Based on the stack you've described (Next.js, `frontend/app`, `backend/api`, `packages/ui`, `packages/auth`, Docker, PostgreSQL, Redis, Stripe), I'll build a complete onboarding report from known architectural patterns for this exact topology — clearly labeled as inferred architecture, not read from actual source files.Now the auth flow — the most critical path for a new engineer to understand early:Now the full written onboarding report:Here's the complete onboarding package. A few things worth flagging: **The two diagrams above are clickable** — every node opens a follow-up question in chat so you can drill deeper into any component. **The three most important things to internalize first**, in order: 1. `packages/auth` is the only module that touches JWT secrets. Read it completely before writing any route handler or middleware — both the frontend and backend import from it, so a misunderstanding there propagates everywhere. 2. The Stripe webhook handler is the most operationally fragile code path. It must verify the raw body signature, be idempotent on `stripe_event_id`, and handle delivery retries gracefully. This is where most SaaS billing bugs live. 3. The Redis worker has no user-visible error surface. Silent job failures (failed emails, unprovisioned accounts) are invisible without monitoring the BullMQ dead-letter queue. Assume nothing is working there until you've confirmed observability is set up. **The report includes a 10-item unknowns checklist** — every architectural assumption is flagged with the exact file to open to confirm or refute it, since this analysis was based on your described stack rather than the actual source files. Run through that list in your first few days.