessages = GetExceptionMessages(legacyException);
             var newMessages = GetExceptionMessages(newException);
@@ -697,5 +847,6 @@ namespace GitHub.Runner.Worker
 
             return messages;
         }
+
     }
 }

src/Runner.Worker/Container/ContainerInfo.cs

@@ -36,6 +36,8 @@ namespace GitHub.Runner.Worker.Container
             this.ContainerImage = containerImage;
             this.ContainerDisplayName = $"{container.Alias}_{Pipelines.Validation.NameValidation.Sanitize(containerImage)}_{Guid.NewGuid().ToString("N").Substring(0, 6)}";
             this.ContainerCreateOptions = container.Options;
+            this.ContainerEntryPoint = container.Entrypoint;
+            this.ContainerEntryPointArgs = container.Command;
             _environmentVariables = container.Environment;
             this.IsJobContainer = isJobContainer;
             this.ContainerNetworkAlias = networkAlias;

src/Runner.Worker/Dap/DapDebugSession.cs

@@ -0,0 +1,644 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Common;
+using Newtonsoft.Json;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Stores information about a completed step for stack trace display.
+    /// </summary>
+    internal sealed class CompletedStepInfo
+    {
+        public string DisplayName { get; set; }
+        public TaskResult? Result { get; set; }
+        public int FrameId { get; set; }
+    }
+
+    /// <summary>
+    /// Minimal production DAP debug session.
+    /// Handles step-level breakpoints with next/continue flow control,
+    /// client reconnection, and cancellation signal propagation.
+    ///
+    /// Scope inspection, REPL, step manipulation, and time-travel debugging
+    /// are intentionally deferred to future iterations.
+    /// </summary>
+    public sealed class DapDebugSession : RunnerService, IDapDebugSession
+    {
+        // Thread ID for the single job execution thread
+        private const int JobThreadId = 1;
+
+        // Frame ID for the current step (always 1)
+        private const int CurrentFrameId = 1;
+
+        // Frame IDs for completed steps start at 1000
+        private const int CompletedFrameIdBase = 1000;
+
+        private IDapServer _server;
+        private DapSessionState _state = DapSessionState.WaitingForConnection;
+
+        // Synchronization for step execution
+        private TaskCompletionSource<DapCommand> _commandTcs;
+        private readonly object _stateLock = new object();
+
+        // Handshake completion — signaled when configurationDone is received
+        private readonly TaskCompletionSource<bool> _handshakeTcs = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        // Whether to pause before the next step (set by 'next' command)
+        private bool _pauseOnNextStep = true;
+
+        // Current execution context
+        private IStep _currentStep;
+        private IExecutionContext _jobContext;
+        private int _currentStepIndex;
+
+        // Track completed steps for stack trace
+        private readonly List<CompletedStepInfo> _completedSteps = new List<CompletedStepInfo>();
+        private int _nextCompletedFrameId = CompletedFrameIdBase;
+
+        // Client connection tracking for reconnection support
+        private volatile bool _isClientConnected;
+
+        public bool IsActive =>
+            _state == DapSessionState.Ready ||
+            _state == DapSessionState.Paused ||
+            _state == DapSessionState.Running;
+
+        public DapSessionState State => _state;
+
+        public override void Initialize(IHostContext hostContext)
+        {
+            base.Initialize(hostContext);
+            Trace.Info("DapDebugSession initialized");
+        }
+
+        public void SetDapServer(IDapServer server)
+        {
+            _server = server;
+            Trace.Info("DAP server reference set");
+        }
+
+        public async Task WaitForHandshakeAsync(CancellationToken cancellationToken)
+        {
+            Trace.Info("Waiting for DAP handshake (configurationDone)...");
+
+            using (cancellationToken.Register(() => _handshakeTcs.TrySetCanceled()))
+            {
+                await _handshakeTcs.Task;
+            }
+
+            Trace.Info("DAP handshake complete, session is ready");
+        }
+
+        #region Message Dispatch
+
+        public async Task HandleMessageAsync(string messageJson, CancellationToken cancellationToken)
+        {
+            Request request = null;
+            try
+            {
+                request = JsonConvert.DeserializeObject<Request>(messageJson);
+                if (request == null)
+                {
+                    Trace.Warning("Failed to deserialize DAP request");
+                    return;
+                }
+
+                Trace.Info($"Handling DAP request: {request.Command}");
+
+                var response = request.Command switch
+                {
+                    "initialize" => HandleInitialize(request),
+                    "attach" => HandleAttach(request),
+                    "configurationDone" => HandleConfigurationDone(request),
+                    "disconnect" => HandleDisconnect(request),
+                    "threads" => HandleThreads(request),
+                    "stackTrace" => HandleStackTrace(request),
+                    "scopes" => HandleScopes(request),
+                    "variables" => HandleVariables(request),
+                    "continue" => HandleContinue(request),
+                    "next" => HandleNext(request),
+                    "setBreakpoints" => HandleSetBreakpoints(request),
+                    "setExceptionBreakpoints" => HandleSetExceptionBreakpoints(request),
+                    _ => CreateResponse(request, false, $"Unsupported command: {request.Command}", body: null)
+                };
+
+                response.RequestSeq = request.Seq;
+                response.Command = request.Command;
+
+                _server?.SendResponse(response);
+            }
+            catch (Exception ex)
+            {
+                Trace.Error($"Error handling request '{request?.Command}': {ex}");
+                if (request != null)
+                {
+                    var errorResponse = CreateResponse(request, false, ex.Message, body: null);
+                    errorResponse.RequestSeq = request.Seq;
+                    errorResponse.Command = request.Command;
+                    _server?.SendResponse(errorResponse);
+                }
+            }
+
+            await Task.CompletedTask;
+        }
+
+        #endregion
+
+        #region DAP Request Handlers
+
+        private Response HandleInitialize(Request request)
+        {
+            if (request.Arguments != null)
+            {
+                try
+                {
+                    var clientCaps = request.Arguments.ToObject<InitializeRequestArguments>();
+                    Trace.Info($"Client: {clientCaps?.ClientName ?? clientCaps?.ClientId ?? "unknown"}");
+                }
+                catch (Exception ex)
+                {
+                    Trace.Warning($"Failed to parse initialize arguments: {ex.Message}");
+                }
+            }
+
+            _state = DapSessionState.Initializing;
+
+            // Build capabilities — MVP only supports configurationDone
+            var capabilities = new Capabilities
+            {
+                SupportsConfigurationDoneRequest = true,
+                // All other capabilities are false for MVP
+                SupportsFunctionBreakpoints = false,
+                SupportsConditionalBreakpoints = false,
+                SupportsEvaluateForHovers = false,
+                SupportsStepBack = false,
+                SupportsSetVariable = false,
+                SupportsRestartFrame = false,
+                SupportsGotoTargetsRequest = false,
+                SupportsStepInTargetsRequest = false,
+                SupportsCompletionsRequest = false,
+                SupportsModulesRequest = false,
+                SupportsTerminateRequest = false,
+                SupportTerminateDebuggee = false,
+                SupportsDelayedStackTraceLoading = false,
+                SupportsLoadedSourcesRequest = false,
+                SupportsProgressReporting = false,
+                SupportsRunInTerminalRequest = false,
+                SupportsCancelRequest = false,
+                SupportsExceptionOptions = false,
+                SupportsValueFormattingOptions = false,
+                SupportsExceptionInfoRequest = false,
+            };
+
+            // Send initialized event after a brief delay to ensure the
+            // response is delivered first (DAP spec requirement)
+            _ = Task.Run(async () =>
+            {
+                await Task.Delay(50);
+                _server?.SendEvent(new Event
+                {
+                    EventType = "initialized"
+                });
+                Trace.Info("Sent initialized event");
+            });
+
+            Trace.Info("Initialize request handled, capabilities sent");
+            return CreateResponse(request, true, body: capabilities);
+        }
+
+        private Response HandleAttach(Request request)
+        {
+            Trace.Info("Attach request handled");
+            return CreateResponse(request, true, body: null);
+        }
+
+        private Response HandleConfigurationDone(Request request)
+        {
+            lock (_stateLock)
+            {
+                _state = DapSessionState.Ready;
+            }
+
+            _handshakeTcs.TrySetResult(true);
+
+            Trace.Info("Configuration done, debug session is ready");
+            return CreateResponse(request, true, body: null);
+        }
+
+        private Response HandleDisconnect(Request request)
+        {
+            Trace.Info("Disconnect request received");
+
+            lock (_stateLock)
+            {
+                _state = DapSessionState.Terminated;
+
+                // Release any blocked step execution
+                _commandTcs?.TrySetResult(DapCommand.Disconnect);
+            }
+
+            return CreateResponse(request, true, body: null);
+        }
+
+        private Response HandleThreads(Request request)
+        {
+            var body = new ThreadsResponseBody
+            {
+                Threads = new List<Thread>
+                {
+                    new Thread
+                    {
+                        Id = JobThreadId,
+                        Name = _jobContext != null
+                            ? $"Job: {_jobContext.GetGitHubContext("job") ?? "workflow job"}"
+                            : "Job Thread"
+                    }
+                }
+            };
+
+            return CreateResponse(request, true, body: body);
+        }
+
+        private Response HandleStackTrace(Request request)
+        {
+            var frames = new List<StackFrame>();
+
+            // Add current step as the top frame
+            if (_currentStep != null)
+            {
+                var resultIndicator = _currentStep.ExecutionContext?.Result != null
+                    ? $" [{_currentStep.ExecutionContext.Result}]"
+                    : " [running]";
+
+                frames.Add(new StackFrame
+                {
+                    Id = CurrentFrameId,
+                    Name = $"{_currentStep.DisplayName ?? "Current Step"}{resultIndicator}",
+                    Line = _currentStepIndex + 1,
+                    Column = 1,
+                    PresentationHint = "normal"
+                });
+            }
+            else
+            {
+                frames.Add(new StackFrame
+                {
+                    Id = CurrentFrameId,
+                    Name = "(no step executing)",
+                    Line = 0,
+                    Column = 1,
+                    PresentationHint = "subtle"
+                });
+            }
+
+            // Add completed steps as additional frames (most recent first)
+            for (int i = _completedSteps.Count - 1; i >= 0; i--)
+            {
+                var completedStep = _completedSteps[i];
+                var resultStr = completedStep.Result.HasValue ? $" [{completedStep.Result}]" : "";
+                frames.Add(new StackFrame
+                {
+                    Id = completedStep.FrameId,
+                    Name = $"{completedStep.DisplayName}{resultStr}",
+                    Line = 1,
+                    Column = 1,
+                    PresentationHint = "subtle"
+                });
+            }
+
+            var body = new StackTraceResponseBody
+            {
+                StackFrames = frames,
+                TotalFrames = frames.Count
+            };
+
+            return CreateResponse(request, true, body: body);
+        }
+
+        private Response HandleScopes(Request request)
+        {
+            // MVP: return empty scopes — scope inspection deferred
+            return CreateResponse(request, true, body: new ScopesResponseBody
+            {
+                Scopes = new List<Scope>()
+            });
+        }
+
+        private Response HandleVariables(Request request)
+        {
+            // MVP: return empty variables — variable inspection deferred
+            return CreateResponse(request, true, body: new VariablesResponseBody
+            {
+                Variables = new List<Variable>()
+            });
+        }
+
+        private Response HandleContinue(Request request)
+        {
+            Trace.Info("Continue command received");
+
+            lock (_stateLock)
+            {
+                if (_state == DapSessionState.Paused)
+                {
+                    _state = DapSessionState.Running;
+                    _pauseOnNextStep = false;
+                    _commandTcs?.TrySetResult(DapCommand.Continue);
+                }
+            }
+
+            return CreateResponse(request, true, body: new ContinueResponseBody
+            {
+                AllThreadsContinued = true
+            });
+        }
+
+        private Response HandleNext(Request request)
+        {
+            Trace.Info("Next (step over) command received");
+
+            lock (_stateLock)
+            {
+                if (_state == DapSessionState.Paused)
+                {
+                    _state = DapSessionState.Running;
+                    _pauseOnNextStep = true;
+                    _commandTcs?.TrySetResult(DapCommand.Next);
+                }
+            }
+
+            return CreateResponse(request, true, body: null);
+        }
+
+        private Response HandleSetBreakpoints(Request request)
+        {
+            // MVP: acknowledge but don't process breakpoints
+            // All steps pause automatically via _pauseOnNextStep
+            return CreateResponse(request, true, body: new { breakpoints = Array.Empty<object>() });
+        }
+
+        private Response HandleSetExceptionBreakpoints(Request request)
+        {
+            // MVP: acknowledge but don't process exception breakpoints
+            return CreateResponse(request, true, body: null);
+        }
+
+        #endregion
+
+        #region Step Lifecycle
+
+        public async Task OnStepStartingAsync(IStep step, IExecutionContext jobContext, bool isFirstStep, CancellationToken cancellationToken)
+        {
+            if (!IsActive)
+            {
+                return;
+            }
+
+            _currentStep = step;
+            _jobContext = jobContext;
+            _currentStepIndex = _completedSteps.Count;
+
+            // Determine if we should pause
+            bool shouldPause = isFirstStep || _pauseOnNextStep;
+
+            if (!shouldPause)
+            {
+                Trace.Info($"Step starting (not pausing): {step.DisplayName}");
+                return;
+            }
+
+            var reason = isFirstStep ? "entry" : "step";
+            var description = isFirstStep
+                ? $"Stopped at job entry: {step.DisplayName}"
+                : $"Stopped before step: {step.DisplayName}";
+
+            Trace.Info($"Step starting: {step.DisplayName} (reason: {reason})");
+
+            // Send stopped event to debugger (only if client is connected)
+            SendStoppedEvent(reason, description);
+
+            // Wait for debugger command
+            await WaitForCommandAsync(cancellationToken);
+        }
+
+        public void OnStepCompleted(IStep step)
+        {
+            if (!IsActive)
+            {
+                return;
+            }
+
+            var result = step.ExecutionContext?.Result;
+            Trace.Info($"Step completed: {step.DisplayName}, result: {result}");
+
+            // Add to completed steps list for stack trace
+            _completedSteps.Add(new CompletedStepInfo
+            {
+                DisplayName = step.DisplayName,
+                Result = result,
+                FrameId = _nextCompletedFrameId++
+            });
+        }
+
+        public void OnJobCompleted()
+        {
+            if (!IsActive)
+            {
+                return;
+            }
+
+            Trace.Info("Job completed, sending terminated event");
+
+            lock (_stateLock)
+            {
+                _state = DapSessionState.Terminated;
+            }
+
+            _server?.SendEvent(new Event
+            {
+                EventType = "terminated",
+                Body = new TerminatedEventBody()
+            });
+
+            var exitCode = _jobContext?.Result == TaskResult.Succeeded ? 0 : 1;
+            _server?.SendEvent(new Event
+            {
+                EventType = "exited",
+                Body = new ExitedEventBody
+                {
+                    ExitCode = exitCode
+                }
+            });
+        }
+
+        public void CancelSession()
+        {
+            Trace.Info("CancelSession called - terminating debug session");
+
+            lock (_stateLock)
+            {
+                if (_state == DapSessionState.Terminated)
+                {
+                    Trace.Info("Session already terminated, ignoring CancelSession");
+                    return;
+                }
+                _state = DapSessionState.Terminated;
+            }
+
+            // Send terminated event to debugger so it updates its UI
+            _server?.SendEvent(new Event
+            {
+                EventType = "terminated",
+                Body = new TerminatedEventBody()
+            });
+
+            // Send exited event with cancellation exit code (130 = SIGINT convention)
+            _server?.SendEvent(new Event
+            {
+                EventType = "exited",
+                Body = new ExitedEventBody { ExitCode = 130 }
+            });
+
+            // Release any pending command waits
+            _commandTcs?.TrySetResult(DapCommand.Disconnect);
+
+            // Release handshake wait if still pending
+            _handshakeTcs.TrySetCanceled();
+
+            Trace.Info("Debug session cancelled");
+        }
+
+        #endregion
+
+        #region Client Connection Tracking
+
+        public void HandleClientConnected()
+        {
+            _isClientConnected = true;
+            Trace.Info("Client connected to debug session");
+
+            // If we're paused, re-send the stopped event so the new client
+            // knows the current state (important for reconnection)
+            lock (_stateLock)
+            {
+                if (_state == DapSessionState.Paused && _currentStep != null)
+                {
+                    Trace.Info("Re-sending stopped event to reconnected client");
+                    var description = $"Stopped before step: {_currentStep.DisplayName}";
+                    SendStoppedEvent("step", description);
+                }
+            }
+        }
+
+        public void HandleClientDisconnected()
+        {
+            _isClientConnected = false;
+            Trace.Info("Client disconnected from debug session");
+
+            // Intentionally do NOT release the command TCS here.
+            // The session stays paused, waiting for a client to reconnect.
+            // The server's connection loop will accept a new client and
+            // call HandleClientConnected, which re-sends the stopped event.
+        }
+
+        #endregion
+
+        #region Private Helpers
+
+        /// <summary>
+        /// Blocks the step execution thread until a debugger command is received
+        /// or the job is cancelled.
+        /// </summary>
+        private async Task WaitForCommandAsync(CancellationToken cancellationToken)
+        {
+            lock (_stateLock)
+            {
+                _state = DapSessionState.Paused;
+                _commandTcs = new TaskCompletionSource<DapCommand>(TaskCreationOptions.RunContinuationsAsynchronously);
+            }
+
+            Trace.Info("Waiting for debugger command...");
+
+            using (cancellationToken.Register(() =>
+            {
+                Trace.Info("Job cancellation detected, releasing debugger wait");
+                _commandTcs?.TrySetResult(DapCommand.Disconnect);
+            }))
+            {
+                var command = await _commandTcs.Task;
+
+                Trace.Info($"Received command: {command}");
+
+                lock (_stateLock)
+                {
+                    if (_state == DapSessionState.Paused)
+                    {
+                        _state = DapSessionState.Running;
+                    }
+                }
+
+                // Send continued event for normal flow commands
+                if (!cancellationToken.IsCancellationRequested &&
+                    (command == DapCommand.Continue || command == DapCommand.Next))
+                {
+                    _server?.SendEvent(new Event
+                    {
+                        EventType = "continued",
+                        Body = new ContinuedEventBody
+                        {
+                            ThreadId = JobThreadId,
+                            AllThreadsContinued = true
+                        }
+                    });
+                }
+            }
+        }
+
+        /// <summary>
+        /// Sends a stopped event to the connected client.
+        /// Silently no-ops if no client is connected.
+        /// </summary>
+        private void SendStoppedEvent(string reason, string description)
+        {
+            if (!_isClientConnected)
+            {
+                Trace.Info($"No client connected, deferring stopped event: {description}");
+                return;
+            }
+
+            _server?.SendEvent(new Event
+            {
+                EventType = "stopped",
+                Body = new StoppedEventBody
+                {
+                    Reason = reason,
+                    Description = description,
+                    ThreadId = JobThreadId,
+                    AllThreadsStopped = true
+                }
+            });
+        }
+
+        /// <summary>
+        /// Creates a DAP response with common fields pre-populated.
+        /// </summary>
+        private Response CreateResponse(Request request, bool success, string message = null, object body = null)
+        {
+            return new Response
+            {
+                Type = "response",
+                RequestSeq = request.Seq,
+                Command = request.Command,
+                Success = success,
+                Message = success ? null : message,
+                Body = body
+            };
+        }
+
+        #endregion
+    }
+}

src/Runner.Worker/Dap/DapServer.cs

@@ -0,0 +1,466 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Net.Sockets;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+using Newtonsoft.Json;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    /// <summary>
+    /// Production TCP server for the Debug Adapter Protocol.
+    /// Handles Content-Length message framing, JSON serialization,
+    /// client reconnection, and graceful shutdown.
+    /// </summary>
+    public sealed class DapServer : RunnerService, IDapServer
+    {
+        private const string ContentLengthHeader = "Content-Length: ";
+
+        private TcpListener _listener;
+        private TcpClient _client;
+        private NetworkStream _stream;
+        private IDapDebugSession _session;
+        private CancellationTokenSource _cts;
+        private TaskCompletionSource<bool> _connectionTcs;
+        private readonly SemaphoreSlim _sendLock = new SemaphoreSlim(1, 1);
+        private int _nextSeq = 1;
+        private volatile bool _acceptConnections = true;
+
+        public override void Initialize(IHostContext hostContext)
+        {
+            base.Initialize(hostContext);
+            Trace.Info("DapServer initialized");
+        }
+
+        public void SetSession(IDapDebugSession session)
+        {
+            _session = session;
+            Trace.Info("Debug session set");
+        }
+
+        public async Task StartAsync(int port, CancellationToken cancellationToken)
+        {
+            Trace.Info($"Starting DAP server on port {port}");
+
+            _cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            _connectionTcs = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+            _listener = new TcpListener(IPAddress.Loopback, port);
+            _listener.Start();
+            Trace.Info($"DAP server listening on 127.0.0.1:{port}");
+
+            // Start the connection loop in the background
+            _ = ConnectionLoopAsync(_cts.Token);
+
+            await Task.CompletedTask;
+        }
+
+        /// <summary>
+        /// Accepts client connections in a loop, supporting reconnection.
+        /// When a client disconnects, the server waits for a new connection
+        /// without blocking step execution.
+        /// </summary>
+        private async Task ConnectionLoopAsync(CancellationToken cancellationToken)
+        {
+            while (_acceptConnections && !cancellationToken.IsCancellationRequested)
+            {
+                try
+                {
+                    Trace.Info("Waiting for debug client connection...");
+
+                    using (cancellationToken.Register(() =>
+                    {
+                        try { _listener?.Stop(); }
+                        catch { /* listener already stopped */ }
+                    }))
+                    {
+                        _client = await _listener.AcceptTcpClientAsync();
+                    }
+
+                    if (cancellationToken.IsCancellationRequested)
+                    {
+                        break;
+                    }
+
+                    _stream = _client.GetStream();
+                    var remoteEndPoint = _client.Client.RemoteEndPoint;
+                    Trace.Info($"Debug client connected from {remoteEndPoint}");
+
+                    // Signal first connection (no-op on subsequent connections)
+                    _connectionTcs.TrySetResult(true);
+
+                    // Notify session of new client
+                    _session?.HandleClientConnected();
+
+                    // Process messages until client disconnects
+                    await ProcessMessagesAsync(cancellationToken);
+
+                    // Client disconnected — notify session and clean up
+                    Trace.Info("Client disconnected, waiting for reconnection...");
+                    _session?.HandleClientDisconnected();
+                    CleanupConnection();
+                }
+                catch (ObjectDisposedException) when (cancellationToken.IsCancellationRequested)
+                {
+                    break;
+                }
+                catch (SocketException) when (cancellationToken.IsCancellationRequested)
+                {
+                    break;
+                }
+                catch (Exception ex)
+                {
+                    Trace.Warning($"Connection error: {ex.Message}");
+                    CleanupConnection();
+
+                    if (!_acceptConnections || cancellationToken.IsCancellationRequested)
+                    {
+                        break;
+                    }
+
+                    // Brief delay before accepting next connection
+                    try
+                    {
+                        await Task.Delay(100, cancellationToken);
+                    }
+                    catch (OperationCanceledException)
+                    {
+                        break;
+                    }
+                }
+            }
+
+            _connectionTcs.TrySetCanceled();
+            Trace.Info("Connection loop ended");
+        }
+
+        /// <summary>
+        /// Cleans up the current client connection without stopping the listener.
+        /// </summary>
+        private void CleanupConnection()
+        {
+            try { _stream?.Close(); } catch { /* best effort */ }
+            try { _client?.Close(); } catch { /* best effort */ }
+            _stream = null;
+            _client = null;
+        }
+
+        public async Task WaitForConnectionAsync(CancellationToken cancellationToken)
+        {
+            Trace.Info("Waiting for debug client to connect...");
+
+            using (cancellationToken.Register(() => _connectionTcs.TrySetCanceled()))
+            {
+                await _connectionTcs.Task;
+            }
+
+            Trace.Info("Debug client connected");
+        }
+
+        public async Task StopAsync()
+        {
+            Trace.Info("Stopping DAP server");
+
+            _acceptConnections = false;
+            _cts?.Cancel();
+
+            CleanupConnection();
+
+            try { _listener?.Stop(); }
+            catch { /* best effort */ }
+
+            await Task.CompletedTask;
+
+            Trace.Info("DAP server stopped");
+        }
+
+        private async Task ProcessMessagesAsync(CancellationToken cancellationToken)
+        {
+            Trace.Info("Starting DAP message processing loop");
+
+            try
+            {
+                while (!cancellationToken.IsCancellationRequested && _client?.Connected == true)
+                {
+                    var json = await ReadMessageAsync(cancellationToken);
+                    if (json == null)
+                    {
+                        Trace.Info("Client disconnected (end of stream)");
+                        break;
+                    }
+
+                    await ProcessSingleMessageAsync(json, cancellationToken);
+                }
+            }
+            catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+            {
+                Trace.Info("Message processing cancelled");
+            }
+            catch (IOException ex)
+            {
+                Trace.Info($"Connection closed: {ex.Message}");
+            }
+            catch (Exception ex)
+            {
+                Trace.Error($"Error in message loop: {ex}");
+            }
+
+            Trace.Info("DAP message processing loop ended");
+        }
+
+        private async Task ProcessSingleMessageAsync(string json, CancellationToken cancellationToken)
+        {
+            Request request = null;
+            try
+            {
+                request = JsonConvert.DeserializeObject<Request>(json);
+                if (request == null || request.Type != "request")
+                {
+                    Trace.Warning($"Received non-request message: {json}");
+                    return;
+                }
+
+                Trace.Info($"Received request: seq={request.Seq}, command={request.Command}");
+
+                if (_session == null)
+                {
+                    Trace.Error("No debug session configured");
+                    SendErrorResponse(request, "No debug session configured");
+                    return;
+                }
+
+                // Pass raw JSON to session — session handles deserialization, dispatch,
+                // and calls back to SendResponse when done.
+                await _session.HandleMessageAsync(json, cancellationToken);
+            }
+            catch (JsonException ex)
+            {
+                Trace.Error($"Failed to parse request: {ex.Message}");
+            }
+            catch (Exception ex)
+            {
+                Trace.Error($"Error processing request: {ex}");
+                if (request != null)
+                {
+                    SendErrorResponse(request, ex.Message);
+                }
+            }
+        }
+
+        private void SendErrorResponse(Request request, string message)
+        {
+            var response = new Response
+            {
+                Type = "response",
+                RequestSeq = request.Seq,
+                Command = request.Command,
+                Success = false,
+                Message = message,
+                Body = new ErrorResponseBody
+                {
+                    Error = new Message
+                    {
+                        Id = 1,
+                        Format = message,
+                        ShowUser = true
+                    }
+                }
+            };
+
+            SendResponse(response);
+        }
+
+        /// <summary>
+        /// Reads a DAP message using Content-Length framing.
+        /// Format: Content-Length: N\r\n\r\n{json}
+        /// </summary>
+        private async Task<string> ReadMessageAsync(CancellationToken cancellationToken)
+        {
+            int contentLength = -1;
+
+            while (true)
+            {
+                var line = await ReadLineAsync(cancellationToken);
+                if (line == null)
+                {
+                    return null;
+                }
+
+                if (line.Length == 0)
+                {
+                    break;
+                }
+
+                if (line.StartsWith(ContentLengthHeader, StringComparison.OrdinalIgnoreCase))
+                {
+                    var lengthStr = line.Substring(ContentLengthHeader.Length).Trim();
+                    if (!int.TryParse(lengthStr, out contentLength))
+                    {
+                        throw new InvalidDataException($"Invalid Content-Length: {lengthStr}");
+                    }
+                }
+            }
+
+            if (contentLength < 0)
+            {
+                throw new InvalidDataException("Missing Content-Length header");
+            }
+
+            var buffer = new byte[contentLength];
+            var totalRead = 0;
+            while (totalRead < contentLength)
+            {
+                var bytesRead = await _stream.ReadAsync(buffer, totalRead, contentLength - totalRead, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    throw new EndOfStreamException("Connection closed while reading message body");
+                }
+                totalRead += bytesRead;
+            }
+
+            var json = Encoding.UTF8.GetString(buffer);
+            Trace.Verbose($"Received: {json}");
+            return json;
+        }
+
+        /// <summary>
+        /// Reads a line terminated by \r\n from the network stream.
+        /// </summary>
+        private async Task<string> ReadLineAsync(CancellationToken cancellationToken)
+        {
+            var lineBuilder = new StringBuilder();
+            var buffer = new byte[1];
+            var previousWasCr = false;
+
+            while (true)
+            {
+                var bytesRead = await _stream.ReadAsync(buffer, 0, 1, cancellationToken);
+                if (bytesRead == 0)
+                {
+                    return lineBuilder.Length > 0 ? lineBuilder.ToString() : null;
+                }
+
+                var c = (char)buffer[0];
+
+                if (c == '\n' && previousWasCr)
+                {
+                    if (lineBuilder.Length > 0 && lineBuilder[lineBuilder.Length - 1] == '\r')
+                    {
+                        lineBuilder.Length--;
+                    }
+                    return lineBuilder.ToString();
+                }
+
+                previousWasCr = (c == '\r');
+                lineBuilder.Append(c);
+            }
+        }
+
+        /// <summary>
+        /// Serializes and writes a DAP message with Content-Length framing.
+        /// Must be called within the _sendLock.
+        /// </summary>
+        private void SendMessageInternal(ProtocolMessage message)
+        {
+            var json = JsonConvert.SerializeObject(message, new JsonSerializerSettings
+            {
+                NullValueHandling = NullValueHandling.Ignore
+            });
+
+            var bodyBytes = Encoding.UTF8.GetBytes(json);
+            var header = $"Content-Length: {bodyBytes.Length}\r\n\r\n";
+            var headerBytes = Encoding.ASCII.GetBytes(header);
+
+            _stream.Write(headerBytes, 0, headerBytes.Length);
+            _stream.Write(bodyBytes, 0, bodyBytes.Length);
+            _stream.Flush();
+
+            Trace.Verbose($"Sent: {json}");
+        }
+
+        public void SendMessage(ProtocolMessage message)
+        {
+            if (_stream == null)
+            {
+                return;
+            }
+
+            try
+            {
+                _sendLock.Wait();
+                try
+                {
+                    message.Seq = _nextSeq++;
+                    SendMessageInternal(message);
+                }
+                finally
+                {
+                    _sendLock.Release();
+                }
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning($"Failed to send message: {ex.Message}");
+            }
+        }
+
+        public void SendEvent(Event evt)
+        {
+            if (_stream == null)
+            {
+                Trace.Warning($"Cannot send event '{evt.EventType}': no client connected");
+                return;
+            }
+
+            try
+            {
+                _sendLock.Wait();
+                try
+                {
+                    evt.Seq = _nextSeq++;
+                    SendMessageInternal(evt);
+                }
+                finally
+                {
+                    _sendLock.Release();
+                }
+                Trace.Info($"Sent event: {evt.EventType}");
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning($"Failed to send event '{evt.EventType}': {ex.Message}");
+            }
+        }
+
+        public void SendResponse(Response response)
+        {
+            if (_stream == null)
+            {
+                Trace.Warning($"Cannot send response for '{response.Command}': no client connected");
+                return;
+            }
+
+            try
+            {
+                _sendLock.Wait();
+                try
+                {
+                    response.Seq = _nextSeq++;
+                    SendMessageInternal(response);
+                }
+                finally
+                {
+                    _sendLock.Release();
+                }
+                Trace.Info($"Sent response: seq={response.Seq}, command={response.Command}, success={response.Success}");
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning($"Failed to send response for '{response.Command}': {ex.Message}");
+            }
+        }
+    }
+}

src/Runner.Worker/Dap/IDapDebugSession.cs

@@ -0,0 +1,32 @@
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    public enum DapSessionState
+    {
+        WaitingForConnection,
+        Initializing,
+        Ready,
+        Paused,
+        Running,
+        Terminated
+    }
+
+    [ServiceLocator(Default = typeof(DapDebugSession))]
+    public interface IDapDebugSession : IRunnerService
+    {
+        bool IsActive { get; }
+        DapSessionState State { get; }
+        void SetDapServer(IDapServer server);
+        Task WaitForHandshakeAsync(CancellationToken cancellationToken);
+        Task OnStepStartingAsync(IStep step, IExecutionContext jobContext, bool isFirstStep, CancellationToken cancellationToken);
+        void OnStepCompleted(IStep step);
+        void OnJobCompleted();
+        void CancelSession();
+        void HandleClientConnected();
+        void HandleClientDisconnected();
+        Task HandleMessageAsync(string messageJson, CancellationToken cancellationToken);
+    }
+}

src/Runner.Worker/Dap/IDapServer.cs

@@ -0,0 +1,18 @@
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Common;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    [ServiceLocator(Default = typeof(DapServer))]
+    public interface IDapServer : IRunnerService
+    {
+        void SetSession(IDapDebugSession session);
+        Task StartAsync(int port, CancellationToken cancellationToken);
+        Task WaitForConnectionAsync(CancellationToken cancellationToken);
+        Task StopAsync();
+        void SendMessage(ProtocolMessage message);
+        void SendEvent(Event evt);
+        void SendResponse(Response response);
+    }
+}

src/Runner.Worker/ExecutionContext.cs

@@ -856,6 +856,9 @@ namespace GitHub.Runner.Worker
             // Job level annotations
             Global.JobAnnotations = new List<Annotation>();
 
+            // Track Node.js 20 actions for deprecation warning
+            Global.DeprecatedNode20Actions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
             // Job Outputs
             JobOutputs = new Dictionary<string, VariableValue>(StringComparer.OrdinalIgnoreCase);
 
@@ -965,6 +968,9 @@ namespace GitHub.Runner.Worker
             // Verbosity (from GitHub.Step_Debug).
             Global.WriteDebug = Global.Variables.Step_Debug ?? false;
 
+            // Debugger enabled flag (from acquire response).
+            Global.EnableDebugger = message.EnableDebugger;
+
             // Hook up JobServerQueueThrottling event, we will log warning on server tarpit.
             _jobServerQueue.JobServerQueueThrottling += JobServerQueueThrottling_EventReceived;
         }
@@ -1325,9 +1331,9 @@ namespace GitHub.Runner.Worker
             UpdateGlobalStepsContext();
         }
 
-        internal IPipelineTemplateEvaluator ToPipelineTemplateEvaluatorInternal(ObjectTemplating.ITraceWriter traceWriter = null)
+        internal IPipelineTemplateEvaluator ToPipelineTemplateEvaluatorInternal(bool allowServiceContainerCommand, ObjectTemplating.ITraceWriter traceWriter = null)
         {
-            return new PipelineTemplateEvaluatorWrapper(HostContext, this, traceWriter);
+            return new PipelineTemplateEvaluatorWrapper(HostContext, this, allowServiceContainerCommand, traceWriter);
         }
 
         private static void NoOp()
@@ -1415,10 +1421,13 @@ namespace GitHub.Runner.Worker
 
         public static IPipelineTemplateEvaluator ToPipelineTemplateEvaluator(this IExecutionContext context, ObjectTemplating.ITraceWriter traceWriter = null)
         {
+            var allowServiceContainerCommand = (context.Global.Variables.GetBoolean(Constants.Runner.Features.ServiceContainerCommand) ?? false)
+                || StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_SERVICE_CONTAINER_COMMAND"));
+
             // Create wrapper?
             if ((context.Global.Variables.GetBoolean(Constants.Runner.Features.CompareWorkflowParser) ?? false) || StringUtil.ConvertToBoolean(Environment.GetEnvironmentVariable("ACTIONS_RUNNER_COMPARE_WORKFLOW_PARSER")))
             {
-                return (context as ExecutionContext).ToPipelineTemplateEvaluatorInternal(traceWriter);
+                return (context as ExecutionContext).ToPipelineTemplateEvaluatorInternal(allowServiceContainerCommand, traceWriter);
             }
 
             // Legacy
@@ -1430,6 +1439,7 @@ namespace GitHub.Runner.Worker
             return new PipelineTemplateEvaluator(traceWriter, schema, context.Global.FileTable)
             {
                 MaxErrorMessageLength = int.MaxValue, // Don't truncate error messages otherwise we might not scrub secrets correctly
+                AllowServiceContainerCommand = allowServiceContainerCommand,
             };
         }
 

src/Runner.Worker/GlobalContext.cs

@@ -27,9 +27,13 @@ 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 string InfrastructureFailureCategory { get; set; }
         public JObject ContainerHookState { get; set; }
         public bool HasTemplateEvaluatorMismatch { get; set; }
         public bool HasActionManifestMismatch { get; set; }
+        public bool HasDeprecatedSetOutput { get; set; }
+        public bool HasDeprecatedSaveState { get; set; }
+        public HashSet<string> DeprecatedNode20Actions { get; set; }
     }
 }

src/Runner.Worker/Handlers/CompositeActionHandler.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -226,6 +227,11 @@ namespace GitHub.Runner.Worker.Handlers
         {
             ArgUtil.NotNull(embeddedSteps, nameof(embeddedSteps));
 
+            bool emitCompositeMarkers =
+                (ExecutionContext.Global.Variables.GetBoolean(Constants.Runner.Features.EmitCompositeMarkers) ?? false)
+                || StringUtil.ConvertToBoolean(
+                    System.Environment.GetEnvironmentVariable(Constants.Variables.Agent.EmitCompositeMarkers));
+
             foreach (IStep step in embeddedSteps)
             {
                 Trace.Info($"Processing embedded step: DisplayName='{step.DisplayName}'");
@@ -297,6 +303,27 @@ namespace GitHub.Runner.Worker.Handlers
                     SetStepConclusion(step, TaskResult.Failed);
                 }
 
+                // Marker ID uses the step's fully qualified context name (ScopeName.ContextName),
+                // which encodes the full composite nesting chain at any depth.
+                var markerId = emitCompositeMarkers ? step.ExecutionContext.GetFullyQualifiedContextName() : null;
+                var stepStopwatch = default(Stopwatch);
+                var endMarkerEmitted = false;
+
+                // Emit start marker after full context setup so display name expressions resolve correctly
+                if (emitCompositeMarkers)
+                {
+                    try
+                    {
+                        step.EvaluateDisplayName(step.ExecutionContext.ExpressionValues, step.ExecutionContext, out _);
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Warning("Caught exception while evaluating embedded step display name. {0}", ex);
+                    }
+                    ExecutionContext.Output($"##[start-action display={EscapeProperty(SanitizeDisplayName(step.DisplayName))};id={EscapeProperty(markerId)}]");
+                    stepStopwatch = Stopwatch.StartNew();
+                }
+
                 // Register Callback
                 CancellationTokenRegistration? jobCancelRegister = null;
                 try
@@ -381,6 +408,14 @@ namespace GitHub.Runner.Worker.Handlers
                         // Condition is false
                         Trace.Info("Skipping step due to condition evaluation.");
                         SetStepConclusion(step, TaskResult.Skipped);
+
+                        if (emitCompositeMarkers)
+                        {
+                            stepStopwatch.Stop();
+                            ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome=skipped;conclusion=skipped;duration_ms=0]");
+                            endMarkerEmitted = true;
+                        }
+
                         continue;
                     }
                     else if (conditionEvaluateError != null)
@@ -389,13 +424,31 @@ namespace GitHub.Runner.Worker.Handlers
                         step.ExecutionContext.Error(conditionEvaluateError);
                         SetStepConclusion(step, TaskResult.Failed);
                         ExecutionContext.Result = TaskResult.Failed;
+
+                        if (emitCompositeMarkers)
+                        {
+                            stepStopwatch.Stop();
+                            ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome=failure;conclusion=failure;duration_ms={stepStopwatch.ElapsedMilliseconds}]");
+                            endMarkerEmitted = true;
+                        }
+
                         break;
                     }
                     else
                     {
                         await RunStepAsync(step);
-                    }
 
+                        if (emitCompositeMarkers)
+                        {
+                            stepStopwatch.Stop();
+                            // Outcome = raw result before continue-on-error (null when continue-on-error didn't fire)
+                            // Result = final result after continue-on-error
+                            var outcome = (step.ExecutionContext.Outcome ?? step.ExecutionContext.Result ?? TaskResult.Succeeded).ToActionResult().ToString().ToLowerInvariant();
+                            var conclusion = (step.ExecutionContext.Result ?? TaskResult.Succeeded).ToActionResult().ToString().ToLowerInvariant();
+                            ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome={outcome};conclusion={conclusion};duration_ms={stepStopwatch.ElapsedMilliseconds}]");
+                            endMarkerEmitted = true;
+                        }
+                    }
                 }
                 finally
                 {
@@ -404,6 +457,14 @@ namespace GitHub.Runner.Worker.Handlers
                         jobCancelRegister?.Dispose();
                         jobCancelRegister = null;
                     }
+
+                    if (emitCompositeMarkers && !endMarkerEmitted)
+                    {
+                        stepStopwatch.Stop();
+                        var outcome = (step.ExecutionContext.Outcome ?? step.ExecutionContext.Result ?? TaskResult.Failed).ToActionResult().ToString().ToLowerInvariant();
+                        var conclusion = (step.ExecutionContext.Result ?? TaskResult.Failed).ToActionResult().ToString().ToLowerInvariant();
+                        ExecutionContext.Output($"##[end-action id={EscapeProperty(markerId)};outcome={outcome};conclusion={conclusion};duration_ms={stepStopwatch.ElapsedMilliseconds}]");
+                    }
                 }
                 // Check failed or cancelled
                 if (step.ExecutionContext.Result == TaskResult.Failed || step.ExecutionContext.Result == TaskResult.Canceled)
@@ -470,5 +531,44 @@ namespace GitHub.Runner.Worker.Handlers
             step.ExecutionContext.Result = result;
             step.ExecutionContext.UpdateGlobalStepsContext();
         }
+
+        /// <summary>
+        /// Escapes marker property values so they cannot break the ##[command key=value] format.
+        /// Delegates to ActionCommand.EscapeValue which escapes `;`, `]`, `\r`, `\n`, and `%`.
+        /// </summary>
+        internal static string EscapeProperty(string value)
+        {
+            return ActionCommand.EscapeValue(value);
+        }
+
+        /// <summary>Maximum character length for display names in markers to prevent log bloat.</summary>
+        internal const int MaxDisplayNameLength = 1000;
+
+        /// <summary>
+        /// Normalizes a step display name for safe embedding in a marker property.
+        /// Trims leading whitespace, drops everything after the first newline, and
+        /// truncates to <see cref="MaxDisplayNameLength"/> characters.
+        /// </summary>
+        internal static string SanitizeDisplayName(string displayName)
+        {
+            if (string.IsNullOrEmpty(displayName)) return displayName;
+
+            // Take first line only (FormatStepName in ActionRunner.cs already does this
+            // for most cases, but be defensive for any code path that skips it)
+            var result = displayName.TrimStart(' ', '\t', '\r', '\n');
+            var firstNewLine = result.IndexOfAny(new[] { '\r', '\n' });
+            if (firstNewLine >= 0)
+            {
+                result = result.Substring(0, firstNewLine);
+            }
+
+            // Truncate excessively long names
+            if (result.Length > MaxDisplayNameLength)
+            {
+                result = result.Substring(0, MaxDisplayNameLength);
+            }
+
+            return result;
+        }
     }
 }

src/Runner.Worker/Handlers/HandlerFactory.cs

@@ -65,6 +65,20 @@ namespace GitHub.Runner.Worker.Handlers
                     nodeData.NodeVersion = Common.Constants.Runner.NodeMigration.Node20;
                 }
 
+                // Track Node.js 20 actions for deprecation annotation
+                if (string.Equals(nodeData.NodeVersion, Constants.Runner.NodeMigration.Node20, StringComparison.InvariantCultureIgnoreCase))
+                {
+                    bool warnOnNode20 = executionContext.Global.Variables?.GetBoolean(Constants.Runner.NodeMigration.WarnOnNode20Flag) ?? false;
+                    if (warnOnNode20)
+                    {
+                        string actionName = GetActionName(action);
+                        if (!string.IsNullOrEmpty(actionName))
+                        {
+                            executionContext.Global.DeprecatedNode20Actions?.Add(actionName);
+                        }
+                    }
+                }
+
                 // Check if node20 was explicitly specified in the action
                 // We don't modify if node24 was explicitly specified
                 if (string.Equals(nodeData.NodeVersion, Constants.Runner.NodeMigration.Node20, StringComparison.InvariantCultureIgnoreCase))
@@ -90,7 +104,8 @@ namespace GitHub.Runner.Worker.Handlers
                     if (useNode24ByDefault && !requireNode24 && string.Equals(finalNodeVersion, Constants.Runner.NodeMigration.Node24, StringComparison.OrdinalIgnoreCase))
                     {
                         string infoMessage = "Node 20 is being deprecated. This workflow is running with Node 24 by default. " +
-                                             "If you need to temporarily use Node 20, you can set the ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true environment variable.";
+                                             "If you need to temporarily use Node 20, you can set the ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true environment variable. " +
+                                             $"For more information see: {Constants.Runner.NodeMigration.Node20DeprecationUrl}";
                         executionContext.Output(infoMessage);
                     }
                 }
@@ -129,5 +144,25 @@ namespace GitHub.Runner.Worker.Handlers
             handler.LocalActionContainerSetupSteps = localActionContainerSetupSteps;
             return handler;
         }
+
+        private static string GetActionName(Pipelines.ActionStepDefinitionReference action)
+        {
+            if (action is Pipelines.RepositoryPathReference repoRef)
+            {
+                var pathString = string.Empty;
+                if (!string.IsNullOrEmpty(repoRef.Path))
+                {
+                    pathString = string.IsNullOrEmpty(repoRef.Name)
+                        ? repoRef.Path
+                        : $"/{repoRef.Path}";
+                }
+                var repoString = string.IsNullOrEmpty(repoRef.Ref)
+                    ? $"{repoRef.Name}{pathString}"
+                    : $"{repoRef.Name}{pathString}@{repoRef.Ref}";
+                return string.IsNullOrEmpty(repoString) ? null : repoString;
+            }
+
+            return null;
+        }
     }
 }

src/Runner.Worker/Handlers/OutputManager.cs

@@ -90,6 +90,14 @@ namespace GitHub.Runner.Worker.Handlers
                 }
             }
 
+            // Strip runner-controlled markers from user output to prevent injection
+            if (!String.IsNullOrEmpty(line) &&
+                (line.Contains("##[start-action") || line.Contains("##[end-action")))
+            {
+                line = line.Replace("##[start-action", @"##[\start-action")
+                           .Replace("##[end-action", @"##[\end-action");
+            }
+
             // Problem matchers
             if (_matchers.Length > 0)
             {

src/Runner.Worker/InternalsVisibleTo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Test")]

src/Runner.Worker/JobExtension.cs

@@ -735,6 +735,15 @@ namespace GitHub.Runner.Worker
                             context.Global.JobTelemetry.Add(new JobTelemetry() { Type = JobTelemetryType.ConnectivityCheck, Message = $"Fail to check service connectivity. {ex.Message}" });
                         }
                     }
+
+                    // Add deprecation warning annotation for Node.js 20 actions
+                    if (context.Global.DeprecatedNode20Actions?.Count > 0)
+                    {
+                        var sortedActions = context.Global.DeprecatedNode20Actions.OrderBy(a => a, StringComparer.OrdinalIgnoreCase);
+                        var actionsList = string.Join(", ", sortedActions);
+                        var deprecationMessage = $"Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: {actionsList}. Actions will be forced to run with Node.js 24 by default starting June 2nd, 2026. Please check if updated versions of these actions are available that support Node.js 24. To opt into Node.js 24 now, set the FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true environment variable on the runner or in your workflow file. Once Node.js 24 becomes the default, you can temporarily opt out by setting ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true. For more information see: {Constants.Runner.NodeMigration.Node20DeprecationUrl}";
+                        context.Warning(deprecationMessage);
+                    }
                 }
                 catch (Exception ex)
                 {

src/Runner.Worker/JobRunner.cs

@@ -13,6 +13,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Services.Common;
 using GitHub.Services.WebApi;
 using Sdk.RSWebApi.Contracts;
@@ -112,6 +113,9 @@ namespace GitHub.Runner.Worker
 
             IExecutionContext jobContext = null;
             CancellationTokenRegistration? runnerShutdownRegistration = null;
+            IDapServer dapServer = null;
+            IDapDebugSession debugSession = null;
+            CancellationTokenRegistration? dapCancellationRegistration = null;
             try
             {
                 // Create the job execution context.
@@ -121,6 +125,36 @@ namespace GitHub.Runner.Worker
                 jobContext.Start();
                 jobContext.Debug($"Starting: {message.JobDisplayName}");
 
+                if (jobContext.Global.EnableDebugger)
+                {
+                    Trace.Info("Debugger enabled for this job run");
+
+                    try
+                    {
+                        var port = 4711;
+                        var portEnv = Environment.GetEnvironmentVariable("ACTIONS_DAP_PORT");
+                        if (!string.IsNullOrEmpty(portEnv) && int.TryParse(portEnv, out var customPort))
+                        {
+                            port = customPort;
+                        }
+
+                        dapServer = HostContext.GetService<IDapServer>();
+                        debugSession = HostContext.GetService<IDapDebugSession>();
+
+                        dapServer.SetSession(debugSession);
+                        debugSession.SetDapServer(dapServer);
+
+                        await dapServer.StartAsync(port, jobRequestCancellationToken);
+                        Trace.Info($"DAP server started on port {port}, listening for debugger client");
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Warning($"Failed to start DAP server: {ex.Message}. Job will continue without debugging.");
+                        dapServer = null;
+                        debugSession = null;
+                    }
+                }
+
                 runnerShutdownRegistration = HostContext.RunnerShutdownToken.Register(() =>
                 {
                     // log an issue, then runner get shutdown by Ctrl-C or Ctrl-Break.
@@ -219,6 +253,39 @@ 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 (dapServer != null && debugSession != null)
+                {
+                    try
+                    {
+                        Trace.Info("Waiting for debugger client connection...");
+                        await dapServer.WaitForConnectionAsync(jobRequestCancellationToken);
+                        Trace.Info("Debugger client connected.");
+
+                        await debugSession.WaitForHandshakeAsync(jobRequestCancellationToken);
+                        Trace.Info("DAP handshake complete.");
+
+                        dapCancellationRegistration = jobRequestCancellationToken.Register(() =>
+                        {
+                            Trace.Info("Job cancellation requested, cancelling debug session.");
+                            debugSession.CancelSession();
+                        });
+                    }
+                    catch (OperationCanceledException) when (jobRequestCancellationToken.IsCancellationRequested)
+                    {
+                        Trace.Info("Job was cancelled before debugger client connected. Continuing without debugger.");
+                        dapServer = null;
+                        debugSession = null;
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Warning($"Failed to complete DAP handshake: {ex.Message}. Job will continue without debugging.");
+                        dapServer = null;
+                        debugSession = null;
+                    }
+                }
+
                 // Run all job steps
                 Trace.Info("Run all job steps.");
                 var stepsRunner = HostContext.GetService<IStepsRunner>();
@@ -259,6 +326,25 @@ namespace GitHub.Runner.Worker
                     runnerShutdownRegistration = null;
                 }
 
+                if (dapCancellationRegistration.HasValue)
+                {
+                    dapCancellationRegistration.Value.Dispose();
+                    dapCancellationRegistration = null;
+                }
+
+                if (dapServer != null)
+                {
+                    try
+                    {
+                        Trace.Info("Stopping DAP server");
+                        await dapServer.StopAsync();
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Warning($"Error stopping DAP server: {ex.Message}");
+                    }
+                }
+
                 await ShutdownQueue(throwOnFailure: false);
             }
         }

src/Runner.Worker/PipelineTemplateEvaluatorWrapper.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using GitHub.Actions.WorkflowParser;
 using GitHub.DistributedTask.Expressions2;
@@ -23,6 +23,7 @@ namespace GitHub.Runner.Worker
         public PipelineTemplateEvaluatorWrapper(
             IHostContext hostContext,
             IExecutionContext context,
+            bool allowServiceContainerCommand,
             ObjectTemplating.ITraceWriter traceWriter = null)
         {
             ArgUtil.NotNull(hostContext, nameof(hostContext));
@@ -40,11 +41,14 @@ namespace GitHub.Runner.Worker
             _legacyEvaluator = new PipelineTemplateEvaluator(traceWriter, schema, context.Global.FileTable)
             {
                 MaxErrorMessageLength = int.MaxValue, // Don't truncate error messages otherwise we might not scrub secrets correctly
+                AllowServiceContainerCommand = allowServiceContainerCommand,
             };
 
             // New evaluator
             var newTraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter();
-            _newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, context.Global.FileTable, features: null)
+            var features = WorkflowFeatures.GetDefaults();
+            features.AllowServiceContainerCommand = allowServiceContainerCommand;
+            _newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, context.Global.FileTable, features)
             {
                 MaxErrorMessageLength = int.MaxValue, // Don't truncate error messages otherwise we might not scrub secrets correctly
             };
@@ -216,12 +220,15 @@ namespace GitHub.Runner.Worker
             }
         }
 
-        private TLegacy EvaluateAndCompare<TLegacy, TNew>(
+        internal TLegacy EvaluateAndCompare<TLegacy, TNew>(
             string methodName,
             Func<TLegacy> legacyEvaluator,
             Func<TNew> newEvaluator,
             Func<TLegacy, TNew, bool> resultComparer)
         {
+            // Capture cancellation state before evaluation
+            var cancellationRequestedBefore = _context.CancellationToken.IsCancellationRequested;
+
             // Legacy evaluator
             var legacyException = default(Exception);
             var legacyResult = default(TLegacy);
@@ -253,14 +260,18 @@ namespace GitHub.Runner.Worker
                     newException = ex;
                 }
 
+                // Capture cancellation state after evaluation
+                var cancellationRequestedAfter = _context.CancellationToken.IsCancellationRequested;
+
                 // Compare results or exceptions
+                bool hasMismatch = false;
                 if (legacyException != null || newException != null)
                 {
                     // Either one or both threw exceptions - compare them
                     if (!CompareExceptions(legacyException, newException))
                     {
                         _trace.Info($"{methodName} exception mismatch");
-                        RecordMismatch($"{methodName}");
+                        hasMismatch = true;
                     }
                 }
                 else
@@ -269,6 +280,20 @@ namespace GitHub.Runner.Worker
                     if (!resultComparer(legacyResult, newResult))
                     {
                         _trace.Info($"{methodName} mismatch");
+                        hasMismatch = true;
+                    }
+                }
+
+                // Only record mismatch if it wasn't caused by a cancellation race condition
+                if (hasMismatch)
+                {
+                    if (!cancellationRequestedBefore && cancellationRequestedAfter)
+                    {
+                        // Cancellation state changed during evaluation window - skip recording
+                        _trace.Info($"{methodName} mismatch skipped due to cancellation race condition");
+                    }
+                    else
+                    {
                         RecordMismatch($"{methodName}");
                     }
                 }
@@ -380,6 +405,18 @@ namespace GitHub.Runner.Worker
                 return false;
             }
 
+            if (!string.Equals(legacyResult.Entrypoint, newResult.Entrypoint, StringComparison.Ordinal))
+            {
+                _trace.Info($"CompareJobContainer mismatch - Entrypoint differs (legacy='{legacyResult.Entrypoint}', new='{newResult.Entrypoint}')");
+                return false;
+            }
+
+            if (!string.Equals(legacyResult.Command, newResult.Command, StringComparison.Ordinal))
+            {
+                _trace.Info($"CompareJobContainer mismatch - Command differs (legacy='{legacyResult.Command}', new='{newResult.Command}')");
+                return false;
+            }
+
             if (!CompareDictionaries(legacyResult.Environment, newResult.Environment, "Environment"))
             {
                 return false;
@@ -612,6 +649,13 @@ namespace GitHub.Runner.Worker
                 return false;
             }
 
+            // Check for known equivalent error patterns (e.g., JSON parse errors)
+            // where both parsers correctly reject invalid input but with different wording
+            if (IsKnownEquivalentErrorPattern(legacyException, newException))
+            {
+                return true;
+            }
+
             // Compare exception messages recursively (including inner exceptions)
             var legacyMessages = GetExceptionMessages(legacyException);
             var newMessages = GetExceptionMessages(newException);
@@ -634,6 +678,67 @@ namespace GitHub.Runner.Worker
             return true;
         }
 
+        /// <summary>
+        /// Checks if two exceptions match a known pattern where both parsers correctly reject
+        /// invalid input but with different error messages (e.g., JSON parse errors from fromJSON).
+        /// </summary>
+        private bool IsKnownEquivalentErrorPattern(Exception legacyException, Exception newException)
+        {
+            // fromJSON('') - both parsers fail when parsing empty string as JSON
+            // The error messages differ but both indicate JSON parsing failure.
+            // Legacy throws raw JsonReaderException: "Error reading JToken from JsonReader..."
+            // New wraps it: "Error parsing fromJson" with inner JsonReaderException
+            // Both may be wrapped in TemplateValidationException: "The template is not valid..."
+            if (HasJsonExceptionType(legacyException) && HasJsonExceptionType(newException))
+            {
+                _trace.Info("CompareExceptions - both exceptions are JSON parse errors, treating as matched");
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Checks if the exception chain contains a JSON-related exception type.
+        /// </summary>
+        internal static bool HasJsonExceptionType(Exception ex)
+        {
+            var toProcess = new Queue<Exception>();
+            toProcess.Enqueue(ex);
+            int count = 0;
+
+            while (toProcess.Count > 0 && count < 50)
+            {
+                var current = toProcess.Dequeue();
+                if (current == null) continue;
+
+                count++;
+
+                if (current is Newtonsoft.Json.JsonReaderException ||
+                    current is System.Text.Json.JsonException)
+                {
+                    return true;
+                }
+
+                if (current is AggregateException aggregateEx)
+                {
+                    foreach (var innerEx in aggregateEx.InnerExceptions)
+                    {
+                        if (innerEx != null && count < 50)
+                        {
+                            toProcess.Enqueue(innerEx);
+                        }
+                    }
+                }
+                else if (current.InnerException != null)
+                {
+                    toProcess.Enqueue(current.InnerException);
+                }
+            }
+
+            return false;
+        }
+
         private IList<string> GetExceptionMessages(Exception ex)
         {
             var messages = new List<string>();

src/Runner.Worker/StepsRunner.cs

@@ -10,6 +10,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Runner.Worker.Expressions;
 
 namespace GitHub.Runner.Worker
@@ -50,6 +51,16 @@ namespace GitHub.Runner.Worker
             jobContext.JobContext.Status = (jobContext.Result ?? TaskResult.Succeeded).ToActionResult();
             var scopeInputs = new Dictionary<string, PipelineContextData>(StringComparer.OrdinalIgnoreCase);
             bool checkPostJobActions = false;
+            IDapDebugSession debugSession = null;
+            try
+            {
+                debugSession = HostContext.GetService<IDapDebugSession>();
+            }
+            catch
+            {
+                // Debug session not available — continue without debugging
+            }
+            bool isFirstStep = true;
             while (jobContext.JobSteps.Count > 0 || !checkPostJobActions)
             {
                 if (jobContext.JobSteps.Count == 0 && !checkPostJobActions)
@@ -226,9 +237,35 @@ namespace GitHub.Runner.Worker
                         }
                         else
                         {
+                            // Pause for DAP debugger before step execution
+                            if (debugSession?.IsActive == true)
+                            {
+                                try
+                                {
+                                    await debugSession.OnStepStartingAsync(step, jobContext, isFirstStep, jobContext.CancellationToken);
+                                    isFirstStep = false;
+                                }
+                                catch (Exception ex)
+                                {
+                                    Trace.Warning($"DAP OnStepStarting error: {ex.Message}");
+                                }
+                            }
+
                             // Run the step
                             await RunStepAsync(step, jobContext.CancellationToken);
                             CompleteStep(step);
+
+                            if (debugSession?.IsActive == true)
+                            {
+                                try
+                                {
+                                    debugSession.OnStepCompleted(step);
+                                }
+                                catch (Exception ex)
+                                {
+                                    Trace.Warning($"DAP OnStepCompleted error: {ex.Message}");
+                                }
+                            }
                         }
                     }
                     finally
@@ -255,6 +292,18 @@ namespace GitHub.Runner.Worker
 
                 Trace.Info($"Current state: job state = '{jobContext.Result}'");
             }
+
+            if (debugSession?.IsActive == true)
+            {
+                try
+                {
+                    debugSession.OnJobCompleted();
+                }
+                catch (Exception ex)
+                {
+                    Trace.Warning($"DAP OnJobCompleted error: {ex.Message}");
+                }
+            }
         }
 
         private async Task RunStepAsync(IStep step, CancellationToken jobCancellationToken)

src/Sdk/DTPipelines/Pipelines/AgentJobRequestMessage.cs

@@ -253,6 +253,13 @@ namespace GitHub.DistributedTask.Pipelines
             set;
         }
 
+        [DataMember(EmitDefaultValue = false)]
+        public bool EnableDebugger
+        {
+            get;
+            set;
+        }
+
         /// <summary>
         /// Gets the collection of variables associated with the current context.
         /// </summary>

src/Sdk/DTPipelines/Pipelines/JobContainer.cs

@@ -39,6 +39,24 @@ namespace GitHub.DistributedTask.Pipelines
             set;
         }
 
+        /// <summary>
+        /// Gets or sets the container entrypoint override.
+        /// </summary>
+        public String Entrypoint
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Gets or sets the container command and args (after the image name).
+        /// </summary>
+        public String Command
+        {
+            get;
+            set;
+        }
+
         /// <summary>
         /// Gets or sets the volumes which are mounted into the container.
         /// </summary>

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

@@ -47,6 +47,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
         public const String NumberStrategyContext = "number-strategy-context";
         public const String On = "on";
         public const String Options = "options";
+        public const String Entrypoint = "entrypoint";
+        public const String Command = "command";
         public const String Outputs = "outputs";
         public const String OutputsPattern = "needs.*.outputs";
         public const String Password = "password";

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

@@ -237,7 +237,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
         internal static JobContainer ConvertToJobContainer(
             TemplateContext context,
             TemplateToken value,
-            bool allowExpressions = false)
+            bool allowExpressions = false,
+            bool allowServiceContainerCommand = false)
         {
             var result = new JobContainer();
             if (allowExpressions && value.Traverse().Any(x => x is ExpressionToken))
@@ -280,6 +281,22 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
                         case PipelineTemplateConstants.Options:
                             result.Options = containerPropertyPair.Value.AssertString($"{PipelineTemplateConstants.Container} {propertyName}").Value;
                             break;
+                        case PipelineTemplateConstants.Entrypoint:
+                            if (!allowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{PipelineTemplateConstants.Entrypoint}' is not allowed");
+                                break;
+                            }
+                            result.Entrypoint = containerPropertyPair.Value.AssertString($"{PipelineTemplateConstants.Container} {propertyName}").Value;
+                            break;
+                        case PipelineTemplateConstants.Command:
+                            if (!allowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{PipelineTemplateConstants.Command}' is not allowed");
+                                break;
+                            }
+                            result.Command = containerPropertyPair.Value.AssertString($"{PipelineTemplateConstants.Container} {propertyName}").Value;
+                            break;
                         case PipelineTemplateConstants.Ports:
                             var ports = containerPropertyPair.Value.AssertSequence($"{PipelineTemplateConstants.Container} {propertyName}");
                             var portList = new List<String>(ports.Count);
@@ -326,7 +343,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
         internal static List<KeyValuePair<String, JobContainer>> ConvertToJobServiceContainers(
             TemplateContext context,
             TemplateToken services,
-            bool allowExpressions = false)
+            bool allowExpressions = false,
+            bool allowServiceContainerCommand = false)
         {
             var result = new List<KeyValuePair<String, JobContainer>>();
 
@@ -340,7 +358,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
             foreach (var servicePair in servicesMapping)
             {
                 var networkAlias = servicePair.Key.AssertString("services key").Value;
-                var container = ConvertToJobContainer(context, servicePair.Value);
+                var container = ConvertToJobContainer(context, servicePair.Value, allowExpressions, allowServiceContainerCommand);
                 result.Add(new KeyValuePair<String, JobContainer>(networkAlias, container));
             }
 

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

@@ -51,6 +51,8 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
 
         public Int32 MaxResultSize { get; set; } = 10 * 1024 * 1024; // 10 mb
 
+        public bool AllowServiceContainerCommand { get; set; }
+
         public Boolean EvaluateStepContinueOnError(
             TemplateToken token,
             DictionaryContextData contextData,
@@ -357,7 +359,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
                 {
                     token = TemplateEvaluator.Evaluate(context, PipelineTemplateConstants.Services, token, 0, null, omitHeader: true);
                     context.Errors.Check();
-                    result = PipelineTemplateConverter.ConvertToJobServiceContainers(context, token);
+                    result = PipelineTemplateConverter.ConvertToJobServiceContainers(context, token, allowServiceContainerCommand: AllowServiceContainerCommand);
                 }
                 catch (Exception ex) when (!(ex is TemplateValidationException))
                 {

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

@@ -430,6 +430,21 @@
       }
     },
 
+    "service-container-mapping": {
+      "mapping": {
+        "properties": {
+          "image": "string",
+          "options": "string",
+          "entrypoint": "string",
+          "command": "string",
+          "env": "container-env",
+          "ports": "sequence-of-non-empty-string",
+          "volumes": "sequence-of-non-empty-string",
+          "credentials": "container-registry-credentials"
+        }
+      }
+    },
+
     "services": {
       "context": [
         "github",
@@ -454,7 +469,7 @@
       ],
       "one-of": [
         "string",
-        "container-mapping"
+        "service-container-mapping"
       ]
     },
 

src/Sdk/WorkflowParser/Conversion/WorkflowTemplateConstants.cs

@@ -62,6 +62,8 @@ namespace GitHub.Actions.WorkflowParser.Conversion
         public const String NumberStrategyContext = "number-strategy-context";
         public const String On = "on";
         public const String Options = "options";
+        public const String Entrypoint = "entrypoint";
+        public const String Command = "command";
         public const String Org = "org";
         public const String Organization = "organization";
         public const String Outputs = "outputs";

src/Sdk/WorkflowParser/Conversion/WorkflowTemplateConverter.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;
@@ -43,7 +43,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                     {
                         case WorkflowTemplateConstants.On:
                             var inputTypes = ConvertToOnWorkflowDispatchInputTypes(workflowPair.Value);
-                            foreach(var item in inputTypes)
+                            foreach (var item in inputTypes)
                             {
                                 result.InputTypes.TryAdd(item.Key, item.Value);
                             }
@@ -432,7 +432,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                 context.Error(snapshotToken, $"job {WorkflowTemplateConstants.Snapshot} {WorkflowTemplateConstants.ImageName} is required.");
                 return null;
             }
-            
+
             return new Snapshot
             {
                 ImageName = imageName,
@@ -445,7 +445,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
         {
             var versionSegments = versionString.Split(".");
 
-            if (versionSegments.Length != 2 || 
+            if (versionSegments.Length != 2 ||
                 !versionSegments[1].Equals("*") ||
                 !Int32.TryParse(versionSegments[0], NumberStyles.None, CultureInfo.InvariantCulture, result: out int parsedMajor) ||
                 parsedMajor < 0)
@@ -1079,7 +1079,8 @@ namespace GitHub.Actions.WorkflowParser.Conversion
         internal static JobContainer ConvertToJobContainer(
             TemplateContext context,
             TemplateToken value,
-            bool isEarlyValidation = false)
+            bool isEarlyValidation = false,
+            bool isServiceContainer = false)
         {
             var result = new JobContainer();
             if (isEarlyValidation && value.Traverse().Any(x => x is ExpressionToken))
@@ -1089,11 +1090,34 @@ namespace GitHub.Actions.WorkflowParser.Conversion
 
             if (value is StringToken containerLiteral)
             {
-                if (String.IsNullOrEmpty(containerLiteral.Value))
+                // Trim "docker://"
+                var trimmedImage = containerLiteral.Value;
+                var hasDockerPrefix = containerLiteral.Value.StartsWith(WorkflowTemplateConstants.DockerUriPrefix, StringComparison.Ordinal);
+                if (hasDockerPrefix)
                 {
+                    trimmedImage = trimmedImage.Substring(WorkflowTemplateConstants.DockerUriPrefix.Length);
+                }
+
+                // Empty shorthand after trimming "docker://" ?
+                if (String.IsNullOrEmpty(trimmedImage))
+                {
+                    // Error at parse-time for:
+                    //   1. container: 'docker://'
+                    //   2. services.foo: ''
+                    //   3. services.foo: 'docker://'
+                    //
+                    // Do not error for:
+                    //   1. container: ''
+                    if (isEarlyValidation && (hasDockerPrefix || isServiceContainer))
+                    {
+                        context.Error(value, "Container image cannot be empty");
+                    }
+
+                    // Short-circuit
                     return null;
                 }
 
+                // Store original, trimmed further below
                 result.Image = containerLiteral.Value;
             }
             else
@@ -1122,6 +1146,22 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                         case WorkflowTemplateConstants.Options:
                             result.Options = containerPropertyPair.Value.AssertString($"{WorkflowTemplateConstants.Container} {propertyName}").Value;
                             break;
+                        case WorkflowTemplateConstants.Entrypoint:
+                            if (!context.GetFeatures().AllowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{WorkflowTemplateConstants.Entrypoint}' is not allowed");
+                                break;
+                            }
+                            result.Entrypoint = containerPropertyPair.Value.AssertString($"{WorkflowTemplateConstants.Container} {propertyName}").Value;
+                            break;
+                        case WorkflowTemplateConstants.Command:
+                            if (!context.GetFeatures().AllowServiceContainerCommand)
+                            {
+                                context.Error(containerPropertyPair.Key, $"The key '{WorkflowTemplateConstants.Command}' is not allowed");
+                                break;
+                            }
+                            result.Command = containerPropertyPair.Value.AssertString($"{WorkflowTemplateConstants.Container} {propertyName}").Value;
+                            break;
                         case WorkflowTemplateConstants.Ports:
                             var ports = containerPropertyPair.Value.AssertSequence($"{WorkflowTemplateConstants.Container} {propertyName}");
                             var portList = new List<String>(ports.Count);
@@ -1152,15 +1192,28 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                 }
             }
 
-            if (String.IsNullOrEmpty(result.Image))
+            // Trim "docker://"
+            var hadDockerPrefix = false;
+            if (!String.IsNullOrEmpty(result.Image) && result.Image.StartsWith(WorkflowTemplateConstants.DockerUriPrefix, StringComparison.Ordinal))
             {
-                context.Error(value, "Container image cannot be empty");
-                return null;
+                hadDockerPrefix = true;
+                result.Image = result.Image.Substring(WorkflowTemplateConstants.DockerUriPrefix.Length);
             }
 
-            if (result.Image.StartsWith(WorkflowTemplateConstants.DockerUriPrefix, StringComparison.Ordinal))
+            if (String.IsNullOrEmpty(result.Image))
             {
-                result.Image = result.Image.Substring(WorkflowTemplateConstants.DockerUriPrefix.Length);
+                // Error at parse-time for:
+                //   1. container: {image: 'docker://'}
+                //   2. services.foo: {image: ''}
+                //   3. services.foo: {image: 'docker://'}
+                //
+                // Do not error for:
+                //   1. container: {image: ''}
+                if (isEarlyValidation && (hadDockerPrefix || isServiceContainer))
+                {
+                    context.Error(value, "Container image cannot be empty");
+                }
+                return null;
             }
 
             return result;
@@ -1183,7 +1236,7 @@ namespace GitHub.Actions.WorkflowParser.Conversion
             foreach (var servicePair in servicesMapping)
             {
                 var networkAlias = servicePair.Key.AssertString("services key").Value;
-                var container = ConvertToJobContainer(context, servicePair.Value);
+                var container = ConvertToJobContainer(context, servicePair.Value, isEarlyValidation, isServiceContainer: true);
                 result.Add(new KeyValuePair<String, JobContainer>(networkAlias, container));
             }
 
@@ -1838,9 +1891,9 @@ namespace GitHub.Actions.WorkflowParser.Conversion
                     case "actions":
                         permissions.Actions = permissionLevel;
                         break;
-					case "artifact-metadata":
-						permissions.ArtifactMetadata = permissionLevel;
-						break;
+                    case "artifact-metadata":
+                        permissions.ArtifactMetadata = permissionLevel;
+                        break;
                     case "attestations":
                         permissions.Attestations = permissionLevel;
                         break;

src/Sdk/WorkflowParser/JobContainer.cs

@@ -35,6 +35,24 @@ namespace GitHub.Actions.WorkflowParser
             set;
         }
 
+        /// <summary>
+        /// Gets or sets the container entrypoint override.
+        /// </summary>
+        public String Entrypoint
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Gets or sets the container command and args (after the image name).
+        /// </summary>
+        public String Command
+        {
+            get;
+            set;
+        }
+
         /// <summary>
         /// Gets or sets the volumes which are mounted into the container.
         /// </summary>

src/Sdk/WorkflowParser/WorkflowFeatures.cs

@@ -48,6 +48,13 @@ namespace GitHub.Actions.WorkflowParser
         [DataMember(EmitDefaultValue = false)]
         public bool StrictJsonParsing { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether service containers may specify "entrypoint" and "command".
+        /// Used during parsing and evaluation.
+        /// </summary>
+        [DataMember(EmitDefaultValue = false)]
+        public bool AllowServiceContainerCommand { get; set; }
+
         /// <summary>
         /// Gets the default workflow features.
         /// </summary>
@@ -60,6 +67,7 @@ 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
+                AllowServiceContainerCommand = false, // Default to false since this feature is gated by actions_service_container_command
             };
         }
 

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

@@ -2589,21 +2589,53 @@
       "mapping": {
         "properties": {
           "image": {
-            "type": "non-empty-string",
-            "description": "Use `jobs.<job_id>.container.image` to define the Docker image to use as the container to run the action. The value can be the Docker Hub image or a registry name."
+            "type": "string",
+            "description": "The Docker image to use as the container. The value can be the Docker Hub image or a registry name."
           },
           "options": {
             "type": "string",
-            "description": "Use `jobs.<job_id>.container.options` to configure additional Docker container resource options."
+            "description": "Additional Docker container resource options."
           },
           "env": "container-env",
           "ports": {
             "type": "sequence-of-non-empty-string",
-            "description": "Use `jobs.<job_id>.container.ports` to set an array of ports to expose on the container."
+            "description": "An array of ports to expose on the container."
           },
           "volumes": {
             "type": "sequence-of-non-empty-string",
-            "description": "Use `jobs.<job_id>.container.volumes` to set an array of volumes for the container to use. You can use volumes to share data between services or other steps in a job. You can specify named Docker volumes, anonymous Docker volumes, or bind mounts on the host."
+            "description": "An array of volumes for the container to use. You can use volumes to share data between services or other steps in a job. You can specify named Docker volumes, anonymous Docker volumes, or bind mounts on the host."
+          },
+          "credentials": "container-registry-credentials"
+        }
+      }
+    },
+    "service-container-mapping": {
+      "mapping": {
+        "properties": {
+          "image": {
+            "type": "string",
+            "description": "The Docker image to use as the container. The value can be the Docker Hub image or a registry name."
+          },
+          "options": {
+            "type": "string",
+            "description": "Additional Docker container resource options."
+          },
+          "entrypoint": {
+            "type": "string",
+            "description": "Override the default ENTRYPOINT in the service container image."
+          },
+          "command": {
+            "type": "string",
+            "description": "Override the default CMD in the service container image."
+          },
+          "env": "container-env",
+          "ports": {
+            "type": "sequence-of-non-empty-string",
+            "description": "An array of ports to expose on the container."
+          },
+          "volumes": {
+            "type": "sequence-of-non-empty-string",
+            "description": "An array of volumes for the container to use. You can use volumes to share data between services or other steps in a job. You can specify named Docker volumes, anonymous Docker volumes, or bind mounts on the host."
           },
           "credentials": "container-registry-credentials"
         }
@@ -2634,12 +2666,12 @@
         "matrix"
       ],
       "one-of": [
-        "non-empty-string",
-        "container-mapping"
+        "string",
+        "service-container-mapping"
       ]
     },
     "container-registry-credentials": {
-      "description": "If the image's container registry requires authentication to pull the image, you can use `jobs.<job_id>.container.credentials` to set a map of the username and password. The credentials are the same values that you would provide to the `docker login` command.",
+      "description": "If the container registry requires authentication to pull the image, set a map of the username and password. The credentials are the same values that you would provide to the `docker login` command.",
       "context": [
         "github",
         "inputs",
@@ -2655,7 +2687,7 @@
       }
     },
     "container-env": {
-      "description": "Use `jobs.<job_id>.container.env` to set a map of variables in the container.",
+      "description": "A map of environment variables to set in the container.",
       "mapping": {
         "loose-key-type": "non-empty-string",
         "loose-value-type": "string-runner-context"

src/Test/L0/Listener/JobDispatcherL0.cs

@@ -739,7 +739,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                 Assert.True(jobDispatcher.RunOnceJobCompleted.Task.IsCompleted, "JobDispatcher should set task complete token for one time agent.");
                 if (jobDispatcher.RunOnceJobCompleted.Task.IsCompleted)
                 {
-                    Assert.True(await jobDispatcher.RunOnceJobCompleted.Task, "JobDispatcher should set task complete token to 'TRUE' for one time agent.");
+                    var result = await jobDispatcher.RunOnceJobCompleted.Task;
+                    Assert.Equal(TaskResult.Succeeded, result);
                 }
             }
         }

src/Test/L0/Listener/RunnerL0.cs

@@ -295,13 +295,13 @@ namespace GitHub.Runner.Common.Tests.Listener
                 _messageListener.Setup(x => x.DeleteMessageAsync(It.IsAny<TaskAgentMessage>()))
                     .Returns(Task.CompletedTask);
 
-                var runOnceJobCompleted = new TaskCompletionSource<bool>();
+                var runOnceJobCompleted = new TaskCompletionSource<TaskResult>();
                 _jobDispatcher.Setup(x => x.RunOnceJobCompleted)
                     .Returns(runOnceJobCompleted);
                 _jobDispatcher.Setup(x => x.Run(It.IsAny<Pipelines.AgentJobRequestMessage>(), It.IsAny<bool>()))
                     .Callback(() =>
                     {
-                        runOnceJobCompleted.TrySetResult(true);
+                        runOnceJobCompleted.TrySetResult(TaskResult.Succeeded);
                     });
                 _jobNotification.Setup(x => x.StartClient(It.IsAny<String>()))
                     .Callback(() =>
@@ -399,13 +399,13 @@ namespace GitHub.Runner.Common.Tests.Listener
                 _messageListener.Setup(x => x.DeleteMessageAsync(It.IsAny<TaskAgentMessage>()))
                     .Returns(Task.CompletedTask);
 
-                var runOnceJobCompleted = new TaskCompletionSource<bool>();
+                var runOnceJobCompleted = new TaskCompletionSource<TaskResult>();
                 _jobDispatcher.Setup(x => x.RunOnceJobCompleted)
                     .Returns(runOnceJobCompleted);
                 _jobDispatcher.Setup(x => x.Run(It.IsAny<Pipelines.AgentJobRequestMessage>(), It.IsAny<bool>()))
                     .Callback(() =>
                     {
-                        runOnceJobCompleted.TrySetResult(true);
+                        runOnceJobCompleted.TrySetResult(TaskResult.Succeeded);
                     });
                 _jobNotification.Setup(x => x.StartClient(It.IsAny<String>()))
                     .Callback(() =>
@@ -733,8 +733,8 @@ namespace GitHub.Runner.Common.Tests.Listener
 
                 _configStore.Setup(x => x.IsServiceConfigured()).Returns(false);
 
-                var completedTask = new TaskCompletionSource<bool>();
-                completedTask.SetResult(true);
+                var completedTask = new TaskCompletionSource<TaskResult>();
+                completedTask.SetResult(TaskResult.Succeeded);
                 _jobDispatcher.Setup(x => x.RunOnceJobCompleted).Returns(completedTask);
 
                 //Act
@@ -834,8 +834,8 @@ namespace GitHub.Runner.Common.Tests.Listener
 
                 _configStore.Setup(x => x.IsServiceConfigured()).Returns(false);
 
-                var completedTask = new TaskCompletionSource<bool>();
-                completedTask.SetResult(true);
+                var completedTask = new TaskCompletionSource<TaskResult>();
+                completedTask.SetResult(TaskResult.Succeeded);
                 _jobDispatcher.Setup(x => x.RunOnceJobCompleted).Returns(completedTask);
 
                 //Act
@@ -954,8 +954,8 @@ namespace GitHub.Runner.Common.Tests.Listener
 
                 _configStore.Setup(x => x.IsServiceConfigured()).Returns(false);
 
-                var completedTask = new TaskCompletionSource<bool>();
-                completedTask.SetResult(true);
+                var completedTask = new TaskCompletionSource<TaskResult>();
+                completedTask.SetResult(TaskResult.Succeeded);
                 _jobDispatcher.Setup(x => x.RunOnceJobCompleted).Returns(completedTask);
 
                 //Act
@@ -1076,75 +1076,5 @@ namespace GitHub.Runner.Common.Tests.Listener
                 Assert.True(hc.AllowAuthMigration);
             }
         }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Runner")]
-        public async Task RunCommand_ShouldReturnTerminatedError_WhenWorkDirCreationFails()
-        {
-            using (var hostCtx = new TestHostContext(this))
-            {
-                // Setup: arrange mocks and runner instance
-                var runnerInstance = new Runner.Listener.Runner();
-                hostCtx.SetSingleton<IConfigurationManager>(_configurationManager.Object);
-                hostCtx.SetSingleton<IJobNotification>(_jobNotification.Object);
-                hostCtx.SetSingleton<IMessageListener>(_messageListener.Object);
-                hostCtx.SetSingleton<IPromptManager>(_promptManager.Object);
-                hostCtx.SetSingleton<IConfigurationStore>(_configStore.Object);
-                hostCtx.SetSingleton<IRunnerServer>(_runnerServer.Object);
-                hostCtx.EnqueueInstance<IErrorThrottler>(_acquireJobThrottler.Object);
-
-                runnerInstance.Initialize(hostCtx);
-
-                // Create a file at the work directory path to block directory creation
-                string workPath = hostCtx.GetDirectory(WellKnownDirectory.Work);
-
-                // Clean up any existing directory first
-                if (Directory.Exists(workPath))
-                {
-                    Directory.Delete(workPath, recursive: true);
-                }
-
-                // Place a file where the work directory should be - this blocks Directory.CreateDirectory
-                string parentPath = Path.GetDirectoryName(workPath);
-                Assert.NotNull(parentPath);
-                Assert.NotEmpty(parentPath);
-                Directory.CreateDirectory(parentPath);
-
-                const string blockingFileContent = "test file blocking directory creation";
-                File.WriteAllText(workPath, blockingFileContent);
-
-                const int testPoolId = 12345;
-                const int testAgentId = 67890;
-
-                var runnerConfig = new RunnerSettings
-                {
-                    PoolId = testPoolId,
-                    AgentId = testAgentId
-                };
-
-                _configurationManager.Setup(m => m.LoadSettings()).Returns(runnerConfig);
-                _configurationManager.Setup(m => m.IsConfigured()).Returns(true);
-                _configStore.Setup(m => m.IsServiceConfigured()).Returns(false);
-
-                try
-                {
-                    // Execute: run the command which should fail during work dir validation
-                    var cmd = new CommandSettings(hostCtx, new string[] { "run" });
-                    int exitCode = await runnerInstance.ExecuteCommand(cmd);
-
-                    // Verify: should return TerminatedError code when dir creation fails
-                    Assert.Equal(Constants.Runner.ReturnCode.TerminatedError, exitCode);
-                }
-                finally
-                {
-                    // Cleanup: remove the blocking file
-                    if (File.Exists(workPath))
-                    {
-                        File.Delete(workPath);
-                    }
-                }
-            }
-        }
     }
 }

src/Test/L0/Listener/SelfUpdaterL0.cs

@@ -228,8 +228,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                                  .Returns(Task.FromResult(new TaskAgent()));
 
 
-                    var ex = await Assert.ThrowsAsync<TaskCanceledException>(() => updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains($"failed after {Constants.RunnerDownloadRetryMaxAttempts} download attempts", ex.Message);
+                    var result = await updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                 }
             }
             finally
@@ -281,8 +281,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                                  .Returns(Task.FromResult(new TaskAgent()));
 
 
-                    var ex = await Assert.ThrowsAsync<Exception>(() => updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains("did not match expected Runner Hash", ex.Message);
+                    var result = await updater.SelfUpdate(_refreshMessage, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                 }
             }
             finally

src/Test/L0/Listener/SelfUpdaterV2L0.cs

@@ -170,8 +170,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                         DownloadUrl = "https://github.com/actions/runner/notexists"
                     };
 
-                    var ex = await Assert.ThrowsAsync<TaskCanceledException>(() => updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains($"failed after {Constants.RunnerDownloadRetryMaxAttempts} download attempts", ex.Message);
+                    var result = await updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                 }
             }
             finally
@@ -220,8 +220,8 @@ namespace GitHub.Runner.Common.Tests.Listener
                         SHA256Checksum = "badhash"
                     };
 
-                    var ex = await Assert.ThrowsAsync<Exception>(() => updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken));
-                    Assert.Contains("did not match expected Runner Hash", ex.Message);
+                    var result = await updater.SelfUpdate(message, _jobDispatcher.Object, true, hc.RunnerShutdownToken);
+                    Assert.False(result);
                 }
             }
             finally

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

@@ -0,0 +1,76 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.Serialization.Json;
+using System.Text;
+using Xunit;
+using GitHub.DistributedTask.Pipelines;
+
+namespace GitHub.Actions.RunService.WebApi.Tests;
+
+public sealed class AgentJobRequestMessageL0
+{
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyEnableDebuggerDeserialization_WithTrue()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string jsonWithEnabledDebugger = DoubleQuotify("{'EnableDebugger': true}");
+        
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(jsonWithEnabledDebugger));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+        
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.True(recoveredMessage.EnableDebugger, "EnableDebugger should be true when JSON contains 'EnableDebugger': true");
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyEnableDebuggerDeserialization_DefaultToFalse()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string jsonWithoutDebugger = DoubleQuotify("{'messageType': 'PipelineAgentJobRequest'}");
+        
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(jsonWithoutDebugger));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+        
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should default to false when JSON field is absent");
+    }
+
+    [Fact]
+    [Trait("Level", "L0")]
+    [Trait("Category", "Common")]
+    public void VerifyEnableDebuggerDeserialization_WithFalse()
+    {
+        // Arrange
+        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
+        string jsonWithDisabledDebugger = DoubleQuotify("{'EnableDebugger': false}");
+        
+        // Act
+        using var stream = new MemoryStream();
+        stream.Write(Encoding.UTF8.GetBytes(jsonWithDisabledDebugger));
+        stream.Position = 0;
+        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
+        
+        // Assert
+        Assert.NotNull(recoveredMessage);
+        Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should be false when JSON contains 'EnableDebugger': false");
+    }
+
+    private static string DoubleQuotify(string text)
+    {
+        return text.Replace('\'', '"');
+    }
+}

src/Test/L0/Worker/ActionCommandManagerL0.cs

@@ -457,6 +457,8 @@ namespace GitHub.Runner.Common.Tests.Worker
                 new SetEnvCommandExtension(),
                 new WarningCommandExtension(),
                 new AddMaskCommandExtension(),
+                new SetOutputCommandExtension(),
+                new SaveStateCommandExtension(),
             };
             foreach (var command in commands)
             {
@@ -499,5 +501,53 @@ namespace GitHub.Runner.Common.Tests.Worker
             };
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SetOutputCommand_EmitsTelemetryOnce()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                _ec.Object.Global.JobTelemetry = new List<JobTelemetry>();
+                var reference = string.Empty;
+                _ec.Setup(x => x.SetOutput(It.IsAny<string>(), It.IsAny<string>(), out reference));
+
+                // First set-output should add telemetry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::set-output name=foo::bar", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+                Assert.Equal(JobTelemetryType.ActionCommand, _ec.Object.Global.JobTelemetry[0].Type);
+                Assert.Equal("DeprecatedCommand: set-output", _ec.Object.Global.JobTelemetry[0].Message);
+                Assert.True(_ec.Object.Global.HasDeprecatedSetOutput);
+
+                // Second set-output should not add another telemetry entry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::set-output name=foo2::bar2", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SaveStateCommand_EmitsTelemetryOnce()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                _ec.Object.Global.JobTelemetry = new List<JobTelemetry>();
+                _ec.Setup(x => x.IsEmbedded).Returns(false);
+                _ec.Setup(x => x.IntraActionState).Returns(new Dictionary<string, string>());
+
+                // First save-state should add telemetry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::save-state name=foo::bar", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+                Assert.Equal(JobTelemetryType.ActionCommand, _ec.Object.Global.JobTelemetry[0].Type);
+                Assert.Equal("DeprecatedCommand: save-state", _ec.Object.Global.JobTelemetry[0].Message);
+                Assert.True(_ec.Object.Global.HasDeprecatedSaveState);
+
+                // Second save-state should not add another telemetry entry
+                Assert.True(_commandManager.TryProcessCommand(_ec.Object, "::save-state name=foo2::bar2", null));
+                Assert.Single(_ec.Object.Global.JobTelemetry);
+            }
+        }
+
     }
 }

src/Test/L0/Worker/ActionManagerL0.cs

@@ -468,6 +468,73 @@ runs:
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async void PrepareActions_SymlinkCacheIsReentrant()
+        {
+            try
+            {
+                //Arrange
+                Environment.SetEnvironmentVariable(Constants.Variables.Agent.SymlinkCachedActions, "true");
+                Setup();
+                var actionId = Guid.NewGuid();
+                var actions = new List<Pipelines.ActionStep>
+                {
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "actions/checkout",
+                            Ref = "master",
+                            RepositoryType = "GitHub"
+                        }
+                    },
+                    new Pipelines.ActionStep()
+                    {
+                        Name = "action",
+                        Id = actionId,
+                        Reference = new Pipelines.RepositoryPathReference()
+                        {
+                            Name = "actions/checkout",
+                            Ref = "master",
+                            RepositoryType = "GitHub"
+                        }
+                    }
+                };
+
+                const string Content = @"
+name: 'Test'
+runs:
+  using: 'node20'
+  main: 'dist/index.js'
+";
+
+                string actionsArchive = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Temp), "actions_archive", "action_checkout");
+                Directory.CreateDirectory(actionsArchive);
+                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", "master-sha"));
+                Directory.CreateDirectory(Path.Combine(actionsArchive, "actions_checkout", "master-sha", "content"));
+                await File.WriteAllTextAsync(Path.Combine(actionsArchive, "actions_checkout", "master-sha", "content", "action.yml"), Content);
+                Environment.SetEnvironmentVariable(Constants.Variables.Agent.ActionArchiveCacheDirectory, actionsArchive);
+
+                //Act
+                await _actionManager.PrepareActionsAsync(_ec.Object, actions);
+
+                //Assert
+                string destDirectory = Path.Combine(_hc.GetDirectory(WellKnownDirectory.Actions), "actions", "checkout", "master");
+                Assert.True(Directory.Exists(destDirectory), "Destination directory does not exist");  
+                var di = new DirectoryInfo(destDirectory);   
+                Assert.NotNull(di.LinkTarget); 
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable(Constants.Variables.Agent.SymlinkCachedActions, null);
+                Teardown();
+            }
+        }
+
 #if OS_LINUX
         [Fact]
         [Trait("Level", "L0")]

src/Test/L0/Worker/ActionManifestParserComparisonL0.cs

@@ -0,0 +1,424 @@
+using GitHub.Actions.WorkflowParser;
+using GitHub.DistributedTask.ObjectTemplating.Tokens;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.Pipelines.ObjectTemplating;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Common;
+using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker;
+using LegacyContextData = GitHub.DistributedTask.Pipelines.ContextData;
+using LegacyExpressions = GitHub.DistributedTask.Expressions2;
+using Moq;
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    /// <summary>
+    /// Tests for parser comparison wrapper classes.
+    /// </summary>
+    public sealed class ActionManifestParserComparisonL0
+    {
+        private CancellationTokenSource _ecTokenSource;
+        private Mock<IExecutionContext> _ec;
+        private TestHostContext _hc;
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ConvertToLegacySteps_ProducesCorrectSteps_WithExplicitPropertyMapping()
+        {
+            try
+            {
+                // Arrange - Test that ActionManifestManagerWrapper properly converts new steps to legacy format
+                Setup();
+
+                // Enable comparison feature
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                // Register required services
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var manifestPath = Path.Combine(TestUtil.GetTestDataPath(), "conditional_composite_action.yml");
+
+                // Act - Load through the wrapper (which internally converts)
+                var result = wrapper.Load(_ec.Object, manifestPath);
+
+                // Assert
+                Assert.NotNull(result);
+                Assert.Equal(ActionExecutionType.Composite, result.Execution.ExecutionType);
+
+                var compositeExecution = result.Execution as CompositeActionExecutionData;
+                Assert.NotNull(compositeExecution);
+                Assert.NotNull(compositeExecution.Steps);
+                Assert.Equal(6, compositeExecution.Steps.Count);
+
+                // Verify steps are NOT null (this was the bug - JSON round-trip produced nulls)
+                foreach (var step in compositeExecution.Steps)
+                {
+                    Assert.NotNull(step);
+                    Assert.NotNull(step.Reference);
+                    Assert.IsType<GitHub.DistributedTask.Pipelines.ScriptReference>(step.Reference);
+                }
+
+                // Verify step with condition
+                var successStep = compositeExecution.Steps[2];
+                Assert.Equal("success-conditional", successStep.ContextName);
+                Assert.Equal("success()", successStep.Condition);
+
+                // Verify step with complex condition
+                var lastStep = compositeExecution.Steps[5];
+                Assert.Contains("inputs.exit-code == 1", lastStep.Condition);
+                Assert.Contains("failure()", lastStep.Condition);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_EmptyImage_BothParsersReturnNull()
+        {
+            try
+            {
+                // Arrange - Test that both parsers return null for empty container image at runtime
+                Setup();
+
+                var fileTable = new List<string>();
+
+                // Create legacy evaluator
+                var legacyTraceWriter = new GitHub.DistributedTask.ObjectTemplating.EmptyTraceWriter();
+                var schema = PipelineTemplateSchemaFactory.GetSchema();
+                var legacyEvaluator = new PipelineTemplateEvaluator(legacyTraceWriter, schema, fileTable);
+
+                // Create new evaluator
+                var newTraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter();
+                var newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, fileTable, features: null);
+
+                // Create a token representing an empty container image (simulates expression evaluated to empty string)
+                var emptyImageToken = new StringToken(null, null, null, "");
+
+                var contextData = new DictionaryContextData();
+                var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+
+                // Act - Call both evaluators
+                var legacyResult = legacyEvaluator.EvaluateJobContainer(emptyImageToken, contextData, expressionFunctions);
+
+                // Convert token for new evaluator
+                var newToken = new GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.StringToken(null, null, null, "");
+                var newContextData = new GitHub.Actions.Expressions.Data.DictionaryExpressionData();
+                var newExpressionFunctions = new List<GitHub.Actions.Expressions.IFunctionInfo>();
+
+                var newResult = newEvaluator.EvaluateJobContainer(newToken, newContextData, newExpressionFunctions);
+
+                // Assert - Both should return null for empty image (no container)
+                Assert.Null(legacyResult);
+                Assert.Null(newResult);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void FromJsonEmptyString_BothParsersFail_WithDifferentMessages()
+        {
+            // This test verifies that both parsers fail with different error messages when parsing fromJSON('')
+            // The comparison layer should treat these as semantically equivalent (both are JSON parse errors)
+            try
+            {
+                Setup();
+
+                var fileTable = new List<string>();
+
+                // Create legacy evaluator
+                var legacyTraceWriter = new GitHub.DistributedTask.ObjectTemplating.EmptyTraceWriter();
+                var schema = PipelineTemplateSchemaFactory.GetSchema();
+                var legacyEvaluator = new PipelineTemplateEvaluator(legacyTraceWriter, schema, fileTable);
+
+                // Create new evaluator
+                var newTraceWriter = new GitHub.Actions.WorkflowParser.ObjectTemplating.EmptyTraceWriter();
+                var newEvaluator = new WorkflowTemplateEvaluator(newTraceWriter, fileTable, features: null);
+
+                // Create expression token for fromJSON('')
+                var legacyToken = new BasicExpressionToken(null, null, null, "fromJson('')");
+                var newToken = new GitHub.Actions.WorkflowParser.ObjectTemplating.Tokens.BasicExpressionToken(null, null, null, "fromJson('')");
+
+                var contextData = new DictionaryContextData();
+                var newContextData = new GitHub.Actions.Expressions.Data.DictionaryExpressionData();
+                var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+                var newExpressionFunctions = new List<GitHub.Actions.Expressions.IFunctionInfo>();
+
+                // Act - Both should throw
+                Exception legacyException = null;
+                Exception newException = null;
+
+                try
+                {
+                    legacyEvaluator.EvaluateStepDisplayName(legacyToken, contextData, expressionFunctions);
+                }
+                catch (Exception ex)
+                {
+                    legacyException = ex;
+                }
+
+                try
+                {
+                    newEvaluator.EvaluateStepName(newToken, newContextData, newExpressionFunctions);
+                }
+                catch (Exception ex)
+                {
+                    newException = ex;
+                }
+
+                // Assert - Both threw exceptions
+                Assert.NotNull(legacyException);
+                Assert.NotNull(newException);
+
+                // Verify the error messages are different (which is why we need semantic comparison)
+                Assert.NotEqual(legacyException.Message, newException.Message);
+
+                // Verify both are JSON parse errors (contain JSON-related error indicators)
+                var legacyFullMsg = GetFullExceptionMessage(legacyException);
+                var newFullMsg = GetFullExceptionMessage(newException);
+
+                // At least one should contain indicators of JSON parsing failure
+                var legacyIsJsonError = legacyFullMsg.Contains("JToken") ||
+                                        legacyFullMsg.Contains("JsonReader") ||
+                                        legacyFullMsg.Contains("fromJson");
+                var newIsJsonError = newFullMsg.Contains("JToken") ||
+                                     newFullMsg.Contains("JsonReader") ||
+                                     newFullMsg.Contains("fromJson");
+
+                Assert.True(legacyIsJsonError, $"Legacy exception should be JSON error: {legacyFullMsg}");
+                Assert.True(newIsJsonError, $"New exception should be JSON error: {newFullMsg}");
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateDefaultInput_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                _ec.Object.ExpressionValues["github"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["strategy"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["matrix"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["steps"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["job"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["runner"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionValues["env"] = new LegacyContextData.DictionaryContextData();
+                _ec.Object.ExpressionFunctions.Add(new LegacyExpressions.FunctionInfo<GitHub.Runner.Worker.Expressions.HashFilesFunction>("hashFiles", 1, 255));
+
+                var result = wrapper.EvaluateDefaultInput(_ec.Object, "testInput", new StringToken(null, null, null, "defaultValue"));
+
+                Assert.Equal("defaultValue", result);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateContainerArguments_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var arguments = new SequenceToken(null, null, null);
+                arguments.Add(new StringToken(null, null, null, "arg1"));
+                arguments.Add(new StringToken(null, null, null, "arg2"));
+
+                var evaluateContext = new Dictionary<string, LegacyContextData.PipelineContextData>(StringComparer.OrdinalIgnoreCase);
+
+                var result = wrapper.EvaluateContainerArguments(_ec.Object, arguments, evaluateContext);
+
+                Assert.Equal(2, result.Count);
+                Assert.Equal("arg1", result[0]);
+                Assert.Equal("arg2", result[1]);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateContainerEnvironment_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var environment = new MappingToken(null, null, null);
+                environment.Add(new StringToken(null, null, null, "hello"), new StringToken(null, null, null, "world"));
+
+                var evaluateContext = new Dictionary<string, LegacyContextData.PipelineContextData>(StringComparer.OrdinalIgnoreCase);
+
+                var result = wrapper.EvaluateContainerEnvironment(_ec.Object, environment, evaluateContext);
+
+                Assert.Equal(1, result.Count);
+                Assert.Equal("world", result["hello"]);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateCompositeOutputs_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var legacyManager = new ActionManifestManagerLegacy();
+                legacyManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManagerLegacy>(legacyManager);
+
+                var newManager = new ActionManifestManager();
+                newManager.Initialize(_hc);
+                _hc.SetSingleton<IActionManifestManager>(newManager);
+
+                var wrapper = new ActionManifestManagerWrapper();
+                wrapper.Initialize(_hc);
+
+                var outputDef = new MappingToken(null, null, null);
+                outputDef.Add(new StringToken(null, null, null, "description"), new StringToken(null, null, null, "test output"));
+                outputDef.Add(new StringToken(null, null, null, "value"), new StringToken(null, null, null, "value1"));
+
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "output1"), outputDef);
+
+                var evaluateContext = new Dictionary<string, LegacyContextData.PipelineContextData>(StringComparer.OrdinalIgnoreCase);
+
+                var result = wrapper.EvaluateCompositeOutputs(_ec.Object, token, evaluateContext);
+
+                Assert.NotNull(result);
+                Assert.False(_ec.Object.Global.HasActionManifestMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        private string GetFullExceptionMessage(Exception ex)
+        {
+            var messages = new List<string>();
+            var current = ex;
+            while (current != null)
+            {
+                messages.Add(current.Message);
+                current = current.InnerException;
+            }
+            return string.Join(" -> ", messages);
+        }
+
+        private void Setup([CallerMemberName] string name = "")
+        {
+            _ecTokenSource?.Dispose();
+            _ecTokenSource = new CancellationTokenSource();
+
+            _hc = new TestHostContext(this, name);
+
+            var expressionValues = new LegacyContextData.DictionaryContextData();
+            var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+
+            _ec = new Mock<IExecutionContext>();
+            _ec.Setup(x => x.Global)
+                .Returns(new GlobalContext
+                {
+                    FileTable = new List<String>(),
+                    Variables = new Variables(_hc, new Dictionary<string, VariableValue>()),
+                    WriteDebug = true,
+                });
+            _ec.Setup(x => x.CancellationToken).Returns(_ecTokenSource.Token);
+            _ec.Setup(x => x.ExpressionValues).Returns(expressionValues);
+            _ec.Setup(x => x.ExpressionFunctions).Returns(expressionFunctions);
+            _ec.Setup(x => x.Write(It.IsAny<string>(), It.IsAny<string>())).Callback((string tag, string message) => { _hc.GetTrace().Info($"{tag}{message}"); });
+            _ec.Setup(x => x.AddIssue(It.IsAny<Issue>(), It.IsAny<ExecutionContextLogOptions>())).Callback((Issue issue, ExecutionContextLogOptions logOptions) => { _hc.GetTrace().Info($"[{issue.Type}]{logOptions.LogMessageOverride ?? issue.Message}"); });
+        }
+
+        private void Teardown()
+        {
+            _hc?.Dispose();
+        }
+    }
+}

src/Test/L0/Worker/DapDebugSessionL0.cs

@@ -0,0 +1,611 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.DistributedTask.ObjectTemplating.Tokens;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Dap;
+using Moq;
+using Newtonsoft.Json;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapDebugSessionL0
+    {
+        private DapDebugSession _session;
+        private Mock<IDapServer> _mockServer;
+        private List<Event> _sentEvents;
+        private List<Response> _sentResponses;
+
+        private TestHostContext CreateTestContext([CallerMemberName] string testName = "")
+        {
+            var hc = new TestHostContext(this, testName);
+
+            _session = new DapDebugSession();
+            _session.Initialize(hc);
+
+            _sentEvents = new List<Event>();
+            _sentResponses = new List<Response>();
+
+            _mockServer = new Mock<IDapServer>();
+            _mockServer.Setup(x => x.SendEvent(It.IsAny<Event>()))
+                .Callback<Event>(e => _sentEvents.Add(e));
+            _mockServer.Setup(x => x.SendResponse(It.IsAny<Response>()))
+                .Callback<Response>(r => _sentResponses.Add(r));
+
+            _session.SetDapServer(_mockServer.Object);
+
+            return hc;
+        }
+
+        private Mock<IStep> CreateMockStep(string displayName, TaskResult? result = null)
+        {
+            var mockEc = new Mock<IExecutionContext>();
+            mockEc.SetupAllProperties();
+            mockEc.Object.Result = result;
+
+            var mockStep = new Mock<IStep>();
+            mockStep.Setup(x => x.DisplayName).Returns(displayName);
+            mockStep.Setup(x => x.ExecutionContext).Returns(mockEc.Object);
+
+            return mockStep;
+        }
+
+        private Mock<IExecutionContext> CreateMockJobContext()
+        {
+            var mockJobContext = new Mock<IExecutionContext>();
+            mockJobContext.Setup(x => x.GetGitHubContext("job")).Returns("test-job");
+            return mockJobContext;
+        }
+
+        private async Task InitializeSessionAsync()
+        {
+            var initJson = JsonConvert.SerializeObject(new Request
+            {
+                Seq = 1,
+                Type = "request",
+                Command = "initialize"
+            });
+            await _session.HandleMessageAsync(initJson, CancellationToken.None);
+
+            var attachJson = JsonConvert.SerializeObject(new Request
+            {
+                Seq = 2,
+                Type = "request",
+                Command = "attach"
+            });
+            await _session.HandleMessageAsync(attachJson, CancellationToken.None);
+
+            var configJson = JsonConvert.SerializeObject(new Request
+            {
+                Seq = 3,
+                Type = "request",
+                Command = "configurationDone"
+            });
+            await _session.HandleMessageAsync(configJson, CancellationToken.None);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitialStateIsWaitingForConnection()
+        {
+            using (CreateTestContext())
+            {
+                Assert.Equal(DapSessionState.WaitingForConnection, _session.State);
+                Assert.False(_session.IsActive);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task InitializeHandlerSetsInitializingState()
+        {
+            using (CreateTestContext())
+            {
+                var json = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "initialize"
+                });
+
+                await _session.HandleMessageAsync(json, CancellationToken.None);
+
+                Assert.Equal(DapSessionState.Initializing, _session.State);
+                Assert.Single(_sentResponses);
+                Assert.True(_sentResponses[0].Success);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task ConfigurationDoneSetsReadyState()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+
+                Assert.Equal(DapSessionState.Ready, _session.State);
+                Assert.True(_session.IsActive);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnStepStartingPausesAndSendsStoppedEvent()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+
+                // Wait for the async initialized event to arrive, then clear
+                await Task.Delay(200);
+                _sentEvents.Clear();
+
+                var step = CreateMockStep("Checkout code");
+                var jobContext = CreateMockJobContext();
+
+                var cts = new CancellationTokenSource();
+                var stepTask = _session.OnStepStartingAsync(step.Object, jobContext.Object, isFirstStep: true, cts.Token);
+
+                await Task.Delay(100);
+                Assert.False(stepTask.IsCompleted);
+                Assert.Equal(DapSessionState.Paused, _session.State);
+
+                var stoppedEvents = _sentEvents.FindAll(e => e.EventType == "stopped");
+                Assert.Single(stoppedEvents);
+
+                var continueJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await _session.HandleMessageAsync(continueJson, CancellationToken.None);
+
+                await Task.WhenAny(stepTask, Task.Delay(5000));
+                Assert.True(stepTask.IsCompleted);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task NextCommandPausesOnFollowingStep()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+                _sentEvents.Clear();
+
+                var step1 = CreateMockStep("Step 1");
+                var jobContext = CreateMockJobContext();
+
+                var step1Task = _session.OnStepStartingAsync(step1.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                var nextJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "next"
+                });
+                await _session.HandleMessageAsync(nextJson, CancellationToken.None);
+                await Task.WhenAny(step1Task, Task.Delay(5000));
+                Assert.True(step1Task.IsCompleted);
+
+                _session.OnStepCompleted(step1.Object);
+                _sentEvents.Clear();
+
+                var step2 = CreateMockStep("Step 2");
+                var step2Task = _session.OnStepStartingAsync(step2.Object, jobContext.Object, isFirstStep: false, CancellationToken.None);
+
+                await Task.Delay(100);
+                Assert.False(step2Task.IsCompleted);
+                Assert.Equal(DapSessionState.Paused, _session.State);
+
+                var stoppedEvents = _sentEvents.FindAll(e => e.EventType == "stopped");
+                Assert.Single(stoppedEvents);
+
+                var continueJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 11,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await _session.HandleMessageAsync(continueJson, CancellationToken.None);
+                await Task.WhenAny(step2Task, Task.Delay(5000));
+                Assert.True(step2Task.IsCompleted);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task ContinueCommandSkipsNextPause()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+                _sentEvents.Clear();
+
+                var step1 = CreateMockStep("Step 1");
+                var jobContext = CreateMockJobContext();
+
+                var step1Task = _session.OnStepStartingAsync(step1.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                var continueJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await _session.HandleMessageAsync(continueJson, CancellationToken.None);
+                await Task.WhenAny(step1Task, Task.Delay(5000));
+                Assert.True(step1Task.IsCompleted);
+
+                _session.OnStepCompleted(step1.Object);
+                _sentEvents.Clear();
+
+                var step2 = CreateMockStep("Step 2");
+                var step2Task = _session.OnStepStartingAsync(step2.Object, jobContext.Object, isFirstStep: false, CancellationToken.None);
+
+                await Task.WhenAny(step2Task, Task.Delay(5000));
+                Assert.True(step2Task.IsCompleted);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task CancellationUnblocksPausedStep()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+                _sentEvents.Clear();
+
+                var step = CreateMockStep("Step 1");
+                var jobContext = CreateMockJobContext();
+
+                var cts = new CancellationTokenSource();
+                var stepTask = _session.OnStepStartingAsync(step.Object, jobContext.Object, isFirstStep: true, cts.Token);
+
+                await Task.Delay(100);
+                Assert.False(stepTask.IsCompleted);
+                Assert.Equal(DapSessionState.Paused, _session.State);
+
+                cts.Cancel();
+
+                await Task.WhenAny(stepTask, Task.Delay(5000));
+                Assert.True(stepTask.IsCompleted);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task CancelSessionSendsTerminatedAndExitedEvents()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _sentEvents.Clear();
+
+                _session.CancelSession();
+
+                Assert.Equal(DapSessionState.Terminated, _session.State);
+                Assert.False(_session.IsActive);
+
+                var terminatedEvents = _sentEvents.FindAll(e => e.EventType == "terminated");
+                var exitedEvents = _sentEvents.FindAll(e => e.EventType == "exited");
+                Assert.Single(terminatedEvents);
+                Assert.Single(exitedEvents);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task CancelSessionReleasesBlockedStep()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+                _sentEvents.Clear();
+
+                var step = CreateMockStep("Blocked Step");
+                var jobContext = CreateMockJobContext();
+
+                var stepTask = _session.OnStepStartingAsync(step.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                await Task.Delay(100);
+                Assert.False(stepTask.IsCompleted);
+
+                _session.CancelSession();
+
+                await Task.WhenAny(stepTask, Task.Delay(5000));
+                Assert.True(stepTask.IsCompleted);
+                Assert.Equal(DapSessionState.Terminated, _session.State);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task ReconnectionResendStoppedEvent()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+
+                // Wait for the async initialized event to arrive, then clear
+                await Task.Delay(200);
+                _sentEvents.Clear();
+
+                var step = CreateMockStep("Step 1");
+                var jobContext = CreateMockJobContext();
+
+                var stepTask = _session.OnStepStartingAsync(step.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                await Task.Delay(100);
+                Assert.Equal(DapSessionState.Paused, _session.State);
+                var stoppedEvents = _sentEvents.FindAll(e => e.EventType == "stopped");
+                Assert.Single(stoppedEvents);
+
+                _session.HandleClientDisconnected();
+                Assert.Equal(DapSessionState.Paused, _session.State);
+
+                _sentEvents.Clear();
+                _session.HandleClientConnected();
+
+                Assert.Single(_sentEvents);
+                Assert.Equal("stopped", _sentEvents[0].EventType);
+
+                var continueJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 20,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await _session.HandleMessageAsync(continueJson, CancellationToken.None);
+                await Task.WhenAny(stepTask, Task.Delay(5000));
+                Assert.True(stepTask.IsCompleted);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task DisconnectCommandTerminatesSession()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+
+                var disconnectJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "disconnect"
+                });
+                await _session.HandleMessageAsync(disconnectJson, CancellationToken.None);
+
+                Assert.Equal(DapSessionState.Terminated, _session.State);
+                Assert.False(_session.IsActive);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnStepCompletedTracksCompletedSteps()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+
+                var step1 = CreateMockStep("Step 1");
+                step1.Object.ExecutionContext.Result = TaskResult.Succeeded;
+                var jobContext = CreateMockJobContext();
+
+                var step1Task = _session.OnStepStartingAsync(step1.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                var continueJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await _session.HandleMessageAsync(continueJson, CancellationToken.None);
+                await Task.WhenAny(step1Task, Task.Delay(5000));
+
+                _session.OnStepCompleted(step1.Object);
+
+                var stackTraceJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 11,
+                    Type = "request",
+                    Command = "stackTrace"
+                });
+                _sentResponses.Clear();
+                await _session.HandleMessageAsync(stackTraceJson, CancellationToken.None);
+
+                Assert.Single(_sentResponses);
+                Assert.True(_sentResponses[0].Success);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnJobCompletedSendsTerminatedAndExitedEvents()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _sentEvents.Clear();
+
+                _session.OnJobCompleted();
+
+                Assert.Equal(DapSessionState.Terminated, _session.State);
+
+                var terminatedEvents = _sentEvents.FindAll(e => e.EventType == "terminated");
+                var exitedEvents = _sentEvents.FindAll(e => e.EventType == "exited");
+                Assert.Single(terminatedEvents);
+                Assert.Single(exitedEvents);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnStepStartingNoOpWhenNotActive()
+        {
+            using (CreateTestContext())
+            {
+                var step = CreateMockStep("Step 1");
+                var jobContext = CreateMockJobContext();
+
+                var task = _session.OnStepStartingAsync(step.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                await Task.WhenAny(task, Task.Delay(5000));
+                Assert.True(task.IsCompleted);
+
+                _mockServer.Verify(x => x.SendEvent(It.IsAny<Event>()), Times.Never);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task ThreadsCommandReturnsJobThread()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+
+                var threadsJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "threads"
+                });
+                _sentResponses.Clear();
+                await _session.HandleMessageAsync(threadsJson, CancellationToken.None);
+
+                Assert.Single(_sentResponses);
+                Assert.True(_sentResponses[0].Success);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task UnsupportedCommandReturnsErrorResponse()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+
+                var json = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 99,
+                    Type = "request",
+                    Command = "stepIn"
+                });
+                _sentResponses.Clear();
+                await _session.HandleMessageAsync(json, CancellationToken.None);
+
+                Assert.Single(_sentResponses);
+                Assert.False(_sentResponses[0].Success);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task FullFlowInitAttachConfigStepContinueComplete()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _session.HandleClientConnected();
+                _sentEvents.Clear();
+                _sentResponses.Clear();
+
+                Assert.Equal(DapSessionState.Ready, _session.State);
+
+                var step = CreateMockStep("Run tests");
+                var jobContext = CreateMockJobContext();
+
+                var stepTask = _session.OnStepStartingAsync(step.Object, jobContext.Object, isFirstStep: true, CancellationToken.None);
+
+                await Task.Delay(100);
+                Assert.Equal(DapSessionState.Paused, _session.State);
+
+                var stoppedEvents = _sentEvents.FindAll(e => e.EventType == "stopped");
+                Assert.Single(stoppedEvents);
+
+                var continueJson = JsonConvert.SerializeObject(new Request
+                {
+                    Seq = 10,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await _session.HandleMessageAsync(continueJson, CancellationToken.None);
+                await Task.WhenAny(stepTask, Task.Delay(5000));
+                Assert.True(stepTask.IsCompleted);
+
+                var continuedEvents = _sentEvents.FindAll(e => e.EventType == "continued");
+                Assert.Single(continuedEvents);
+
+                step.Object.ExecutionContext.Result = TaskResult.Succeeded;
+                _session.OnStepCompleted(step.Object);
+
+                _sentEvents.Clear();
+                _session.OnJobCompleted();
+
+                Assert.Equal(DapSessionState.Terminated, _session.State);
+                var terminatedEvents = _sentEvents.FindAll(e => e.EventType == "terminated");
+                var exitedEvents = _sentEvents.FindAll(e => e.EventType == "exited");
+                Assert.Single(terminatedEvents);
+                Assert.Single(exitedEvents);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task DoubleCancelSessionIsIdempotent()
+        {
+            using (CreateTestContext())
+            {
+                await InitializeSessionAsync();
+                _sentEvents.Clear();
+
+                _session.CancelSession();
+                _session.CancelSession();
+
+                Assert.Equal(DapSessionState.Terminated, _session.State);
+
+                var terminatedEvents = _sentEvents.FindAll(e => e.EventType == "terminated");
+                Assert.Single(terminatedEvents);
+            }
+        }
+    }
+}

src/Test/L0/Worker/DapMessagesL0.cs

@@ -0,0 +1,233 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using Xunit;
+using GitHub.Runner.Worker.Dap;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapMessagesL0
+    {
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void RequestSerializesCorrectly()
+        {
+            var request = new Request
+            {
+                Seq = 1,
+                Type = "request",
+                Command = "initialize",
+                Arguments = JObject.FromObject(new { clientID = "test-client" })
+            };
+
+            var json = JsonConvert.SerializeObject(request);
+            var deserialized = JsonConvert.DeserializeObject<Request>(json);
+
+            Assert.Equal(1, deserialized.Seq);
+            Assert.Equal("request", deserialized.Type);
+            Assert.Equal("initialize", deserialized.Command);
+            Assert.Equal("test-client", deserialized.Arguments["clientID"].ToString());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ResponseSerializesCorrectly()
+        {
+            var response = new Response
+            {
+                Seq = 2,
+                Type = "response",
+                RequestSeq = 1,
+                Success = true,
+                Command = "initialize",
+                Body = new Capabilities { SupportsConfigurationDoneRequest = true }
+            };
+
+            var json = JsonConvert.SerializeObject(response);
+            var deserialized = JsonConvert.DeserializeObject<Response>(json);
+
+            Assert.Equal(2, deserialized.Seq);
+            Assert.Equal("response", deserialized.Type);
+            Assert.Equal(1, deserialized.RequestSeq);
+            Assert.True(deserialized.Success);
+            Assert.Equal("initialize", deserialized.Command);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EventSerializesWithCorrectType()
+        {
+            var evt = new Event
+            {
+                EventType = "stopped",
+                Body = new StoppedEventBody
+                {
+                    Reason = "entry",
+                    Description = "Stopped at entry",
+                    ThreadId = 1,
+                    AllThreadsStopped = true
+                }
+            };
+
+            Assert.Equal("event", evt.Type);
+
+            var json = JsonConvert.SerializeObject(evt);
+            Assert.Contains("\"type\":\"event\"", json);
+            Assert.Contains("\"event\":\"stopped\"", json);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StoppedEventBodyOmitsNullFields()
+        {
+            var body = new StoppedEventBody
+            {
+                Reason = "step"
+            };
+
+            var json = JsonConvert.SerializeObject(body);
+            Assert.Contains("\"reason\":\"step\"", json);
+            Assert.DoesNotContain("\"threadId\"", json);
+            Assert.DoesNotContain("\"allThreadsStopped\"", json);
+            Assert.DoesNotContain("\"description\"", json);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void CapabilitiesMvpDefaults()
+        {
+            var caps = new Capabilities
+            {
+                SupportsConfigurationDoneRequest = true,
+                SupportsFunctionBreakpoints = false,
+                SupportsStepBack = false
+            };
+
+            var json = JsonConvert.SerializeObject(caps);
+            var deserialized = JsonConvert.DeserializeObject<Capabilities>(json);
+
+            Assert.True(deserialized.SupportsConfigurationDoneRequest);
+            Assert.False(deserialized.SupportsFunctionBreakpoints);
+            Assert.False(deserialized.SupportsStepBack);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ContinueResponseBodySerialization()
+        {
+            var body = new ContinueResponseBody { AllThreadsContinued = true };
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ContinueResponseBody>(json);
+
+            Assert.True(deserialized.AllThreadsContinued);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ThreadsResponseBodySerialization()
+        {
+            var body = new ThreadsResponseBody
+            {
+                Threads = new List<Thread>
+                {
+                    new Thread { Id = 1, Name = "Job Thread" }
+                }
+            };
+
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ThreadsResponseBody>(json);
+
+            Assert.Single(deserialized.Threads);
+            Assert.Equal(1, deserialized.Threads[0].Id);
+            Assert.Equal("Job Thread", deserialized.Threads[0].Name);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StackFrameSerialization()
+        {
+            var frame = new StackFrame
+            {
+                Id = 1,
+                Name = "Step: Checkout",
+                Line = 1,
+                Column = 1,
+                PresentationHint = "normal"
+            };
+
+            var json = JsonConvert.SerializeObject(frame);
+            var deserialized = JsonConvert.DeserializeObject<StackFrame>(json);
+
+            Assert.Equal(1, deserialized.Id);
+            Assert.Equal("Step: Checkout", deserialized.Name);
+            Assert.Equal("normal", deserialized.PresentationHint);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ExitedEventBodySerialization()
+        {
+            var body = new ExitedEventBody { ExitCode = 130 };
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ExitedEventBody>(json);
+
+            Assert.Equal(130, deserialized.ExitCode);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void DapCommandEnumValues()
+        {
+            Assert.Equal(0, (int)DapCommand.Continue);
+            Assert.Equal(1, (int)DapCommand.Next);
+            Assert.Equal(4, (int)DapCommand.Disconnect);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void RequestDeserializesFromRawJson()
+        {
+            var json = @"{""seq"":5,""type"":""request"",""command"":""continue"",""arguments"":{""threadId"":1}}";
+            var request = JsonConvert.DeserializeObject<Request>(json);
+
+            Assert.Equal(5, request.Seq);
+            Assert.Equal("request", request.Type);
+            Assert.Equal("continue", request.Command);
+            Assert.Equal(1, request.Arguments["threadId"].Value<int>());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void ErrorResponseBodySerialization()
+        {
+            var body = new ErrorResponseBody
+            {
+                Error = new Message
+                {
+                    Id = 1,
+                    Format = "Something went wrong",
+                    ShowUser = true
+                }
+            };
+
+            var json = JsonConvert.SerializeObject(body);
+            var deserialized = JsonConvert.DeserializeObject<ErrorResponseBody>(json);
+
+            Assert.Equal(1, deserialized.Error.Id);
+            Assert.Equal("Something went wrong", deserialized.Error.Format);
+            Assert.True(deserialized.Error.ShowUser);
+        }
+    }
+}

src/Test/L0/Worker/DapServerL0.cs

@@ -0,0 +1,170 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+using GitHub.Runner.Worker.Dap;
+using Moq;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class DapServerL0
+    {
+        private DapServer _server;
+
+        private TestHostContext CreateTestContext([CallerMemberName] string testName = "")
+        {
+            var hc = new TestHostContext(this, testName);
+            _server = new DapServer();
+            _server.Initialize(hc);
+            return hc;
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void InitializeSucceeds()
+        {
+            using (CreateTestContext())
+            {
+                Assert.NotNull(_server);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SetSessionAcceptsMock()
+        {
+            using (CreateTestContext())
+            {
+                var mockSession = new Mock<IDapDebugSession>();
+                _server.SetSession(mockSession.Object);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SendEventNoClientDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                var evt = new Event
+                {
+                    EventType = "stopped",
+                    Body = new StoppedEventBody
+                    {
+                        Reason = "entry",
+                        ThreadId = 1,
+                        AllThreadsStopped = true
+                    }
+                };
+
+                _server.SendEvent(evt);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SendResponseNoClientDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                var response = new Response
+                {
+                    Type = "response",
+                    RequestSeq = 1,
+                    Command = "initialize",
+                    Success = true
+                };
+
+                _server.SendResponse(response);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SendMessageNoClientDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                var msg = new ProtocolMessage
+                {
+                    Type = "response",
+                    Seq = 1
+                };
+
+                _server.SendMessage(msg);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StopWithoutStartDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                await _server.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAndStopOnAvailablePort()
+        {
+            using (CreateTestContext())
+            {
+                var cts = new CancellationTokenSource();
+                await _server.StartAsync(0, cts.Token);
+                await _server.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task WaitForConnectionCancelledByCancellationToken()
+        {
+            using (CreateTestContext())
+            {
+                var cts = new CancellationTokenSource();
+                await _server.StartAsync(0, cts.Token);
+
+                var waitTask = _server.WaitForConnectionAsync(cts.Token);
+
+                cts.Cancel();
+
+                await Assert.ThrowsAnyAsync<OperationCanceledException>(async () =>
+                {
+                    await waitTask;
+                });
+
+                await _server.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StartAndStopMultipleTimesDoesNotThrow()
+        {
+            using (CreateTestContext())
+            {
+                var cts1 = new CancellationTokenSource();
+                await _server.StartAsync(0, cts1.Token);
+                await _server.StopAsync();
+
+                _server = new DapServer();
+                _server.Initialize(CreateTestContext());
+                var cts2 = new CancellationTokenSource();
+                await _server.StartAsync(0, cts2.Token);
+                await _server.StopAsync();
+            }
+        }
+    }
+}

src/Test/L0/Worker/HandlerFactoryL0.cs

@@ -74,7 +74,7 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
-      
+
 
         [Fact]
         [Trait("Level", "L0")]
@@ -116,5 +116,259 @@ namespace GitHub.Runner.Common.Tests.Worker
                 Assert.Equal("node24", handler.Data.NodeVersion);
             }
         }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Node20Action_TrackedWhenWarnFlagEnabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange.
+                var hf = new HandlerFactory();
+                hf.Initialize(hc);
+
+                var variables = new Dictionary<string, VariableValue>
+                {
+                    { Constants.Runner.NodeMigration.WarnOnNode20Flag, new VariableValue("true") }
+                };
+                Variables serverVariables = new(hc, variables);
+                var deprecatedActions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+                _ec.Setup(x => x.Global).Returns(new GlobalContext()
+                {
+                    Variables = serverVariables,
+                    EnvironmentVariables = new Dictionary<string, string>(),
+                    DeprecatedNode20Actions = deprecatedActions
+                });
+
+                var actionRef = new RepositoryPathReference
+                {
+                    Name = "actions/checkout",
+                    Ref = "v4"
+                };
+
+                // Act.
+                var data = new NodeJSActionExecutionData();
+                data.NodeVersion = "node20";
+                hf.Create(
+                    _ec.Object,
+                    actionRef,
+                    new Mock<IStepHost>().Object,
+                    data,
+                    new Dictionary<string, string>(),
+                    new Dictionary<string, string>(),
+                    new Variables(hc, new Dictionary<string, VariableValue>()),
+                    "",
+                    new List<JobExtensionRunner>()
+                );
+
+                // Assert.
+                Assert.Contains("actions/checkout@v4", deprecatedActions);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Node20Action_NotTrackedWhenWarnFlagDisabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange.
+                var hf = new HandlerFactory();
+                hf.Initialize(hc);
+
+                var variables = new Dictionary<string, VariableValue>();
+                Variables serverVariables = new(hc, variables);
+                var deprecatedActions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+                _ec.Setup(x => x.Global).Returns(new GlobalContext()
+                {
+                    Variables = serverVariables,
+                    EnvironmentVariables = new Dictionary<string, string>(),
+                    DeprecatedNode20Actions = deprecatedActions
+                });
+
+                var actionRef = new RepositoryPathReference
+                {
+                    Name = "actions/checkout",
+                    Ref = "v4"
+                };
+
+                // Act.
+                var data = new NodeJSActionExecutionData();
+                data.NodeVersion = "node20";
+                hf.Create(
+                    _ec.Object,
+                    actionRef,
+                    new Mock<IStepHost>().Object,
+                    data,
+                    new Dictionary<string, string>(),
+                    new Dictionary<string, string>(),
+                    new Variables(hc, new Dictionary<string, VariableValue>()),
+                    "",
+                    new List<JobExtensionRunner>()
+                );
+
+                // Assert - should not track when flag is disabled
+                Assert.Empty(deprecatedActions);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Node24Action_NotTrackedEvenWhenWarnFlagEnabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange.
+                var hf = new HandlerFactory();
+                hf.Initialize(hc);
+
+                var variables = new Dictionary<string, VariableValue>
+                {
+                    { Constants.Runner.NodeMigration.WarnOnNode20Flag, new VariableValue("true") }
+                };
+                Variables serverVariables = new(hc, variables);
+                var deprecatedActions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+                _ec.Setup(x => x.Global).Returns(new GlobalContext()
+                {
+                    Variables = serverVariables,
+                    EnvironmentVariables = new Dictionary<string, string>(),
+                    DeprecatedNode20Actions = deprecatedActions
+                });
+
+                var actionRef = new RepositoryPathReference
+                {
+                    Name = "actions/checkout",
+                    Ref = "v5"
+                };
+
+                // Act.
+                var data = new NodeJSActionExecutionData();
+                data.NodeVersion = "node24";
+                hf.Create(
+                    _ec.Object,
+                    actionRef,
+                    new Mock<IStepHost>().Object,
+                    data,
+                    new Dictionary<string, string>(),
+                    new Dictionary<string, string>(),
+                    new Variables(hc, new Dictionary<string, VariableValue>()),
+                    "",
+                    new List<JobExtensionRunner>()
+                );
+
+                // Assert - node24 actions should not be tracked
+                Assert.Empty(deprecatedActions);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void Node12Action_TrackedAsDeprecatedWhenWarnFlagEnabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange.
+                var hf = new HandlerFactory();
+                hf.Initialize(hc);
+
+                var variables = new Dictionary<string, VariableValue>
+                {
+                    { Constants.Runner.NodeMigration.WarnOnNode20Flag, new VariableValue("true") }
+                };
+                Variables serverVariables = new(hc, variables);
+                var deprecatedActions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+                _ec.Setup(x => x.Global).Returns(new GlobalContext()
+                {
+                    Variables = serverVariables,
+                    EnvironmentVariables = new Dictionary<string, string>(),
+                    DeprecatedNode20Actions = deprecatedActions
+                });
+
+                var actionRef = new RepositoryPathReference
+                {
+                    Name = "some-org/old-action",
+                    Ref = "v1"
+                };
+
+                // Act - node12 gets migrated to node20, then should be tracked
+                var data = new NodeJSActionExecutionData();
+                data.NodeVersion = "node12";
+                hf.Create(
+                    _ec.Object,
+                    actionRef,
+                    new Mock<IStepHost>().Object,
+                    data,
+                    new Dictionary<string, string>(),
+                    new Dictionary<string, string>(),
+                    new Variables(hc, new Dictionary<string, VariableValue>()),
+                    "",
+                    new List<JobExtensionRunner>()
+                );
+
+                // Assert - node12 gets migrated to node20 and should be tracked
+                Assert.Contains("some-org/old-action@v1", deprecatedActions);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void LocalNode20Action_TrackedWhenWarnFlagEnabled()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange.
+                var hf = new HandlerFactory();
+                hf.Initialize(hc);
+
+                var variables = new Dictionary<string, VariableValue>
+                {
+                    { Constants.Runner.NodeMigration.WarnOnNode20Flag, new VariableValue("true") }
+                };
+                Variables serverVariables = new(hc, variables);
+                var deprecatedActions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+                _ec.Setup(x => x.Global).Returns(new GlobalContext()
+                {
+                    Variables = serverVariables,
+                    EnvironmentVariables = new Dictionary<string, string>(),
+                    DeprecatedNode20Actions = deprecatedActions
+                });
+
+                // Local action: Name is empty, Path is the local path
+                var actionRef = new RepositoryPathReference
+                {
+                    Name = "",
+                    Path = "./.github/actions/my-action",
+                    RepositoryType = "self"
+                };
+
+                // Act.
+                var data = new NodeJSActionExecutionData();
+                data.NodeVersion = "node20";
+                hf.Create(
+                    _ec.Object,
+                    actionRef,
+                    new Mock<IStepHost>().Object,
+                    data,
+                    new Dictionary<string, string>(),
+                    new Dictionary<string, string>(),
+                    new Variables(hc, new Dictionary<string, VariableValue>()),
+                    "",
+                    new List<JobExtensionRunner>()
+                );
+
+                // Assert - local action should be tracked with its path
+                Assert.Contains("./.github/actions/my-action", deprecatedActions);
+            }
+        }
     }
 }

src/Test/L0/Worker/Handlers/CompositeActionHandlerL0.cs

@@ -0,0 +1,335 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using GitHub.DistributedTask.Pipelines;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Common.Util;
+using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker;
+using GitHub.Runner.Worker.Handlers;
+using Moq;
+using Newtonsoft.Json.Linq;
+using Xunit;
+using DTWebApi = GitHub.DistributedTask.WebApi;
+using Pipelines = GitHub.DistributedTask.Pipelines;
+
+namespace GitHub.Runner.Common.Tests.Worker.Handlers
+{
+    public sealed class CompositeActionHandlerL0
+    {
+        // Test EscapeProperty helper logic via reflection or by testing the markers output
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EscapeProperty_EscapesSpecialCharacters()
+        {
+            // Test the escaping logic that would be applied
+            var input = "value;with%special\r\n]chars";
+            var escaped = EscapeProperty(input);
+            Assert.Equal("value%3Bwith%25special%0D%0A%5Dchars", escaped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EscapeProperty_HandlesNullAndEmpty()
+        {
+            Assert.Null(EscapeProperty(null));
+            Assert.Equal("", EscapeProperty(""));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SanitizeDisplayName_TruncatesLongNames()
+        {
+            var longName = new string('a', 1500);
+            var sanitized = SanitizeDisplayName(longName);
+            Assert.Equal(CompositeActionHandler.MaxDisplayNameLength, sanitized.Length);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SanitizeDisplayName_TakesFirstLineOnly()
+        {
+            var multiline = "First line\nSecond line\nThird line";
+            var sanitized = SanitizeDisplayName(multiline);
+            Assert.Equal("First line", sanitized);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SanitizeDisplayName_TrimsLeadingWhitespace()
+        {
+            var withLeading = "   \n  \t  Actual name\nSecond line";
+            var sanitized = SanitizeDisplayName(withLeading);
+            Assert.Equal("Actual name", sanitized);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SanitizeDisplayName_HandlesCarriageReturn()
+        {
+            var withCR = "First line\r\nSecond line";
+            var sanitized = SanitizeDisplayName(withCR);
+            Assert.Equal("First line", sanitized);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SanitizeDisplayName_HandlesNullAndEmpty()
+        {
+            Assert.Null(SanitizeDisplayName(null));
+            Assert.Equal("", SanitizeDisplayName(""));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EmitMarkers_DisplayNameEscaping()
+        {
+            // Verify that special characters in display names get escaped properly
+            var displayName = "Step with semicolons; and more; here";
+            var escaped = EscapeProperty(SanitizeDisplayName(displayName));
+            Assert.Equal("Step with semicolons%3B and more%3B here", escaped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EmitMarkers_DisplayNameWithBrackets()
+        {
+            var displayName = "Step with [brackets] inside";
+            var escaped = EscapeProperty(SanitizeDisplayName(displayName));
+            Assert.Equal("Step with [brackets%5D inside", escaped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripUserEmittedMarkers_StartAction()
+        {
+            // Simulate what OutputManager does to strip markers
+            var userLine = "##[start-action display=Fake;id=fake]";
+            var stripped = StripMarkers(userLine);
+            Assert.Equal(@"##[\start-action display=Fake;id=fake]", stripped);
+            Assert.DoesNotContain("##[start-action", stripped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripUserEmittedMarkers_EndAction()
+        {
+            var userLine = "##[end-action id=fake;outcome=success;conclusion=success;duration_ms=100]";
+            var stripped = StripMarkers(userLine);
+            Assert.Equal(@"##[\end-action id=fake;outcome=success;conclusion=success;duration_ms=100]", stripped);
+            Assert.DoesNotContain("##[end-action", stripped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripUserEmittedMarkers_PreservesOtherCommands()
+        {
+            var userLine = "##[group]My Group";
+            var stripped = StripMarkers(userLine);
+            Assert.Equal("##[group]My Group", stripped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripUserEmittedMarkers_HandlesEmbeddedMarkers()
+        {
+            var userLine = "Some text ##[start-action display=fake;id=fake] more text";
+            var stripped = StripMarkers(userLine);
+            Assert.Equal(@"Some text ##[\start-action display=fake;id=fake] more text", stripped);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void TaskResultToActionResult_Success()
+        {
+            var result = GitHub.DistributedTask.WebApi.TaskResult.Succeeded;
+            var actionResult = result.ToActionResult();
+            Assert.Equal(ActionResult.Success, actionResult);
+            Assert.Equal("success", actionResult.ToString().ToLowerInvariant());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void TaskResultToActionResult_Failure()
+        {
+            var result = GitHub.DistributedTask.WebApi.TaskResult.Failed;
+            var actionResult = result.ToActionResult();
+            Assert.Equal(ActionResult.Failure, actionResult);
+            Assert.Equal("failure", actionResult.ToString().ToLowerInvariant());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void TaskResultToActionResult_Cancelled()
+        {
+            var result = GitHub.DistributedTask.WebApi.TaskResult.Canceled;
+            var actionResult = result.ToActionResult();
+            Assert.Equal(ActionResult.Cancelled, actionResult);
+            Assert.Equal("cancelled", actionResult.ToString().ToLowerInvariant());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void TaskResultToActionResult_Skipped()
+        {
+            var result = GitHub.DistributedTask.WebApi.TaskResult.Skipped;
+            var actionResult = result.ToActionResult();
+            Assert.Equal(ActionResult.Skipped, actionResult);
+            Assert.Equal("skipped", actionResult.ToString().ToLowerInvariant());
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void MarkerFormat_StartAction()
+        {
+            var display = "My Step";
+            var id = "my-step";
+            var marker = $"##[start-action display={EscapeProperty(display)};id={EscapeProperty(id)}]";
+            Assert.Equal("##[start-action display=My Step;id=my-step]", marker);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void MarkerFormat_EndAction()
+        {
+            var id = "my-step";
+            var outcome = "success";
+            var conclusion = "success";
+            var durationMs = 1234;
+            var marker = $"##[end-action id={EscapeProperty(id)};outcome={outcome};conclusion={conclusion};duration_ms={durationMs}]";
+            Assert.Equal("##[end-action id=my-step;outcome=success;conclusion=success;duration_ms=1234]", marker);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void MarkerFormat_NestedId()
+        {
+            var prefix = "outer-composite";
+            var contextName = "inner-step";
+            var stepId = $"{prefix}.{contextName}";
+            Assert.Equal("outer-composite.inner-step", stepId);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void MarkerFormat_SkippedStep()
+        {
+            var id = "skipped-step";
+            var marker = $"##[end-action id={EscapeProperty(id)};outcome=skipped;conclusion=skipped;duration_ms=0]";
+            Assert.Equal("##[end-action id=skipped-step;outcome=skipped;conclusion=skipped;duration_ms=0]", marker);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void MarkerFormat_ContinueOnError()
+        {
+            // When continue-on-error is true and step fails:
+            // outcome = failure (raw result)
+            // conclusion = success (after continue-on-error applied)
+            var id = "failing-step";
+            var marker = $"##[end-action id={EscapeProperty(id)};outcome=failure;conclusion=success;duration_ms=500]";
+            Assert.Equal("##[end-action id=failing-step;outcome=failure;conclusion=success;duration_ms=500]", marker);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void PostStepMarker_UsesEvaluatedDisplayName()
+        {
+            // Arrange: create an ActionRunner with a RepositoryPathReference (simulating actions/cache@v4)
+            // and Stage = Post. Verify that EvaluateDisplayName produces the correct display name
+            // so the composite marker emits "Run actions/cache@v4" instead of the fallback "run".
+            var hc = new TestHostContext(this, nameof(PostStepMarker_UsesEvaluatedDisplayName));
+            var actionManifestLegacy = new ActionManifestManagerLegacy();
+            actionManifestLegacy.Initialize(hc);
+            hc.SetSingleton<IActionManifestManagerLegacy>(actionManifestLegacy);
+            var actionManifestNew = new ActionManifestManager();
+            actionManifestNew.Initialize(hc);
+            hc.SetSingleton<IActionManifestManager>(actionManifestNew);
+            var actionManifestManager = new ActionManifestManagerWrapper();
+            actionManifestManager.Initialize(hc);
+            hc.SetSingleton<IActionManifestManagerWrapper>(actionManifestManager);
+
+            var ec = new Mock<IExecutionContext>();
+            var contextData = new DictionaryContextData();
+            var githubContext = new GitHubContext();
+            githubContext.Add("event", JToken.Parse("{\"foo\":\"bar\"}").ToPipelineContextData());
+            contextData.Add("github", githubContext);
+#if OS_WINDOWS
+            contextData["env"] = new DictionaryContextData();
+#else
+            contextData["env"] = new CaseSensitiveDictionaryContextData();
+#endif
+            ec.Setup(x => x.Global).Returns(new GlobalContext());
+            ec.Setup(x => x.ExpressionValues).Returns(contextData);
+            ec.Setup(x => x.ExpressionFunctions).Returns(new List<GitHub.DistributedTask.Expressions2.IFunctionInfo>());
+            ec.Setup(x => x.Write(It.IsAny<string>(), It.IsAny<string>()));
+            ec.Object.Global.Variables = new Variables(hc, new Dictionary<string, VariableValue>());
+
+            var actionRunner = new ActionRunner();
+            actionRunner.Initialize(hc);
+            actionRunner.ExecutionContext = ec.Object;
+            actionRunner.Stage = ActionRunStage.Post;
+            actionRunner.Action = new Pipelines.ActionStep()
+            {
+                Name = "cache",
+                Id = Guid.NewGuid(),
+                Reference = new Pipelines.RepositoryPathReference()
+                {
+                    Name = "actions/cache",
+                    Ref = "v4"
+                }
+            };
+
+            // Act: call EvaluateDisplayName directly, which is what CompositeActionHandler now does
+            // for embedded steps (including Post stage) instead of TryUpdateDisplayName.
+            var result = actionRunner.EvaluateDisplayName(contextData, ec.Object, out bool updated);
+
+            // Assert: display name should be "Run actions/cache@v4", not the fallback "run"
+            Assert.True(result);
+            Assert.True(updated);
+            Assert.Equal("Run actions/cache@v4", actionRunner.DisplayName);
+        }
+
+        // Helper methods that call the real production code
+        private static string EscapeProperty(string value) =>
+            CompositeActionHandler.EscapeProperty(value);
+
+        private static string SanitizeDisplayName(string displayName) =>
+            CompositeActionHandler.SanitizeDisplayName(displayName);
+
+        private static string StripMarkers(string line)
+        {
+            if (!string.IsNullOrEmpty(line) &&
+                (line.Contains("##[start-action") || line.Contains("##[end-action")))
+            {
+                line = line.Replace("##[start-action", @"##[\start-action")
+                           .Replace("##[end-action", @"##[\end-action");
+            }
+            return line;
+        }
+    }
+}

src/Test/L0/Worker/OutputManagerL0.cs

@@ -1006,6 +1006,66 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripCompositeMarkers_StartAction()
+        {
+            using (Setup())
+            using (_outputManager)
+            {
+                Process("##[start-action display=Fake;id=fake]");
+                Assert.Single(_messages);
+                Assert.Contains(@"##[\start-action", _messages[0]);
+                Assert.DoesNotContain("##[start-action", _messages[0]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripCompositeMarkers_EndAction()
+        {
+            using (Setup())
+            using (_outputManager)
+            {
+                Process("##[end-action id=fake;outcome=success;conclusion=success;duration_ms=100]");
+                Assert.Single(_messages);
+                Assert.Contains(@"##[\end-action", _messages[0]);
+                Assert.DoesNotContain("##[end-action", _messages[0]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripCompositeMarkers_PreservesOtherCommands()
+        {
+            using (Setup())
+            using (_outputManager)
+            {
+                Process("##[group]My Group");
+                // Should not be stripped (not a composite marker)
+                Assert.Single(_messages);
+                Assert.Equal("##[group]My Group", _messages[0]);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void StripCompositeMarkers_EmbeddedInLine()
+        {
+            using (Setup())
+            using (_outputManager)
+            {
+                Process("Some text ##[start-action display=fake;id=fake] more text");
+                Assert.Single(_messages);
+                Assert.Contains(@"##[\start-action", _messages[0]);
+                Assert.DoesNotContain("##[start-action", _messages[0]);
+            }
+        }
+
         private TestHostContext Setup(
             [CallerMemberName] string name = "",
             IssueMatchersConfig matchers = null,

src/Test/L0/Worker/PipelineTemplateEvaluatorWrapperL0.cs

@@ -0,0 +1,891 @@
+using GitHub.DistributedTask.ObjectTemplating.Tokens;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using GitHub.DistributedTask.Pipelines.ObjectTemplating;
+using GitHub.DistributedTask.WebApi;
+using GitHub.Runner.Common;
+using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker;
+using LegacyContextData = GitHub.DistributedTask.Pipelines.ContextData;
+using LegacyExpressions = GitHub.DistributedTask.Expressions2;
+using Moq;
+using System;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Worker
+{
+    public sealed class PipelineTemplateEvaluatorWrapperL0
+    {
+        private CancellationTokenSource _ecTokenSource;
+        private Mock<IExecutionContext> _ec;
+        private TestHostContext _hc;
+
+        // -------------------------------------------------------------------
+        // EvaluateAndCompare core behavior
+        // -------------------------------------------------------------------
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateAndCompare_DoesNotRecordMismatch_WhenResultsMatch()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+
+                var token = new StringToken(null, null, null, "test-value");
+                var contextData = new DictionaryContextData();
+                var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateStepDisplayName(token, contextData, expressionFunctions);
+
+                Assert.Equal("test-value", result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateAndCompare_SkipsMismatchRecording_WhenCancellationOccursDuringEvaluation()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+
+                // Call EvaluateAndCompare directly: the new evaluator cancels the token
+                // and returns a different value, forcing hasMismatch = true.
+                // Because cancellation flipped during the evaluation window, the
+                // mismatch should be skipped.
+                var result = wrapper.EvaluateAndCompare<string, string>(
+                    "TestCancellationSkip",
+                    () => "legacy-value",
+                    () =>
+                    {
+                        _ecTokenSource.Cancel();
+                        return "different-value";
+                    },
+                    (legacy, @new) => string.Equals(legacy, @new, StringComparison.Ordinal));
+
+                Assert.Equal("legacy-value", result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateAndCompare_RecordsMismatch_WhenResultsDifferWithoutCancellation()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+
+                // Different results without cancellation — mismatch SHOULD be recorded.
+                var result = wrapper.EvaluateAndCompare<string, string>(
+                    "TestMismatchRecorded",
+                    () => "legacy-value",
+                    () => "different-value",
+                    (legacy, @new) => string.Equals(legacy, @new, StringComparison.Ordinal));
+
+                Assert.Equal("legacy-value", result);
+                Assert.True(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        // -------------------------------------------------------------------
+        // Smoke tests — both parsers agree, no mismatch recorded
+        // -------------------------------------------------------------------
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateStepContinueOnError_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new BooleanToken(null, null, null, true);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateStepContinueOnError(token, contextData, functions);
+
+                Assert.True(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateStepEnvironment_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "FOO"), new StringToken(null, null, null, "bar"));
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateStepEnvironment(token, contextData, functions, StringComparer.OrdinalIgnoreCase);
+
+                Assert.NotNull(result);
+                Assert.Equal("bar", result["FOO"]);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateStepIf_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new BasicExpressionToken(null, null, null, "true");
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+                var expressionState = new List<KeyValuePair<string, object>>();
+
+                var result = wrapper.EvaluateStepIf(token, contextData, functions, expressionState);
+
+                Assert.True(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateStepInputs_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "input1"), new StringToken(null, null, null, "val1"));
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateStepInputs(token, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Equal("val1", result["input1"]);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateStepTimeout_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new NumberToken(null, null, null, 10);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateStepTimeout(token, contextData, functions);
+
+                Assert.Equal(10, result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_EmptyImage_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new StringToken(null, null, null, "");
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobContainer(token, contextData, functions);
+
+                Assert.Null(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_DockerPrefixOnly_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new StringToken(null, null, null, "docker://");
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobContainer(token, contextData, functions);
+
+                Assert.Null(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_DockerPrefixOnlyMapping_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, "docker://"));
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobContainer(token, contextData, functions);
+
+                Assert.Null(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_EmptyImageMapping_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, ""));
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobContainer(token, contextData, functions);
+
+                Assert.Null(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_ValidImage_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new StringToken(null, null, null, "ubuntu:latest");
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobContainer(token, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Equal("ubuntu:latest", result.Image);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobContainer_DockerPrefixWithImage_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new StringToken(null, null, null, "docker://ubuntu:latest");
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobContainer(token, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Equal("ubuntu:latest", result.Image);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobOutput_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "out1"), new StringToken(null, null, null, "val1"));
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobOutput(token, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Equal("val1", result["out1"]);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateEnvironmentUrl_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new StringToken(null, null, null, "https://example.com");
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateEnvironmentUrl(token, contextData, functions);
+
+                Assert.NotNull(result);
+                var stringResult = result as StringToken;
+                Assert.NotNull(stringResult);
+                Assert.Equal("https://example.com", stringResult.Value);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobDefaultsRun_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var token = new MappingToken(null, null, null);
+                token.Add(new StringToken(null, null, null, "shell"), new StringToken(null, null, null, "bash"));
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobDefaultsRun(token, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Equal("bash", result["shell"]);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_Null_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobServiceContainers(null, contextData, functions);
+
+                Assert.Null(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_EmptyImage_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                // Build a services mapping token with one service whose image is empty string
+                // Similar to: services: { db: { image: '' } }
+                var servicesMapping = new MappingToken(null, null, null);
+                var serviceMapping = new MappingToken(null, null, null);
+                serviceMapping.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, ""));
+                servicesMapping.Add(new StringToken(null, null, null, "db"), serviceMapping);
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobServiceContainers(servicesMapping, contextData, functions);
+
+                // Should get a list with one entry where the container is null (empty image = no container)
+                Assert.NotNull(result);
+                Assert.Single(result);
+                Assert.Equal("db", result[0].Key);
+                Assert.Null(result[0].Value);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_DockerPrefixOnlyImage_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var servicesMapping = new MappingToken(null, null, null);
+                var serviceMapping = new MappingToken(null, null, null);
+                serviceMapping.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, "docker://"));
+                servicesMapping.Add(new StringToken(null, null, null, "db"), serviceMapping);
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobServiceContainers(servicesMapping, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Single(result);
+                Assert.Equal("db", result[0].Key);
+                Assert.Null(result[0].Value);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_ExpressionEvalsToEmpty_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                // Simulates: services: { db: { image: ${{ condition && 'img' || '' }} } }
+                // where the expression evaluates to '' at runtime
+                var servicesMapping = new MappingToken(null, null, null);
+                var serviceMapping = new MappingToken(null, null, null);
+                serviceMapping.Add(new StringToken(null, null, null, "image"), new BasicExpressionToken(null, null, null, "''"));
+                servicesMapping.Add(new StringToken(null, null, null, "db"), serviceMapping);
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobServiceContainers(servicesMapping, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Single(result);
+                Assert.Equal("db", result[0].Key);
+                Assert.Null(result[0].Value);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_ValidImage_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var servicesMapping = new MappingToken(null, null, null);
+                var serviceMapping = new MappingToken(null, null, null);
+                serviceMapping.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, "postgres:latest"));
+                servicesMapping.Add(new StringToken(null, null, null, "db"), serviceMapping);
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobServiceContainers(servicesMapping, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Single(result);
+                Assert.Equal("db", result[0].Key);
+                Assert.NotNull(result[0].Value);
+                Assert.Equal("postgres:latest", result[0].Value.Image);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_EntrypointAndCommand_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var servicesMapping = new MappingToken(null, null, null);
+                var serviceMapping = new MappingToken(null, null, null);
+                serviceMapping.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, "postgres:latest"));
+                serviceMapping.Add(new StringToken(null, null, null, "entrypoint"), new StringToken(null, null, null, "/bin/bash"));
+                serviceMapping.Add(new StringToken(null, null, null, "command"), new StringToken(null, null, null, "-lc echo hi"));
+                servicesMapping.Add(new StringToken(null, null, null, "db"), serviceMapping);
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: true);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobServiceContainers(servicesMapping, contextData, functions);
+
+                Assert.NotNull(result);
+                Assert.Single(result);
+                Assert.Equal("db", result[0].Key);
+                Assert.NotNull(result[0].Value);
+                Assert.Equal("postgres:latest", result[0].Value.Image);
+                Assert.Equal("/bin/bash", result[0].Value.Entrypoint);
+                Assert.Equal("-lc echo hi", result[0].Value.Command);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobServiceContainers_EntrypointAndCommand_FlagOff_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var servicesMapping = new MappingToken(null, null, null);
+                var serviceMapping = new MappingToken(null, null, null);
+                serviceMapping.Add(new StringToken(null, null, null, "image"), new StringToken(null, null, null, "postgres:latest"));
+                serviceMapping.Add(new StringToken(null, null, null, "entrypoint"), new StringToken(null, null, null, "/bin/bash"));
+                serviceMapping.Add(new StringToken(null, null, null, "command"), new StringToken(null, null, null, "-lc echo hi"));
+                servicesMapping.Add(new StringToken(null, null, null, "db"), serviceMapping);
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                Assert.Throws<GitHub.DistributedTask.ObjectTemplating.TemplateValidationException>(() =>
+                    wrapper.EvaluateJobServiceContainers(servicesMapping, contextData, functions));
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateJobSnapshotRequest_Null_BothParsersAgree()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+                var contextData = new DictionaryContextData();
+                var functions = new List<LegacyExpressions.IFunctionInfo>();
+
+                var result = wrapper.EvaluateJobSnapshotRequest(null, contextData, functions);
+
+                Assert.Null(result);
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        // -------------------------------------------------------------------
+        // JSON parse error equivalence via EvaluateAndCompare
+        // -------------------------------------------------------------------
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateAndCompare_JsonReaderExceptions_TreatedAsEquivalent()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+
+                // Both throw JsonReaderException with different messages — should be treated as equivalent
+                var legacyEx = new Newtonsoft.Json.JsonReaderException("Error reading JToken from JsonReader. Path '', line 0, position 0.");
+                var newEx = new Newtonsoft.Json.JsonReaderException("Error parsing fromJson", new Newtonsoft.Json.JsonReaderException("Unexpected end"));
+
+                Assert.Throws<Newtonsoft.Json.JsonReaderException>(() =>
+                    wrapper.EvaluateAndCompare<string, string>(
+                        "TestJsonEquivalence",
+                        () => throw legacyEx,
+                        () => throw newEx,
+                        (a, b) => string.Equals(a, b, StringComparison.Ordinal)));
+
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateAndCompare_MixedJsonExceptionTypes_TreatedAsEquivalent()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+
+                // Legacy throws Newtonsoft JsonReaderException, new throws System.Text.Json.JsonException
+                var legacyEx = new Newtonsoft.Json.JsonReaderException("Error reading JToken");
+                var newEx = new System.Text.Json.JsonException("Error parsing fromJson");
+
+                Assert.Throws<Newtonsoft.Json.JsonReaderException>(() =>
+                    wrapper.EvaluateAndCompare<string, string>(
+                        "TestMixedJsonTypes",
+                        () => throw legacyEx,
+                        () => throw newEx,
+                        (a, b) => string.Equals(a, b, StringComparison.Ordinal)));
+
+                Assert.False(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void EvaluateAndCompare_NonJsonExceptions_RecordsMismatch()
+        {
+            try
+            {
+                Setup();
+                _ec.Object.Global.Variables.Set(Constants.Runner.Features.CompareWorkflowParser, "true");
+
+                var wrapper = new PipelineTemplateEvaluatorWrapper(_hc, _ec.Object, allowServiceContainerCommand: false);
+
+                // Both throw non-JSON exceptions with different messages — should record mismatch
+                var legacyEx = new InvalidOperationException("some error");
+                var newEx = new InvalidOperationException("different error");
+
+                Assert.Throws<InvalidOperationException>(() =>
+                    wrapper.EvaluateAndCompare<string, string>(
+                        "TestNonJsonMismatch",
+                        () => throw legacyEx,
+                        () => throw newEx,
+                        (a, b) => string.Equals(a, b, StringComparison.Ordinal)));
+
+                Assert.True(_ec.Object.Global.HasTemplateEvaluatorMismatch);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        // -------------------------------------------------------------------
+        // Helpers
+        // -------------------------------------------------------------------
+
+        private void Setup([CallerMemberName] string name = "")
+        {
+            _ecTokenSource?.Dispose();
+            _ecTokenSource = new CancellationTokenSource();
+
+            _hc = new TestHostContext(this, name);
+
+            var expressionValues = new LegacyContextData.DictionaryContextData();
+            var expressionFunctions = new List<LegacyExpressions.IFunctionInfo>();
+
+            _ec = new Mock<IExecutionContext>();
+            _ec.Setup(x => x.Global)
+                .Returns(new GlobalContext
+                {
+                    FileTable = new List<String>(),
+                    Variables = new Variables(_hc, new Dictionary<string, VariableValue>()),
+                    WriteDebug = true,
+                });
+            _ec.Setup(x => x.CancellationToken).Returns(_ecTokenSource.Token);
+            _ec.Setup(x => x.ExpressionValues).Returns(expressionValues);
+            _ec.Setup(x => x.ExpressionFunctions).Returns(expressionFunctions);
+            _ec.Setup(x => x.Write(It.IsAny<string>(), It.IsAny<string>())).Callback((string tag, string message) => { _hc.GetTrace().Info($"{tag}{message}"); });
+            _ec.Setup(x => x.AddIssue(It.IsAny<Issue>(), It.IsAny<ExecutionContextLogOptions>())).Callback((Issue issue, ExecutionContextLogOptions logOptions) => { _hc.GetTrace().Info($"[{issue.Type}]{logOptions.LogMessageOverride ?? issue.Message}"); });
+        }
+
+        private void Teardown()
+        {
+            _hc?.Dispose();
+        }
+    }
+}

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="8.0.417"
+DOTNETSDK_VERSION="8.0.418"
 DOTNETSDK_INSTALLDIR="$DOTNETSDK_ROOT/$DOTNETSDK_VERSION"
 RUNNER_VERSION=$(cat runnerversion)
 

src/global.json

@@ -1,5 +1,5 @@
 {
   "sdk": {
-    "version": "8.0.417"
+    "version": "8.0.418"
   }
 }

src/runnerversion

@@ -1 +1 @@
-2.331.0
+2.332.0