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Codex Rules Reference

A reference skill that explains which rule files Codex Rules reads and which environment variables control it.

Dev & CodingIntermediate★ 67,531⑂ 5,507AI score 6/10Last updated: Aug 9, 2026

What it does

  • Explains when Codex Rules injects context: static project instructions on SessionStart and UserPromptSubmit, plus file-matched rules after Codex apply_patch, with per-session deduplication.
  • Lists every supported rule source: CONTEXT.md, .omo/rules/**/*.md, .claude/rules/**/*.md, .cursor/rules/**/*.md, .github/instructions/**/*.md, .github/copilot-instructions.md.
  • Documents the environment knobs (CODEX_RULES_DISABLED, CODEX_RULES_MODE, CODEX_RULES_MAX_RULE_CHARS, CODEX_RULES_MAX_RESULT_CHARS, CODEX_RULES_ENABLED_SOURCES) and the legacy PI_RULES_* fallbacks.

Who it's for

  • Developers running the oh-my-openagent / omo-codex plugin who need fine control over rule injection.
  • Repo maintainers mixing multiple rule conventions such as .cursor/rules and .github/instructions.
  • Anyone migrating from pi-rules who needs to know whether old variables still work.

Examples

  1. "Why aren't my project rules showing up?" — the skill checks your file path against the supported source list and CODEX_RULES_ENABLED_SOURCES.
  2. "Temporarily disable rule injection" — it points you to CODEX_RULES_DISABLED=1 or CODEX_RULES_MODE=off.
  3. "Injected rules are too long" — it explains capping output with CODEX_RULES_MAX_RULE_CHARS / CODEX_RULES_MAX_RESULT_CHARS.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/code-yeongyu/oh-my-openagent/HEAD/packages/omo-codex/plugin/components/rules/skills/rules/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
↓ Download ZIP
Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the packages/omo-codex/plugin/components/rules/skills/rules folder from the GitHub repo code-yeongyu/oh-my-openagent into my ~/.claude/skills/rules/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/code-yeongyu/oh-my-openagent.git && mkdir -p ~/.claude/skills/rules && cp -r oh-my-openagent/packages/omo-codex/plugin/components/rules/skills/rules/* ~/.claude/skills/rules/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Open a terminal and go to your working directory.
  2. Clone the repository: git clone https://github.com/code-yeongyu/oh-my-openagent.git
  3. Create the skill folder: mkdir -p ~/.claude/skills/rules
  4. Copy the skill files: cp -r oh-my-openagent/packages/omo-codex/plugin/components/rules/skills/rules/* ~/.claude/skills/rules/
  5. Restart Claude Code, then ask something like "How do I configure Codex Rules?" to trigger the skill.
  6. (Optional) To use the actual rule-injection feature, install and enable the omo-codex plugin itself as described in the repo README.
View source on GitHub ↗License: NOASSERTION