rules

A set of automatic project instructions for Codex. It reads rules from supported files and applies them to relevant work in a project.

In plain words
What is it for?
Use it to load instructions from files such as CONTEXT.md, GitHub instruction files, and editor rule folders, and to control how those rules are enabled.
Why use it?
It keeps coding work aligned with the project's written conventions without requiring the same guidance to be repeated in every request. It can also add rules that match the files being changed.

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/code-yeongyu/lazycodex/rules
Any agent
npx skills add code-yeongyu/lazycodex --skill rules
Clone the repo
git clone --depth 1 https://github.com/code-yeongyu/lazycodex

Made for: Claude Code, Codex.

Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 264 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 $0.00028 $0.00264
Opus 5 $0.00014 $0.00132
Sonnet 5 $0.00006 $0.00053
Haiku 4.5 $0.00003 $0.00026

Measured yesterday against content hash 266d44b17f9c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

rules 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 yesterday.

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

2 near-identical copies found in the catalogue:

  • rules — 89% identical, 6 lines differ
  • rules — 89% identical, 6 lines differ
plugins/omo/components/rules/skills/rules/SKILL.md · 33 lines

What it actually says

Codex Rules

Codex Rules is automatic once the plugin is enabled. It injects:

  • static project instructions on SessionStart and UserPromptSubmit
  • matching file-specific rules after Codex apply_patch by default

Dynamic PostToolUse output is injected as additional context and is deduplicated per plugin data session. Codex Rules does not rewrite tool output.

Supported project sources:

  • CONTEXT.md
  • .omo/rules/**/*.md
  • .claude/rules/**/*.md
  • .cursor/rules/**/*.md
  • .github/instructions/**/*.md
  • .github/copilot-instructions.md

Supported environment knobs:

  • CODEX_RULES_DISABLED=1
  • CODEX_RULES_MODE=both|static|dynamic|off
  • CODEX_RULES_MAX_RULE_CHARS=<number>
  • CODEX_RULES_MAX_RESULT_CHARS=<number>
  • CODEX_RULES_ENABLED_SOURCES=CONTEXT.md,.omo/rules

The legacy PI_RULES_* variables are accepted as fallbacks for users migrating from pi-rules.

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. yesterday First seen · 33 lines · 28 tokens per session scan A 266d44b17f9c

Subscribe to this mod's changes

rules is a skill published in the GitHub repository code-yeongyu/lazycodex (3,350 stars, last pushed 23d ago), licensed MIT. It adds 28 tokens to every session and 264 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 2026-08-30.

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