diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fdac4226a..93cf05329 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,6 +10,8 @@ on:
     branches:
       - "*"
 
+permissions: {}
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
@@ -19,12 +21,14 @@ jobs:
     runs-on: blacksmith-2vcpu-ubuntu-2404
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
       - name: Install uv and set Python version
         uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8
         with:
           version: "0.11.2"
           python-version: "3.13"
-          enable-cache: true
+          enable-cache: true # zizmor: ignore[cache-poisoning] CI-only, no artifacts published
       - name: Install dependencies
         run: uv sync --locked
       - name: Run Ruff
@@ -34,13 +38,15 @@ jobs:
     runs-on: blacksmith-2vcpu-ubuntu-2404
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
       - name: Install uv and set Python version
         uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8
         with:
           version: "0.11.2"
           python-version: "3.13"
-          enable-cache: true
-      - uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5
+          enable-cache: true # zizmor: ignore[cache-poisoning] CI-only, no artifacts published
+      - uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4 # zizmor: ignore[cache-poisoning]
         name: Cache mypy cache
         with:
           path: ./.mypy_cache
@@ -73,12 +79,14 @@ jobs:
     name: Unit tests on Python ${{ matrix.python-version }}
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
       - name: Install uv and set Python version
         uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8
         with:
           version: "0.11.2"
           python-version: ${{ matrix.python-version }}
-          enable-cache: true
+          enable-cache: true # zizmor: ignore[cache-poisoning] CI-only, no artifacts published
 
       - name: Check Python version
         run: python --version
@@ -134,12 +142,14 @@ jobs:
     name: ${{ matrix.job_name }}
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
       - name: Install uv and set Python version
         uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8
         with:
           version: "0.11.2"
           python-version: "3.13"
-          enable-cache: true
+          enable-cache: true # zizmor: ignore[cache-poisoning] CI-only, no artifacts published
       - name: Install the project dependencies
         run: uv sync --locked
       - name: Check uv Python version
diff --git a/.github/workflows/claude-review-maintainer-prs.yml b/.github/workflows/claude-review-maintainer-prs.yml
index 1e1034106..3aa865bdd 100644
--- a/.github/workflows/claude-review-maintainer-prs.yml
+++ b/.github/workflows/claude-review-maintainer-prs.yml
@@ -1,14 +1,15 @@
 name: Claude Review on Maintainer PRs
 
 on:
-  pull_request_target:
+  pull_request:
     types:
       - opened
       - ready_for_review
 
 jobs:
   comment:
-    if: github.event.pull_request.draft == false
+    # Only run on PRs that are not drafts and are from the same repository (i.e., not from forks)
+    if: github.event.pull_request.draft == false && github.event.pull_request.head.repo.full_name == github.repository
     runs-on: ubuntu-latest
     permissions:
       issues: write
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 19d682989..1834f6f10 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -56,6 +56,8 @@ jobs:
     steps:
     - name: Checkout repository
       uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      with:
+        persist-credentials: false
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
diff --git a/.github/workflows/dependabot-merge.yml b/.github/workflows/dependabot-merge.yml
index 1a86ae8f8..aa321ee4d 100644
--- a/.github/workflows/dependabot-merge.yml
+++ b/.github/workflows/dependabot-merge.yml
@@ -11,7 +11,7 @@ permissions:
 jobs:
   dependabot:
     runs-on: ubuntu-latest
-    if: ${{ github.actor == 'dependabot[bot]' }}
+    if: github.event.pull_request.user.id == 49699333 # dependabot[bot]
     steps:
       - name: Dependabot metadata
         id: metadata
diff --git a/.github/workflows/dependabot-rebase-stale.yml b/.github/workflows/dependabot-rebase-stale.yml
index dcbe57211..534506864 100644
--- a/.github/workflows/dependabot-rebase-stale.yml
+++ b/.github/workflows/dependabot-rebase-stale.yml
@@ -6,6 +6,8 @@ on:
       - main
   workflow_dispatch:
 
+permissions: {}
+
 jobs:
   rebase-dependabot:
     runs-on: ubuntu-latest
diff --git a/.github/workflows/package-availability-check.yml b/.github/workflows/package-availability-check.yml
index e8074a9ba..3f43ddd21 100644
--- a/.github/workflows/package-availability-check.yml
+++ b/.github/workflows/package-availability-check.yml
@@ -5,6 +5,8 @@ on:
     - cron: "*/30 * * * *"
   workflow_dispatch:
 
+permissions: {}
+
 jobs:
   build:
     runs-on: ubuntu-latest
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index e24bd45a0..ced019620 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -47,32 +47,35 @@ jobs:
     steps:
       - name: Verify branch
         run: |
-          if [ "${{ github.ref }}" != "refs/heads/main" ]; then
+          if [ "${GITHUB_REF}" != "refs/heads/main" ]; then
             echo "❌ Error: Releases can only be triggered from main branch"
-            echo "Current ref: ${{ github.ref }}"
+            echo "Current ref: ${GITHUB_REF}"
             exit 1
           fi
 
       - name: Confirm major release
         if: ${{ inputs.version == 'major' || inputs.version == 'premajor' }}
         run: |
-          if [ "${{ inputs.confirm_major }}" != "RELEASE MAJOR" ]; then
+          if [ "${INPUTS_CONFIRM_MAJOR}" != "RELEASE MAJOR" ]; then
             echo "❌ For major/premajor releases, set confirm_major to RELEASE MAJOR"
             exit 1
           fi
+        env:
+          INPUTS_CONFIRM_MAJOR: ${{ inputs.confirm_major }}
 
       - name: Checkout repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           fetch-depth: 0
           token: ${{ secrets.GH_ACCESS_TOKEN }}
+          persist-credentials: false
 
       - name: Install uv and set Python version
         uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8
         with:
           version: "0.11.2"
           python-version: "3.12"
-          enable-cache: true
+          enable-cache: false
 
       - name: Configure Git
         env:
@@ -94,10 +97,10 @@ jobs:
       - name: Calculate new version
         id: new-version
         run: |
-          current_version="${{ steps.current-version.outputs.version }}"
-          version_type="${{ inputs.version }}"
-          prerelease_type="${{ inputs.prerelease_type }}"
-          prerelease_increment="${{ inputs.prerelease_increment }}"
+          current_version="${STEPS_CURRENT_VERSION_OUTPUTS_VERSION}"
+          version_type="${INPUTS_VERSION}"
+          prerelease_type="${INPUTS_PRERELEASE_TYPE}"
+          prerelease_increment="${INPUTS_PRERELEASE_INCREMENT}"
 
           # Extract base version (strip any pre-release suffix like a1, b2, rc1)
           base_version=$(echo "$current_version" | sed -E 's/(a|b|rc)[0-9]+$//')
@@ -195,18 +198,27 @@ jobs:
           echo "version=$new_version" >> $GITHUB_OUTPUT
           echo "is_prerelease=$is_prerelease" >> $GITHUB_OUTPUT
           echo "New version: $new_version (prerelease: $is_prerelease)"
+        env:
+          STEPS_CURRENT_VERSION_OUTPUTS_VERSION: ${{ steps.current-version.outputs.version }}
+          INPUTS_VERSION: ${{ inputs.version }}
+          INPUTS_PRERELEASE_TYPE: ${{ inputs.prerelease_type }}
+          INPUTS_PRERELEASE_INCREMENT: ${{ inputs.prerelease_increment }}
 
       - name: Check if tag already exists
         run: |
-          if git rev-parse "v${{ steps.new-version.outputs.version }}" >/dev/null 2>&1; then
-            echo "❌ Error: Tag v${{ steps.new-version.outputs.version }} already exists"
+          if git rev-parse "v${STEPS_NEW_VERSION_OUTPUTS_VERSION}" >/dev/null 2>&1; then
+            echo "❌ Error: Tag v${STEPS_NEW_VERSION_OUTPUTS_VERSION} already exists"
             exit 1
           fi
-          echo "✅ Tag v${{ steps.new-version.outputs.version }} does not exist"
+          echo "✅ Tag v${STEPS_NEW_VERSION_OUTPUTS_VERSION} does not exist"
+        env:
+          STEPS_NEW_VERSION_OUTPUTS_VERSION: ${{ steps.new-version.outputs.version }}
 
       - name: Update version in pyproject.toml
         run: |
-          uv version ${{ steps.new-version.outputs.version }}
+          uv version ${STEPS_NEW_VERSION_OUTPUTS_VERSION}
+        env:
+          STEPS_NEW_VERSION_OUTPUTS_VERSION: ${{ steps.new-version.outputs.version }}
 
       - name: Verify version consistency
         run: |
@@ -214,12 +226,14 @@ jobs:
 
           echo "pyproject.toml version: $pyproject_version"
 
-          if [ "$pyproject_version" != "${{ steps.new-version.outputs.version }}" ]; then
+          if [ "$pyproject_version" != "${STEPS_NEW_VERSION_OUTPUTS_VERSION}" ]; then
             echo "❌ Error: Version in files doesn't match expected version"
             exit 1
           fi
 
           echo "✅ Versions are consistent: $pyproject_version"
+        env:
+          STEPS_NEW_VERSION_OUTPUTS_VERSION: ${{ steps.new-version.outputs.version }}
 
       - name: Build package
         run: uv build --no-sources
@@ -250,7 +264,7 @@ jobs:
           ls -lh dist/
 
           # Verify the version in the built artifacts matches
-          expected_version="${{ steps.new-version.outputs.version }}"
+          expected_version="${STEPS_NEW_VERSION_OUTPUTS_VERSION}"
           wheel_file=$(ls dist/*.whl | head -1)
           if ! echo "$wheel_file" | grep -q "$expected_version"; then
             echo "❌ Error: Wheel filename doesn't contain expected version $expected_version"
@@ -258,6 +272,8 @@ jobs:
             exit 1
           fi
           echo "✅ Artifact version verified"
+        env:
+          STEPS_NEW_VERSION_OUTPUTS_VERSION: ${{ steps.new-version.outputs.version }}
 
       - name: Smoke test wheel
         run: |
@@ -270,32 +286,38 @@ jobs:
       - name: Commit version changes
         run: |
           git add pyproject.toml uv.lock
-          git commit -m "chore: release v${{ steps.new-version.outputs.version }}"
+          git commit -m "chore: release v${STEPS_NEW_VERSION_OUTPUTS_VERSION}"
+        env:
+          STEPS_NEW_VERSION_OUTPUTS_VERSION: ${{ steps.new-version.outputs.version }}
 
       - name: Create and push tag
         id: push-tag
         run: |
-          git tag "v${{ steps.new-version.outputs.version }}"
+          git tag "v${STEPS_NEW_VERSION_OUTPUTS_VERSION}"
           git push origin main
-          git push origin "v${{ steps.new-version.outputs.version }}"
+          git push origin "v${STEPS_NEW_VERSION_OUTPUTS_VERSION}"
+        env:
+          STEPS_NEW_VERSION_OUTPUTS_VERSION: ${{ steps.new-version.outputs.version }}
 
       - name: Publish to PyPI
         id: publish-pypi
         run: uv publish --trusted-publishing always
 
       - name: Create GitHub Release
-        id: create-release
-        uses: softprops/action-gh-release@153bb8e04406b158c6c84fc1615b65b24149a1fe # v2
-        with:
-          tag_name: v${{ steps.new-version.outputs.version }}
-          name: v${{ steps.new-version.outputs.version }}
-          generate_release_notes: true
-          prerelease: ${{ steps.new-version.outputs.is_prerelease == 'true' }}
-          files: |
-            dist/*.whl
-            dist/*.tar.gz
+        run: |
+          prerelease_flag=""
+          if [ "${IS_PRERELEASE}" = "true" ]; then
+            prerelease_flag="--prerelease"
+          fi
+          gh release create "v${VERSION}" \
+            --title "v${VERSION}" \
+            --generate-notes \
+            $prerelease_flag \
+            dist/*.whl dist/*.tar.gz
         env:
-          GITHUB_TOKEN: ${{ secrets.GH_ACCESS_TOKEN }}
+          GH_TOKEN: ${{ secrets.GH_ACCESS_TOKEN }}
+          VERSION: ${{ steps.new-version.outputs.version }}
+          IS_PRERELEASE: ${{ steps.new-version.outputs.is_prerelease }}
 
       - name: Notify Slack on success
         if: success()
diff --git a/.github/workflows/zizmor.yml b/.github/workflows/zizmor.yml
new file mode 100644
index 000000000..c706f5c43
--- /dev/null
+++ b/.github/workflows/zizmor.yml
@@ -0,0 +1,32 @@
+---
+name: Check GitHub Actions
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - "main"
+  merge_group:
+  pull_request:
+    branches:
+      - "main"
+
+permissions: {}
+
+jobs:
+  zizmor:
+    name: Check GitHub Actions security
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
+      - name: Run zizmor
+        uses: zizmorcore/zizmor-action@b1d7e1fb5de872772f31590499237e7cce841e8e # v0.5.3
+        with:
+          advanced-security: true