310251 2026-03-18 23:16:19 -0700 Web Inspector: Site Isolation: Network domain sourceMappingURL forwarding 2026-03-18 23:16:25 -0700 1 1 1 Unclassified WebKit Web Inspector WebKit Nightly Build Unspecified Unspecified NEW InRadar P2 Normal --- 308890 1 bburg webkit-unassigned inspector-bugzilla-changes webkit-bug-importer oldest_to_newest 2191608 0 bburg 2026-03-18 23:16:19 -0700 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. 2191609 1 webkit-bug-importer 2026-03-18 23:16:25 -0700 <rdar://problem/172894304>