The noise filter is the first of triagepilot's three moves and the only one that uses no model at all. In-app bug reports arrive mostly as noise: a "test test asdf", an empty description, a stray keystroke someone submitted by accident. The filter catches those with plain heuristics, no reasoning and no API call, so the cheapest possible check runs before anything expensive does.
The ordering is the whole point. A model asked to diagnose a junk report will happily produce a fluent, confident diagnosis of a bug that is not there, and it will charge a token to do it. Putting a free, mechanical screen in front of the model means the expensive step is spent only on reports that might actually be real. Cheapest move first, and the report has to earn its way to the next one.
A dropped report is a terminal outcome, not a verdict about a defect. The filter is not claiming the report is wrong, only that it carries none of the marks of a real one. That narrow, mechanical job is exactly why it can run for free.