Run sessions on Codex

Codex is OpenAI's coding agent. In Yardmaster it works like any other session, with the same sessions list, Inbox and chat. A common use is a second opinion: when Claude is stuck, start a Codex session on the same project and compare.

Set up Codex#

1. 1

   Open Settings > Accounts and turn on Show alternative AI providers.

2. 2

   Under Other AI tools, open Codex. If the Codex program is missing, click Install Codex CLI.

3. 3

   Click Sign in with ChatGPT. A terminal window opens: finish the ChatGPT sign-in there, then come back.

4. 4

   Turn on Allow Codex sessions in any project.

Then start a session and, before your first message, pick Codex from the engine name next to the session title. See Choose your AI engine.

Your Claude rules come along#

A Codex session follows the same rules you wrote for Claude: your own CLAUDE.md file (and the files it pulls in), your House Rules, and the project's CLAUDE.md. Yardmaster hands them to Codex when the conversation starts, with a short note that explains Claude-only words, such as "Skill tool".

If the project already has an AGENTS.md file, Codex reads that one itself, so Yardmaster leaves the project's CLAUDE.md out to avoid giving it the same rules twice. Yardmaster never reads secret files, such as keys or passwords, into these rules, even when a rules file points at one.

Common key, token and password formats written in the rules themselves are removed before the rules are sent. This is a safety net, not a guarantee, so do not keep secrets in these files.

To keep your own rules to Claude, turn off Give Codex and Anti-Gravity my Claude rules in Settings > Accounts under Other AI tools. New Codex conversations then get only the project's rules.

Choose how often Codex asks#

Codex permission level decides when a Codex session stops to ask you: Ask before every command (the default), Ask only when Codex reaches outside the project, or Allow all (never ask). Its questions appear as Needs You, like Claude's. A change applies to Codex sessions you start afterwards.

Use more than one ChatGPT account#

At the top of Settings > Accounts, switch to the Codex tab. Click Log In with ChatGPT to add an account; each one is kept separate from your own Codex login, and the active one is used for new Codex sessions. The optional OpenAI API key there overrides the logins.