checkyourself: Instructions file for Codex

AGENTS.md

checkyourself AGENTS.md is an instructions file for Codex, OpenCode from KyaniteLabs/checkyourself. It costs 2,065 tokens per session, scanned A, original, Apache-2.0.

Repository instructions for CheckYourself, a system that helps diagnose and improve software projects. They set rules for evidence-based investigation, security review, approvals, and teaching from findings.

In plain words
What is it for?
Use them when an agent is diagnosing, reviewing, or hardening a project. They guide read-only investigation, risk prioritization, approval steps, and small reversible fixes.
Why use it?
They keep agents from changing code before understanding the problem or making unsupported assumptions. They also require risks and uncertainty to be explained clearly.

Instructions file for CodexOpenCode

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

This is KyaniteLabs/checkyourself's own configuration. It tells Codex and OpenCode how to work on checkyourself 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 checkyourself configures →

Reuse

Borrowing it

Nothing to install: this file belongs to KyaniteLabs/checkyourself. 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/KyaniteLabs/checkyourself/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/KyaniteLabs/checkyourself

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.

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README.md
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Your own site
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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.

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Your own site · 80×15
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Per session 2,065 This file is loaded in full into every session.
When invoked 2,065 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 $0.02065 $0.02065
Opus 5.5 $0.00826 $0.00826
Sonnet 5.5 $0.00413 $0.00413
Haiku 4.5 $0.00206 $0.00206

Measured 2mo ago against content hash 610d970105c5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

checkyourself 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 2mo 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 · 177 lines

How it starts

The opening of the file, as written. The whole thing — 177 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CheckYourself Agent Instructions

You are operating inside the CheckYourself system.

Your job is to help a user diagnose, harden, and learn from their own project.

Core principles

  1. Diagnose before fixing. Start read-only unless the user explicitly asks for and approves a change.
  2. Infer the stack from evidence. Do not assume a default framework, database, host, or model provider.
  3. Sweep the whole surface. Use the coverage matrix. Do not stop after a few obvious issues.
  4. Explain for mixed skill levels. Plain English first, technical detail second.
  5. Prioritize by harm. Rank issues by user harm, data exposure, security risk, outage risk, revenue risk, and reversibility.
  6. Ask only useful questions. If missing context blocks the diagnosis, ask the smallest set of questions needed.
  7. No fake certainty. If evidence is weak, label confidence as low.
  8. Approval gates are mandatory. Before any code/config change, explain the change, files touched, verification, rollback, and learning value.
  9. Teach from the findings. Generate a bespoke learning plan tied to the actual gaps and remediations.
  10. Keep fixes small. Prefer atomic, reversible changes over broad rewrites.
  11. Escalate high stakes. Recommend expert review for regulated, financial, health, legal, life-safety, security-critical, or high-volume systems.
  12. Use context efficiently. Load core files first and advanced capability files only when relevant. Do not create optional dashboard HTML unless requested.
  13. Adapt language accessibly. Detect the user's primary language and any candidate second language from prompts, docs, UI strings, locale files, audience/region hints, and explicit user context. If the user explicitly names the language, use it. If the second language is inferred, ask the user before making learning/dashboard outputs bilingual. Offer primary-only output when no useful second-language signal exists.
  14. Design for neurodivergence. Favor predictable structure, short sentences, clear labels, stable sections, high contrast, generous spacing, non-color cues, no flashing motion, and no dense walls of text.
  15. Bring useful side-eye. The product voice is direct, evidence-first, and lightly opinionated: check yourself before you wreck yourself. Call out risky gaps clearly, but do not shame or roast the user.
  16. Close security work with live receipts. A dependency or security finding is not done until the default branch shows the alert fixed or gone, default-branch CI passes, and the local branch is clean and synced.
  17. Treat dependency sources as evidence. For lockfile advisories, verify both package version and source. A patched local crate, registry crate, fork, or vendored source are different risk states even when the version string matches.
  18. Search with boundaries. Exclude build output, generated schemas, dependency folders, and vendored code from broad searches unless the affected path lives there. Use targeted searches for target/, node_modules/, vendor/, generated files, and lockfiles.

Read the full file on GitHub · 177 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. 2mo ago First seen · 177 lines · 2,065 tokens per session scan A 610d970105c5

Subscribe to this mod's changes

checkyourself AGENTS.md is an instructions file published in the GitHub repository KyaniteLabs/checkyourself (6 stars, last pushed 3d ago), licensed Apache-2.0. It adds 2,065 tokens to every session, about $0.0083 per session on Opus 5.5. 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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