fix(ci): least-privilege permissions + fork-safe concurrency keys

- evals.yml / evals-periodic.yml evals jobs: explicit contents:read +
  packages:read (container-image pull) and persist-credentials:false —
  the jobs that execute PR-authored code with three provider API keys
  ran on the repo-default token grant with the token written into
  .git/config
- permissions blocks for the 4 workflows that had none (skill-docs,
  make-pdf-gate, windows-free-tests, windows-setup-e2e)
- fork-safe concurrency keys: actionlint, skill-docs, make-pdf-gate,
  windows-setup-e2e switch from head_ref to PR-number keying — a bare
  branch name carries no fork prefix, so same-name branches from two
  forks shared one group and cancelled each other's runs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/actionlint.yml

@@ -6,11 +6,11 @@ on:
     branches: [main]
   pull_request:
 
-# Cancel superseded runs for the same branch (matches evals.yml,
-# windows-free-tests.yml, etc.). head_ref is set on pull_request; ref_name is
-# the fallback for push so a rapid push series doesn't pile up stale lint runs.
+# PR-number keyed (run_id fallback for push): a bare branch name carries no
+# fork prefix, so same-name branches from two forks would share one group and
+# cancel each other's runs (same rationale as free-tests.yml).
 concurrency:
-  group: actionlint-${{ github.head_ref || github.ref_name }}
+  group: actionlint-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
 # Lint needs nothing from the token; the job runs a third-party image with

.github/workflows/evals-periodic.yml

@@ -68,6 +68,11 @@ jobs:
   evals:
     runs-on: ubicloud-standard-8
     needs: build-image
+    # Least privilege (mirrors evals.yml): read-only contents, packages:read
+    # for the container-image pull.
+    permissions:
+      contents: read
+      packages: read
     container:
       image: ${{ needs.build-image.outputs.image-tag }}
       credentials:
@@ -110,6 +115,7 @@ jobs:
       - uses: actions/checkout@v7
         with:
           fetch-depth: 0
+          persist-credentials: false
 
       - name: Fix bun temp
         run: |

.github/workflows/evals.yml

@@ -89,6 +89,13 @@ jobs:
     runs-on: ${{ matrix.suite.runner || 'ubicloud-standard-8' }}
     needs: build-image
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
+    # Least privilege for the job that executes PR-authored code with three
+    # provider API keys in env: read-only contents, packages:read for the
+    # container-image pull below. Without this block the job ran on the
+    # repo-default token grant.
+    permissions:
+      contents: read
+      packages: read
     container:
       image: ${{ needs.build-image.outputs.image-tag }}
       credentials:
@@ -176,6 +183,9 @@ jobs:
       - uses: actions/checkout@v7
         with:
           fetch-depth: 0
+          # Don't write the token into .git/config — this job runs
+          # PR-authored code; nothing in it pushes.
+          persist-credentials: false
 
       # Bun creates root-owned temp dirs during Docker build. GH Actions runs as
       # runner user with HOME=/github/home. Redirect bun's cache to a writable dir.

.github/workflows/make-pdf-gate.yml

@@ -16,9 +16,15 @@ on:
   workflow_dispatch:
 
 concurrency:
-  group: make-pdf-gate-${{ github.head_ref || github.run_id }}
+  # PR-number keyed: head_ref carries no fork prefix, so same-name branches
+  # from two forks would share one group and cancel each other's runs.
+  group: make-pdf-gate-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
+# Build + test only — no token writes.
+permissions:
+  contents: read
+
 jobs:
   gate:
     strategy:

.github/workflows/skill-docs.yml

@@ -10,9 +10,16 @@ on:
 # windows-free-tests.yml, etc.). head_ref is set on pull_request; ref_name is
 # the fallback for push so a rapid push series doesn't pile up stale runs.
 concurrency:
-  group: skill-docs-${{ github.head_ref || github.ref_name }}
+  # PR-number keyed (run_id fallback for push/dispatch): a bare branch name
+  # carries no fork prefix, so same-name branches from two forks would share
+  # one group and cancel each other's runs (same rationale as free-tests.yml).
+  group: skill-docs-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
+# The job only reads the checkout and runs the generator — no token writes.
+permissions:
+  contents: read
+
 jobs:
   check-freshness:
     runs-on: ubicloud-standard-2

.github/workflows/windows-free-tests.yml

@@ -31,6 +31,10 @@ concurrency:
   group: windows-free-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
+# Test-only lane — no token writes.
+permissions:
+  contents: read
+
 jobs:
   windows-free-tests:
     # Ubicloud Windows runner (same provider as the Linux evals workflow).

.github/workflows/windows-setup-e2e.yml

@@ -26,9 +26,15 @@ on:
   workflow_dispatch:
 
 concurrency:
-  group: windows-setup-e2e-${{ github.head_ref || github.run_id }}
+  # PR-number keyed: head_ref carries no fork prefix, so same-name branches
+  # from two forks would share one group and cancel each other's runs.
+  group: windows-setup-e2e-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
+# Install-path exercise only — no token writes.
+permissions:
+  contents: read
+
 jobs:
   windows-setup:
     runs-on: windows-latest