prove-the-negative SKILL.md skillA
prove-the-negative from broomva/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add broomva/skills/prove-the-negative@git:20260823.391a76aPins git:20260823.391a76a in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- broomva/skills
- Path
skills/tooling/prove-the-negative/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260823.391a76a, committed Aug 23, 2026
- Size
- 7,978 bytes
- Repository stars
- 5
- License
- MIT
Verify a claim whose evidence is an ABSENCE — blocked, denied, unreachable, isolated, not-logged, no-longer-present. Enforces that every denial is paired with a positive control that must SUCCEED, because "everything is denied" and "nothing ran at all" are the same observation. Ships a verdict gate that returns INVALID (exit 2) rather than PASS when the controls did not fire. USE WHEN validating a security boundary or sandbox, writing an eval whose passes are denials, confirming a capability…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# prove-the-negative A negative result is evidence **only if a positive control proves the apparatus was live**. Without one, a suite of denials reports its healthiest possible result at the exact moment its subject is switched off. This is not a hypothetical failure mode. It is the one that keeps happening. ## The inference this refuses > every probe returned "denied" → the boundary holds Invalid, always. `denied` and `never ran` are the **same observation** through the instrument you are using. A run that cannot tell them apart has not measured the boundary; it has measured nothing, and reported success. ## The three rules **1. Every denial needs a control that must SUCCEED.** Not a second denial — a case that fails loudly if the apparatus is dead. `echo HELLO` passing is what licenses `curl` being blocked to mean anything. **2. The subject's own account is never the verdict.** A model that declines a probe on its own judgment has told you about its disposition, not about its cage. Compute the verdict from literal output, from outside, in code. Where possible check the filesystem or process table rather …
Read the whole file at its exact version.
How to install
mdr add broomva/skills/prove-the-negative@sha256:a8b1ded0d6106128The line at the top of this page pins the label git:20260823.391a76a, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_4p5wfnrbd2ddfjjf)
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Versions
The registry has recorded 1 version of this file, committed on Aug 23, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (7978 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
broomva/skills · 5 stars · license MIT · pushed 2026-11-07 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_4p5wfnrbd2ddfjjf GET https://markdownregistry.com/api/v1/resolve?ref=broomva/skills/prove-the-negative GET https://markdownregistry.com/api/v1/blob/a8b1ded0d610612844ebef7b185b1217393c502b0a95a60ae958cf1ba9528c92
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.