recover-business-rules

Recover implicit business rules from legacy source before a modernization touches it, in the shape of research-existing-code but aimed at legacy code instead of a live-codebase question. Turns a magic number, an unexplained null check, a swallowed exception, or a commented-out branch into an explicit, numbered, file:line-cited rule with a confidence level. Use at Stage 1 (Research) of any modernization engagement, before writing the constitution, and before any legacy source is rewritten, wrapped, or ported.