fix(trace): replay sub-resources from archive in trace snapshot CLI#40632
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Skn0tt wants to merge 2 commits intomicrosoft:mainfrom
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fix(trace): replay sub-resources from archive in trace snapshot CLI#40632Skn0tt wants to merge 2 commits intomicrosoft:mainfrom
Skn0tt wants to merge 2 commits intomicrosoft:mainfrom
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The trace snapshot CLI (and `trace serve`) only served the recorded HTML; sub-resources like stylesheets, images, and fonts were fetched live from the original origin, which meant snapshots would render without styles whenever the origin was unreachable. Serve sub-resources from the trace archive via a small service worker registered on a bootstrap page. The service worker forwards cross-origin requests to a `/__pwsnapshot/resource` endpoint on the CLI HTTP server, which delegates to `SnapshotServer.serveResource`. Same code path works for both `trace snapshot` and `trace serve`.
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dgozman
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May 5, 2026
| response.statusCode = 200; | ||
| response.setHeader('Content-Type', 'application/javascript'); | ||
| response.setHeader('Service-Worker-Allowed', '/'); | ||
| response.end(` |
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Can we extract this from a string literal? I find things like this hard to maintain.
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Test results for "MCP"1 failed 6906 passed, 1062 skipped Merge workflow run. |
pavelfeldman
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May 5, 2026
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Not sure I like the code fork, why doesn't it work out of the box?
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Subresource URLs are not rewritten, so they to whatever was the original host. In trace viewer, we also use a service worker to catch them. |
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Summary
trace snapshotCLI (andtrace serve) only replayed the recorded HTML; sub-resources fetched live from the original origin, so snapshots rendered unstyled whenever that origin was unreachable./__pwsnapshot/resourceendpoint that delegates toSnapshotServer.serveResource. Same path works for bothtrace snapshotandtrace serve.