Blast Radius: fix the whole family

Every factory in this hackathon has a reviewer. When it finds a bug, the bug gets fixed. But a bug is usually born somewhere: one spec sentence, one handoff, one decision or one shared function. Everything else born there has the same mistake, and nobody checks it until a hidden test does. Blast Radius adds a fifth seat for exactly that: the investigator. Five seats run in BAND Desktop: a coordinator, two builders, a verifier and the investigator. Every builder commit must say which work item and spec lines it came from (a git hook refuses it otherwise). When any defect is found, the investigator walks git blame back to its origin, names the family born there, and checks every sibling with a probe it first saw failing on a known-bad version. A failing sibling becomes a REJECT to its owner. The family then goes forward as a risk for later stages. The judged run: one dispatch built all four stages of tablekeeper in 2 hours 16 minutes, and the official harness claims stage 4. At stage 1 the verifier rejected one bad booking reference accepted on reset. The investigator traced it to spec line L1.41: data entering through reset or import never went through the API's checks. It swept 9 siblings and found 5 more that nobody had reported. The same family caught two more defects at stages 2 and 3. In total 8 defects, 7 found by the sweep, all from one origin, all fixed. A sealed exam written before the run (169 checks the band never saw) passes 168. In Band a seat wakes only when a message names it; twice a seat ended its turn early, so we sent two short wake-up messages. Room log, cards, probes and the script behind every number are in the repo.