I Ran 23 AI Agents Simultaneously on One Codebase Overnight. Here's What Happened.

I set 23 AI agents loose on a single Next.js codebase at 23:45. By 06:34 the next morning, the codebase had doubled — from ~28,000 to 56,381 lines of code, 264 TypeScript files, 120 commits, zero TypeScript errors, and a live Railway deploy. This is the story of what worked, what was terrifying, and what I'd do differently. The Setup The project — a multi-tenant SaaS platform for brand builders — already had a working v3.2.0 with ~110 source files and functional core flows. But there was a long backlog: product reviews, discount codes, AI blog writer, mobile responsiveness, newsletter system, analytics charts, social preview, design studio, and more. I could work through the backlog sequentially. Or I could try something else. The platform already had two cron orchestrators running periodic sprint agents. I decided to use that pattern at a different scale: spawn all the sprints in parallel, let them run overnight, and review the results in the morning. 23 agents total. Two orchestrator