The worst bugs don't throw. Events were disappearing from search results the moment they started — even though they were still live and still sellable. No exception, no alert, no error in any log. Just the right result quietly missing from the list.
The root cause was a boundary condition in how records were indexed: the logic that decided what counted as an upcoming event drew its line one step too early. The one-line date fix was easy. The real fix was harder and more valuable — integration tests around the reindex path so that this class of silent regression can't slip back in unnoticed.
Test the edges, cover the invisible
Two things stuck with me. First, the boundaries between before, during, and after are exactly where search relevance breaks, and they're exactly the cases a quick manual check skips. Second, reindexing logic deserves real integration coverage precisely because its failures are invisible until a user notices something they expected simply isn't there.