[gg582]

Summary

Fixes the intermittent wasm-sw-browser-test failure, page.waitForSelector: Timeout 30000ms exceeded … 'text=Session visits'. It failed 6 times on 10-27/10-29, on dev pushes and PRs alike (e.g. #461, #462), always at the same step. It is not a test flake: a race in the example's boot shell (example/wasm-service-worker/index.html) can leave a real user on the static shell too.

Cause

The shell called register('/sw.js'), and if no worker controlled the page yet it reloaded immediately, before the worker had installed. The reload loops until the worker is active. The worker's activate handler then runs clients.claim().

The problem is when that claim lands while a later shell is still awaiting register(). For an existing registration, register() waits on the /sw.js update check. That shell then sees a controller, prints "Service worker active." and returns. Nothing reloads it, so the static shell stays up and the CWIST page ("Session visits") never appears. The test's controller !== null wait passes and the selector wait times out, which matches the CI log.

Fix

The shell is only ever what the network serves. A controlled / is answered by CWIST through the worker, and the worker's cache serves the file only as /index.html. Whenever the shell's script runs, the app has therefore not been loaded:

• Controller already present (claimed during register(), or opened as /index.html): location.replace('/').
• No controller yet: wait for controllerchange (the claim), then location.replace('/').

The test now reports where it stopped instead of a bare selector timeout: URL, whether the page is controlled, the shell's status text, and worker errors.

Verification (local, Chromium via Playwright 1.63, the CI pin)

• Reproduction before the fix: a copy of the test delays the /sw.js update check and the core .wasm fetches by 3 s, as on a busy runner. 2 of 3 runs got stuck with exactly the CI state: shell status "Service worker active.", controlled=true, no CWIST page.
• Same harness after the fix: 6/6 pass.
• Unmodified test after the fix: 5/5 pass.
• No reload loop: opening /index.html once the worker is installed lands on the CWIST page at / after 2 navigations.