> cs·fundamentals
interview 0% an interactive refresher
09 [B][J] Stage 4

Backend for Vibe Coders

The server mental model for people who ship by directing AI. Understand where data lives, what a good API contract is, how auth and async actually work, and how to review the backend the AI writes — without becoming a backend specialist. (Module 02 is the code-level version.)

chapters
8
objectives
48
core
32
est. time
3h 32m
  1. 01
    9.1 The server mental model ★ core

    What a backend is for and what it can do that a browser can't. The trust boundary is the whole idea — and where each piece (runtime, API, data, auth, jobs) lives. (Module 2 is the code-level version.)

    6 objectives · 3 readings · 26m
  2. 02
    9.2 API contracts & REST ★ core

    An API is a promise about shapes and verbs. Design the contract well and the AI fills in the implementation correctly.

    6 objectives · 3 readings · 28m
  3. 03
    9.3 Data & where it lives ★ core

    A builder's view of databases: SQL vs NoSQL at decision level, schemas and relationships, what an ORM buys you, and where the DB sits — all pointing into Module 3 for depth.

    6 objectives · 3 readings · 26m
  4. 04
    9.4 Authentication & authorization ★ core

    Who you are vs what you're allowed to do — the two questions every real backend must answer, and the ownership check AI forgets.

    6 objectives · 3 readings · 26m
  5. 05
    9.5 Server architecture & where the backend runs ★ core

    Serverless vs always-on vs managed platform, and how to structure a backend so it stays understandable — the decisions, not the deep patterns.

    6 objectives · 3 readings · 26m
  6. 06
    9.6 Async work: jobs, queues & webhooks ★ core

    Not everything finishes inside one request. Queues, workers, scheduled jobs, and webhooks are how a backend does slow and event-driven work.

    6 objectives · 3 readings · 26m
  7. 07
    9.7 Performance, reliability & ops at a glance ★ core

    The operational concerns a builder must respect: caching, the failure cases, idempotent retries, logging, and “did it actually deploy and stay up” — orientation, with depth in Module 6.

    6 objectives · 3 readings · 26m
  8. 08
    9.8 Directing AI to build good backends ★ core

    Turn the whole module into leverage: specify an endpoint contract precisely and review AI server code for the mistakes it reliably makes.

    6 objectives · 3 readings · 28m

Section assessment

Harder, multi-concept questions drawn from across the module. Aim for 75%.

section assessment12 questions · pass ≥ 75%
  1. 01medium

    Authentication vs authorization:

  2. 02medium

    A validation check in the frontend is enough to keep an endpoint secure.

  3. 03medium

    A logged-in user requests something they're not permitted to do. The right status code is…

  4. 04medium

    Returning 200 for every response and signalling failure only in the body is fine.

  5. 05medium

    What is an N+1 query problem?

  6. 06medium

    For an app with related, structured data and joins, the safe default is…

  7. 07medium

    Which check do AI-generated handlers most often forget?

  8. 08medium

    A JWT's payload is encrypted, so it's safe to store secrets in it.

  9. 09medium

    Why is a websocket server awkward to run as a serverless function?

  10. 10medium

    What property lets you run many identical server instances behind a load balancer?

  11. 11medium

    A webhook is…

  12. 12medium

    Because a job or webhook can be delivered more than once, its handler should be idempotent.