Borrowing it
Nothing to install: this file belongs to mattwynne/yaks. 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/mattwynne/yaks/main/AGENTS.mdgit clone --depth 1 https://github.com/mattwynne/yaksWrote 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/mattwynne/yaks/agents-md)<a href="https://agentmods.dev/instructions/mattwynne/yaks/agents-md"><img src="https://agentmods.dev/badge/instructions/mattwynne/yaks/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.
<a href="https://agentmods.dev/instructions/mattwynne/yaks/agents-md"><img src="https://agentmods.dev/badge/instructions/mattwynne/yaks/agents-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 | $0.01106 | $0.01106 |
| Opus 5.5 | $0.00442 | $0.00442 |
| Sonnet 5.5 | $0.00221 | $0.00221 |
| Haiku 4.5 | $0.00111 | $0.00111 |
Grade C, and why
yaks AGENTS.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.
- **NEVER**: Run `rm -rf .yaks` or modify `.yaks` contents directly How it starts
The opening of the file, as written. The whole thing — 126 lines — stays where its author put it; the contents beside it link to each section on GitHub.
This file provides guidance to Agents working in this repository.
We use yaks for task tasking. See !yx help
See CONTRIBUTING for dev tooling and commands.
Architecture
Hexagonal architecture with CQRS and Event Sourcing. Commands flow
through use cases to the YakMap aggregate, which emits domain events.
Events are persisted to git refs and projected to the .yaks/
directory-based read model.
See src/README.md for the full architecture
guide: layers, key types, ports, adapters, and how commands flow.
See docs/adr/ for Architecture Decision
Records explaining why the design is the way it is.
When making architectural decisions, invoke the cqrs-event-sourcing
skill for guidance on aggregate boundaries, event design, read models,
policies, and sagas.
Testing layers
- Cucumber acceptance tests (
features/*.feature): For executable specifications, agreed with human partner. Dual-mode execution viacargo test --test cucumber --features test-support:- FullStackWorld: spawns yx binary (real integration test)
- InProcessWorld: calls Rust directly with in-memory adapters (fast)
- ShellSpec tests (
tests/shellspec/): For tests that don't fit Cucumber (tmux smoke, git checks, installer). Run withshellspec. - Rust unit tests: Internal logic (
cargo test)
Mutation Testing
Validates test quality by injecting code changes and checking tests catch them.
dev mutate-diff # Fast: only mutants in your changes (~seconds)
dev mutate # Full run (~7 min, ~400 mutants)
dev mutate -F 'slug' # Full run filtered to specific files
dev mutate-sync # Sync missed mutants to yaks
Daily workflow: Use dev mutate-diff (alias dev md) while coding.
After a full run: dev mutate-sync (alias dev ms) creates yaks
for missed mutants. Then yx sync to share results.
Config: .cargo/mutants.toml excludes infrastructure-only files.
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 · 126 lines · 1,106 tokens per session scan C 10e05ff2117a
yaks AGENTS.md is an instructions file published in the GitHub repository mattwynne/yaks (61 stars, last pushed yesterday), licensed MIT. It adds 1,106 tokens to every session, about $0.0044 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.