Borrowing it
Nothing to install: this file belongs to cwensel/arcaneum. 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/cwensel/arcaneum/main/AGENTS.mdgit clone --depth 1 https://github.com/cwensel/arcaneumWrote 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/cwensel/arcaneum/agents-md)<a href="https://agentmods.dev/instructions/cwensel/arcaneum/agents-md"><img src="https://agentmods.dev/badge/instructions/cwensel/arcaneum/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/cwensel/arcaneum/agents-md"><img src="https://agentmods.dev/badge/instructions/cwensel/arcaneum/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 | $0.00484 | $0.00484 |
| Opus 5.5 | $0.00194 | $0.00194 |
| Sonnet 5.5 | $0.00097 | $0.00097 |
| Haiku 4.5 | $0.00048 | $0.00048 |
Grade A, and why
arcaneum AGENTS.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.
What it actually says
AGENTS.md
This file provides guidance for AI agents working with this repository.
Commit Message Convention
This project follows Conventional Commits. Release notes are generated by grouping commits by type, so non-conforming messages land in a generic "Other" section.
Format
<type>(<scope>): <description>
[optional body]
[optional footer]
- type (required, lowercase): one of the types below
- scope (optional): area affected, e.g.
search,cli,ci,indexing - description (required): imperative mood, no trailing period
- breaking change: add
!after type/scope (e.g.feat(cli)!: ...) or aBREAKING CHANGE:footer
Types
| Type | Use for |
|---|---|
feat |
New feature visible to users |
fix |
Bug fix |
perf |
Performance improvement (no behavior change) |
refactor |
Code change that's neither a fix nor a feature |
docs |
Documentation only |
test |
Adding or updating tests |
build |
Build system or dependencies (pyproject.toml, packaging) |
ci |
CI/CD workflows (.github/workflows/) |
chore |
Maintenance, tooling, release commits |
style |
Formatting (no code change) |
revert |
Reverts a previous commit |
Examples
feat(search): add --limit flag to arc search semantic
fix(cli): handle empty corpus argument
ci: pin third-party actions to commit SHAs
docs(readme): update install instructions
chore(release): 0.4.2
refactor(indexing)!: rename BatchIndexer to ChunkIndexer
Rules
- ✅ Use the convention for all commits on
main - ✅ Release commits are
chore(release): X.Y.Z - ✅ Use
!orBREAKING CHANGE:footer for breaking changes — these surface at the top of release notes - ❌ Do NOT capitalize the description
- ❌ Do NOT end the description with a period
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 · 62 lines · 484 tokens per session scan A 5520a61788c7
arcaneum AGENTS.md is an instructions file published in the GitHub repository cwensel/arcaneum (8 stars, last pushed 14d ago), licensed MIT. It adds 484 tokens to every session, about $0.0019 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.
arcaneum AGENTS.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| arcaneum AGENTS.mdcwensel/arcaneum | Instructions file | 8 | 14d ago | MIT | A | 484 | Codex, OpenCode |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | yesterday | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | yesterday | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 5,516 | GitHub Copilot |
| 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 |