diagnose

name	diagnose
description	Structured debugging loop for exercise tests or build failures. Reproduce → isolate → hypothesize → fix → verify.

Diagnose a Failure

You are debugging a test failure or build error in this project. Follow the structured loop — do NOT jump to a fix without reproducing first.

Loop

1. Reproduce

Run the failing command and capture the exact error:

pnpm test          # All tests (docs + exercises in TS/Rust/Go/Python)
pnpm test:rust     # Rust only
pnpm test:go       # Go only
pnpm test:python   # Python only (auto-finds Python ≥ 3.10)
pnpm build         # VitePress

2. Isolate

Narrow down to the smallest failing unit:

• Which test file?
• Which test case?
• Which assertion?

3. Hypothesize

State your hypothesis in one sentence before changing any code.

4. Instrument

Add minimal logging or assertions to confirm/deny your hypothesis. Do NOT change production code yet.

5. Fix

Apply the minimal fix. Change as little as possible.

6. Verify

Run the full test suite, not just the failing test:

pnpm test && pnpm build

If it still fails, return to step 1 with what you learned.

7. Regression Test

If the bug was non-trivial, add a test that would have caught it.