Call Codex

Invoke OpenAI Codex CLI non-interactively to get a second opinion or critique, then present the result.

Command Pattern

cat <<'PROMPT' | codex exec --full-auto --skip-git-repo-check -o /tmp/codex_output.md -
<your prompt here>
Do NOT modify any files. Do NOT run any shell commands. Only output your analysis as text.
PROMPT

Then read /tmp/codex_output.md for the clean response.

Workflow

1. Construct the prompt. Combine the user's request with relevant context (file contents, code snippets, error messages). Always append: Do NOT modify any files. Do NOT run any shell commands. Only output your analysis as text.
2. Run the command. Use cat <<'PROMPT' | codex exec --full-auto --skip-git-repo-check -o /tmp/codex_output.md - with the constructed prompt. Use single-quoted heredoc delimiter ('PROMPT') to prevent shell expansion.
3. Read the output. Read /tmp/codex_output.md for Codex's response. The -o file contains only the agent's final message (stdout includes session metadata).
4. Present the result. Summarize or relay Codex's response to the user. If the user asked for a comparison, contrast Codex's view with your own.

Key Flags

Flag	Purpose
exec	Non-interactive subcommand (required for scripted use)
--full-auto	Skips confirmation prompts (alias for -a on-request --sandbox workspace-write)
--skip-git-repo-check	Run outside or independent of current git repo
-o /tmp/codex_output.md	Write final message to file for clean reading
- (trailing)	Read prompt from stdin (avoids shell quoting issues)

Optional Flags

• -m <model> to override the default model (default: gpt-5.4)
• -C /path to set a different working directory for Codex

Example

User asks: "Ask codex to review my sort function in utils.py"

1. Read utils.py to get the sort function code
2. Run:

cat <<'PROMPT' | codex exec --full-auto --skip-git-repo-check -o /tmp/codex_output.md -
Review the following Python sort function for correctness, efficiency, and style:

```python
<contents of the sort function>

Do NOT modify any files. Do NOT run any shell commands. Only output your critique as text. PROMPT

3. Read `/tmp/codex_output.md`
4. Present Codex's feedback to the user

## Important Notes

- Always include the safety instruction ("Do NOT modify any files...") since `--full-auto` grants write access to the sandbox.
- Use single-quoted heredoc delimiter `'PROMPT'` to prevent `$variable` expansion and `` `backtick` `` execution in the prompt text.
- If `codex` is not found, inform the user to install it (`brew install codex` or see OpenAI docs).
- Token usage is printed to stdout at the end of the session.