feat(app-router): filter skipped layouts from RSC responses and cached reads [3/6]#840
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NathanDrake2406 wants to merge 3 commits intocloudflare:mainfrom
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Reshape buildPageElements to accept a single pageRequest object bundling opts, searchParams, isRscRequest, request, and mountedSlotsHeader. Lift the mounted-slots header read to the handler scope so every call site shares one source of truth and a future refactor cannot silently drift one read path out of the other.
Wire runtime layout classification through renderAppPageLifecycle and attach the resulting flags as __layoutFlags in the outgoing RSC payload via buildOutgoingAppPayload. Payload-shape helpers (withLayoutFlags, isAppElementsRecord, buildOutgoingAppPayload, AppOutgoingElements) live alongside the existing readAppElementsMetadata so the write and read boundaries sit next to each other.
…d reads Introduce app-page-skip-filter.ts with the canonical-bytes guarantee: the render path always produces the full RSC payload and writes it to the cache; the egress branch applies a byte-level filter that omits layouts the client asked to skip, but only if the server independently classified them as static (computeSkipDecision). Wire the filter into renderAppPageLifecycle and buildAppPageCachedResponse so both fresh renders and cache hits honor the skip header. Parse the incoming X-Vinext-Router-Skip header at the handler scope and thread the resulting set through render and ISR. Gate the filter behind supportsFilteredRscStream: false in the generated entry so this PR is dormant at runtime until the canonical-stream story is validated. Tests exercise the filter directly by injecting the skip set into renderAppPageLifecycle options.
This was referenced Apr 14, 2026
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Summary
PR 3 of 6 — restack of #768. Stacked on #839.
Introduces `app-page-skip-filter.ts` with the canonical-bytes guarantee: the render path always produces the full RSC payload and writes it to the cache; the egress branch applies a byte-level filter that omits layouts the client asked to skip, but only if the server independently classified them as static (`computeSkipDecision`).
Wires the filter into `renderAppPageLifecycle` and `buildAppPageCachedResponse` so both fresh renders and cache hits honor the skip header. Parses the incoming `X-Vinext-Router-Skip` header at the handler scope and threads the resulting set through render and ISR.
Dormant until canonical-stream is validated: gated behind `supportsFilteredRscStream: false` in the generated entry so this PR lands inert at runtime. Tests exercise the filter directly by injecting the skip set into `renderAppPageLifecycle` options.
Canonical-bytes invariant
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Test plan