diff --git a/.github/actions/post-coverage-comment/action.yml b/.github/actions/post-coverage-comment/action.yml
index 0f3a862ac..7fe2a8e15 100644
--- a/.github/actions/post-coverage-comment/action.yml
+++ b/.github/actions/post-coverage-comment/action.yml
@@ -31,7 +31,7 @@ runs:
   using: composite
   steps:
     - name: Post coverage comment
-      uses: marocchino/sticky-pull-request-comment@v2
+      uses: marocchino/sticky-pull-request-comment@773744901bac0e8cbb5a0dc842800d45e9b2b405 # v2.9.4
       with:
         header: Code Coverage Report
         number: ${{ inputs.pr_number }}
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 000000000..2c48305b7
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    groups:
+      github-actions:
+        patterns: ["*"]
+    schedule:
+      interval: "weekly"
+    cooldown:
+      default-days: 7
diff --git a/.github/workflows/devskim.yml b/.github/workflows/devskim.yml
index 2ae1a3746..c82bab74c 100644
--- a/.github/workflows/devskim.yml
+++ b/.github/workflows/devskim.yml
@@ -26,18 +26,18 @@ jobs:
       security-events: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
         with:
           persist-credentials: false
 
       - name: Run DevSkim scanner
-        uses: microsoft/DevSkim-Action@v1
+        uses: microsoft/DevSkim-Action@4b5047945a44163b94642a1cecc0d93a3f428cc6 # v1.0.16
         with:
           ignore_globs: "tests/**,**/test_*.py,benchmarks/**"
           # DS176209: TODO comments — not a security concern
           ignore_rules_list: "DS176209"
 
       - name: Upload DevSkim scan results to GitHub Security tab
-        uses: github/codeql-action/upload-sarif@v3
+        uses: github/codeql-action/upload-sarif@c4dd10e44af883a891fe31ced449bcb4a6728b9b # v3.37.6
         with:
           sarif_file: devskim-results.sarif
diff --git a/.github/workflows/forked-pr-coverage.yml b/.github/workflows/forked-pr-coverage.yml
index 6ff9a326c..e597f788f 100644
--- a/.github/workflows/forked-pr-coverage.yml
+++ b/.github/workflows/forked-pr-coverage.yml
@@ -37,7 +37,7 @@ jobs:
     
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
         with:
           persist-credentials: false
 
diff --git a/.github/workflows/issue-acknowledge.yml b/.github/workflows/issue-acknowledge.yml
index 05514dac0..937b65f25 100644
--- a/.github/workflows/issue-acknowledge.yml
+++ b/.github/workflows/issue-acknowledge.yml
@@ -20,7 +20,7 @@ jobs:
       # Step 2: Check if a maintainer already responded
       - name: Check for existing maintainer response
         id: check
-        uses: actions/github-script@v7
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |
@@ -42,7 +42,7 @@ jobs:
       # Step 3: Post acknowledgement ONLY if no maintainer has responded
       - name: Post acknowledgement comment
         if: steps.check.outputs.skip == 'false'
-        uses: actions/github-script@v7
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |
@@ -56,7 +56,7 @@ jobs:
       # Step 4: Add "triage needed" label if no maintainer has responded
       - name: Add triage needed label
         if: steps.check.outputs.skip == 'false'
-        uses: actions/github-script@v7
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |
diff --git a/.github/workflows/issue-triage.yml b/.github/workflows/issue-triage.yml
index e94b4b779..c4556061e 100644
--- a/.github/workflows/issue-triage.yml
+++ b/.github/workflows/issue-triage.yml
@@ -25,7 +25,7 @@ jobs:
 
       - name: Triage Analysis
         id: triage
-        uses: actions/github-script@v7
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
diff --git a/.github/workflows/lint-check.yml b/.github/workflows/lint-check.yml
index 35e36f7b2..224fea494 100644
--- a/.github/workflows/lint-check.yml
+++ b/.github/workflows/lint-check.yml
@@ -28,12 +28,12 @@ jobs:
     
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4
+      uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
       with:
         persist-credentials: false
       
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
       with:
         python-version: '3.13'
         cache: 'pip'
@@ -86,12 +86,12 @@ jobs:
     
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4
+      uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
       with:
         persist-credentials: false
       
     - name: Set up Python (for cpplint)
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
       with:
         python-version: '3.13'
         
diff --git a/.github/workflows/pr-code-coverage.yml b/.github/workflows/pr-code-coverage.yml
index 337615d46..2e2bf3424 100644
--- a/.github/workflows/pr-code-coverage.yml
+++ b/.github/workflows/pr-code-coverage.yml
@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
         with:
           fetch-depth: 0
           persist-credentials: false
@@ -458,7 +458,7 @@ jobs:
         # Only upload artifact for forked PRs since same-repo PRs post comment directly
         # This prevents unnecessary workflow_run triggers for same-repo PRs
         if: github.event.pull_request.head.repo.full_name != github.repository
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: coverage-comment-data
           path: coverage-comment-data/
diff --git a/.github/workflows/pr-format-check.yml b/.github/workflows/pr-format-check.yml
index 0d1772c3c..371d60063 100644
--- a/.github/workflows/pr-format-check.yml
+++ b/.github/workflows/pr-format-check.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Validate PR title and description content
-        uses: actions/github-script@v7
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
         with:
           script: |
             const title = context.payload.pull_request.title;
@@ -73,7 +73,7 @@ jobs:
             }
       - name: Add size label based on PR diff
         if: github.event.pull_request.head.repo.full_name == github.repository
-        uses: actions/github-script@v7
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
         with:
           script: |
             const pr = context.payload.pull_request;