One source of truth for agent rules · Challenge 04

Verify and wire it in

Checkpoint l0410 ptsgated by test suiteAny coding agent (Claude Code 2.x / Codex CLI 0.x / Cursor)

Prove both verifier directions, run all three skins, then add the checker to your repository's review loop.

Doing this with your agent? One sentence starts the whole course:

Read https://flypython.com/skills/flypython/SKILL.md and start the FlyPython course `agent-rules-single-source`.

Verify and wire it in

Objective

Prove both verifier directions, run all three skins, then add the checker to your repository’s review loop.

The lesson

Run python verify.py starter (11/11 after your change) and python verify.py solution. Then apply it for real: point the checker at your own repository root and read the report. Wire it into review — a pre-commit hook, a CI step, or a checklist line — so drift fails loudly.

Exercise

Hand-review the diff: every change must be forced by a test
Record what the checker does NOT prove (it reads files; it cannot see agent behavior)

Checkpoint

The lesson’s commands run, and you can answer these in your own words (the agent asks; you answer — that is the gate):

Which command did this lesson run, and what did it decide?
What failed at the start, and why — in your own words?
Before trusting a similar change next time, what would you check first?

Expected evidence

The command transcript and your answers.

Hints

Stuck? Open one at a time.

Hint 1 — What this checkpoint tests

Both suites plus wiring: prove both verifier directions, run all three skins, then add the checker where your review loop actually runs.

Hint 2 — Both directions

The starter must fail where the scenario is broken and pass where it is clean — --expect-failure and the plain run tell you which side you are on.

Hint 3 — Wire it where it bites

A checker nobody runs is a rule file nobody reads: add it to a pre-commit hook or CI step in one repo you own, and record what it caught first.

Submit

Done? Record it.

Use the 8-character code printed by python verify.py. For a self-reported checkpoint, answer the lesson questions first, then run python verify.py --attest l04.

Youbrowser

Submit the claim code

Your agentauto-submit

Let the agent solve and submit

Hand it this checkpoint (copy button on hover) — it solves, verifies, and submits on its own:

Work on the FlyPython challenge "One source of truth for agent rules" (course id course-agent-rules), checkpoint l04.
Machine-readable brief: https://flypython.com/api/challenges/agent-rules-single-source
Open the course folder and read TASK.md first — it is the contract.
Rules: smallest change, no new dependencies, never edit tests/ or solution/.
Check starter/ with python verify.py; ask me the lesson questions before using --attest ID for any self-reported checkpoint.
Target: solve only checkpoint l04, and submit it as soon as it passes.

With a token from your agent page (env FLYPYTHON_TOKEN), it records the result directly:

curl -X POST https://flypython.com/api/claims \
  -H "Authorization: Bearer $FLYPYTHON_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"claims":[{"course":"agent-rules-single-source","checkpoint":"l04","code":"<8-char code>"}]}'

Or install the full FlyPython agent skill once and skip the paste.

Files

The starter and verifier

Solving runs on your machine — your agent fetches the course files itself via /api/challenges/agent-rules-single-source/files; you download nothing by hand. Prefer reading the source? Browse the folder on GitHub ↗