Case Study: From Broken AI Prototype to Production Fintech in 6 Weeks
A Series A fintech with a Bolt-built MVP couldn't onboard their first paying enterprise customer. Here's what was broken under the hood — and what we shipped to fix it.
NeuroX AI · April 30, 2026
Composite from recent Prototype → Production engagements. Specific clients anonymized at their request. Every failure mode and every fix is from work we've shipped in the last 12 months.
The setup. A Series A fintech founder built an MVP on Bolt over a weekend. Investor demos crushed it. Then the first paying enterprise pilot — a six-figure design partner — logged in, and the wheels came off.
The issue — what was actually broken:
- Auth was a
setIsLoggedIn(true)state flag. No sessions, no tokens, no user table. - KYC documents lived in
localStorage. Browser refresh = data gone. Compliance flagged it inside 48 hours. - Stripe was a UI mock. No webhooks, no subscription state, no idempotency.
- The app crashed at ~40 concurrent users. No caching, no pagination, no error boundaries.
- Infra was running ~$4,200/month for a workload that should cost under $100.
The solution — what we shipped in 6 weeks:
- Real Supabase auth with row-level security and a proper user/role model.
- Postgres-backed KYC tables with full audit logs (compliance-ready).
- Stripe wired with webhooks, idempotency keys, and a real subscription state machine.
- Sentry + structured logging + on-call runbooks.
- Caching + pagination — load-tested clean to 5,000 concurrent users.
- Infra cost rebuilt down to ~$90/month.
The outcome. Enterprise pilot signed. Three more design partners closed the next quarter. Founder stopped firefighting infrastructure and got back to shipping product.
This is what Prototype → Production actually looks like — auth, DB, payments, tests, monitoring. The boring stack that doesn't crash. Audit your prototype.