case study / 01 / product / saas
Lesson Labs
A SaaS for tutoring studios. One Next.js app becomes four products at the subdomain: admin, studio, client, and marketing, sharing auth, scheduling, and Stripe billing.
The four surfaces all route through one edge middleware: it reads the Host header, classifies the request, and rewrites into the right App Router segment.
Bookings carry both UTC and the studio's local time, so "10am for me, 1pm for my student" survives DST. Stripe webhooks generate per-booking invoices with idempotency keys on every write.