module 4 of 8 · 50 min

APIs

Design stable service boundaries for data and model capabilities.

Explain APIs clearlyImplement a small APIs exampleEvaluate whether APIs improves a simpler baselineIdentify failure cases and operational constraints
learning statenot started
0% completesign in to track progress
mental model

start with the idea before the implementation.

An API is a contract between systems and its error behavior matters as much as its happy path.
core concepts

the mechanisms you need to reason about.

01

Resource and action design

Resource and action design is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

02

Validation

Validation is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

03

Idempotency

Idempotency is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

04

Versioning and observability

Versioning and observability is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

engineering lab

turn the lesson into evidence.

LAB 1

design a model inference endpoint

Build the smallest version first. Record the input, expected output, measured result and one failure you discovered.

LAB 2

add validation and error codes

Build the smallest version first. Record the input, expected output, measured result and one failure you discovered.

LAB 3

instrument latency

Build the smallest version first. Record the input, expected output, measured result and one failure you discovered.

knowledge checks

prove you can explain and decide.

1

define request/response contracts

ask cortex to test me →
2

explain retry safety

ask cortex to test me →
3

identify sensitive data

ask cortex to test me →
failure modes

what usually goes wrong.

risk

leaking internals

Detect this early by defining a baseline, a measurable signal and a condition that would cause you to stop or redesign the approach.

risk

inconsistent errors

Detect this early by defining a baseline, a measurable signal and a condition that would cause you to stop or redesign the approach.

risk

no rate limits

Detect this early by defining a baseline, a measurable signal and a condition that would cause you to stop or redesign the approach.

proof of learning

Create a short APIs engineering note with one working artifact one metric one failure case and one decision about when you would or would not use it.

Save the result in your portfolio or project repository. A strong learning artifact should make your assumptions, metrics and failure analysis visible.