Module · Codex Engineer
Working in a Codebase
Read before you write - how to find the real code and shrink the change to fit.
TOPIC 01
Orientation
Find the code that actually runs, instead of the code that looks like it.
What you'll practice
- Read Before You Write — guided · beginner
- Search the Way a Maintainer Would — practice · intermediate
A command you'll meet
cat ~/codex/repo/orientation.mdThe fastest way to a good change is reading the code that already exists. Open the task below for the full walkthrough.
Hands-On Tasks in This Topic (2)
Read Before You Write
An agent that edits before it reads produces code that duplicates what is already there. Write the orientation routine that prevents it.
Search the Way a Maintainer Would
Searching by the name of a function finds the call site, not the definition. Write the search strategy that finds the code that decides the behaviour.
TOPIC 02
Narrowing the Scope
Turn a vague request into a change that fits the code that is already there.
What you'll practice
- Narrow a Vague Request — practice · intermediate
- Verify the Change Against the Repo — challenge · advanced
A command you'll meet
cat ~/codex/repo/narrowing.mdA vague request produces a vague diff. Open the task below for the full walkthrough.
Hands-On Tasks in This Topic (2)
Narrow a Vague Request
Make it faster is not a task, it is a direction. Write the questions that turn a vague request into a change with a boundary.
Verify the Change Against the Repo
The agent believes it is done. You check against the repository, not against its summary. Write the verification routine.