Most SaaS starters are Next.js, ship raw Stripe, and predate AI-assisted coding. SarvStack fixes all three: built for TanStack Start, Polar merchant-of-record billing (EU/UK VAT handled), and agent-ready docs — CLAUDE.md, Cursor rules and slash commands that teach AI agents your conventions. Plus documented RLS patterns, teams, API keys, notifications, audit log, AI quotas, trilingual UI. The site itself runs on the kit. $99 one-time (soon $149).