Optimistic routes wrongly predicts rewritten pages

Link to the code that reproduces this issue

https://github.com/blurrah/repro-optimistic-routes

To Reproduce

1. Open vercel deployment
2. wait for /de prefetch to be completed (page will notify)
3. Click on Team (no prefetch)
4. The page will shortly show a marker that it received the wrong locale (team as locale)

Current vs. Expected behavior

When using optimisticRoutes with rewritten paths it will wrongly predict the non-rewritten path until the page resolves post-navigation. In this locale based example it means that /team will get team as a locale rather than en. This can lead to all sorts of weird bugs like flashing 404's or wrongly fetched data.

Disabling optimisticRoutes fixes the behavior.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.6.0: Tue Apr 21 20:19:12 PDT 2026; root:xnu-11417.140.69.710.16~1/RELEASE_ARM64_T6041
  Available memory (MB): 49152
  Available CPU cores: 12
Binaries:
  Node: 24.12.0
  npm: 11.6.2
  Yarn: N/A
  pnpm: 10.33.4
Relevant Packages:
  next: 16.3.1-canary.7
  eslint-config-next: N/A
  react: 19.2.8
  react-dom: 19.2.8
  typescript: 5.9.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Linking and Navigating

Which stage(s) are affected? (Select all that apply)

Vercel (Deployed)

Additional context

Tested against latest and canary, happens locally and on Vercel.

Start with the linked reproduction and verify the failure with optimisticRoutes and rewritten paths, focusing on the linking and navigating area. The payload names no repository files or tests; done means the optimistic prediction preserves the rewritten locale for the reported /de and /team flow.