## Summary
- stop the preview route dropdown from showing "Loading routes..." after
route discovery has already finished
- expand React Router discovery to scan common route files like
`src/routes/*`, `*routes.tsx`, and `router.tsx` instead of only
`src/App.tsx`
- add parser tests covering modular route files and merged route
discovery

## Test plan
- `npm run fmt && npm run lint:fix && npm run ts`
- `npm test`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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---------
Co-authored-by: Will Chen <7344640+wwwillchen@users.noreply.github.com>