crux: Instructions file for Codex

AGENTS.md

crux AGENTS.md is an instructions file for Codex, OpenCode from mehdiforoozandeh/crux. It costs 586 tokens per session, scanned A, original, MIT.

Repository instructions for crux, a scientific-method lab notebook driven by an AI agent. It describes the project's four skills, Python engine, browser cockpit, and rules for contributing safely.

In plain words
What is it for?
Orienting agents in the crux repository, running its self-test, enforcing tests-first development, keeping the engine dependency-free, migrating format changes, and regenerating generated documents correctly.
Why use it?
It gives coding agents the project structure and constraints they need to avoid breaking research vaults, generated files, or the read-only browser interface.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md.

This is mehdiforoozandeh/crux's own configuration. It tells Codex and OpenCode how to work on crux itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything crux configures →

Reuse

Borrowing it

Nothing to install: this file belongs to mehdiforoozandeh/crux. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/mehdiforoozandeh/crux/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/mehdiforoozandeh/crux

Made for: Codex, OpenCode.

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 crux AGENTS.md

README.md
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Your own site
<a href="https://agentmods.dev/instructions/mehdiforoozandeh/crux/agents-md"><img src="https://agentmods.dev/badge/instructions/mehdiforoozandeh/crux/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for crux AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/mehdiforoozandeh/crux/agents-md"><img src="https://agentmods.dev/badge/instructions/mehdiforoozandeh/crux/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 586 This file is loaded in full into every session.
When invoked 586 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00586 $0.00586
Opus 5 $0.00293 $0.00293
Sonnet 5 $0.00117 $0.00117
Haiku 4.5 $0.00059 $0.00059

Measured 10d ago against content hash 80d51ea06b8c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

crux AGENTS.md 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 10d 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.

AGENTS.md · 34 lines

What it actually says

AGENTS.md — repo orientation for coding agents

crux is four agent skills under skills/crux, crux-wiki, crux-cockpit, evolve-crux — plus a stdlib-only Python engine at skills/crux/scaffold/ (engine.py, crux.py, render.py, serve.py, webui/). The root ./crux wrapper forwards to the engine: ./crux --help for the verb tour, ./crux selftest to validate a checkout.

Contributing? The full workflow (ideate → build → validate → ship) is the skills/evolve-crux/SKILL.md playbook; follow it.

Hard rules, gated before every PR:

  • ./crux selftest fully green, and a behavior change adds asserts first (tests-first — the failing assert is the reproduction).
  • Stdlib only. The engine takes no third-party dependency; the webui is no-build vanilla JS.
  • Existing vaults still load. A vault-format or verdict/roll-up/view-logic change needs an ENGINE_VERSION bump in engine.py plus migration proof.
  • The cockpit (crux serve) is read-only — no route ever writes.
  • Never hand-edit generated files (META.md, EXPERIMENTS.md, WIKI.md, ledger blocks) — regenerate via the engine.
  • skills/crux/SKILL.md stays under 34,000 bytes (wc -c skills/crux/SKILL.md). It loads on every crux session, and it grew 42% in five commits before anyone was counting. New material earns its place inline by one test: if the agent never reads it, does it do the wrong thing — or does it visibly fail? Content the engine itself refuses or validates may live in references/ or scaffold/README.md behind a pointer, because the refusal is what sends the agent to go read it. Content only the agent can enforce — the leash, the voice rules, the migration guardrail, "never write glossary.md directly" — must be inline, however rare the path, because a missed read there is silent. Two riders: a prohibition stays inline even when its procedure moves out, and rare content whose trigger the agent would not notice needs a one-line tripwire left behind pointing at the reference. Repetition of a prohibition at each point of temptation is load-bearing, not bloat — do not dedupe it.
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. 10d ago First seen · 34 lines · 586 tokens per session scan A 80d51ea06b8c

Subscribe to this mod's changes

crux AGENTS.md is an instructions file published in the GitHub repository mehdiforoozandeh/crux (5 stars, last pushed 4d ago), licensed MIT. It adds 586 tokens to every session, about $0.0029 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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