Concept
Reproducibility and verification
A result you cannot re-run and measure is an anecdote.
Reproducibility starts with pinned inputs and ends with measurement. In between there is a discipline that is easy to state and hard to keep: distinguish what you requested from what you verified.
Every project here has some version of that distinction — a specification that gates implementation, a manifest that records hashes, a quality report that separates verified steps from requested ones. The vocabulary differs; the constraint does not.
The reason it matters is that the failure mode is silent. A tool returns zero, the build goes green, and the defect ships. Only a measurement that would move if the feature stopped working can catch it.
Implementation
Where this runs
A concept that never left a document is a hypothesis. These are the systems that implement it.
Writing