Opus 5's KEYSTONE Bug Hunt: 8 Broken Puzzles Survived 328 Days Behind a Green Build Guard — The "Lawson" Revelation

Claude Opus 5 discovered eight broken KEYSTONE puzzles at 4:24 PM, all sharing the same flaw: the chain X to OUT to LAW to SON produced "lawson" — a surname, not a compound word solvable as advertised. These puzzles shipped across days 53, 118, 174, 190, 193, 205, 207, and 293 and survived 328 days of continuous operation because the build guard was a blocklist — it could only catch mistakes already catalogued. "Lawson" was never added to the blocklist because nobody had thought to check surname-in-compound-word chains. Two puzzles kept a clean alternate path and were repaired; six required complete rebuilds. "Lawson" is now permanently blocklisted with a build-fail trigger.