How do I install the Codex Exec skill?

Run npx skillmds add majiayu000/codex-exec-4 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Codex Exec safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: docs only. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Codex Exec?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Codex Exec free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Codex Exec?

majiayu000 (@majiayu000) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Codex Exec by majiayu000 — Agent Skill

Name: Codex Exec
Rating: 4.5 (4 reviews)
Author: majiayu000

File contents

Codex Exec — one-shot runtime adapter

Run exactly one caller-supplied Codex prompt and capture its result. This skill does not choose work, retry failures, validate by itself, or control continuation.

One prompt, one process, one captured artifact is what makes the run auditable: when nothing loops, every byte of output traces to exactly one invocation, and a disagreement about what happened is settled by the artifact.

Named failure mode — stdin hang: a non-TTY run left waiting forever on an open stdin nobody will write to; always pipe the prompt or close the stream.

Anti-pattern: granting workspace-write or network access "in case the prompt needs it". Corrective: match the sandbox to the declared effects; a review prompt runs read-only, full stop.

Procedure

Confirm codex login status for the intended profile.
Set the working root explicitly with -C.
Match the sandbox to the requested effects: read-only for offline review, workspace-write for authorized edits, and broader access only when the caller explicitly requires network or external effects.
Pipe the prompt to stdin (or close stdin) in non-TTY execution so the process cannot wait indefinitely for input.
Capture the final response with -o, JSONL, or an output schema.
Report the process exit status and captured artifact, then stop.

A nonzero process exit is runtime evidence, not a semantic verdict. The caller decides whether to launch another invocation.

Example

printf '%s\n' "$PROMPT" | codex exec -C "$WORKSPACE" -s read-only \
  -o "$OUTPUT" -

For a validator, the prompt must name the acceptance digest, exact subject manifest digest, author context ID, evidence, and required checked/not-checked report. The validator context ID must be distinct from the author's before a PASS verdict is possible. When the caller elects a cross-model fresh validator, record model identities per the agent-native model-dispatch recipe and match the sandbox to declared effects.

---name: codex-exec-4description: Run one caller-supplied Codex command non-interactively and capture evidence. Triggers: "run Codex headless", "capture Codex evidence".---# Codex Exec — one-shot runtime adapter Run exactly one caller-supplied Codex prompt and capture its result. This skill does not choose work, retry failures, validate by itself, or control continuation. One prompt, one process, one captured artifact is what makes the run auditable: when nothing loops, every byte of output traces to exactly one invocation, and a disagreement about what happened is settled by the artifact. Named failure mode — **stdin hang**: a non-TTY run left waiting forever on an open stdin nobody will write to; always pipe the prompt or close the stream. Anti-pattern: granting workspace-write or network access "in case the prompt needs it". Corrective: match the sandbox to the declared effects; a review prompt runs read-only, full stop. ## Procedure 1. Confirm `codex login status` for the intended profile. 2. Set the working root explicitly with `-C`. 3. Match the sandbox to the requested effects: read-only for offline review, workspace-write for authorized edits, and broader access only when the caller explicitly requires network or external effects. 4. Pipe the prompt to stdin (or close stdin) in non-TTY execution so the process cannot wait indefinitely for input. 5. Capture the final response with `-o`, JSONL, or an output schema. 6. Report the process exit status and captured artifact, then stop. A nonzero process exit is runtime evidence, not a semantic verdict. The caller decides whether to launch another invocation. ## Example ```bash printf '%s\n' "$PROMPT" | codex exec -C "$WORKSPACE" -s read-only \ -o "$OUTPUT" - ``` For a validator, the prompt must name the acceptance digest, exact subject manifest digest, author context ID, evidence, and required checked/not-checked report. The validator context ID must be distinct from the author's before a `PASS` verdict is possible. When the caller elects a cross-model fresh validator, record model identities per the `agent-native` model-dispatch recipe and match the sandbox to declared effects.

Frequently asked questions