next.js

cb4cc5b1 - Resolve parallel route params from the URL when predicting routes (#101477)

Resolve parallel route params from the URL when predicting routes (#101477) When the client predicts a route from a learned pattern, it matched the URL against the known-route trie and collected param values along the matched path. That path follows one parallel route branch, usually `children`. Other branches map the same URL onto their own segments, so a param that only exists in another branch, like a slot's catch-all, never got a value. The pattern's old value was kept instead, which produced a tree mixing params from two URLs: ``` URL: /de-de/f/herren children: [locale]=de-de / f / [slug]=herren @desktopNav: [locale]=de-de / [...catchAll]=f/women <- learned from /en-de/f/women ``` The server then rendered a different tree, and the client retried the navigation with a second request. The retry could lose the scroll-to-top, because the slot leaf with no layout boxes held the scroll intent. This affects the documented `@modal/[...catchAll]` pattern for closing a modal on navigation, and the same stale value causes the prefetch loops traced in #98073. Now the trie only selects the pattern. When the pattern is reified, each active branch reads its own params from the URL parts, using the same rules as route discovery. If a branch doesn't fit the URL, prediction falls back to the server. Inactive parallel routes become default segments, which is what the server sends for them; on navigation the client reuses the active segment in that slot. #98073 fixed this by not predicting these routes at all. This change keeps them predictable, so apps using a catch-all slot don't lose prediction on most routes. The prefetch loop test from #98073 is included unchanged. A new test covers the route shape from #98021, a catch-all slot under `[locale]` next to `f/[slug]`: a locale `router.replace` makes one request, scrolls to the top, and sends the predicted tree with the slot's catch-all read from the target URL. Another checks that a route whose slot renders a default segment is still predicted and keeps the slot's active segment. Fixes #98021 Co-authored-by: Lucas Doell <lucas@lux.dev> Co-authored-by: Lucas Doell <lucas@lux.dev>