feat(trace-viewer): show film strip lanes for all videos, grouped by page

[Pavel Feldman (pavelfeldman)]

Summary

• useVideoThumbnails now takes all trace videos and subscribes to each cache entry
• film strip renders one video lane per page, merging that page's videos sorted by timestamp

[github-actions]

Test results for "MCP"

8603 passed, 1446 skipped

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Merge workflow run.

[github-actions]

Test results for "tests 1"

2 failed
❌ [installation tests] › playwright-cdn.spec.ts:43 › playwright cdn failover should work (https://cdn.playwright.dev/dbazure/download/playwright) @package-installations-macos-latest
❌ [installation tests] › playwright-cdn.spec.ts:43 › playwright cdn failover should work (https://playwright.download.prss.microsoft.com/dbazure/download/playwright) @package-installations-macos-latest

6 flaky

⚠️ [chromium-library] › library/chromium/chromium.spec.ts:301 › should report intercepted service worker requests in HAR `@chromium-ubuntu-22.04-node20`
⚠️ [chromium-library] › library/beforeunload.spec.ts:130 › should support dismissing the dialog multiple times `@chromium-ubuntu-22.04-node22`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:257 › third party 'Partitioned;' cookies `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:470 › top level 'Partitioned;' cookie and same origin iframe `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-page] › page/page-event-request.spec.ts:181 › should return response body when Cross-Origin-Opener-Policy is set `@firefox-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:827 › should update state on subsequent run `@windows-latest-node22`

51980 passed, 1247 skipped

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Merge workflow run.

[github-actions]

🟢 CI is clear — both failures are a macOS CDN download flake

Hi, I'm the Playwright bot and I triaged the failing CI on this PR.

Both failures are installation-tests/playwright-cdn.spec.ts:43 on package-installations-macos-latest, where npx playwright install dies part-way through downloading Chromium. The same test is failing right now on other PRs and on main pushes, so it isn't yours. This PR only touches trace-viewer film strip rendering, which no installation test loads.

Details

Nothing in this PR reaches the failures. The diff is two files — packages/trace-viewer/src/ui/filmStrip.tsx and videoThumbnails.ts — trace-viewer UI code that the package-installation suite never imports or executes.

Pre-existing flake / infra

• [installation tests] › playwright-cdn.spec.ts:43 › playwright cdn failover should work (https://cdn.playwright.dev/dbazure/download/playwright) and the https://playwright.download.prss.microsoft.com/... variant — one story, both variants of the same test on the same bot.

  Across the results DB this test is bimodal on exactly one bot: 27 failed of 652 runs on package-installations-macos-latest, 625 passed. On every other bot — ubuntu-latest, ubuntu-latest-node20/24/26, windows-latest — it is 0 failures across ~300–640 runs each, so this is macOS-specific infra, not test logic.

  It is currently failing in a cluster unrelated to this PR. Recent reds on that bot, newest first:

  run	PR / branch	sha
  35288561056	feat(reporter): and printOnlyFailures and --reporter-only-failures #42766	cb72afe4
  35273711245	fix(docs): document credentials, opfs, and indexeddb in storageState #42761	652e036e
  35288368292	push to main	da3a50aa
  35288002438	push to main	464318b1
  35287890634	push to main	3cd10253
  35286036872	push to main	d7ce229c
  35285835566	push to main	cd80f507

  All share one error — the download aborts mid-stream rather than failing to start:

  Error: Expected the command to exit cleanly (0 status code), but exited with 1.
  Command: npx playwright install
  Downloading Chrome for Testing 154.0.8037.0 (playwright chromium v1246) from
  https://cdn.playwright.dev/builds/cft/154.0.8037.0/mac-arm64/chrome-mac-arm64.zip
  ... 80% of 182.5 MiB
  

  That's a CDN/network hiccup on the macOS runners, not a failover-logic bug: the progress bar reaches ~80% of 182.5 MiB before the connection drops.

The 6 flaky results in the report all passed on retry and are likewise in areas this PR doesn't touch (service worker HAR, third-party cookies, beforeunload dialogs, UI-mode trace).

A re-run of the installation job should go green once the CDN settles.

_{Triaged by the Playwright bot - agent run}