Agent skill · software engineering · sickn33
codex-subagent
Launch Codex CLI as an isolated subagent for bounded coding, review, or verification tasks.
Why this skill is useful
Adds executable scripts for launching Codex CLI as a subagent, enabling bounded coding tasks and independent verification workflows.
What it needs
Requires codex installed locally. Requires openai account access. About 3k tokens when loaded. Last updated 2026-08-07. 44,571 stars on the source repository.
What this skill does
Codex CLI as a Subagent When to Use Use when a bounded coding, review, or verification task can run in a separate Codex CLI session. Use when parallel work needs explicit file ownership and a clear definition of done. Codex CLI is OpenAI's terminal coding agent. codex exec runs it non-interactively: it works autonomously in a sandbox, streams progress to stderr, and prints only the final message to stdout. Auth reuses the user's ChatGPT subscription — never an API key. When to delegate Self-contained coding task with clear success criteria (fix, feature, refactor, review). Parallel work: several independent tasks at once (see Parallel runs). Second opinion / independent verification of your own changes. Do NOT delegate tasks that need conversation context you can't fully write into the prompt. Preflight Not logged in → stop and tell the user to run codex login (one-time browser OAuth). Never read, print, or copy credentials (~/.codex/auth.json). Launch </dev/null is MANDATORY when stdin is not a real terminal (background shells, scripts): codex treats open stdin as extra context and waits forever for EOF. Codex sees NOTHING of your conversation. Put all context in the prompt: goal, relevant paths, constraints, and how to verify it's done. Long prompt? Pipe it via stdin instead: codex exec [flags] - < /tmp/task.md. Wrap the command in a background/Bash subagent if your host agent has one (Cursor: Task tool with a shell subagent) so Codex's verbose stream stays out of the parent context. Fallback: a plain background terminal. Runs take minutes and have no built-in timeout — background it and monitor. Optional: -m <model> to override the model, --json for JSONL event stream. Collect results Follow-up in the same session (run from the same cwd — resume filters by cwd): Parallel runs Parallelize only genuinely independent tasks, and assign file ownership upfront so results merge cleanly. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills sickn33/codex-subagent