codex-build

codex-build is a skill for Claude Code, Codex from chaseai-yt/claudex-loop. It costs 0 tokens per session (2,517 once invoked), scanned B, original, no licence file.

A build process in which OpenAI Codex implements a locked software specification while Claude remains the plan writer and reviewer. Codex receives write access, then the resulting changes are reviewed and tested.

In plain words
What is it for?
Use it to implement a frozen PLAN.md or other locked plan, inspect the full code diff, and run a proof test.
Why use it?
It separates the agreed requirements from implementation and provides a review step after the code is built.

Skill for Claude CodeCodex

Part of the claudex-loop plugin — 5 skills shipped together

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/chaseai-yt/claudex-loop/codex-build
Any agent
npx skills add chaseai-yt/claudex-loop --skill codex-build
Clone the repo
git clone --depth 1 https://github.com/chaseai-yt/claudex-loop

Made for: Claude Code, Codex.

Or install claudex-loop, the plugin that ships this one along with the rest of its 5 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for codex-build

README.md
[![agentmods](https://agentmods.dev/badge/skills/chaseai-yt/claudex-loop/codex-build.svg)](https://agentmods.dev/skills/chaseai-yt/claudex-loop/codex-build)
Your own site
<a href="https://agentmods.dev/skills/chaseai-yt/claudex-loop/codex-build"><img src="https://agentmods.dev/badge/skills/chaseai-yt/claudex-loop/codex-build.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,517 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin unknown 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 5.1 $0.00000 $0.02517
Opus 5 $0.00000 $0.01259
Sonnet 5 $0.00000 $0.00503
Haiku 4.5 $0.00000 $0.00252

Measured 6d ago against content hash 31cb7b906a52, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade B, and why

codex-build scanned grade B with 1 finding 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 6d 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

- Do NOT pin `-m` or model config (e.g. `model_reasoning_effort`) unless the user asks. Pinning `gpt-5.x-codex` variants 400s on ChatGPT-account auth; config defaults come from `~/.codex/config.toml`.
skills/codex-build/SKILL.md · 116 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

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. 6d ago First seen · 116 lines · 0 tokens per session scan B 31cb7b906a52

Subscribe to this mod's changes

codex-build is a skill published in the GitHub repository chaseai-yt/claudex-loop (1,618 stars, last pushed 11d ago), with no licence file. It costs nothing until one of its globs matches a file; then it loads 2,517 tokens. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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