Immutable state, only reassigning changed subtree

.github/workflows/ci.yml

@@ -0,0 +1,32 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '24'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build
+
+      - name: Test
+        run: npm test -- --run

.gitignore

@@ -22,3 +22,4 @@ dist-ssr
 *.njsproj
 *.sln
 *.sw?
+*.tsbuildinfo