Borrowing it
Nothing to install: this file belongs to TheDecipherist/claude-code-mastery. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/TheDecipherist/claude-code-mastery/main/CLAUDE.mdgit clone --depth 1 https://github.com/TheDecipherist/claude-code-masteryWrote 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.
[](https://agentmods.dev/instructions/thedecipherist/claude-code-mastery/claude-md)<a href="https://agentmods.dev/instructions/thedecipherist/claude-code-mastery/claude-md"><img src="https://agentmods.dev/badge/instructions/thedecipherist/claude-code-mastery/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.
<a href="https://agentmods.dev/instructions/thedecipherist/claude-code-mastery/claude-md"><img src="https://agentmods.dev/badge/instructions/thedecipherist/claude-code-mastery/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00676 | $0.00676 |
| Opus 5.5 | $0.00270 | $0.00270 |
| Sonnet 5.5 | $0.00135 | $0.00135 |
| Haiku 4.5 | $0.00068 | $0.00068 |
Grade C, and why
claude-code-mastery CLAUDE.md scanned grade C with 1 finding 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 1mo 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.
Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
│ ├── block-dangerous-commands.sh # PreToolUse: blocks rm -rf, etc. How it starts
The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Overview
This is a documentation and template repository for Claude Code best practices. It contains:
- Educational guide (GUIDE.md) explaining Claude Code configuration
- Ready-to-use templates for CLAUDE.md files, settings.json, and .gitignore
- Example hooks (Python/Bash) for deterministic security enforcement
- Example skills for reusable AI expertise
This is NOT a code project — there is no build system, no tests, no runtime application.
Repository Structure
├── GUIDE.md # Main educational content (~900 lines)
├── templates/ # Copy-and-use templates
│ ├── global-claude.md # Template for ~/.claude/CLAUDE.md
│ ├── project-claude.md # Template for ./CLAUDE.md in any project
│ ├── settings.json # Hook configuration template
│ └── .gitignore # Recommended ignore patterns
├── hooks/ # Security enforcement scripts
│ ├── block-secrets.py # PreToolUse: blocks .env/credentials access
│ ├── block-dangerous-commands.sh # PreToolUse: blocks rm -rf, etc.
│ ├── after-edit.sh # PostToolUse: run formatters
│ ├── end-of-turn.sh # Stop: quality gates
│ └── notify.sh # Desktop notifications
└── skills/ # Packaged AI expertise
├── commit-messages/ # Conventional commit generation
└── security-audit/ # Vulnerability scanning checklist
Key Concepts
Hooks vs CLAUDE.md
CLAUDE.md rules are suggestions that Claude can override under context pressure. Hooks are deterministic enforcement — they always execute.
block-secrets.py: Exit code 2 blocks Read/Edit/Write operations on sensitive filesblock-dangerous-commands.sh: Exit code 2 blocks dangerous Bash patterns
Hook Exit Codes
| Code | Behavior |
|---|---|
| 0 | Allow operation |
| 1 | Error (shown to user only) |
| 2 | Block operation, stderr fed back to Claude |
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.
- 1mo ago First seen · 65 lines · 676 tokens per session scan C 56d40b52df13
claude-code-mastery CLAUDE.md is an instructions file published in the GitHub repository TheDecipherist/claude-code-mastery (555 stars, last pushed 5mo ago), licensed MIT. It adds 676 tokens to every session, about $0.0027 per session on Opus 5.5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deno copilot-instructions.md
Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.