diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..3ec60ef
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,23 @@
+# Keep the SHA-pinned GitHub Actions current. Dependabot bumps the commit pin AND the trailing
+# "# vX.Y.Z" comment together, and opens PRs for any security advisories affecting an action we use.
+#
+# Scope is github-actions ONLY (#11): this repo is a static Hugo site with no app dependencies —
+# no package.json, go.mod, pip, or docker to track. Hugo itself is installed by version-pinned
+# `wget` of a release .deb in the workflows (HUGO_VERSION), which Dependabot cannot see, so Hugo
+# bumps stay manual (see #15).
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/" # github-actions ecosystem watches .github/workflows/
+    schedule:
+      interval: "weekly"
+    commit-message:
+      prefix: "ci" # -> "ci(deps): bump actions/checkout ..."
+      include: "scope"
+    labels:
+      - "infra"
+    groups:
+      # One rollup PR for all action bumps rather than one-per-action — low-noise for a repo this small.
+      github-actions:
+        patterns:
+          - "*"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a64f722..3483934 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,9 +25,10 @@ jobs:
       HTMLTEST_VERSION: "0.17.0"
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           fetch-depth: 0
+          persist-credentials: false   # zizmor: artipacked
 
       - name: Install Hugo (extended)
         run: |
diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index 325acad..6c6a9aa 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -9,10 +9,10 @@ on:
     - cron: "17 6 * * *"
   workflow_dispatch:
 
+# Least-privilege floor: the build job only reads the tree. Only the deploy job
+# needs pages:write + id-token:write, scoped to it below. (zizmor: excessive-permissions)
 permissions:
   contents: read
-  pages: write
-  id-token: write
 
 # Allow one concurrent deployment; don't cancel an in-progress production deploy.
 concurrency:
@@ -35,13 +35,14 @@ jobs:
             https://github.com/gohugoio/hugo/releases/download/v${HUGO_VERSION}/hugo_extended_${HUGO_VERSION}_linux-amd64.deb \
           && sudo dpkg -i ${{ runner.temp }}/hugo.deb
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           submodules: recursive
           fetch-depth: 0
+          persist-credentials: false   # zizmor: artipacked
       - name: Setup Pages
         id: pages
-        uses: actions/configure-pages@v6
+        uses: actions/configure-pages@45bfe0192ca1faeb007ade9deae92b16b8254a0d # v6.0.0
         with:
           enablement: true
       - name: Refresh release versions (best-effort)
@@ -52,13 +53,16 @@ jobs:
         env:
           HUGO_ENVIRONMENT: production
           TZ: UTC
+          # Pass the Pages URL through env rather than expanding it inline in the
+          # script (avoids template-injection; zizmor: template-injection).
+          BASE_URL: ${{ steps.pages.outputs.base_url }}
         run: |
           hugo \
             --gc \
             --minify \
-            --baseURL "${{ steps.pages.outputs.base_url }}/"
+            --baseURL "${BASE_URL}/"
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v5
+        uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0
         with:
           path: ./public
 
@@ -68,7 +72,11 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     runs-on: ubuntu-latest
     needs: build
+    # Only this job touches Pages — grant the write scopes here, not repo-wide.
+    permissions:
+      pages: write
+      id-token: write
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v5
+        uses: actions/deploy-pages@cd2ce8fcbc39b97be8ca5fce6e763baed58fa128 # v5.0.0
diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
new file mode 100644
index 0000000..4a000de
--- /dev/null
+++ b/.github/workflows/security.yml
@@ -0,0 +1,75 @@
+name: Security
+
+# Supply-chain & secrets gates (#11):
+#   - gitleaks: scan the full git history for committed secrets (tokens, credentials) on every
+#     push and PR.
+#   - zizmor: static-audit the GitHub Actions workflows themselves (template injection, over-broad
+#     GITHUB_TOKEN, unpinned actions, credential persistence) AND cross-reference the actions we
+#     pin against the GitHub Advisory Database (online audit).
+# Dependabot (github-actions) lives in .github/dependabot.yml; the matching gitleaks pre-commit
+# hook lives in .pre-commit-config.yaml.
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  # Re-audit on a schedule so a newly-published advisory against an action we pin trips the gate
+  # even during quiet periods with no pushes — the online zizmor audit is time-varying by design.
+  schedule:
+    - cron: "0 7 * * 1" # Mondays 07:00 UTC
+
+# Both jobs only read the tree to scan it. Pin the floor to read-only (zizmor: excessive-permissions).
+permissions:
+  contents: read
+
+jobs:
+  gitleaks:
+    name: Secret scan (gitleaks)
+    runs-on: ubuntu-24.04
+    # The weekly tick exists for zizmor's advisory re-audit; history doesn't change between pushes,
+    # so there's nothing new for gitleaks to scan on a schedule.
+    if: github.event_name != 'schedule'
+    env:
+      # Pinned + checksum-verified — reproducible and immune to runner-image drift. Keep
+      # GITLEAKS_VERSION in lockstep with .pre-commit-config.yaml.
+      GITLEAKS_VERSION: "8.30.1"
+      GITLEAKS_SHA256: "551f6fc83ea457d62a0d98237cbad105af8d557003051f41f3e7ca7b3f2470eb"
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          fetch-depth: 0 # scan EVERY commit, not just the tip — a secret is still a leak once pushed
+          persist-credentials: false # zizmor: artipacked
+      - name: Install pinned gitleaks
+        run: |
+          set -euo pipefail
+          tarball="gitleaks_${GITLEAKS_VERSION}_linux_x64.tar.gz"
+          curl -fsSL "https://github.com/gitleaks/gitleaks/releases/download/v${GITLEAKS_VERSION}/${tarball}" -o "$tarball"
+          echo "${GITLEAKS_SHA256}  ${tarball}" | sha256sum -c -
+          tar -xzf "$tarball" gitleaks
+          sudo install gitleaks /usr/local/bin/gitleaks
+          gitleaks version
+      # Full-history scan with the built-in ruleset. --redact keeps any match out of the public logs;
+      # the job still fails (non-zero exit) so a leak blocks the merge.
+      - name: Scan git history for secrets
+        run: gitleaks git . --redact --no-banner --verbose
+
+  zizmor:
+    name: Workflow audit (zizmor)
+    runs-on: ubuntu-24.04
+    env:
+      ZIZMOR_VERSION: "1.25.2"
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          persist-credentials: false # zizmor: artipacked
+      # pipx is preinstalled on ubuntu-24.04.
+      - name: Install pinned zizmor
+        run: pipx install "zizmor==${ZIZMOR_VERSION}"
+      # Online audits ON (zizmor's default): GH_TOKEN lets the `known-vulnerable-actions` audit query
+      # the GitHub Advisory Database, so a CVE disclosed against an action we pin fails the gate. The
+      # built-in token (read-only here) is enough — advisory data is public; it's only for API access.
+      # This complements Dependabot: zizmor blocks the merge, Dependabot opens the bump.
+      - name: Audit GitHub Actions workflows
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: zizmor .github/workflows/
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..542e6fb
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,12 @@
+# Pre-commit hooks for the site. Install once per clone:
+#
+#   pipx install pre-commit   # or: pip install pre-commit
+#   pre-commit install
+#
+# Scope here is the secret-scanning gate from #11: gitleaks, pinned to the SAME version CI runs
+# (.github/workflows/security.yml) so a leak is caught locally before it's ever pushed.
+repos:
+  - repo: https://github.com/gitleaks/gitleaks
+    rev: v8.30.1 # keep in lockstep with GITLEAKS_VERSION in .github/workflows/security.yml
+    hooks:
+      - id: gitleaks
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 6c09f05..e38d4df 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -34,6 +34,17 @@ not in the templates. See the [README](README.md#where-the-content-lives) for th
    ```
 4. Update the README or other docs for any user-facing change.
 
+## Secret scanning
+
+CI runs [gitleaks](https://github.com/gitleaks/gitleaks) over the full history on every push and PR,
+so an accidentally committed token or credential blocks the merge. Catch it locally first by
+installing the pre-commit hook (it runs the same pinned gitleaks on staged changes):
+
+```bash
+pipx install pre-commit   # or: pip install pre-commit
+pre-commit install
+```
+
 ## Opening a pull request
 
 - Target the `main` branch and fill out the PR template.