diff --git a/.github/workflows/cd.yml b/.github/workflows/cd.yml
index 9ca5273..933cde5 100644
--- a/.github/workflows/cd.yml
+++ b/.github/workflows/cd.yml
@@ -8,6 +8,10 @@ on:
 permissions:
   contents: write
 
+concurrency:
+  group: deploy
+  cancel-in-progress: false
+
 jobs:
   deploy:
     runs-on: ubuntu-latest
@@ -15,10 +19,10 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Set up Node.js
-        uses: actions/setup-node@v6
+        uses: actions/setup-node@v7
         with:
           node-version: 24
 
@@ -29,7 +33,7 @@ jobs:
         run: npm run build
 
       - name: Deploy to GitHub Pages
-        uses: JamesIves/github-pages-deploy-action@v4.8.0
+        uses: JamesIves/github-pages-deploy-action@v4.9.0
         with:
           branch: gh-pages
           folder: ./dist
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2e0635e..b6a7cdb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,6 +1,9 @@
 name: CI
 
-on: [push]
+on:
+  push:
+    branches: [main]
+  pull_request:
 
 jobs:
   build-and-test:
@@ -8,15 +11,26 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Set up Node.js
-        uses: actions/setup-node@v6
+        uses: actions/setup-node@v7
         with:
           node-version: 24
 
       - name: Install dependencies
         run: npm install
 
+      # Runs before Build, because the prebuild script rewrites formatting.
+      # A failure shows a warning but does not fail the job.
+      - name: Check formatting
+        id: format
+        continue-on-error: true
+        run: npm run format:check
+
+      - name: Warn on formatting issues
+        if: steps.format.outcome == 'failure'
+        run: echo "::warning title=Formatting::Prettier found unformatted files. Run 'npm run format' and commit the result."
+
       - name: Build
         run: npm run build