diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
new file mode 100644
index 0000000..ac48398
--- /dev/null
+++ b/.github/CODEOWNERS
@@ -0,0 +1,4 @@
+# Require explicit review for workflow and GitHub automation changes.
+.github/CODEOWNERS @intertwine
+.github/workflows/** @intertwine
+.github/actions/** @intertwine
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6ee51d4..b519b2d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,6 +7,9 @@ on:
     branches: [main]
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   test:
     runs-on: ubuntu-latest
@@ -16,15 +19,15 @@ jobs:
       fail-fast: false
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
           python-version: ${{ matrix.python-version }}
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v8.0.0
+        uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
 
       - name: Install dependencies
         run: uv sync
diff --git a/.github/workflows/claude-code-review.yml b/.github/workflows/claude-code-review.yml
index 71bea42..2c41fcc 100644
--- a/.github/workflows/claude-code-review.yml
+++ b/.github/workflows/claude-code-review.yml
@@ -10,6 +10,9 @@ on:
     #   - "src/**/*.js"
     #   - "src/**/*.jsx"
 
+permissions:
+  contents: read
+
 jobs:
   claude-review:
     # Optional: Filter by PR author
@@ -29,13 +32,28 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
-          fetch-depth: 1
+          fetch-depth: 0
+
+      - name: Skip when the review workflow itself changes
+        id: workflow-change
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        run: |
+          set -euo pipefail
+          if git diff --name-only "${BASE_SHA}...${HEAD_SHA}" | grep -Fxq ".github/workflows/claude-code-review.yml"; then
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+            echo "Skipping Claude review because this pull request updates the review workflow itself."
+          else
+            echo "skip=false" >> "$GITHUB_OUTPUT"
+          fi
 
       - name: Run Claude Code Review
         id: claude-review
-        uses: anthropics/claude-code-action@v1
+        if: steps.workflow-change.outputs.skip != 'true'
+        uses: anthropics/claude-code-action@c7c8889b30499b4e46f4c32b892e43cd364bc2fe # v1
         with:
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
           plugin_marketplaces: 'https://github.com/anthropics/claude-code.git'
diff --git a/.github/workflows/claude.yml b/.github/workflows/claude.yml
index 9370e4f..7b80cdc 100644
--- a/.github/workflows/claude.yml
+++ b/.github/workflows/claude.yml
@@ -28,13 +28,13 @@ jobs:
       actions: read # Required for Claude to read CI results on PRs
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           fetch-depth: 1
 
       - name: Run Claude Code
         id: claude
-        uses: anthropics/claude-code-action@v1
+        uses: anthropics/claude-code-action@c7c8889b30499b4e46f4c32b892e43cd364bc2fe # v1
         with:
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
 
diff --git a/.github/workflows/dependency-review.yml b/.github/workflows/dependency-review.yml
new file mode 100644
index 0000000..4198a71
--- /dev/null
+++ b/.github/workflows/dependency-review.yml
@@ -0,0 +1,23 @@
+name: Dependency Review
+
+on:
+  pull_request:
+    branches: [main]
+    paths:
+      - "pyproject.toml"
+      - "uv.lock"
+      - "poetry.lock"
+      - "requirements*.txt"
+      - ".github/workflows/**" # GitHub tracks Actions in the dependency graph.
+
+permissions:
+  contents: read
+  pull-requests: read
+
+jobs:
+  dependency-review:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Dependency Review
+        uses: actions/dependency-review-action@2031cfc080254a8a887f58cffee85186f0e49e48 # v4.9.0
diff --git a/.github/workflows/homebrew-release.yml b/.github/workflows/homebrew-release.yml
index 7070cfd..5f94a05 100644
--- a/.github/workflows/homebrew-release.yml
+++ b/.github/workflows/homebrew-release.yml
@@ -6,21 +6,24 @@ on:
       - "v*"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   update-tap:
     runs-on: ubuntu-latest
 
     steps:
       - name: Checkout source repo
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
           python-version: "3.13"
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v8.0.0
+        uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
 
       - name: Check formula name availability in Homebrew/core
         run: |
@@ -71,7 +74,7 @@ jobs:
         run: uv run --with pip python scripts/generate_homebrew_formula.py --output packaging/homebrew/observational-memory.rb
 
       - name: Checkout tap repo
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           repository: ${{ vars.HOMEBREW_TAP_REPO }}
           token: ${{ secrets.HOMEBREW_TAP_GITHUB_TOKEN }}