Codex Integration

Codex Integration Skill

This skill defines delegation patterns for Codex-assisted coding.

Pre-check

Before Codex operations:

1. Check for .codex/config.toml.
2. If missing, ask user before bootstrapping.
3. Bootstrap using skills/codex-ecosystem/SKILL.md guidance after confirmation.

Default configuration

model = "gpt-5.4"
model_reasoning_effort = "xhigh"
sandbox_mode = "workspace-write"
approval_policy = "on-request"

When to delegate

Delegate when tasks are multi-file, long-running, architecture-heavy, or require deep analysis.

Interaction modes

MCP mode

Use mcp__codex-native__codex and mcp__codex-native__codex-reply for interactive multi-turn work.

Headless mode

Use codex exec for one-off scripted tasks.

Background mode

Use background execution for long tasks and summarize results after completion.

Session handling

• threadId should be preserved for follow-up calls.
• Session bookkeeping in scripts/codex-interactive.py is process-local and in-memory.

Model selection

• Simple: gpt-5.4 + low reasoning
• Medium: gpt-5.4 + medium reasoning
• Complex: gpt-5.4 + high reasoning
• Critical/security: gpt-5.4 + xhigh reasoning

Prompt guidance

When crafting prompts for Codex, follow the GPT-5.4 prompt patterns in references/codex-prompt-guidance.md. Key patterns:

• Use output contracts to constrain what and how much the model outputs.
• Use tool persistence rules so Codex doesn't stop early.
• Use completeness contracts for multi-step or batch tasks.
• Use verification loops before finalizing results.
• For coding tasks, apply autonomy & persistence — Codex should carry changes through implementation, not stop at analysis.

Best practices

1. Keep prompts specific — follow prompt guidance patterns.
2. Validate outputs before applying.
3. Ask before enabling MCP servers or writing config files.
4. Enable only MCPs needed for the current task.
5. Use dependency checking for multi-step workflows.
6. Apply action safety frames for irreversible operations.

References

• references/codex-cli-reference.md — CLI commands, flags, config
• references/codex-prompt-guidance.md — GPT-5.4 prompt patterns and best practices
• examples/delegation-patterns.md — delegation examples
• skills/codex-ecosystem/SKILL.md — bootstrap and MCP setup