Learning Space

Module 03

Codex mastery path

Build fluent Codex practice
one submodule at a time.

Module 03 is no longer one long reference page. It is a guided learning path that splits Codex into practical stages: start safely, prompt with structure, debug and review well, build repo memory, then scale into safe autonomy.

Start Submodule 03.1 View the full roadmap

Course map

Move through Module 03 like a real progression, not a single scroll.

The overview page stays thin on purpose. Use it to orient yourself, then enter the next lesson with a concrete practice target.

Overview

Hub

Roadmap, surfaces, cadence, and the practice loop for the whole module.

 03.1

Get started

Install, choose the surface, run a first bounded task, and resume a thread.

 03.2

Prompting

Shape tasks with goal, context, constraints, and done-when.

 03.3

Review

Reproduce, validate, inspect diffs, and review with discipline.

 03.4

Memory

Build durable repo guidance with AGENTS.md, skills, rules, and MCP.

 03.5

Autonomy

Choose approvals, sandboxing, cloud runs, and parallel work intentionally.

Learning path

Five submodules, five different kinds of Codex judgment.

Do not skip ahead just because later topics sound more powerful. Most Codex mistakes come from weak fundamentals, not missing advanced flags.

03.1

45-60 min

Start well

Choose CLI or IDE, learn the first-session loop, and finish one task you can actually verify.

Enter 03.1
03.2

60-75 min

Prompt well

Turn ambiguous asks into structured work requests that give Codex the right frame to operate.

Enter 03.2
03.3

60-75 min

Verify well

Use reproduction steps, validation commands, `/review`, and diffs to build trust correctly.

Enter 03.3
03.4

60 min

Remember well

Capture durable repo guidance in AGENTS.md, rules, skills, and MCP only when it pays off.

Enter 03.4
03.5

60-90 min

Scale well

Control approvals, sandboxing, cloud runs, and parallel work so more autonomy does not mean more chaos.

Enter 03.5

Surfaces

Learn where Codex fits before you learn how to push it harder.

The surface changes what context Codex sees by default, how you validate work, and how much friction you feel.

CLI

Best for deliberate practice

Use the Codex CLI when you want visible command flow, explicit prompts, approval control, and a clean training environment.

IDE

Best for local coding flow

Use the IDE extension when open files and editor context help, but still force yourself to write strong task framing and validation steps.

Cloud

Best for long-running work

Use remote tasks when the work should keep going after you disconnect, but avoid overlapping threads that touch the same files.

Study cadence

Treat Codex fluency as repeated reps, not one heroic binge.

Codex skill compounds when each session teaches both task completion and operational judgment.

7-day sprint

Fast path

Do one submodule per day, then spend days six and seven replaying the exercises with your own repository.

3-week path

Deep path

Take two to three sessions per submodule: first read, then practice, then rewrite your own prompts, AGENTS.md, and safeguards from evidence.

Session loop

Every Codex session should leave behind more than code.

Good practice does three jobs at once: it solves something, teaches you something, and upgrades the system for next time.

Before the session

Pick one bounded objective, define what done means, and decide how you will verify the result before Codex touches anything.

After the session

Capture what should move into AGENTS.md, a reusable prompt, a skill, a rule, or a personal checklist so the next run starts stronger.

Start with 03.1 unless you already have a clean, repeatable first-session workflow.

The biggest mistake is trying to learn advanced Codex controls before you can run one safe, well-scoped task end to end.

Start 03.1