diff --git a/.github/workflows/pr-governance-tests.yml b/.github/workflows/pr-governance-tests.yml
index 57e8704..09b1e33 100644
--- a/.github/workflows/pr-governance-tests.yml
+++ b/.github/workflows/pr-governance-tests.yml
@@ -20,9 +20,10 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false
-      - name: Test the gate, label binding and review request
+      - name: Test the gate, labels, reviewer evidence, runner and review request
         run: >-
           node --test pr-governance/scripts/test-gate.cjs
+          pr-governance/scripts/test-labels.cjs pr-governance/scripts/test-codex.cjs
           pr-governance/scripts/test-runner.cjs pr-governance/scripts/test-nudge.cjs
       - name: Install the pinned scanner
         run: bash pr-governance/scripts/install-gitleaks.sh
diff --git a/pr-governance/README.md b/pr-governance/README.md
index 1b82be8..34cae99 100644
--- a/pr-governance/README.md
+++ b/pr-governance/README.md
@@ -65,7 +65,11 @@ organization community-health files.
 2. Copy `templates/risk-gate.yml`, `templates/codex-nudge.yml`,
    `templates/gitleaks.yml` and `templates/weekly-secret-scan.yml` into
    `.github/workflows/`, replacing `__GOVERNANCE_REPO__` with the
-   `owner/repository` of this governance repository.
+   `owner/repository` of this governance repository and `__GOVERNANCE_SHA__`
+   with the full commit SHA at the head of `v1`. Copy
+   `templates/pr-review-signal.yml` unchanged as well: review events on fork
+   and Dependabot pull requests get a read-only token, so the gate is started
+   by that workflow's completion instead.
 3. Add the required contexts to branch protection on the default branch:
    `pr-template`, `ai-review`, `risk-gate`, `Gitleaks`, and the repository's
    own checks. Keep `strict` (require branches to be up to date) and
@@ -79,8 +83,8 @@ file, which is read from the default branch head.
 ## Trust model
 
 - Workflows never check out or execute pull request code.
-- The action is pinned by the `v1` branch of this repository, not by the
-  repository under judgement.
+- The action is pinned to a full commit SHA of this repository, not by the
+  repository under judgement. Update the pins after `v1` moves.
 - The policy is read from the default branch head, so a pull request cannot
   change the rules that judge it.
 - Reviewer evidence is a marker comment written by the configured reviewer
diff --git a/pr-governance/scripts/__pycache__/secret_scan.cpython-313.pyc b/pr-governance/scripts/__pycache__/secret_scan.cpython-313.pyc
new file mode 100644
index 0000000..856784b
Binary files /dev/null and b/pr-governance/scripts/__pycache__/secret_scan.cpython-313.pyc differ
diff --git a/pr-governance/scripts/runner.cjs b/pr-governance/scripts/runner.cjs
index fc576e0..d91273b 100644
--- a/pr-governance/scripts/runner.cjs
+++ b/pr-governance/scripts/runner.cjs
@@ -36,6 +36,22 @@ async function selectTargets(github, context, defaultBranch) {
     if (!Number.isSafeInteger(event.issue.number) || event.issue.number < 1) throw new Error('Invalid PR number');
     return [event.issue.number];
   }
+  if (context.eventName === 'workflow_run') {
+    // Reviews on fork and Dependabot pull requests arrive through a
+    // permissionless signal workflow; only its completion is trusted here.
+    const run = event.workflow_run;
+    if (!run) throw new Error('Missing workflow run payload');
+    const listed = Array.isArray(run.pull_requests) ? run.pull_requests : [];
+    const numbers = listed
+      .map(item => item?.number)
+      .filter(number => Number.isSafeInteger(number) && number > 0);
+    if (numbers.length) return [...new Set(numbers)];
+    const owner = run.head_repository?.owner?.login;
+    if (!owner || typeof run.head_branch !== 'string' || !run.head_branch) return [];
+    const pulls = await github.paginate(github.rest.pulls.list,
+      { ...repo, state: 'open', base: defaultBranch, head: `${owner}:${run.head_branch}`, per_page: 100 });
+    return pulls.map(pull => pull.number);
+  }
   if (context.eventName === 'workflow_dispatch') {
     if (context.ref !== `refs/heads/${defaultBranch}`) throw new Error('Dispatch must use the default branch');
     const number = Number(event.inputs?.pr_number);
diff --git a/pr-governance/scripts/secret_scan.py b/pr-governance/scripts/secret_scan.py
index 711625d..92bec15 100644
--- a/pr-governance/scripts/secret_scan.py
+++ b/pr-governance/scripts/secret_scan.py
@@ -69,10 +69,15 @@ def fail_walk(error):
             raise RuntimeError('Source ignore files are not permitted')
 
 
-def git(target, *arguments):
+def git(target, *arguments, capture=False):
+    # Patch output is only needed for its exit status, and historical blobs are
+    # not guaranteed to be UTF-8. Decoding them would abort the scan on any
+    # repository that ever committed a non-UTF-8 file.
     try:
         return subprocess.run(['git', '-C', str(target), *arguments],
-                              capture_output=True, text=True, check=False)
+                              stdout=subprocess.PIPE if capture else subprocess.DEVNULL,
+                              stderr=subprocess.DEVNULL,
+                              text=True, encoding='utf-8', errors='replace', check=False)
     except OSError:
         raise RuntimeError('Git history is unreadable; scan blocked') from None
 
@@ -81,7 +86,7 @@ def verify_history(target):
     # Gitleaks can report success after its internal Git reader fails. Read the
     # complete patch history first, suppressing every source-controlled diagnostic.
     try:
-        root = git(target, 'rev-parse', '--show-toplevel')
+        root = git(target, 'rev-parse', '--show-toplevel', capture=True)
         if root.returncode or Path(root.stdout.strip()).resolve() != Path(target).resolve():
             raise RuntimeError('Git history is unreadable; scan blocked')
     except (OSError, ValueError):
diff --git a/pr-governance/scripts/test-runner.cjs b/pr-governance/scripts/test-runner.cjs
index 159cf26..2414e45 100644
--- a/pr-governance/scripts/test-runner.cjs
+++ b/pr-governance/scripts/test-runner.cjs
@@ -146,6 +146,25 @@ test('a comment on an issue that is not a pull request evaluates nothing', async
   assert.deepEqual(await runner.selectTargets(m.github, m.context, 'main'), [8]);
 });
 
+test('a review relay evaluates the pull requests named by the run', async () => {
+  const m = mock(fixture(), { eventName: 'workflow_run' });
+  m.context.payload = { workflow_run: { pull_requests: [{ number: 42 }, { number: 7 }, { number: 42 }] } };
+  assert.deepEqual(await runner.selectTargets(m.github, m.context, 'main'), [42, 7]);
+  m.context.payload = { workflow_run: { pull_requests: [{ number: 0 }, { number: 'x' }] } };
+  assert.deepEqual(await runner.selectTargets(m.github, m.context, 'main'), []);
+});
+
+test('a review relay without pull request entries falls back to the head branch', async () => {
+  const m = mock(fixture(), { eventName: 'workflow_run', open: [{ number: 42 }] });
+  m.context.payload = { workflow_run: { pull_requests: [], head_repository: { owner: { login: 'example-org' } }, head_branch: 'feature' } };
+  assert.deepEqual(await runner.selectTargets(m.github, m.context, 'main'), [42]);
+  assert.equal(m.calls.at(-1).params.head, 'example-org:feature');
+  m.context.payload = { workflow_run: { pull_requests: [], head_branch: 'feature' } };
+  assert.deepEqual(await runner.selectTargets(m.github, m.context, 'main'), []);
+  m.context.payload = {};
+  await assert.rejects(runner.selectTargets(m.github, m.context, 'main'), /workflow run payload/);
+});
+
 test('dispatch validates the number and the default branch', async () => {
   const m = mock(fixture(), { eventName: 'workflow_dispatch' });
   m.context.payload = { inputs: { pr_number: '42' } };
diff --git a/pr-governance/scripts/test_secret_scan.py b/pr-governance/scripts/test_secret_scan.py
index d7a9db4..c537cf5 100644
--- a/pr-governance/scripts/test_secret_scan.py
+++ b/pr-governance/scripts/test_secret_scan.py
@@ -123,6 +123,13 @@ def test_range_scan_empty_range_passes(self):
         base = self.suppression_repository()
         self.assertEqual(self.range_scan(base), 0)
 
+    def test_range_scan_survives_non_utf8_history(self):
+        base = self.suppression_repository()
+        (self.source / 'legacy.txt').write_bytes(b'\xd2\xbb\xb6\xce\xce\xc4\xb1\xbe\n')
+        self.git('add', '.')
+        self.git('commit', '--quiet', '-m', 'test: legacy encoding')
+        self.assertEqual(self.range_scan(base), 0)
+
     def test_range_scan_unknown_head_fails(self):
         base = self.suppression_repository()
         with self.assertRaises(RuntimeError):
diff --git a/pr-governance/templates/codex-nudge.yml b/pr-governance/templates/codex-nudge.yml
index 053ce61..352362a 100644
--- a/pr-governance/templates/codex-nudge.yml
+++ b/pr-governance/templates/codex-nudge.yml
@@ -25,6 +25,6 @@ jobs:
     timeout-minutes: 5
     steps:
       - name: Request
-        uses: __GOVERNANCE_REPO__/pr-governance@v1
+        uses: __GOVERNANCE_REPO__/pr-governance@__GOVERNANCE_SHA__
         with:
           mode: nudge
diff --git a/pr-governance/templates/gitleaks.yml b/pr-governance/templates/gitleaks.yml
index b1fa5a7..8e1706b 100644
--- a/pr-governance/templates/gitleaks.yml
+++ b/pr-governance/templates/gitleaks.yml
@@ -24,6 +24,6 @@ jobs:
           fetch-depth: 0
           persist-credentials: false
       - name: Scan added commits
-        uses: __GOVERNANCE_REPO__/pr-governance@v1
+        uses: __GOVERNANCE_REPO__/pr-governance@__GOVERNANCE_SHA__
         with:
           mode: scan
diff --git a/pr-governance/templates/pr-review-signal.yml b/pr-governance/templates/pr-review-signal.yml
new file mode 100644
index 0000000..0d9fc3b
--- /dev/null
+++ b/pr-governance/templates/pr-review-signal.yml
@@ -0,0 +1,25 @@
+name: PR review signal
+
+# Copy to .github/workflows/pr-review-signal.yml and replace nothing: this
+# workflow holds no permissions and runs no repository code. It exists because a
+# review event on a fork or Dependabot pull request gets a read-only token, so
+# the gate that publishes statuses has to be started by `workflow_run` instead.
+# Keep the workflow name; risk-gate.yml refers to it.
+
+on:
+  pull_request_review:
+    types: [submitted, edited, dismissed]
+  pull_request_review_comment:
+    types: [created, edited, deleted]
+
+permissions:
+  contents: read
+
+jobs:
+  signal:
+    name: Signal review change
+    runs-on: ubuntu-latest
+    timeout-minutes: 2
+    steps:
+      - name: Signal
+        run: echo "review event recorded"
diff --git a/pr-governance/templates/risk-gate.yml b/pr-governance/templates/risk-gate.yml
index 3585f67..7874788 100644
--- a/pr-governance/templates/risk-gate.yml
+++ b/pr-governance/templates/risk-gate.yml
@@ -9,10 +9,12 @@ on:
     types: [opened, reopened, synchronize, edited, labeled, unlabeled, ready_for_review, closed]
   issue_comment:
     types: [created, edited, deleted]
-  pull_request_review:
-    types: [submitted, edited, dismissed]
-  pull_request_review_comment:
-    types: [created, edited, deleted]
+  # A review or inline comment on a fork or Dependabot pull request gets a
+  # read-only token, so those events are relayed through the permissionless
+  # `PR review signal` workflow and evaluated by this trusted run.
+  workflow_run:
+    workflows: ["PR review signal"]
+    types: [completed]
   push:
     branches: [main, master]
   # A merge made with GITHUB_TOKEN raises no push, and nothing raises an event
@@ -49,7 +51,7 @@ jobs:
       statuses: write
     steps:
       - name: Record label head
-        uses: __GOVERNANCE_REPO__/pr-governance@v1
+        uses: __GOVERNANCE_REPO__/pr-governance@__GOVERNANCE_SHA__
         with:
           mode: gate
 
@@ -74,10 +76,10 @@ jobs:
     # Job-level, so an irrelevant comment skips the job without cancelling an
     # evaluation already running. Label evidence no longer rides on this run.
     concurrency:
-      group: pr-governance-${{ github.event.pull_request.number || github.event.issue.number || inputs.pr_number || github.run_id }}
+      group: pr-governance-${{ github.event.pull_request.number || github.event.issue.number || github.event.workflow_run.pull_requests[0].number || inputs.pr_number || github.run_id }}
       cancel-in-progress: true
     steps:
       - name: Evaluate
-        uses: __GOVERNANCE_REPO__/pr-governance@v1
+        uses: __GOVERNANCE_REPO__/pr-governance@__GOVERNANCE_SHA__
         with:
           mode: gate
diff --git a/pr-governance/templates/weekly-secret-scan.yml b/pr-governance/templates/weekly-secret-scan.yml
index 8fcd03a..339de27 100644
--- a/pr-governance/templates/weekly-secret-scan.yml
+++ b/pr-governance/templates/weekly-secret-scan.yml
@@ -30,7 +30,7 @@ jobs:
       - name: Fetch all remote branches
         run: git fetch origin '+refs/heads/*:refs/remotes/origin/*'
       - name: Scan history
-        uses: __GOVERNANCE_REPO__/pr-governance@v1
+        uses: __GOVERNANCE_REPO__/pr-governance@__GOVERNANCE_SHA__
         env:
           SECRET_SCAN_BASELINE_B64: ${{ secrets.SECRET_SCAN_BASELINE_B64 }}
         with: