ci: Add actionlint and zizmor workflow linting

.github/dependabot.yml

@@ -10,6 +10,8 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     open-pull-requests-limit: 10
     groups:
       # Maven build and reporting plugins
@@ -28,15 +30,19 @@ updates:
 
   # -----------------------------------------------------------------------
   # GitHub Actions — daily, all actions grouped into one PR.
-  # (Kept daily so security-relevant action pins are updated quickly.)
+  # Checked daily so security-relevant action pins are picked up quickly;
+  # a short 3-day cooldown still lets an obviously-bad release be pulled.
   # The second directory covers the composite action's setup-java pin.
   # -----------------------------------------------------------------------
+  # zizmor: ignore[dependabot-cooldown]  # 3 days is a deliberate tradeoff for actions
   - package-ecosystem: "github-actions"
     directories:
       - "/"
       - "/.github/actions/jdk-setup"
     schedule:
       interval: "daily"
+    cooldown:
+      default-days: 3
     open-pull-requests-limit: 10
     groups:
       actions-updates:                 # Group all action updates into one PR

.github/workflows/build-any-branch.yml

@@ -14,8 +14,7 @@ on:
       - "**/*.adoc"
       - "**/*.md"
 
-permissions:
-  contents: write # needed as the default GITHUB_TOKEN is read-only and submission 403s without it
+permissions: {}
 
 env:
   MAVEN_COMMAND: ./mvnw
@@ -29,11 +28,29 @@ jobs:
   compile-and-unit-test:
     runs-on: ubuntu-latest
     timeout-minutes: 20 # cold runs pull ~1 GB of database container images
+    permissions:
+      contents: read
     steps:
       - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
       - uses: ./.github/actions/jdk-setup
       - name: Compile and run unit and integration tests
         run: ${{ env.MAVEN_COMMAND }} ${{ env.MAVEN_CLI_COMMON }} clean verify
+
+  # Isolated from the build job so its write-scoped token is never present
+  # while a build of pull-request code runs. Only fires for pushes to main.
+  submit-dependencies:
+    needs: compile-and-unit-test
+    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+      - uses: ./.github/actions/jdk-setup
       - name: Submit dependencies to GitHub
-        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-        uses: advanced-security/maven-dependency-submission-action@v5
+        uses: advanced-security/maven-dependency-submission-action@a64327a7329c9939cf675e458452febe1894a70c # v6.0.1

.github/workflows/deploy-snapshot.yml

@@ -1,6 +1,11 @@
 name: Deploy Snapshot
 
 on:
+  # zizmor: ignore[dangerous-triggers]
+  # workflow_run is used safely: the job's `if` requires a successful "Build any
+  # branch" run from this repository (head_repository guard, so a fork branch
+  # named `main` cannot reach it) on `main` (branches filter), and it checks out
+  # exactly that run's commit (head_sha) — never fork-controlled code.
   workflow_run:
     workflows: ["Build any branch"]
     types: [completed]
@@ -19,7 +24,9 @@ concurrency:
 
 jobs:
   deploy-snapshot:
-    if: github.event.workflow_run.conclusion == 'success'
+    if: >-
+      github.event.workflow_run.conclusion == 'success' &&
+      github.event.workflow_run.head_repository.full_name == github.repository
     runs-on: ubuntu-latest
     timeout-minutes: 20
     steps:
@@ -36,7 +43,7 @@ jobs:
 
       - name: Get project version
         id: ver
-        run: echo "version=$(${{ env.MAVEN_COMMAND }} help:evaluate -Dexpression=project.version -q -DforceStdout)" >> $GITHUB_OUTPUT
+        run: echo "version=$(${{ env.MAVEN_COMMAND }} help:evaluate -Dexpression=project.version -q -DforceStdout)" >> "$GITHUB_OUTPUT"
 
       - name: Deploy snapshot to Maven Central
         if: endsWith(steps.ver.outputs.version, '-SNAPSHOT')
@@ -47,4 +54,6 @@ jobs:
 
       - name: Skip (not a snapshot version)
         if: "!endsWith(steps.ver.outputs.version, '-SNAPSHOT')"
-        run: echo "Version ${{ steps.ver.outputs.version }} is a release version — skipping snapshot deploy"
+        env:
+          VERSION: ${{ steps.ver.outputs.version }}
+        run: echo "Version ${VERSION} is a release version — skipping snapshot deploy"

.github/workflows/lint-workflows.yml

@@ -0,0 +1,54 @@
+name: Lint workflows
+
+on:
+  pull_request:
+    paths:
+      - '.github/**'
+  push:
+    branches: [main]
+    paths:
+      - '.github/**'
+  schedule:
+    - cron: '0 6 * * 1'  # Mondays 06:00 UTC — surface newly added lint rules and freshly deprecated actions
+  workflow_dispatch:
+
+permissions: {}
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  actionlint:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+      - name: Run actionlint
+        uses: raven-actions/actionlint@3d39aea434753780c3b3d4a1a31c854b4dbf49d7 # v2.2.0
+        with:
+          version: 1.7.12  # pin the tool; the action otherwise resolves 'latest' at run time
+
+  zizmor:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+      - name: Run zizmor
+        env:
+          GH_TOKEN: ${{ github.token }}
+        # Pinned tool, run directly (not via zizmor-action) so --strict-collection
+        # can fail the job on a malformed collected file — dependabot.yml, an
+        # action.yml — instead of warning and skipping it. pipx is preinstalled
+        # on ubuntu-latest.
+        run: >-
+          pipx run zizmor==1.30.1 --strict-collection --format github
+          --persona regular --collect all -- .github/

.github/zizmor.yml

@@ -0,0 +1,21 @@
+# zizmor configuration — see .github/workflows/lint-workflows.yml.
+# https://docs.zizmor.sh/configuration/
+rules:
+  unpinned-uses:
+    config:
+      # Symbolic (tag) refs are acceptable for actions published by GitHub's
+      # own organizations; anything else must be pinned to a full commit SHA.
+      policies:
+        "actions/*": ref-pin
+        "github/*": ref-pin
+        "dependabot/*": ref-pin
+        "*": hash-pin
+
+  self-repository:
+    ignore:
+      # The `$/...` self-repository syntax is only a few weeks old (GitHub,
+      # Jul 2026). The workspace-relative `./...` form is used deliberately
+      # until that syntax has settled; revisit and switch over later.
+      - build-any-branch.yml
+      - deploy-snapshot.yml
+      - release.yml