I Built an AI Agent Platform in One Night — Here's the Architecture

Last week I shipped AgentDesk — a platform that gives professional services firms pre-built AI agents for client intake, proposal generation, and reporting. The full stack: Next.js 16, Claude API with tool use, Stripe billing, and a real-time dashboard. Here is the exact architecture, with code. The Stack Next.js 16.2.1 — App Router, React 19, Server Components @anthropic-ai/sdk — Claude API with structured tool use Stripe 21.x — Subscriptions, checkout, webhooks Tailwind CSS 4 — Styling TypeScript 5 — End-to-end type safety Vercel — Deployment + edge functions Why this stack? Next.js 16 with React 19 gives us Server Components for the landing page (zero JS shipped) and client components for the interactive dashboard. The Anthropic SDK has first-class TypeScript support with proper tool-use typing. Stripe handles billing without us building payment infrastructure. The Core Pattern: Agent Engine The key architectural decision was building a generic agent engine that all agents share. Ea