Do you keep my existing code or rewrite from scratch?

Mostly keep. Roughly 60 percent of the codebase stays — the UI, the brand, the marketing site, anything stateless and reviewable. We rewrite 30 percent (auth, payments, multi-tenant boundaries, anything connected to AI tools). We delete 10 percent (dead routes, ghost integrations, abandoned experiments). We do not throw away the product. The product won your customers.