Track vary params for segments without server-side param access#88998
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acdlite merged 1 commit intovercel:canaryfrom Jan 29, 2026
Merged
Track vary params for segments without server-side param access#88998acdlite merged 1 commit intovercel:canaryfrom
acdlite merged 1 commit intovercel:canaryfrom
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This implements a partial "vary params" optimization for the segment cache. When a segment doesn't access params on the server, its prefetched data can be reused across different param values. Two cases are handled: 1. Segments without a user-provided layout (only loading.tsx or nothing) 2. Segments with a 'use client' layout The server now includes a varyParams field in segment prefetch responses. When varyParams is an empty Set, the client re-keys the cache entry with Fallback for all param values, making it reusable across different params. This is a stepping stone toward full vary params tracking where server components would track which specific params they access during rendering.
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Based on: - #88834 - #88989 - #88998 --- Adds optimistic routing, enabling the client to predict route structure for URLs that haven't been prefetched yet. When navigating to a URL like /blog/post-2, if we've previously learned the pattern from /blog/post-1, we can predict the route structure without waiting for a server response. The client learns route patterns from server responses and builds a trie indexed by URL parts. When a cache miss occurs, we check if the URL matches a known pattern. If so, we create a synthetic cache entry from the template, allowing immediate rendering of loading boundaries. Static siblings (like /blog/featured alongside /blog/[slug]) are tracked to avoid incorrect predictions — we only predict dynamic routes when we're confident no static sibling matches.
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Based on:
This implements a partial "vary params" optimization for the segment cache. When a segment doesn't access params on the server, its prefetched data can be reused across different param values.
Two cases are handled:
The server now includes a varyParams field in segment prefetch responses. When varyParams is an empty Set, the client re-keys the cache entry with Fallback for all param values, making it reusable across different params.
This is a stepping stone toward full vary params tracking where Server Components would track which specific params they access during rendering.