Codex Practice Lab

This repo is a small operations gym for practicing Codex itself. The goal is not to build one large app. The goal is to rehearse the workflows that make Codex useful in a real engineering interview or work session: orienting in a repo, writing good instructions, planning before edits, handling risky commands, checking diffs, and validating results.

This lab is intentionally separate from support-ticket-practice. Use this repo for practicing Codex behavior: instruction writing, context gathering, safety judgment, config reasoning, and session steering. Use the app repo for realistic feature and bug-fix drills.

How to Practice

For each exercise:

1. Open the exercise brief.md.
2. Start a new Codex thread from this repo.
3. Give Codex the task from the brief.
4. Make Codex inspect the fixture before editing.
5. Ask for a short plan when the task is ambiguous.
6. Let Codex implement only after the plan is clear.
7. Review the diff, run the listed checks, and write a short debrief.

Exercises

Exercise	Skill	Status
01-agents-instructions	Root and nested AGENTS.md guidance	Ready
02-context-gathering	Repo orientation before edits	Ready
03-security-approvals	Risk review, secrets, and command safety	Ready
04-config-profiles	User config, project config, profiles, and safety boundaries	Ready
05-slash-command-flow	Session steering with slash commands	Ready
06-diff-commit-hygiene	Diff review, staging discipline, and commit-ready summaries	Ready
07-delegation-worktrees	Subagent/worktree delegation and evidence merging	Ready

See docs/codex-skill-map.md when choosing which skill to practice next.

Validation

This repo has no global build. Validate individual fixtures from inside their directories when they include a package.json:

npm test

Current JavaScript fixtures:

• exercises/01-agents-instructions/fixture/legacy-widget
• exercises/02-context-gathering/fixture/ticket-search
• exercises/06-diff-commit-hygiene/fixture/changelog-helper

Some exercises are review-only or documentation-oriented and do not have a test harness. For those, validate by checking the brief's "Done When" section, reading the final diff, and confirming any changed TOML or Markdown still parses or renders sensibly.

For repo structure checks:

rg --files
git status --short