This file is byte-identical to the first copy the registry indexed, one of 3 indexed copies. Same content hash, so the same checks give both the same grade.
principle-explain-the-number from painhardcore/pstack is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
Apply before you measure, and before you trust, report, or act on a number you measured: a speedup, a regression, a throughput, a latency, or an eval result. Find what limits it, and rule out that it measured something other than the work you think.
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
# Explain the Number
- **Write the decision before you run.** Name the result that would change a decision, and the noise floor. Stop when the run-to-run spread is larger than the effect.
- **Ask "why not double?"** Name the resource or code path that bounds the result, such as a core, a lock, the disk, the network, or the load generator itself. Get it from a profile or from system counters taken during a run, then map it to source. A guess from reading the code is not a limiter. If you cannot say why the number is not twice as good, you do not know what you measured.
- **List what else the number could be measuring, and rule out each one with evidence.** The usual suspects are errors, skipped or cached work, code that never ran, an untuned side (one left on default settings), noise, and a piece too small to matter end to end.
- **Keep the evidence with the number.** Put the run count, the spread, and the limiter in the notes or a linked artifact.
…
The line at the top of this page pins the label git:20261101.1922dfd, 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.
GET https://markdownregistry.com/api/v1/artifacts/art_ajjauke7gro725u2
GET https://markdownregistry.com/api/v1/resolve?ref=painhardcore/pstack/principle-explain-the-number
GET https://markdownregistry.com/api/v1/blob/415aa700fbdc1dd7dc5dc7d34bcb91abe07534a7c7ee8f1cd6d9f57187446c30
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.
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cursor/plugins · pstack/skills/principle-explain-the-number/SKILL.md · Apply before you measure, and before you trust, report, or act on a number you measured: a speedup, a regression, a…
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