coverage-differential SKILL.md skillA
coverage-differential from sshadows/lethal is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add sshadows/lethal/coverage-differential@git:20260827.b14163cPins git:20260827.b14163c in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- sshadows/lethal
- Path
.claude/skills/coverage-differential/SKILL.md- Versions recorded
- 3
- Latest version
- git:20260827.b14163c, committed Aug 27, 2026
- First version recorded
- Jul 28, 2026
- Size
- 7,043 bytes
- Repository stars
- 10
- License
- MIT
Run the two-mode differential gate for any change to coverage collection, selection or attribution — one project twice, identical except the coverage mode, compared per mutant on a verified join. Use before claiming such a change is safe, because the frozen live gates cannot detect these regressions.
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
# The coverage differential gate ## Why the ordinary gates cannot do this All four frozen gates have GREEN baselines. A change to how coverage is COLLECTED or ATTRIBUTED is a no-op for them: every test passes either way, so every mutant is scored either way, and the verdict tables match whatever the attribution did. R55's first candidate fix looked verified for exactly this reason. So did R58's client half, whose unit suite was fully green while the real call was hanging for 300 s against a live container. A regression here does not fail anything. It changes WHICH tests are believed to cover WHICH mutants, and the only visible consequence is mutants quietly moving to `no-coverage` — which reads as "the suite does not cover this code", the most reassuring possible misreading. ## Run it ```bash # fixtures: the probe drives runSession directly and dumps per-test coverage sets bun scripts/probe-r58-differential.ts --project fixtures/sandbox-app \ --tests fixtures/sandbox-tests --mode procedure --out <scratch>/a.json bun scripts/probe-r58-differential.ts --project fixtures/sandbox-app \ --tests fixtures/sandbox-tests --mode fenced --out <scratch>/b.json …
Read the whole file at its exact version.
How to install
mdr add sshadows/lethal/coverage-differential@sha256:7a53074abdcc3c85The line at the top of this page pins the label git:20260827.b14163c, 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_wnimg4g247wc2rwy)
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Versions
The registry has recorded 3 versions of this file, between Jul 28, 2026 and Aug 27, 2026, about one every 15 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260827.b14163c latest | 2026-08-27 | b14163c | 7,043 B | A | view · diff |
| git:20260820.185caa7 | 2026-08-20 | 185caa7 | 5,397 B | A | view · diff |
| git:20260728.0655956 | 2026-07-28 | 0655956 | 5,301 B | A | view |
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 (7043 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
sshadows/lethal · 10 stars · license MIT · pushed 2026-11-07 · branch master
API
GET https://markdownregistry.com/api/v1/artifacts/art_wnimg4g247wc2rwy GET https://markdownregistry.com/api/v1/resolve?ref=sshadows/lethal/coverage-differential GET https://markdownregistry.com/api/v1/blob/7a53074abdcc3c855f92dbaa375f1869a731a551070bc371f1b79f95c1af182b
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.