Module 03 — Practice: from "make it nice" to a spec

Time: 200 minutes · Artifact: labs/03-specs/

Task 1. Break down three tasks (40 min)

Take three vague tasks:

A) "Add caching"
B) "Fix the bugs in the API"
C) "Make the interface prettier"

For each, write a spec using the templates/spec.md template, including the "out of scope" block.

Acceptance: each spec has at least 3 verifiable requirements and 2 acceptance criteria (a command or a test).

Task 2. Comparison in practice (60 min)

Pick one spec (for example, A) and implement the task twice:

Run 1 — "vibe":

Add caching to the project.

Run 2 — by the spec:

<insert the full spec>
Start with a plan. Don't write code until I confirm.

Record a table: | Metric | Run 1 | Run 2 | | --- | --- | --- | | files touched | | | | unnecessary changes | | | | tests added | | | | passed on the first try | | | | cost | | |

Acceptance: there is a conclusion about which part of the spec had the biggest effect.

Task 3. Plan before code (30 min)

For spec B (bugs in the API):

Don't write code. Give me a plan:
1) which files you'll look at and why;
2) hypotheses about the causes of the bugs;
3) how you'll verify each hypothesis;
4) what might break.

Edit the plan (remove the excess, add what's missing), then allow the implementation.

Acceptance: the report contains the original plan, your edits, and the final diff. Compare: how many plan edits vs how many code edits.

Task 4. Decomposition (40 min)

Take task C and break it into 4–6 steps so that each one:

• changes ≤ 2 files;
• has its own verification criterion;
• is committed separately.

Acceptance: a list of steps with criteria + at least 2 completed steps with commits.

Task 5. Prompt library (30 min)

Create labs/03-specs/prompts.md — 5 reusable templates:

1. "Give me a plan, don't write code"
2. "Explain the existing code"
3. "Add tests for a function"
4. "Find the cause of a failing test"
5. "Review my diff like a strict reviewer"

Format: title, template, when to use it, a filled-in example.

Submission criteria

• Three specs from the template, with an "out of scope" block.
• "Vibe vs spec" comparison table.
• A plan with your edits and the final diff.
• Decomposition + ≥ 2 commits.
• prompts.md with 5 templates.