diff --git a/.github/workflows/hide-codex-limit-comments.yml b/.github/workflows/hide-codex-limit-comments.yml
index ed525b7..2bbd050 100644
--- a/.github/workflows/hide-codex-limit-comments.yml
+++ b/.github/workflows/hide-codex-limit-comments.yml
@@ -23,7 +23,7 @@ jobs:
       pull-requests: write
     steps:
       - name: Minimize comment
-        uses: actions/github-script@v8
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         with:
           script: |
             const mutation = `
diff --git a/.github/workflows/monthly_snapshot_audit.yml b/.github/workflows/monthly_snapshot_audit.yml
index 2317dc0..e623435 100644
--- a/.github/workflows/monthly_snapshot_audit.yml
+++ b/.github/workflows/monthly_snapshot_audit.yml
@@ -31,11 +31,11 @@ jobs:
     steps:
       - name: Checkout
         if: env.MONTHLY_SNAPSHOT_AUDIT_ENABLED != 'false'
-        uses: actions/checkout@v6
+        uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6
 
       - name: Set Up Python
         if: env.MONTHLY_SNAPSHOT_AUDIT_ENABLED != 'false'
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
         with:
           python-version: "3.11"
 
@@ -72,7 +72,7 @@ jobs:
 
       - name: Upload Monthly Snapshot Audit Artifact
         if: env.MONTHLY_SNAPSHOT_AUDIT_ENABLED != 'false'
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: ${{ steps.monthly_audit.outputs.artifact_name }}
           path: data/output/monthly_snapshot_audit
@@ -168,7 +168,7 @@ jobs:
         id: codex_review_app_token
         if: steps.codex_review_app_credentials.outputs.available == 'true'
         continue-on-error: true
-        uses: actions/create-github-app-token@v3
+        uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1 # v3
         with:
           app-id: ${{ vars.CROSS_REPO_GITHUB_APP_ID }}
           private-key: ${{ secrets.CROSS_REPO_GITHUB_APP_PRIVATE_KEY }}
diff --git a/tests/test_monthly_snapshot_audit_workflow.py b/tests/test_monthly_snapshot_audit_workflow.py
index c8e3fc9..6c97e64 100644
--- a/tests/test_monthly_snapshot_audit_workflow.py
+++ b/tests/test_monthly_snapshot_audit_workflow.py
@@ -13,10 +13,10 @@ def test_monthly_snapshot_audit_workflow_dispatches_codex_bridge():
     assert "actions: write" in workflow
     assert "contents: read" in workflow
     assert "issues: write" in workflow
-    assert "actions/checkout@v6" in workflow
-    assert "actions/setup-python@v6" in workflow
-    assert "actions/upload-artifact@v7" in workflow
-    assert "actions/create-github-app-token@v3" in workflow
+    assert "actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6" in workflow
+    assert "actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6" in workflow
+    assert "actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7" in workflow
+    assert "actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1 # v3" in workflow
     assert "write_monthly_snapshot_audit_issue.py" in workflow
     assert "monthly_snapshot_audit_issue.json" in workflow
     assert "QuantStrategyLab/AIAuditBridge" in workflow
diff --git a/tests/test_privileged_workflow_action_pins.py b/tests/test_privileged_workflow_action_pins.py
new file mode 100644
index 0000000..583884e
--- /dev/null
+++ b/tests/test_privileged_workflow_action_pins.py
@@ -0,0 +1,18 @@
+from pathlib import Path
+import re
+
+
+WORKFLOWS = (
+    Path(".github/workflows/monthly_snapshot_audit.yml"),
+    Path(".github/workflows/hide-codex-limit-comments.yml"),
+)
+FULL_SHA_ACTION = re.compile(r"uses:\s+[^\s@]+@[0-9a-f]{40}(?:\s+#\s+v\d+)?$")
+
+
+def test_privileged_workflows_pin_remote_actions_to_full_commit_shas():
+    for path in WORKFLOWS:
+        workflow = path.read_text(encoding="utf-8")
+        action_lines = [line.strip() for line in workflow.splitlines() if "uses:" in line]
+
+        assert action_lines
+        assert all(FULL_SHA_ACTION.fullmatch(line) for line in action_lines)