The challenge
Choose a repository with tests and add one scoped improvement: a filter, empty state, validation, or small command. It should fit within one reviewable session.
Phase 1: understand
Do not edit yet. Trace current behavior, locate patterns and tests, read repository instructions, and propose a plan of at most five steps with risks.
Phase 2: build
Implement the approved plan with the smallest change. Add or adjust a test that protects the behavior. Preserve unrelated work and follow existing conventions.
Phase 3: verify
Run focused tests, lint, and build. Manually inspect the flow when UI is involved. Review the diff and fix regressions before summarizing.
Rubric
- Scope: the diff contains only the requested improvement.
- Correctness: the test protects the behavior and passes.
- Quality: the code fits the repository and avoids duplicate solutions.
- Security: no secrets or unnecessary permissions appear.
- Handoff: the summary separates verified facts from remaining risks.
Finish
End with git status, the diff, executed commands, and a self-review. Only then create a commit with one clear idea. The goal is not more code, but a change another programmer can trust and maintain.
Lesson deliverable
What you will build
Practical evidence for "Final project: deliver a complete change" applied to a real or training repository.
Why it matters
The goal is to turn the lesson into a verifiable action, not just reading.
Starter repository or files
A small Git repository with Git, README, and one known validation command.
Steps
- 1. Inspect Git status before starting.
- 2. Ask Codex to work with limited scope.
- 3. Run the verification command.
- 4. Review the diff or produced evidence.
- 5. Record what is verified and what remains open.
Copy-ready Codex request
Apply the lesson "Final project: deliver a complete change" in this repository. Work in small changes, cite concrete files, run one verification, and finish with evidence and risks.
Expected result
A reviewable output: map, plan, diff, test, or report depending on the lesson.
Verification command
git status --short && git diff --stat
Manual check
Check that the result matches the requested scope and Codex did not touch unrelated files.
Mini exercise
Repeat the practice in another folder of the same repository, changing only one constraint.
Show solution
Keep the same goal, add one explicit constraint, and compare whether the final evidence improves.
Evidence to save
Save the prompt, commands run, relevant output, and git diff --stat.