Constellation · The Forge

Codex: OpenAI's coding agent, decoded

Seventeen guides to working with Codex: repository instructions, CLI use, skills, review, longer task loops, and measured harness improvement.

17 of 17 guides live · fact-checked against official docs

Chapter 0

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Codex 101

Understand Codex across the CLI, IDE, ChatGPT desktop app, and cloud — then get running.

8 minbasics / install / codex

Chapter 1

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AGENTS.md

Write the instruction file Codex actually follows — and nest it right.

10 minagents.md / configuration / memory

Chapter 2

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Prompting

Frame tasks so Codex plans, implements, and verifies the way you want.

9 minprompting / patterns / templates

Chapter 3

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Playbook

Apply OpenAI's own best practices — context, planning, review, MCP.

9 minbest practices / workflow / codex

Chapter 4

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CLI Config

Configure approvals, sandboxing, profiles, and MCP — once, correctly.

10 mincli / configuration / security

Chapter 5

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The Bridge

Know which agent fits which job — and how to run both in one repo.

11 mincomparison / claude / codex

Chapter 6

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CLI Reference

Drive Codex from the terminal with the core subcommands, flags, and slash commands.

11 mincli / reference / codex

Chapter 7

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Cloud & CI

Delegate to isolated cloud containers, review the diffs, and wire Codex into GitHub and CI.

11 mincloud / ci / automation

Chapter 8

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Codex MCP

Connect Codex to your tools the right way — stdio vs HTTP, OAuth, per-tool approval, and Codex-as-server.

10 minmcp / integrations / codex

Chapter 9

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SDK & Subagents

Drive Codex from TypeScript or Python and fan tasks out to parallel sub-agents.

11 minsdk / subagents / codex

Chapter 10

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Surfaces

Pick the right Codex surface — and use the IDE, app, and web features most people miss.

8 minsurfaces / ide / codex

Chapter 11

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Extensions

Codex’s extension ecosystem — apps, plugins, hooks, memories, and experimental flags — installed, scoped, and managed.

8 minextensions / plugins / codex

Chapter 12

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TUI Tuning

Turn Codex’s catalogued-but-unexplained UI commands into real habits — personality, themes, Vim, keymaps, and the fast lane.

7 mininterface / customization / codex

Chapter 13

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Code Review

Make Codex review every pull request and only surface the issues that matter.

11 mincodex / code-review / github / ci / agents-md / automation

Chapter 14

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Loop Engineering

Use /goal, automations, AGENTS.md, skills, subagents, and review gates as one control system.

21 minloop engineering / goal / automations / agents.md / subagents

Chapter 15

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Harness Config

Build a repeatable Codex harness with AGENTS.md, config.toml, skills, MCP, approvals, sandboxing, goals, and validation.

18 minharness engineering / configuration / codex / agents.md / sandboxing

Chapter 16

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Recursive Self-Improvement Guide

Turn repeated delivery failures into one measured Codex skill change.

21 mincodex / recursive improvement / skills / evals