mellions-falsificationlisted

<!-- Mellions Engineer | LetA Tech Ltd. | leta@letatech.ca --> # Establishing that a fix holds A green run is a claim about the harness until something shows it could have been red. ## The copy you falsify in One copy per arm: a neutralisation left from the previous arm can mask the next, which then passes while testing nothing. `git archive <rev>` carries that commit, not the index: a test staged but not committed is as absent as an untracked one. Never falsify by restoring a working tree: it discards uncommitted work — yours, or another session's in a shared tree. With one arm and nothing uncommitted at stake, toggling the edit in place — red, then green — is the arm. ## The oracle Where a test asserts the output equals what the mechanism under test computes, it has no independent side: whatever moves the mechanism moves both halves, and the test stays green through the defect it was written for. Replace that with something the mechanism cannot reach — a literal, a figure from the requirement, a value read from the other side of the boundary the fix crosses. A golden file, a reference implementation or an invariant is an independent side; a call into the code under test is not. ## The revert arms Revert every part of the fix at once and watch the named tests fail. A complete revert that stays green has four readings, the third of which points at deleting the test: the edit did not land — confirm off disk, since an edit that no-ops (a `sed` that matched nothing, an u