NEW310251
Web Inspector: Site Isolation: Network domain sourceMappingURL forwarding 
https://bugs.webkit.org/show_bug.cgi?id=310251
Summary Web Inspector: Site Isolation: Network domain sourceMappingURL forwarding
Blaze Burg
Reported 2026-03-18 23:16:19 PDT
FrameNetworkAgentProxy::didFinishLoading sends an empty string for the sourceMappingURL parameter because the SI path does not hold CachedResource references. In the legacy path, InspectorNetworkAgent reads the source map URL from the CachedResource parsed metadata (ResourceUtilities::sourceMapURLForResource). Without this, source maps do not auto-link in the Network panel for resources loaded in cross-origin iframes under Site Isolation. Possible fixes: (1) Extract the SourceMap HTTP response header during responseReceived and store it on the BackendResourceDataStore entry. This handles server-provided source maps but not inline //# sourceMappingURL= directives. (2) Parse the buffered content for the sourceMappingURL pattern after decoding. (3) Add a new instrumentation hook that fires after CachedResource processes its headers/content. Sub-bug of rdar://143782685.
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Radar WebKit Bug Importer
Comment 1 2026-03-18 23:16:25 PDT
<rdar://problem/172894304>
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