Borrowing it
Nothing to install: this file belongs to Sounio-lang/sounio. 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/Sounio-lang/sounio/main/CLAUDE.mdgit clone --depth 1 https://github.com/Sounio-lang/sounioWrote 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/sounio-lang/sounio/claude-md)<a href="https://agentmods.dev/instructions/sounio-lang/sounio/claude-md"><img src="https://agentmods.dev/badge/instructions/sounio-lang/sounio/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/sounio-lang/sounio/claude-md"><img src="https://agentmods.dev/badge/instructions/sounio-lang/sounio/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 | $0.08578 | $0.08578 |
| Opus 5 | $0.04289 | $0.04289 |
| Sonnet 5 | $0.01716 | $0.01716 |
| Haiku 4.5 | $0.00858 | $0.00858 |
Grade A, and why
sounio 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 443 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file is the entry-point for Claude Code (claude.ai/code) and other AI assistants working in the Sounio repository. It is the active source of truth for AI behavior; AGENTS.md is the Codex-facing execution contract; together they cover all AI roles in the project.
If you are a human reader: see §11.
| Quick reference | |
|---|---|
| Founder intent and collaboration contract | FOUNDER_INTENT.md |
| Semantic concept registry | docs/internal/concepts/README.md |
| Semantic lane contract | docs/internal/concepts/SEMANTIC_LANE_CONTRACT.md |
| Recovery context | CLAUDE_HANDOFF.md |
| Codex contract | AGENTS.md |
| Programming guide | docs/guide/LLM_PROGRAMMING_GUIDE.md |
| LLM cookbook | docs/llm-guide/ |
| Minimum viable Sounio | docs/guide/MINIMUM_VIABLE_SOUNIO.md |
| Style guide | docs/guide/SOUNIO_STYLE_GUIDE.md |
| Gotchas | docs/guide/SOUNIO_GOTCHAS.md |
| Known limitations | docs/compiler/KNOWN_LIMITATIONS.md |
| Governance | docs/governance/ |
| LLM offload policy | .claude/AGENT_OFFLOAD_POLICY.md |
1. Calibration — read before any analysis
Sounio is not a small experimental repository. Past AI sessions, including those with many hours of context, have consistently underestimated its scope by roughly an order of magnitude. Calibrate before producing analysis. The most predictable AI failure mode in this repository is measuring stdlib/ and treating it as the whole.
Measured 2026-07-11 on main via bash scripts/dev/measure_repo_scale.sh:
Versioned .sio source |
Value |
|---|---|
| Files | 6,130 |
| Lines (raw) | 2,208,306 |
| Bytes | 76 MB |
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.
- 9d ago First seen · 443 lines · 8,578 tokens per session scan A daea21e8175d
sounio CLAUDE.md is an instructions file published in the GitHub repository Sounio-lang/sounio (6 stars, last pushed today), licensed Apache-2.0. It adds 8,578 tokens to every session, about $0.0429 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 2026-08-31.
Other instructions, from other repositories
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.
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
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).
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).
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.
spec-kit AGENTS.md
AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.