ci: add test workflow with Playwright browser caching

.github/workflows/test.yml

@@ -0,0 +1,42 @@
+name: Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4.2.2
+
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Get Playwright version
+        id: playwright-version
+        run: echo "version=$(node -p "require('./package-lock.json').packages['node_modules/playwright'].version")" >> "$GITHUB_OUTPUT"
+
+      - name: Cache Playwright browsers
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-${{ runner.os }}-${{ steps.playwright-version.outputs.version }}
+
+      - name: Install Playwright Chromium
+        run: npx playwright install --with-deps chromium
+
+      - name: Type check
+        run: npm run check
+
+      - name: Run tests
+        run: npm test

vite.config.ts

@@ -72,6 +72,11 @@ export default defineConfig(({ mode }) => {
         },
         {
           extends: "./vite.config.ts",
+          // Pre-bundle the component-test dependency graph: on a cold Vite cache
+          // (every CI runner) a mid-run dep-optimization reload can flake the suite.
+          optimizeDeps: {
+            include: ["layerchart", "mode-watcher", "bits-ui", "d3-scale", "d3-shape"],
+          },
           test: {
             name: "client",
             browser: {