code-quality-instruments skillA
code-quality-instruments is agent-read markdown (skill) from jakeselby/agent-harness: Measure whether a test suite is any good, not only that it passes: branch coverage, mutation score, complexity-times-coverage risk, duplication. Use when adding or reviewing tests on a change that matters, a suite passes but a bug still shipped, coverage is high and confidence is not, or before promising a module is well tested..
Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.
What the file says
The `testing` stance says whether tests are required. This is how you find out whether the ones you wrote are worth anything. A suite can reach full line coverage with no assertions at all. Every line executes, nothing is checked, and the gate is green. Coverage measures what ran; it does not measure what was verified. Everything below exists to close that gap. ## What to measure, in order of what it tells you 1. **Branch coverage, not line coverage.** Line coverage counts a two-way branch as covered when one side ran. Branch coverage is the cheapest upgrade available and usually the one that reveals the untested error path. 2. **Mutation score.** Change an operator, flip a boundary, delete a statement, then rerun the suite. A mutant that survives is a change to your code no test objects to. This is the only instrument here that measures assertions rather than execution, so it is the one that catches an assertion-free suite. 3. **Complexity against coverage.** A function that is both branchy and thinly covered is where defects concentrate. Either number alone is weak; the pair ranks the work. Robert Martin's CRAP …
Read the whole file at its exact version.
How to install
mdr add jakeselby/agent-harness/code-quality-instruments@git:20260923.097bdb0mdr add jakeselby/agent-harness/code-quality-instruments@sha256:3f31d34c071cb875Pin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.
[](https://markdownregistry.com/a/art_cczmnxov2232runi)
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Versions
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260923.097bdb0 latest | 2026-09-23 | 097bdb0 | 4,488 B | A | view · diff |
| git:20260919.6cf18f7 | 2026-09-19 | 6cf18f7 | 4,598 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 (4488 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
jakeselby/agent-harness · 17 stars · license MIT · pushed 2026-09-25 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_cczmnxov2232runi GET https://markdownregistry.com/api/v1/resolve?ref=jakeselby/agent-harness/code-quality-instruments GET https://markdownregistry.com/api/v1/blob/3f31d34c071cb875be4c9337b3d3c61d9fca99baf89013e7adcbbc94e158b974
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