Borrowing it
Nothing to install: this file belongs to akahkhanna/groundtruth. 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/akahkhanna/groundtruth/main/CLAUDE.mdgit clone --depth 1 https://github.com/akahkhanna/groundtruthWrote 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/akahkhanna/groundtruth/claude-md)<a href="https://agentmods.dev/instructions/akahkhanna/groundtruth/claude-md"><img src="https://agentmods.dev/badge/instructions/akahkhanna/groundtruth/claude-md.svg" alt="Measured on agentmods" 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 | $0.02531 | $0.02531 |
| Opus 5 | $0.01265 | $0.01265 |
| Sonnet 5 | $0.00506 | $0.00506 |
| Haiku 4.5 | $0.00253 | $0.00253 |
Grade A, and why
groundtruth 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 7d 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 — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
What this is
Groundtruth is a Claude Code plugin (distributed via the plugin marketplace, not npm) that catches the false "Done." It's a deterministic local hook — no LLM calls, no network, no API key. It reads an agent turn from the outside (the request, the claim, the real git diff, the project rules) and renders a one-screen verdict before the turn ends.
As of v2.0.0 the default honesty/completeness engine is the "claims contract" (declare-then-verify) in hooks/claims-contract.mjs: the agent ends a code-changing turn with one fenced groundtruth-claims block, and the engine verifies every claim against the diff/transcript (CA — claimed-but-absent), every agent-authored change against the claims (UC — undeclared), and a missing/invalid block on authored work (NC). This replaced the old prose-parsing layer (v1 class-1/class-3, retired). Opt back out with GROUNDTRUTH_CONTRACT=0. The diff-facing checks (secrets, RLS, stubs, dropped symbols, compiled rules, Rule Zero) are unchanged.
Design invariant, enforced in review: a false positive is treated as fatal. A check earns its place only if it's provably correct in a defined scope. Outside that scope a check must abstain or degrade to a bounded warn — never a clean green. When adding or changing a check, this is the bar. See CONTRIBUTING.md.
Commands
node hooks/groundtruth.test.mjs # 479 engine unit checks, no deps, no framework
node hooks/claims-contract.test.mjs # 217 v2 claims-contract checks (same assert style)
node hooks/redteam.mjs # live adversarial harness (37 checks across sandboxed throwaway repos)
npm test # runs BOTH unit files (479 engine + 217 contract = 696)
npm run check-self # engine checks, but echoes the exit code as a GREEN/RED done-verdict
The test files are a flat sequence of ok(label, cond) asserts — there is no single-test runner; you run the whole file (it's fast). They import the pure exports of groundtruth.mjs/claims-contract.mjs/compile-rules.mjs/symbol-integrity.mjs directly, so a new check is only testable if it's exported and pure. Add a regression test in the same style next to the code it covers, and log the fix in FIXES.md (symptom → root cause → fix → regression test).
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.
- 7d ago First seen · 74 lines · 2,531 tokens per session scan A 180a0fad2669
groundtruth CLAUDE.md is an instructions file published in the GitHub repository akahkhanna/groundtruth (6 stars, last pushed 1mo ago), licensed MIT. It adds 2,531 tokens to every session, about $0.0127 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.
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