diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 000000000..204e30ea2
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,80 @@
+name: "CodeQL - JavaScript (Advanced)"
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+  schedule:
+    - cron: '0 2 * * 3'    # weekly on Wed 02:00 UTC
+  workflow_dispatch:
+
+jobs:
+  analyze:
+    name: Analyze (CodeQL, Node ${{ matrix.node }})
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      contents: read
+      packages: read
+      actions: read
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+        - language: javascript-typescript
+          node: 18
+          build-mode: none
+        - language: javascript-typescript
+          node: 20
+          build-mode: none
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node }}
+        cache: 'npm'
+
+    - name: Cache node modules
+      uses: actions/cache@v4
+      with:
+        path: |
+          ~/.npm
+          node_modules
+        key: ${{ runner.os }}-node-${{ matrix.node }}-${{ hashFiles('**/package-lock.json', '**/yarn.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-node-${{ matrix.node }}-
+
+    - name: Install dependencies
+      run: |
+        if [ -f package-lock.json ]; then
+          npm ci
+        else
+          npm install
+        fi
+
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v4
+      with:
+        languages: ${{ matrix.language }}
+        build-mode: ${{ matrix.build-mode }}
+        # Use built-in query packs plus extended security rules
+        queries: security-extended,security-and-quality
+
+    - name: Autobuild (CodeQL)
+      uses: github/codeql-action/autobuild@v4
+      env:
+        CI: true
+
+    - name: Perform CodeQL analysis
+      uses: github/codeql-action/analyze@v4
+      with:
+        # Optional: narrow category to help triage results in the dashboard
+        category: "language:javascript-typescript"