ci: canary direct, pinned cicd-squabbler chains gate

.github/workflows/actions.lock

@@ -15,6 +15,9 @@ workflows:
         - 'actions/upload-artifact@v7.0.2'
         - 'dtolnay/rust-toolchain@v1'
         - 'taiki-e/install-action@v2.88.0'
+    '.github/workflows/cicd-squabbler.yml':
+        - 'actions/checkout@v7.0.1'
+        - 'hyperpolymath/cicd-squabbler@1ab1507a424c9edfe6cb53dea4e33a2f3cc558e3'
     '.github/workflows/ci-health-sweep.yml':
         - 'actions/checkout@v7.0.1'
         - 'step-security/harden-runner@v2.22.3'

.github/workflows/cicd-squabbler.yml

@@ -0,0 +1,72 @@
+# SPDX-License-Identifier: MPL-2.0
+# This workflow is managed by gh actions-lock.
+#
+# Independent squabbler canary: use the same-owner, commit-pinned action.
+# Cross-owner reusable startup is blocked in this caller's effective Actions
+# policy; this avoids silently equating a zero-job startup_failure to green.
+# No administration token, no --apply, and no write permissions.
+name: CICD Squabbler
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+  schedule:
+    - cron: '17 7 * * 1'
+  workflow_dispatch:
+
+concurrency:
+  group: squabbler-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+  attestations: read
+
+jobs:
+  chains:
+    name: Squabble chains (hard gate)
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - name: Check out repository at the event SHA
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+
+      - name: Install pinned and attested squabble
+        id: squabble
+        uses: hyperpolymath/cicd-squabbler/.github/actions/squabble@1ab1507a424c9edfe6cb53dea4e33a2f3cc558e3
+        with:
+          args: ""
+
+      - name: Audit dependency chains (fail closed)
+        env:
+          GH_TOKEN: ${{ github.token }}
+          REPO: ${{ github.repository }}
+          SQUABBLE_BIN: ${{ steps.squabble.outputs.path }}
+        run: |
+          set -uo pipefail
+          if [ ! -x "$SQUABBLE_BIN" ]; then
+            echo "::error::Pinned squabble did not install"
+            exit 1
+          fi
+          rc=0
+          "$SQUABBLE_BIN" chains ".=$REPO" --follow 1 | tee "$RUNNER_TEMP/squabble-chains.txt" || rc=$?
+          {
+            echo "### Squabble chains"
+            echo
+            echo '~~~'
+            cat "$RUNNER_TEMP/squabble-chains.txt"
+            echo '~~~'
+            echo
+            echo "Exit code: $rc; no remediation was applied."
+          } >> "$GITHUB_STEP_SUMMARY"
+          if [ "$rc" -eq 4 ]; then
+            echo "::error::Cycle or dead upstream blocked the CI dependency graph"
+            exit 1
+          fi
+          if [ "$rc" -ne 0 ]; then
+            echo "::error::Squabble could not establish the CI dependency graph (exit $rc)"
+            exit 1
+          fi