diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4855e43164..cfdd33fe9c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,10 +43,12 @@ jobs:
   classify_pr:
     name: 'Classify PR'
     if: "${{ github.event_name == 'pull_request' }}"
-    runs-on: 'ubuntu-latest'
+    # Gate runs on ECS for in-repo PRs too, else a busy hosted pool delays it and blocks the ECS-bound jobs. The kill-switch is read here, so flipping it reverts everything to hosted.
+    runs-on: "${{ (vars.MAINTAINER_ECS_RUNNER_DISABLED != 'true' && github.event.pull_request.head.repo.full_name == github.repository) && fromJSON('[\"self-hosted\", \"linux\", \"x64\", \"ecs-qwen\"]') || fromJSON('[\"ubuntu-latest\"]') }}"
     continue-on-error: true
     outputs:
       skip_ci: '${{ steps.release_sync.outputs.skip_ci }}'
+      ubuntu_runner: '${{ steps.pick_runner.outputs.ubuntu_runner }}'
     steps:
       - name: 'Detect release version-sync PR'
         id: 'release_sync'
@@ -84,11 +86,26 @@ jobs:
           echo "skip_ci=${skip_ci}" >> "${GITHUB_OUTPUT}"
           echo "skip_ci=${skip_ci}"
 
+      # In-repo PR (head branch in this repo => author has write access) runs the
+      # Linux Test on ECS; forks stay hosted. Disable via repo var MAINTAINER_ECS_RUNNER_DISABLED=true.
+      - name: 'Select Linux runner'
+        id: 'pick_runner'
+        env:
+          SAME_REPO: '${{ github.event.pull_request.head.repo.full_name == github.repository }}'
+          ECS_DISABLED: '${{ vars.MAINTAINER_ECS_RUNNER_DISABLED }}'
+        run: |-
+          ubuntu_runner='["ubuntu-latest"]'
+          if [[ "${ECS_DISABLED}" != "true" && "${SAME_REPO}" == "true" ]]; then
+            ubuntu_runner='["self-hosted", "linux", "x64", "ecs-qwen"]'
+          fi
+          echo "ubuntu_runner=${ubuntu_runner}" >> "${GITHUB_OUTPUT}"
+          echo "Selected Linux runner: ${ubuntu_runner}"
+
   lint:
     name: 'Lint'
     needs: 'classify_pr'
     if: "${{ !cancelled() && needs.classify_pr.outputs.skip_ci != 'true' }}"
-    runs-on: 'ubuntu-latest'
+    runs-on: "${{ fromJSON(needs.classify_pr.outputs.ubuntu_runner || '[\"ubuntu-latest\"]') }}"
     steps:
       - name: 'Checkout'
         uses: 'actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd' # v6.0.2
@@ -96,12 +113,23 @@ jobs:
           ref: '${{ github.event.inputs.branch_ref || github.ref }}'
           fetch-depth: 0
 
-      - name: 'Set up Node.js 22.x'
+      # Self-hosted reuses the machine's Node (nodejs.org unreachable via proxy); linters are pre-installed on PATH so scripts/lint.js skips downloading them.
+      - name: 'Set up Node.js 22.x (hosted)'
+        if: "${{ runner.environment == 'github-hosted' }}"
         uses: 'actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e' # v6.4.0
         with:
           node-version: '22.x'
           cache: 'npm'
 
+      - name: 'Use pre-installed Node.js (self-hosted)'
+        if: "${{ runner.environment == 'self-hosted' }}"
+        run: |-
+          if ! command -v node >/dev/null 2>&1; then
+            echo "::error::Node.js is not on PATH for this self-hosted runner. Provision Node 22.x or set MAINTAINER_ECS_RUNNER_DISABLED='true' to route PRs back to hosted runners."
+            exit 1
+          fi
+          echo "Using pre-installed Node $(node -v) / npm $(npm -v)"
+
       - name: 'Install dependencies and run prepare'
         run: 'npm ci'
 
@@ -158,7 +186,7 @@ jobs:
     # Stay running on release-sync PRs so the required Test contexts still
     # report; the per-step skip_ci guards below make them no-op (pass) there.
     if: '${{ !cancelled() }}'
-    runs-on: '${{ matrix.runner }}'
+    runs-on: '${{ fromJSON(matrix.runner) }}'
     permissions:
       contents: 'read'
       checks: 'write'
@@ -168,15 +196,15 @@ jobs:
       matrix:
         include:
           - os: 'macos-latest'
-            runner: 'macos-latest'
+            runner: '["macos-latest"]'
             node-version: '22.x'
             upload-coverage: 'false'
           - os: 'ubuntu-latest'
-            runner: 'ubuntu-latest'
+            runner: "${{ needs.classify_pr.outputs.ubuntu_runner || '[\"ubuntu-latest\"]' }}"
             node-version: '22.x'
             upload-coverage: 'true'
           - os: 'windows-latest'
-            runner: 'windows-2022'
+            runner: '["windows-2022"]'
             node-version: '22.x'
             upload-coverage: 'false'
     steps:
@@ -184,8 +212,9 @@ jobs:
         if: "${{ needs.classify_pr.outputs.skip_ci != 'true' }}"
         uses: 'actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd' # v6.0.2
 
-      - name: 'Set up Node.js ${{ matrix.node-version }}'
-        if: "${{ needs.classify_pr.outputs.skip_ci != 'true' }}"
+      # Self-hosted can't reach nodejs.org reliably; reuse the machine's Node.
+      - name: 'Set up Node.js ${{ matrix.node-version }} (hosted)'
+        if: "${{ needs.classify_pr.outputs.skip_ci != 'true' && runner.environment == 'github-hosted' }}"
         uses: 'actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e' # v6.4.0
         with:
           node-version: '${{ matrix.node-version }}'
@@ -193,6 +222,18 @@ jobs:
           cache-dependency-path: 'package-lock.json'
           registry-url: 'https://registry.npmjs.org/'
 
+      - name: 'Use pre-installed Node.js (self-hosted)'
+        if: "${{ needs.classify_pr.outputs.skip_ci != 'true' && runner.environment == 'self-hosted' }}"
+        run: |-
+          if ! command -v node >/dev/null 2>&1; then
+            echo "::error::Node.js is not on PATH for this self-hosted runner. Provision Node ${{ matrix.node-version }} or set the MAINTAINER_ECS_RUNNER_DISABLED repository variable to 'true' to route PRs back to hosted runners."
+            exit 1
+          fi
+          echo "Using pre-installed Node $(node -v) / npm $(npm -v)"
+          if [[ "$(node -p 'process.versions.node.split(".")[0]')" != "22" ]]; then
+            echo "::warning::Expected Node 22.x but found $(node -v); tests will run against the runner's Node."
+          fi
+
       - name: 'Configure npm for rate limiting'
         if: "${{ needs.classify_pr.outputs.skip_ci != 'true' }}"
         run: |-
diff --git a/.github/workflows/qwen-code-pr-review.yml b/.github/workflows/qwen-code-pr-review.yml
index c4b3281ea0..82f019159e 100644
--- a/.github/workflows/qwen-code-pr-review.yml
+++ b/.github/workflows/qwen-code-pr-review.yml
@@ -70,7 +70,7 @@ jobs:
     concurrency:
       group: 'qwen-pr-ack-${{ github.event.issue.number || github.event.pull_request.number }}'
       cancel-in-progress: false
-    runs-on: 'ubuntu-latest'
+    runs-on: "${{ vars.MAINTAINER_ECS_RUNNER_DISABLED != 'true' && fromJSON('[\"self-hosted\", \"linux\", \"x64\", \"ecs-qwen\"]') || fromJSON('[\"ubuntu-latest\"]') }}"
     timeout-minutes: 5
     permissions:
       pull-requests: 'write'
@@ -112,7 +112,7 @@ jobs:
     if: |-
       github.event_name == 'pull_request_target' &&
       github.event.action == 'review_requested'
-    runs-on: 'ubuntu-latest'
+    runs-on: "${{ vars.MAINTAINER_ECS_RUNNER_DISABLED != 'true' && fromJSON('[\"self-hosted\", \"linux\", \"x64\", \"ecs-qwen\"]') || fromJSON('[\"ubuntu-latest\"]') }}"
     permissions: {}
     outputs:
       bot_login: '${{ steps.values.outputs.bot_login }}'
@@ -131,7 +131,7 @@ jobs:
       github.event.pull_request.state == 'open' &&
       !github.event.pull_request.draft &&
       needs.authorize.outputs.should_review == 'true'
-    runs-on: 'ubuntu-latest'
+    runs-on: "${{ vars.MAINTAINER_ECS_RUNNER_DISABLED != 'true' && fromJSON('[\"self-hosted\", \"linux\", \"x64\", \"ecs-qwen\"]') || fromJSON('[\"ubuntu-latest\"]') }}"
     # Configured in repo settings with a 30-minute wait timer.
     environment:
       name: 'qwen-pr-review-delay'
@@ -183,7 +183,7 @@ jobs:
         startsWith(github.event.comment.body, '@qwen-code /review')) ||
        (github.event_name == 'pull_request_review' &&
         startsWith(github.event.review.body, '@qwen-code /review')))
-    runs-on: 'ubuntu-latest'
+    runs-on: "${{ vars.MAINTAINER_ECS_RUNNER_DISABLED != 'true' && fromJSON('[\"self-hosted\", \"linux\", \"x64\", \"ecs-qwen\"]') || fromJSON('[\"ubuntu-latest\"]') }}"
     timeout-minutes: 5
     permissions:
       contents: 'read'
diff --git a/.github/workflows/qwen-triage.yml b/.github/workflows/qwen-triage.yml
index fa9c922329..56fcf16529 100644
--- a/.github/workflows/qwen-triage.yml
+++ b/.github/workflows/qwen-triage.yml
@@ -51,7 +51,7 @@ jobs:
          startsWith(github.event.comment.body, '@qwen-code /tmux '))) ||
        (github.event_name == 'workflow_dispatch' &&
         github.event.inputs.tmux_pr != ''))
-    runs-on: 'ubuntu-latest'
+    runs-on: "${{ vars.MAINTAINER_ECS_RUNNER_DISABLED != 'true' && fromJSON('[\"self-hosted\", \"linux\", \"x64\", \"ecs-qwen\"]') || fromJSON('[\"ubuntu-latest\"]') }}"
     timeout-minutes: 5
     permissions:
       contents: 'read'
diff --git a/scripts/tests/install-script.test.js b/scripts/tests/install-script.test.js
index ccbcf3eccc..8fac2982e4 100644
--- a/scripts/tests/install-script.test.js
+++ b/scripts/tests/install-script.test.js
@@ -3608,7 +3608,13 @@ describe('Linux/macOS installer end-to-end', { timeout: 15000 }, () => {
       const fakeBin = path.join(tmpDir, 'bin');
       mkdirSync(fakeBin, { recursive: true });
       writeFileSync(path.join(fakeBin, 'curl'), '#!/usr/bin/env sh\nexit 22\n');
+      // Shadow any system Node on PATH (e.g. /usr/bin/node on self-hosted
+      // runners) with a stub that fails version detection, so the npm fallback
+      // deterministically fails with "Unable to determine Node.js version"
+      // regardless of whether the host has Node installed in /usr/bin.
+      writeFileSync(path.join(fakeBin, 'node'), '#!/usr/bin/env sh\nexit 1\n');
       chmodSync(path.join(fakeBin, 'curl'), 0o755);
+      chmodSync(path.join(fakeBin, 'node'), 0o755);
 
       let failureMessage = '';
       try {