| Fix client navigation between sibling pages of an optional catch-all route. If a fully static catch-all index is prefetched first, navigating to another slug must fetch and render that slug instead of updating the URL while leaving the index content on screen. | |
| An App Shell may be reused across parameter values only when it is actually parameter-independent. A response without a shell/full split is not sufficient evidence, because it may be a concrete prerender whose content depends on the requested params. Use the segment parameter-dependency information reported by the server when it is available. If it is unavailable, conservatively assume every parameter varies, except that a true shell variant may still be shared across its parameter fallbacks. | |
| The behavior must work whether the vary-params optimization is enabled or disabled. Prefetching the index, navigating to it, then prefetching and navigating to a sibling slug must show the sibling's content and preserve the expected prefetch/network behavior. | |