Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/cosmix/loom/loom-pythonnpx skills add cosmix/loom --skill loom-pythongit clone --depth 1 https://github.com/cosmix/loomWhat 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 | $0.00069 | $0.08803 |
| Opus 5 | $0.00034 | $0.04401 |
| Sonnet 5 | $0.00014 | $0.01761 |
| Haiku 4.5 | $0.00007 | $0.00880 |
Grade A, and why
loom-python 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 yesterday.
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 — 609 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Python Language Expertise
Overview
Idiomatic, production-grade Python: modern typing, async, packaging, and the web/data/ML ecosystem. Assumes competence — the value is in what is easy to get wrong (interning, mutable defaults, blocking the event loop, GIL, dataclass/Pydantic boundaries), not syntax tutorials.
Tooling (uv / ruff / mypy)
Ruff is a strong default for linting and formatting. uv is a capable project and environment manager, but preserve the repository's existing package manager and lockfile unless a migration is explicitly requested.
uv — a single tool for project environments, locking, Python installation, and pip-compatible workflows. Use it for new work or repositories that already use it; do not treat it as an implicit replacement for Poetry or another established workflow.
| Task | Command |
|---|---|
| New project | uv init (writes pyproject.toml) |
| Add / remove dep | uv add httpx / uv remove httpx (updates pyproject.toml + uv.lock) |
| Add dev dep | uv add --dev pytest |
| Sync env from lock | uv sync (creates .venv, exact/reproducible) |
| Run in project env | uv run pytest (auto-syncs first; no manual activate) |
| Install a Python | uv python install 3.12 |
| Ephemeral tool | uvx ruff check (= uv tool run) |
| pip shim | uv pip install ... (drop-in, no project file) |
- In a uv-managed project, use
uv add/uv removeso the manifest anduv.lockstay in sync; useuv sync --frozenin CI to fail on drift.
ruff — single linter+formatter replacing flake8, isort, pyupgrade, pydocstyle, autoflake, and much of bandit.
ruff check --fix(lint+autofix),ruff format(near-identical to black, replaces it).- Config lives under
[tool.ruff.lint]since 0.1 — top-levelselectis deprecated and warns. - Useful rule groups:
E/Wpycodestyle,Fpyflakes,Iisort,UPpyupgrade (keeps typing current),Bbugbear (catches mutable defaults,lru_cacheon methods),SIM,Sbandit-security,ASYNC,PLpylint,RUF. Suppress with# noqa: E501(never bare# noqa).
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.
- yesterday First seen · 609 lines · 69 tokens per session scan A 0a01052f7b3f
loom-python is a skill published in the GitHub repository cosmix/loom (54 stars, last pushed 3d ago), licensed MIT. It adds 69 tokens to every session and 8,803 once invoked, about $0.0003 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 2026-08-30.
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