diff --git a/.github/workflows/bundle-push.yml b/.github/workflows/bundle-push.yml
index 82160f4..59daf17 100644
--- a/.github/workflows/bundle-push.yml
+++ b/.github/workflows/bundle-push.yml
@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Lean
         run: |
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2def4d8..83b91e4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Setup Lean toolchain
         run: |
           wget https://github.com/leanprover/lean4/releases/download/v4.7.0/lean-4.7.0-linux.tar.gz
@@ -35,7 +35,7 @@ jobs:
     needs: verify
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Setup Lean toolchain
         run: |
           wget https://github.com/leanprover/lean4/releases/download/v4.7.0/lean-4.7.0-linux.tar.gz
@@ -50,6 +50,6 @@ jobs:
     if: github.event_name == 'pull_request'
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Dependency review
         uses: actions/dependency-review-action@v4
diff --git a/.github/workflows/policy-lint.yml b/.github/workflows/policy-lint.yml
index 3bd3b17..9aa8cc7 100644
--- a/.github/workflows/policy-lint.yml
+++ b/.github/workflows/policy-lint.yml
@@ -6,7 +6,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions/setup-python@v5
         with:
           python-version: "3.11"
diff --git a/.github/workflows/repo-hygiene.yml b/.github/workflows/repo-hygiene.yml
index fd48095..fb42ac5 100644
--- a/.github/workflows/repo-hygiene.yml
+++ b/.github/workflows/repo-hygiene.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Markdown lint
         uses: DavidAnson/markdownlint-cli2-action@v18
@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Run gitleaks
         uses: gitleaks/gitleaks-action@v2
diff --git a/.github/workflows/slo-gate.yml b/.github/workflows/slo-gate.yml
index 6e0a618..476c8db 100644
--- a/.github/workflows/slo-gate.yml
+++ b/.github/workflows/slo-gate.yml
@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Setup Lean toolchain
         run: |
           wget https://github.com/leanprover/lean4/releases/download/v4.7.0/lean-4.7.0-linux.tar.gz