feat: add E2E tests for CDP connections and MV3 service workers

[rgarcia]

Summary

• Add E2E tests for CDP connection stability after Chromium restarts
• Add E2E test for MV3 extension service worker registration and messaging
• Fix chromium-launcher to properly kill existing processes before restart

Details

CDP Connection Tests (e2e_combined_flow_test.go)

TestExtensionViewportThenCDPConnection - Reproduces the scenario where profile loading fails to connect to CDP after back-to-back restarts:

1. Upload extension (triggers Chromium restart)
2. Change viewport (triggers another Chromium restart)
3. Immediately attempt CDP WebSocket connection
4. Verify Browser.getVersion command succeeds

TestMultipleCDPConnectionsAfterRestart - Tests connection stability:

1. Upload extension to trigger restart
2. Rapidly attempt 5 consecutive CDP connections
3. Verify all connections succeed

MV3 Service Worker Tests (e2e_mv3_service_worker_test.go)

TestMV3ServiceWorkerRegistration - Verifies MV3 extensions work correctly:

1. Upload test extension with service worker via /chromium/upload-extensions-and-restart
2. Navigate to chrome://extensions and enable developer mode
3. Verify extension is loaded with active service worker (not "(Inactive)")
4. Navigate to extension popup and click "Ping Service Worker"
5. Verify service worker responds with success message

Includes a test extension (server/e2e/test-extension/) with:

• MV3 manifest with service worker background script
• Popup that sends ping messages to service worker
• Service worker that responds to verify it's alive

Chromium Launcher Fix

Added killExistingChromium() function that:

• Kills any existing chromium processes before starting new one
• Waits up to 2 seconds for processes to fully terminate
• Fixes race condition where old process holds IPv4 port during restart

Test plan

• TestExtensionViewportThenCDPConnection passes
• TestMultipleCDPConnectionsAfterRestart passes
• TestMV3ServiceWorkerRegistration passes

cd server/e2e
go test -v -run "TestExtensionViewport|TestMultipleCDP|TestMV3"

🤖 Generated with Claude Code

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Note

Adds robust E2E coverage for browser restarts, CDP connectivity, and MV3 service workers, plus a launcher hardening to ensure clean Chromium restarts.

• New Go tests: TestExtensionViewportThenCDPConnection and TestMultipleCDPConnectionsAfterRestart validate CDP stability after extension upload and viewport-change restarts and multiple rapid connects
• New MV3 test (e2e_mv3_service_worker_test.go) with Playwright command verify-mv3-service-worker to inspect chrome://extensions, confirm active service worker, and verify popup -> SW messaging
• Adds test extension assets under server/e2e/test-extension/ and expands Playwright index.ts with the verification flow; updates tsconfig.json libs to include DOM
• Chromium launcher (server/cmd/chromium-launcher/main.go) now calls killExistingChromium() to pkill -9 -x chromium and wait up to 2s before relaunch, preventing IPv4/IPv6 bind conflicts

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