tscircuit (AI PCB design agent backend)ECADConfidence: Medium
An LLM-generated tscircuit design wrote holeDiameter on a hole element, a natural guess since platedhole and via use that prop name. The zod schema silently stripped the unknown key instead of rejecting it, leaving a null-diameter hole that turned into NaN bounds in the autorouter. Compilation reported 0 errors while the entire autoroute pass died for every net on the board; the crash only showed in stderr.
From the Grok Haitch pain-radar compilation, finding 41, found 2026-09-27, score 9/10. Verbatim evidence: "Printed to stderr during render (compile itself reports 0 errors)" and "the entire autoroute pass dies, for every net on the board." Cost model assumes the bad prop is bisected and fixed, with the lost compile-debug cycle as the main cost.