next.js

5a18a71b - Cached Navigations: Cache static stage of partially static initial HTML (#90539)

Cached Navigations: Cache static stage of partially static initial HTML (#90539) When a partially static page is loaded via initial HTML (PPR resume), the RSC payload now includes the `l` (static stage byte length) field, enabling the client router to extract and cache the static stage during hydration. Subsequent navigations to the same page serve the cached static content instantly while streaming in dynamic content. On the server, the resume path in `renderToStream` now uses staged rendering (mirroring `generateStagedDynamicFlightRenderResult`) when Cache Components is enabled. A `StagedRenderingController` separates the static and dynamic stages, and `countStaticStageBytes` resolves the byte length promise that Flight serializes into the stream as `l`. `getRSCPayload` accepts `staleTimeIterable` and `staticStageByteLengthPromise` options to wire `s` and `l` into the `InitialRSCPayload`. On the client, `app-index.tsx` tees the inlined Flight stream when Cache Components is enabled. One copy goes to React for decoding, the other is passed to `createInitialRouterState`. When `l` is present (partially static), the clone is truncated at the byte boundary via `decodeStaticStage` and written into the segment cache via `writeStaticStageResponseIntoCache` with `isResponsePartial: true`. When `l` is absent but `s` is present (fully static), the same function is used with `isResponsePartial: false`. `createInitialRouterState` now accepts a single `initialRSCPayload: InitialRSCPayload` prop instead of individual destructured fields.