Clean up GitHub workflows and Dependabot config

- Fix spellcheck crashing when no Markdown/HTML files change, and drop
  tj-actions/changed-files in favour of git diff and the repo's cspell
- Merge the static analysis jobs into one job that runs the npm scripts
- Run pr-auto-update only on pushes to main, and add concurrency groups
- Merge the PR label and auto-merge workflows, using the GitHub App
  token instead of GITHUB_TOKEN and PR_AUTO_UPDATE_TOKEN
- Drop Ruby and Autobuild from CodeQL and scan workflow files instead
- Use setup-node's npm cache with npm ci
- Add npm to Dependabot, cover the composite action, switch to weekly
  grouped updates and delete the unused root dependabot.yml
- Replace the sync label bot comment with a note in CONTRIBUTING.md

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: MattyTheHacker

.github/actions/setup-node/action.yml

@@ -1,24 +1,15 @@
-name: Setup node
-description: Local node setup for runners
+name: Set up Node.js
+description: Install Node.js and the project's npm dependencies
 
 runs:
-  using: "composite"
+  using: composite
   steps:
-  - name: Cache npm and node_modules
-    uses: actions/cache@v6
-    with:
-      path: |
-        ~/.npm
-        node_modules
-      key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
-      restore-keys: |
-        ${{ runner.os }}-npm-
+    - name: Set up Node.js
+      uses: actions/setup-node@v7
+      with:
+        node-version: "24"
+        cache: npm
 
-  - name: Set up Node.js
-    uses: actions/setup-node@v7
-    with:
-      node-version: '24'
-
-  - name: Install dependencies
-    shell: bash
-    run: npm install
+    - name: Install dependencies
+      shell: bash
+      run: npm ci

.github/dependabot.yml

@@ -1,16 +1,34 @@
 version: 2
 updates:
-  - package-ecosystem: "docker"
-    directory: "/"
+  - package-ecosystem: npm
+    directory: /
     schedule:
-      interval: "daily"
+      interval: weekly
+    groups:
+      npm:
+        patterns: ["*"]
 
-  - package-ecosystem: "bundler"
-    directory: "/"
+  - package-ecosystem: bundler
+    directory: /
     schedule:
-      interval: "daily"
+      interval: weekly
+    groups:
+      bundler:
+        patterns: ["*"]
 
-  - package-ecosystem: "github-actions"
-    directory: "/"
+  - package-ecosystem: docker
+    directory: /
     schedule:
-      interval: "daily"
+      interval: weekly
+    groups:
+      docker:
+        patterns: ["*"]
+
+  - package-ecosystem: github-actions
+    # "/" only covers .github/workflows, so the local composite actions are listed too
+    directories: ["/", "/.github/actions/*"]
+    schedule:
+      interval: weekly
+    groups:
+      github-actions:
+        patterns: ["*"]

.github/workflows/codeql-analysis.yml

@@ -1,52 +1,40 @@
-name: "CodeQL"
+name: CodeQL
 
 on:
   push:
-    branches: [ "main" ]
+    branches: [main]
   pull_request:
-    branches: [ "main" ]
+    branches: [main]
   schedule:
-    - cron: '39 7 * * 6'
+    - cron: "39 7 * * 6"
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 jobs:
   analyze:
     name: Analyze
     runs-on: ubuntu-latest
     permissions:
-      actions: read
       contents: read
       security-events: write
-
     strategy:
       fail-fast: false
       matrix:
-        language: [ 'javascript', 'ruby' ]
-
+        language: [actions, javascript]
     steps:
-    - name: Checkout repository
-      uses: actions/checkout@v7
-
-    # Initializes the CodeQL tools for scanning.
-    - name: Initialize CodeQL
-      uses: github/codeql-action/init@v4
-      with:
-        languages: ${{ matrix.language }}
-
-        
-    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
-    # If this step fails, then you should remove it and run the build manually (see below)
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@v4
-
-    # ℹ️ Command-line programs to run using the OS shell.
-    # 📚 See https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstepsrun
-
-    #   If the Autobuild fails above, remove it and uncomment the following three lines. 
-    #   modify them (or add more) to build your code if your project, please refer to the EXAMPLE below for guidance.
+      - name: Checkout repository
+        uses: actions/checkout@v7
 
-    # - run: |
-    #   echo "Run, Build Application using script"
-    #   ./location_of_script_within_repo/buildscript.sh
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v4
+        with:
+          languages: ${{ matrix.language }}
+          build-mode: none
 
-    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v4
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/analyze@v4

.github/workflows/pr-auto-label.yml

@@ -0,0 +1,41 @@
+name: PR auto-setup
+
+# pull_request_target gives fork PRs access to the App secrets. This is safe only
+# because no step checks out or runs code from the PR.
+on:
+  pull_request_target:
+    types: [opened, ready_for_review]
+    branches: [main]
+
+# The job uses the GitHub App token, not GITHUB_TOKEN
+permissions: {}
+
+jobs:
+  pr-auto-setup:
+    name: Label and enable auto-merge
+    runs-on: ubuntu-latest
+    steps:
+      - name: Generate App token
+        id: app-token
+        uses: actions/create-github-app-token@v3
+        with:
+          client-id: ${{ vars.PR_AUTO_UPDATE_CLIENT_ID }}
+          private-key: ${{ secrets.PR_AUTO_UPDATE_PRIVATE_KEY }}
+
+      # Only for branches in this repo; bots such as Dependabot rebase their own PRs
+      - name: Add sync label
+        if: >-
+          github.event.action == 'opened'
+          && github.event.pull_request.head.repo.full_name == github.repository
+          && github.event.pull_request.user.type != 'Bot'
+        run: gh pr edit "$PR_URL" --add-label sync
+        env:
+          GH_TOKEN: ${{ steps.app-token.outputs.token }}
+          PR_URL: ${{ github.event.pull_request.html_url }}
+
+      - name: Enable auto-merge
+        if: ${{ !github.event.pull_request.draft }}
+        run: gh pr merge "$PR_URL" --auto --squash
+        env:
+          GH_TOKEN: ${{ steps.app-token.outputs.token }}
+          PR_URL: ${{ github.event.pull_request.html_url }}

.github/workflows/pr-auto-merge.yml

@@ -1,27 +1,36 @@
-name: pr-auto-update
+name: PR auto-update
+
 on:
-  push: {}
+  push:
+    branches: [main]
+
+# The job uses the GitHub App token, not GITHUB_TOKEN
+permissions: {}
+
+# Queue rather than cancel, so an update is never stopped part way through
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: false
 
 jobs:
   pr-auto-update:
-    name: Automatic PR Updater
+    name: Update PRs labelled sync
     runs-on: ubuntu-latest
+    # Dependabot-triggered runs can't read the App secrets
     if: github.repository == 'CSSUoB/cssuob.github.io' && github.actor != 'dependabot[bot]'
-    permissions: 
-      pull-requests: write
-      contents: write
     steps:
-      - name: Generate Access Token
+      - name: Generate App token
+        id: app-token
         uses: actions/create-github-app-token@v3
-        id: generate-token
         with:
-          app-id: ${{ vars.PR_AUTO_UPDATE_CLIENT_ID }}
+          client-id: ${{ vars.PR_AUTO_UPDATE_CLIENT_ID }}
           private-key: ${{ secrets.PR_AUTO_UPDATE_PRIVATE_KEY }}
 
-      - uses: CSSUoB/pr-auto-updater@v4.0.0
+      - name: Update PRs labelled sync
+        uses: CSSUoB/pr-auto-updater@v4.0.0
         env:
-          GITHUB_TOKEN: ${{ steps.generate-token.outputs.token }}
-          PR_FILTER: 'labelled'
-          PR_LABELS: 'sync'
-          MERGE_CONFLICT_ACTION: 'label'
-          MERGE_CONFLICT_LABEL: 'conflict'
+          GITHUB_TOKEN: ${{ steps.app-token.outputs.token }}
+          PR_FILTER: labelled
+          PR_LABELS: sync
+          MERGE_CONFLICT_ACTION: label
+          MERGE_CONFLICT_LABEL: conflict

.github/workflows/pr-auto-setup.yml

@@ -0,0 +1,50 @@
+name: Static analysis
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  static-analysis:
+    name: Format, lint and spellcheck
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+        with:
+          # The parent commit is needed to work out which files changed
+          fetch-depth: 2
+
+      - name: Set up Node.js
+        uses: ./.github/actions/setup-node
+
+      # Each check runs even if an earlier one fails, so all problems are reported at once
+      - name: Check formatting
+        if: ${{ !cancelled() }}
+        run: npm run format
+
+      - name: Lint JavaScript
+        if: ${{ !cancelled() }}
+        run: npm run lint:js
+
+      - name: Lint Markdown
+        if: ${{ !cancelled() }}
+        run: npm run lint:md
+
+      # Advisory only: unknown words are shown as warnings on the PR without failing the check
+      - name: Spellcheck changed files
+        if: ${{ !cancelled() }}
+        continue-on-error: true
+        run: |
+          git diff --name-only --diff-filter=d HEAD^ HEAD -- '*.md' '*.html' \
+            | npx cspell --file-list stdin --no-must-find-files --no-progress \
+              --issue-template '::warning file=$filename,line=$row,col=$col::Unknown word: $text'