The agent patched the lookalike function from a keyword search, so the failing symbol stayed broken

An agent facing a normalization bug searches the repo by keyword, gets back a family of lookalike helpers, and patches the first match rather than the symbol in the failing stack trace. It writes tests against the edited function, goes green, and reports done while the original path stays broken. This article walks through a carrier-lookup case, explains why token-overlap retrieval beats the call graph, lists the tells (edited symbol absent from the traceback, new tests target the wrong helper, original repro still fails), and gives the cheap guards: pin the failing symbol from the stack frame, require a before/after repro on the exact input, grep callers against the reported request, and search outward from the frame instead of picking from a generic keyword list.