I built a $150 SaaS Billing Platform in 12 hours using an Autonomous AI Agent. Here’s why deployment is the new bottleneck.

The Challenge: Zero to Production in 12 hours Everyone is talking about AI coding assistants. I wanted to go further. I built an autonomous development system and gave it a high-stakes stress test: "Build a production-ready SaaS billing platform from scratch. No human code. No manual deployment. Go." The Result: BillingCore — a functional billing engine with subscriptions, usage-based metrics, and a dashboard. The Cost: ~$150 in AI API tokens. The Time: 12 hours (including a few "AI existential crises"). 🛠 The Stack (Chosen Autonomously) I didn't pick the tech. The system did, based on a "performance vs. dev speed" trade-off: Backend: Fastify (picked over Express for lower overhead) + Prisma + PostgreSQL + Redis. Frontend: React 18 + Vite + TypeScript. Infrastructure: Dockerized services deployed to Railway. Auth: JWT Bearer tokens + bcrypt. 📉 The "Aha!" Moment: Why AI Still Struggles Writing 10,000 lines of code was the easy part. The system hit a brick wall during Production Deployme