diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 19bd1ee..dacd662 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,7 +8,7 @@
 #   - test: Run test suites (Haskell, OCaml)
 #   - build: Verify everything compiles
 #
-# All jobs use actions/checkout@v6 (current stable version as of 2024)
+# All jobs use actions/checkout@v6.0.1 (current stable version as of 2024)
 # =============================================================================
 
 name: CI
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.1
 
       - name: Setup Deno
         uses: denoland/setup-deno@v2
@@ -69,7 +69,7 @@ jobs:
         working-directory: TOOLS/validation/haskell
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.1
 
       - name: Setup Haskell
         uses: haskell-actions/setup@v2
@@ -102,7 +102,7 @@ jobs:
         working-directory: ocaml
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.1
 
       - name: Setup OCaml
         uses: ocaml/setup-ocaml@v3
@@ -130,7 +130,7 @@ jobs:
     needs: [lint]  # Run after lint passes
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.1
 
       - name: Setup Node.js (for SCSS)
         uses: actions/setup-node@v6
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 7d8eba7..585d209 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -26,15 +26,15 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
 
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@662472033e021d55d94146f66f6058822b0b39fd # v3.28.1
+        uses: github/codeql-action/init@1b168cd39490f61582a9beae412bb7057a6b2c4e # v3.28.1
         with:
           languages: ${{ matrix.language }}
           build-mode: ${{ matrix.build-mode }}
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@662472033e021d55d94146f66f6058822b0b39fd # v3.28.1
+        uses: github/codeql-action/analyze@1b168cd39490f61582a9beae412bb7057a6b2c4e # v3.28.1
         with:
           category: "/language:${{ matrix.language }}"
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index dff691a..72c595b 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -42,7 +42,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.1
 
       - name: Setup Pages
         uses: actions/configure-pages@v5
diff --git a/.github/workflows/guix-nix-policy.yml b/.github/workflows/guix-nix-policy.yml
index 6771253..b2d87cb 100644
--- a/.github/workflows/guix-nix-policy.yml
+++ b/.github/workflows/guix-nix-policy.yml
@@ -4,7 +4,7 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       - name: Enforce Guix primary / Nix fallback
         run: |
           # Check for package manager files
diff --git a/.github/workflows/language-policy.yml b/.github/workflows/language-policy.yml
index f99823b..b4ace90 100644
--- a/.github/workflows/language-policy.yml
+++ b/.github/workflows/language-policy.yml
@@ -4,7 +4,7 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       - name: Enforce language policies
         run: |
           # Block new Python files (except SaltStack)
diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index c1a7b7a..56d5585 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -5,7 +5,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       
       - name: Check file permissions
         run: |
@@ -35,7 +35,7 @@ jobs:
   docs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       - name: Check documentation
         run: |
           MISSING=""
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 3f2f928..37e919e 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.1
         with:
           fetch-depth: 0  # Full history for changelog generation
 
diff --git a/.github/workflows/rescript-deno-ci.yml b/.github/workflows/rescript-deno-ci.yml
index b83048a..2ab2b1d 100644
--- a/.github/workflows/rescript-deno-ci.yml
+++ b/.github/workflows/rescript-deno-ci.yml
@@ -5,7 +5,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       - uses: denoland/setup-deno@v2
         with:
           deno-version: v1.x
@@ -32,7 +32,7 @@ jobs:
   security:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       - uses: denoland/setup-deno@v2
       - name: Check permissions
         run: |
diff --git a/.github/workflows/rsr-antipattern.yml b/.github/workflows/rsr-antipattern.yml
index e6ce6a0..964c51c 100644
--- a/.github/workflows/rsr-antipattern.yml
+++ b/.github/workflows/rsr-antipattern.yml
@@ -16,7 +16,7 @@ jobs:
   antipattern-check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
 
       - name: Check for TypeScript
         run: |
diff --git a/.github/workflows/scorecard.yml b/.github/workflows/scorecard.yml
index c1071e6..69a6b31 100644
--- a/.github/workflows/scorecard.yml
+++ b/.github/workflows/scorecard.yml
@@ -14,7 +14,7 @@ jobs:
       security-events: write
       id-token: write
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
         with:
           persist-credentials: false
       
@@ -25,6 +25,6 @@ jobs:
           results_format: sarif
       
       - name: Upload results
-        uses: github/codeql-action/upload-sarif@v4
+        uses: github/codeql-action/upload-sarif@v4.31.8
         with:
           sarif_file: results.sarif
diff --git a/.github/workflows/security-policy.yml b/.github/workflows/security-policy.yml
index 96d0562..10be49a 100644
--- a/.github/workflows/security-policy.yml
+++ b/.github/workflows/security-policy.yml
@@ -4,7 +4,7 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       - name: Security checks
         run: |
           FAILED=false
diff --git a/.github/workflows/wellknown-enforcement.yml b/.github/workflows/wellknown-enforcement.yml
index 2108364..af2216d 100644
--- a/.github/workflows/wellknown-enforcement.yml
+++ b/.github/workflows/wellknown-enforcement.yml
@@ -17,7 +17,7 @@ jobs:
   validate:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.1
       
       - name: RFC 9116 security.txt validation
         run: |
diff --git a/.github/workflows/workflow-linter.yml b/.github/workflows/workflow-linter.yml
index f2beab8..040d798 100644
--- a/.github/workflows/workflow-linter.yml
+++ b/.github/workflows/workflow-linter.yml
@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
 
       - name: Check SPDX Headers
         run: |
@@ -72,7 +72,7 @@ jobs:
             echo "$unpinned"
             echo ""
             echo "Replace version tags with SHA pins, e.g.:"
-            echo "  uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1"
+            echo "  uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v4.1.1"
             exit 1
           fi
           echo "All actions are SHA-pinned"