Use Codex

Use Codex

Codex is a separate agent with its own model and reasoning. You orchestrate it and own the final integration: Codex drafts → you review and reconcile → user approves. Never auto-apply its output. It starts cold on this repo — always include the house rules (bottom) in the brief.

Setup

Requires the codex CLI: npm install -g @openai/codex, then the user runs codex login (interactive, ChatGPT/OpenAI account). On Windows, npm globals often aren't on the shell PATH — if codex isn't found but node is installed, prepend them first:

$env:Path = "C:\Program Files\nodejs;$env:APPDATA\npm;$env:Path"

Delegate a generic task

codex exec --sandbox workspace-write -a never "<task, acceptance criteria, constraints>"

• Codex edits the working tree directly. Show the user its plan and the resulting git diff before integrating.
• Analysis only, no edits: use --sandbox read-only.
• Model / effort per run: -m <model> and -c model_reasoning_effort=<minimal|low|medium|high>. Deep pass: codex exec -m gpt-5-codex -c model_reasoning_effort=high …. Persistent defaults live in ~/.codex/config.toml (or -p <profile>).

Delegate a code review

If the official plugin is installed, tell the user to run /codex:review (--base <ref>, --wait/--background) or /codex:adversarial-review (challenges the design, good before big merges) — you cannot type slash commands yourself. Otherwise run it directly:

codex exec review --base dev

Feature branches review against dev. Require file:line citations; priority correctness > security > spec > performance > maintainability > tests; no style nits. Render verdict + findings for the user; do not apply fixes unasked.

Other routes

• MCP server (autonomous multi-turn hand-off): user registers once with claude mcp add codex -- codex mcp-server; you then get mcp__codex__codex / mcp__codex__codex-reply tools to drive Codex sessions yourself.
• Official plugin (codex-plugin-cc) — user installs with: /plugin marketplace add openai/codex-plugin-cc, then /plugin install codex@openai-codex, /reload-plugins, /codex:setup. Beyond reviews it adds /codex:rescue (delegate a fix), /codex:transfer (persistent Codex thread), /codex:status|result|cancel (background jobs). Optional --enable-review-gate blocks Claude until Codex signs off — off by default, suggest only if asked. Plugin commands take model/effort from ~/.codex/config.toml, not flags.

House rules (include in every brief)

• Follow the repo's licensing policy: no third-party CV library names in committed text; respect clean-room boundaries.
• Branch flow is dev → release; feature branches base on dev.
• No new dependencies without surfacing them; match existing style; leave tests runnable.