codex

A guide for handing coding work to OpenAI Codex CLI, a command-line coding agent. It covers using Codex in a Git repository for feature work, refactoring, pull-request reviews, and batches of fixes.

In plain words
What is it for?
Use it to build features, refactor projects, review pull requests, fix several issues at once, or run one-off coding tasks such as creating a small program.
Why use it?
It provides a documented way to ask Codex to inspect and modify a project, reducing the need to perform multi-file coding tasks manually. It also explains the required CLI installation, authentication, and repository setup.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/john-data-chen/hermes-agent-backup/codex
Any agent
npx skills add john-data-chen/hermes-agent-backup --skill codex
Clone the repo
git clone --depth 1 https://github.com/john-data-chen/hermes-agent-backup

Made for: Claude Code, Codex.

Per session 17 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,413 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00017 $0.01413
Opus 5 $0.00009 $0.00707
Sonnet 5 $0.00003 $0.00283
Haiku 4.5 $0.00002 $0.00141

Measured 2d ago against content hash bdf27c02052f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codex scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • codex — 100% identical, 0 lines differ
skills/autonomous-ai-agents/codex/SKILL.md · 150 lines

How it starts

The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codex CLI

Delegate coding tasks to Codex via the Hermes terminal. Codex is OpenAI's autonomous coding agent CLI.

When to use

  • Building features
  • Refactoring
  • PR reviews
  • Batch issue fixing

Requires the codex CLI and a git repository.

Prerequisites

  • Codex installed: npm install -g @openai/codex
  • OpenAI auth configured: either OPENAI_API_KEY or Codex OAuth credentials from the Codex CLI login flow
  • Must run inside a git repository — Codex refuses to run outside one
  • Use pty=true in terminal calls — Codex is an interactive terminal app

For Hermes itself, model.provider: openai-codex uses Hermes-managed Codex OAuth from ~/.hermes/auth.json after hermes auth add openai-codex. For the standalone Codex CLI, a valid CLI OAuth session may live under ~/.codex/auth.json; do not treat a missing OPENAI_API_KEY alone as proof that Codex auth is missing.

One-Shot Tasks

terminal(command="codex exec 'Add dark mode toggle to settings'", workdir="~/project", pty=true)

For scratch work (Codex needs a git repo):

terminal(command="cd $(mktemp -d) && git init && codex exec 'Build a snake game in Python'", pty=true)

Background Mode (Long Tasks)

# Start in background with PTY
terminal(command="codex exec --full-auto 'Refactor the auth module'", workdir="~/project", background=true, pty=true)
# Returns session_id

# Monitor progress
process(action="poll", session_id="<id>")
process(action="log", session_id="<id>")

# Send input if Codex asks a question
process(action="submit", session_id="<id>", data="yes")

# Kill if needed
process(action="kill", session_id="<id>")

Key Flags

Flag Effect
exec "prompt" One-shot execution, exits when done
--full-auto Sandboxed but auto-approves file changes in workspace
--yolo No sandbox, no approvals (fastest, most dangerous)
--sandbox danger-full-access No Codex sandbox; useful when the host service context breaks bubblewrap

Read the full file on GitHub · 150 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 150 lines · 17 tokens per session scan A bdf27c02052f

Subscribe to this mod's changes

codex is a skill published in the GitHub repository john-data-chen/hermes-agent-backup (2 stars, last pushed 1mo ago), licensed MIT. It adds 17 tokens to every session and 1,413 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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