hasty sun
Hey all! I'm planning a migration of a production Next.js 15 (App Router) app to TanStack Start and would love guidance from anyone who's been through it. I searched first — apologies if I missed an existing thread.
My situation
~50 API routes (mostly thin proxies to a separate backend)
~40 React Server Components I'd actually like to move off of
Auth: Kinde (Next.js SDK)
Feature flags: DevCycle (Next.js SDK)
The rest should port cleanly: React Query v5, React Hook Form + Zod, Tailwind, shadcn/ui, TypeScript strict
From my initial research, a partial / side-by-side migration doesn't look realistic, so this would likely be a single big-bang PR — which is a bit scary for a production app.
Questions
Has anyone migrated something of similar scope? How did it go in hindsight?
Where did you start — routing, data layer, auth, or somewhere else?
What was your workflow: scaffold a fresh TS Start app and port pages in, or transform the existing repo in place?
Any prompts or strategies that worked well with AI assistants (Cursor, Claude Code, etc.) for the repetitive bits (route handlers, RSC → loaders, etc.)?
Kinde + DevCycle specifically: has anyone swapped the Next-specific SDKs for the framework-agnostic React SDKs (+ server SDKs where needed)? Any gotchas around session handling or SSR flag evaluation?
Thanks in advance!
trim lily
heady badger