metatron CLAUDE.md

metatron CLAUDE.md is an instructions file for Claude Code from kerbelp/metatron. It costs 1,156 tokens per session, scanned A, original, MIT.

A contributor guide explains Metatron, a self-hosted system that stores a company's coding decisions and conventions for agents to consult. It covers the fixed technology choices and the project's storage and testing approach.

In plain words
What is it for?
It is for orienting developers, understanding the Python, SQLite, tree-sitter, and pytest setup, and working on the decision store or MCP server.
Why use it?
It gives contributors the context needed to change a system that preserves internal engineering knowledge. It also explains where those decisions are stored and how the optional MCP server exposes them.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md.

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 instructions/kerbelp/metatron/claude-md
Clone the repo
git clone --depth 1 https://github.com/kerbelp/metatron

Made for: Claude Code.

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 metatron CLAUDE.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/kerbelp/metatron/claude-md.svg)](https://agentmods.dev/instructions/kerbelp/metatron/claude-md)
Your own site
<a href="https://agentmods.dev/instructions/kerbelp/metatron/claude-md"><img src="https://agentmods.dev/badge/instructions/kerbelp/metatron/claude-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 1,156 This file is loaded in full into every session.
When invoked 1,156 The same file — it is already loaded in full.
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 5.1 $0.01156 $0.01156
Opus 5 $0.00578 $0.00578
Sonnet 5 $0.00231 $0.00231
Haiku 4.5 $0.00116 $0.00116

Measured 6d ago against content hash f38f2a9443b6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

metatron CLAUDE.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 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.

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.

CLAUDE.md · 99 lines

How it starts

The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

Ground rules for working in this repo. Read this first.

What Metatron is

Metatron is a self-hosted system that captures a company's real implementation decisions — preferred patterns, rejected approaches, edge cases, internal conventions — as structured decisions. In the primary, files-first mode they live as git-tracked OKF markdown consulted directly by coding agents; an optional MCP (Model Context Protocol) server layer serves the same decisions over the wire. The goal is for an agent to write code like a senior engineer who already knows this codebase. It runs against a private codebase, so assume sensitive data and on-prem deployment.

Tech stack (decided — not open for debate)

These are locked. Do not re-litigate or substitute them:

  • Python 3.12+
  • Official MCP Python SDK for the server
  • tree-sitter for language-agnostic code parsing
  • SQLite for the decision store — but always behind a storage interface, because the schema must be portable to Postgres later
  • pytest for tests
  • uv for dependency management

Core principle

  • Decisions are stored as structured records (fields: pattern, context/scope, rationale, confidence, source refs) — never as prose specs.
  • Nothing enters the canonical set without human curation. No decision self-promotes. Crossing the canonical boundary — promote, demote, reject — is always human-gated. This invariant is absolute.

Source of truth (depends on deployment)

Metatron supports two ways of operating, and the source of truth differs:

  • Files-first mode (primary/default). The git-tracked OKF files are the source of truth: the directory (candidate/ vs decisions/) is the status, decisions are curated as plain files reviewed via pull request (default review gate: pr), and the database is a derived, rebuildable serving index (metatron mirror import). The curation UI mounts the bundle directly (metatron ui --files).
  • MCP / database mode (optional serving layer). SQLite is the source of truth; the git-tracked OKF markdown bundle is a synced mirror (metatron mirror sync). Curation happens in the store (CLI/UI), and decisions are served to agents over MCP with relevance ranking and the feedback loop.

Read the full file on GitHub · 99 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. 6d ago First seen · 99 lines · 1,156 tokens per session scan A f38f2a9443b6

Subscribe to this mod's changes

metatron CLAUDE.md is an instructions file published in the GitHub repository kerbelp/metatron (24 stars, last pushed 1mo ago), licensed MIT. It adds 1,156 tokens to every session, about $0.0058 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.

Related

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