What is archcodex CLAUDE.md?

Project instructions for ArchCodex, a system that records architectural rules and relationships between parts of a codebase.

Use them when modifying an ArchCodex-managed project to load context, read file-specific constraints, follow the required change order, and run the configured checks.

They require the agent to inspect those rules before editing code and validate the result afterward, reducing changes that break project boundaries.

How ArchCodexOrg/archcodex configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to ArchCodexOrg/archcodex. 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/ArchCodexOrg/archcodex/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/ArchCodexOrg/archcodex

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/archcodexorg/archcodex/claude-md/github.svg)](https://agentmods.dev/instructions/archcodexorg/archcodex/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/archcodexorg/archcodex/claude-md"><img src="https://agentmods.dev/badge/instructions/archcodexorg/archcodex/claude-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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/archcodexorg/archcodex/claude-md"><img src="https://agentmods.dev/badge/instructions/archcodexorg/archcodex/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 2,323 This file is loaded in full into every session.

When invoked 2,323 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.

Model	Per session	Once invoked
Fable 5.1	$0.02323	$0.02323
Opus 5.5	$0.00929	$0.00929
Sonnet 5.5	$0.00465	$0.00465
Haiku 4.5	$0.00232	$0.00232

Measured 2mo ago against content hash 465c68e0833e, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

archcodex 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 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.

CLAUDE.md · 278 lines

How it starts

The opening of the file, as written. The whole thing — 278 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Claude Code Instructions for ArchCodex

This project uses ArchCodex for architectural constraints.

BEFORE MODIFYING CODE

STOP. Call this MCP tool first:

archcodex_context { "projectRoot": "/absolute/path/to/project", "module": "src/path/to/module/" }

projectRoot must be an absolute path where .arch/ exists (contains the SQLite database).

This gives you everything in one call:

Project Rules - Layer hierarchy + shared constraints across all architectures
Modification Order - DEFINES → IMPLEMENTS → ORCHESTRATES
🔴N Impact - How many files break if you change this one
Layer Boundaries - CAN/CANNOT import lists
Entity Schemas - Fields, relationships, behaviors (inline)
Architecture Constraints - forbid, patterns, require, all hints
Validation Command - Run after changes

Workflow

1. archcodex_context       ← GET FULL CONTEXT FIRST (module or entity)
2. Read tool               ← READ files (code content)
   archcodex_read          ← GET per-file constraints (auto-injected via pre-read hook)
3. Write code              ← Follow modification order, respect constraints
4. archcodex_check         ← VALIDATE AFTER CHANGES (auto-run via post-write hook)

Note: archcodex_read returns only architectural data (constraints, boundaries, hints) — never file content. Use the agent's native Read tool for code content. The pre-read hook auto-injects constraints when reading src/ files.

MCP Tools

When	Tool Call
Before modifying	`archcodex_context { "projectRoot": "/path", "module": "src/dir/" }`
Before creating	`archcodex_discover { "projectRoot": "/path", "query": "description" }`
After changes	`archcodex_check { "projectRoot": "/path", "files": ["src/*/.ts"] }`
Entity work	`archcodex_context { "projectRoot": "/path", "entity": "EntityName" }`
Task guidance	`archcodex_action { "projectRoot": "/path", "query": "add order action" }`
Verify wiring	`archcodex_feature_audit { "projectRoot": "/path", "mutation": "duplicateOrder", "entity": "orders" }`
Scaffold spec	`archcodex_spec_scaffold_touchpoints { "projectRoot": "/path", "specId": "spec.orders.duplicateOrder", "entity": "orders" }`

Read the full file on GitHub · 278 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.

2mo ago First seen · 278 lines · 2,323 tokens per session scan A 465c68e0833e

Subscribe to this mod's changes

archcodex CLAUDE.md is an instructions file published in the GitHub repository ArchCodexOrg/archcodex (5 stars, last pushed 5mo ago), licensed MIT. It adds 2,323 tokens to every session, about $0.0093 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.

LLM architecture cli coding-agents mcp spec

archcodex CLAUDE.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
archcodex CLAUDE.mdArchCodexOrg/archcodex	Instructions file	5	5mo ago	MIT	A	2,323	Claude Code
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vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

archcodex: Instructions file for Claude Code