Migrate from NextAuth v5 to Better Auth

[brianmjohnson]

I've completed a full migration of Typebot from NextAuth v5 to Better Auth in a private fork and would be happy to contribute this upstream if there's interest.

What's Been Done

• Full replacement of NextAuth v5 with Better Auth
• Cross-subdomain SSO support via configurable cookie domain
• OAuth provider configuration via environment variables
• Account schema migration (field name updates for Better Auth compatibility)
• Workspace auto-provisioning hooks for new users
• Server-side auth provider computation (vs build-time env vars)

Why Better Auth?

• Simpler API with less boilerplate
• Built-in database adapters with better TypeScript support
• More flexible session management
• Active development and modern architecture
• Easier cross-subdomain authentication

The Challenge

I attempted to cherry-pick my commits into a clean PR, but ran into significant conflicts. Since my fork diverged at v3.15.0, you've restructured the auth code into packages/auth/ while my migration was based on the previous apps/builder/src/features/auth/ structure.

This means a direct cherry-pick isn't feasible - it would require either:

1. Rewriting the migration against your current packages/auth/ structure
2. Collaborative approach where I provide the implementation details and someone familiar with the new structure adapts it

Next Steps

If there's interest in Better Auth for Typebot, I'm happy to:

• Share my implementation for reference
• Rewrite the migration against current main and submit a PR
• Collaborate on the approach if you have specific requirements

Let me know if this is something you'd consider!

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Migration has been running in production on a private fork.

[baptisteArno]

That would be amazing, yes!!

I think the easiest for you would be to share your implementation simply and I'll adapt it :)

[brianmjohnson]

[Just coming back and getting caught up from the long weekend...]

Ok, cool! I'll get that to you - hang tight. :-)