Architecture Atlas A visual reference of the diagrams you will keep redrawing as the application evolves from two processes into a production system.
Book 5 · Visual architecture reference Course baseline: September 17, 2026 · Windows-first · Project-driven · Production-oriented
Contents 1. Atlas usage 7. Stage F server state
Phase 00 | Page 2 of 7
Use this atlas to test your mental model Do not treat these figures as posters. Cover the labels and redraw them from memory. If a diagram stops matching the implementation in a later phase, the implementation or the documentation needs correction.
Figure 1 - Stage A: presentation only - The first mental model contains only a browser and Next.js.
Figure 2 - Stage B: independent API - The frontend now crosses an HTTP boundary to a separately running NestJS process.
Phase 00 | Page 3 of 7
Figure 3 - Stage C: persistence - Prisma enters because the API now needs durable relational data.
Figure 4 - Stage D: authentication - Supabase Auth establishes identity; the backend validates the access token.
Phase 00 | Page 4 of 7
Figure 5 - Stage E: authorization boundary - Identity and resource access are separate decisions.
TanStack Query Local / URL / Form state tasks · projects · users · API results dialogs · filters · inputs · navigation
PostgreSQL Services / optional stores authoritative business data rules and interaction logic
Figure 6 - Stage F: state ownership - Server state, persistent truth, UI state and domain behavior should not be collapsed into one bucket.
Phase 00 | Page 5 of 7
Figure 7 - Stage G: collaborative update paths - Realtime is optional and complements normal HTTP mutations rather than replacing them.
E2E Playwright
Unit tests services · rules · utilities
Figure 8 - Stage H: testing pyramid - Tests become broader and slower as they approach full-system behavior.
Phase 00 | Page 6 of 7
Vercel API host Users / browsers Next.js NestJS
Observability Supabase logs / errors Postgres + Auth
CI/CD: lint → typecheck → test → build → deploy
Figure 9 - Stage I: production topology - A deployment is multiple runtimes connected through explicit boundaries.
Close this PDF and redraw Figures 3, 5 and 9 from memory. Then explain which boundary you would inspect for a 403, a unique-constraint conflict, and a stale UI.
Phase 00 | Page 7 of 7
Architecture Atlas matters because it changes a real boundary in TaskFlow. The goal is to understand the inputs, owner, observable output, and failure modes before adding more abstraction.
Restate the goal of “Architecture Atlas” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: User intent → UI boundary → API contract → business rule → persistence → observable result. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: A one-page architecture map plus an ADR-style note describing the responsibilities of Next.js, NestJS, Prisma, PostgreSQL/Supabase, and supporting infrastructure.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
Input -> owner -> transformation -> observable output -> failure evidenceDo not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Return to the nearest observable boundary: input, network, process log, database, or rendered UI. Compare actual evidence with the predicted path.
Change one variable at a time and reproduce the original failure after the fix; otherwise you have correlation, not diagnosis.
Without copying the final source, create a second small scenario that applies “Architecture Atlas” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Trace one failure: invalid input, missing authentication, forbidden action, database outage.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Putting business rules in React components
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.