The agent fixed the failing call site and left the same bug on its sibling

The agent patches the single call site where the user reported the error and ships a guard that only protects that one input. This piece explains why agents search the literal stack line instead of the invariant, what a local fix leaves behind on copied sibling routes, how tests written around the reported case miss the recurrence, and how to generalize a fix across every call site that builds the same value before closing the ticket.