captain-obvious CLAUDE.md

captain-obvious CLAUDE.md is an instructions file for coding agents from shmulc8/captain-obvious. It costs 413 tokens per session, scanned A, original, MIT.

Contributor instructions for Captain Obvious, a scanner that finds tests that can never fail by checking their logic with a type checker. It supports TypeScript test tools and Python tests with pytest or mypy.

In plain words
What is it for?
Use them when changing detectors, test-analysis rules, command-line scripts, documentation, or the self-test setup.
Why use it?
They explain how to run its tests and keep the Python and TypeScript scanners consistent.

Instructions file

Install

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.

agentmods
npx agentmods add instructions/shmulc8/captain-obvious/claude-md
Clone the repo
git clone --depth 1 https://github.com/shmulc8/captain-obvious

Wrote 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.

agentmods badge for captain-obvious CLAUDE.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/shmulc8/captain-obvious/claude-md.svg)](https://agentmods.dev/instructions/shmulc8/captain-obvious/claude-md)
Your own site
<a href="https://agentmods.dev/instructions/shmulc8/captain-obvious/claude-md"><img src="https://agentmods.dev/badge/instructions/shmulc8/captain-obvious/claude-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 413 This file is loaded in full into every session.
When invoked 413 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00413 $0.00413
Opus 5 $0.00206 $0.00206
Sonnet 5 $0.00083 $0.00083
Haiku 4.5 $0.00041 $0.00041

Measured 5d ago against content hash 20d2985be751, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

captain-obvious 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 5d 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.

CLAUDE.md · 25 lines

What it actually says

captain-obvious — contributor notes

  • Run the self-tests: npm install typescript@^5 --no-save --no-audit --no-fund once, then python3 -m unittest discover -v tests. The tests are unittest TestCase classes with pytest-style filenames — plain pytest also works, but CI runs unittest discover; keep new tests compatible with it (no pytest fixtures/parametrize).
  • TS tests skip silently when typescript is not installed at the repo root. A fully green run must show zero skipped lines.
  • Parity rule: the Python (skills/captain-obvious/scripts/co_py/) and TypeScript (.../co_ts/) engines implement the same detector catalog. A detector change lands on BOTH sides (analyzer.py + analyzer.mjs / classifier.mjs) plus a row in references/detectors.md and the README table, or states in the PR why it is language-specific.
  • Zero dependencies, on purpose: the Python scripts are stdlib-only; the Node scripts import nothing but node:* and the TARGET repo's own typescript. The skill must run when copied bare into ~/.claude/skills/. Never add a manifest dependency to skills/.
  • Finding contract: every finding is {file, line, test, category, level: proven|advisory, deletable: safe|aggressive|report-only, reason}. Only proven + deletable: safe is auto-deleted by --fix — treat any change that widens that set as high-risk and test it in tests/.
  • Write-time hook: hooks/prevent.py, off by default; enable with CAPTAIN_OBVIOUS_HOOK=block|warn. It must always fail open.
Changes

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.

  1. 5d ago First seen · 25 lines · 413 tokens per session scan A 20d2985be751

Subscribe to this mod's changes

captain-obvious CLAUDE.md is an instructions file published in the GitHub repository shmulc8/captain-obvious (12 stars, last pushed 19d ago), licensed MIT. It adds 413 tokens to every session, about $0.0021 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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