BFM-decomp/cookbook/C0475.md

§427 ★★ — A HASH IS A CORRECTNESS ORACLE WITH ZERO DIAGNOSTIC CONTENT; PRESERVE THE RED ARTIFACT BEFORE ANYTHING REBUILDS OVER IT (P31 S72)

[FAIL] got <sha> want <sha> cannot distinguish "your body is wrong" from "your body is perfect and the substitution moved a caller/table". Attributing the second to the draft is R40 — blaming the subject for a harness effect — and it cost this project 11 functions parked as unmatchable.

Three rules, each earned here:

1. A failing gate must save its artifact before the next build starts. gate_main's own R40 baseline control was destroying the evidence it needed; the control is right, its ORDER was wrong.
2. Attribute per byte, not per run. A differing run that straddles two symbols belongs to both; crediting it to the symbol its first byte lands in reports a one-byte spill as "two functions diverged".
3. Negative-control the localizer itself, in both directions — flip one byte at a known address and assert it names the containing symbol (and its exclusive end: a flip at next_symbol must name the NEXT symbol), then assert an identical pair reports zero. Five of S69's biggest "findings" were artifacts of the instrument; a localizer that has never fingered a KNOWN perturbation is not evidence about an unknown one.