ci: shard Playwright runs per browser project (#193)

The suite grew past what a single serial job can finish inside the
30-minute timeout — every recent run was killed at 30m and reported as
cancelled. One matrix shard per Playwright project (Chrome, Firefox,
WebKit, mobile Chromium) keeps each job well under the limit, installs
only the browser it needs, and fails independently per engine.

Author: justin-schroeder

.github/workflows/ci.yml

@@ -2,9 +2,27 @@ name: Drag and drop tests
 on: [push, workflow_dispatch]
 jobs:
   playwright:
-    name: "Playwright tests"
+    name: "Playwright tests (${{ matrix.project }})"
     timeout-minutes: 30
     runs-on: ubuntu-latest
+    strategy:
+      # One shard per Playwright project: the full suite serially exceeds the
+      # job timeout, and sharding keeps each run well inside it.
+      fail-fast: false
+      matrix:
+        include:
+          - project: Desktop Chrome
+            browser: chromium
+            slug: chrome
+          - project: Desktop Firefox
+            browser: firefox
+            slug: firefox
+          - project: Desktop Webkit
+            browser: webkit
+            slug: webkit
+          - project: iPhone 13 Chromium
+            browser: chromium
+            slug: mobile-chromium
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
@@ -27,12 +45,12 @@ jobs:
       - name: Build Dev
         run: cd tests && pnpm install && cd ..
       - name: Install Playwright
-        run: pnpm exec playwright install --with-deps
+        run: pnpm exec playwright install --with-deps ${{ matrix.browser }}
       - name: Run Playwright tests
-        run: pnpm exec playwright test
+        run: pnpm exec playwright test --project "${{ matrix.project }}"
       - uses: actions/upload-artifact@v7
         if: always()
         with:
-          name: playwright-report
+          name: playwright-report-${{ matrix.slug }}
           path: playwright-report/
           retention-days: 30