Debug an async race by making it fail on demand: deferred promises, one failing test, then the fix

Sun, 08 Nov 2026 11:05:00 +0000

The bug report says the search box sometimes shows results for the wrong query. Not always. Not on the developer’s machine. Someone types “ab”, pauses, types “c”, and the list that settles on screen belongs to “ab”. Paste that report into an agent and a typical answer is a plausible patch (a debounce, a loading flag, a useEffect cleanup) that nobody can show fixes anything, because nobody has shown the bug.

Async on Tokenise

Debug an async race by making it fail on demand: deferred promises, one failing test, then the fix