ax-detect — the detector engine

A [Detector] is a contract: given a normalized [RecordSet], it either runs and emits [Finding]s, or it declares honest [Absence] (e.g. "no numeric columns"). It never fabricates a clean result for data it couldn't assess. The [Registry] runs a set of detectors deterministically and collects everything into one [Report], which the CLI turns into a tq1 envelope.

All math routes through [ax_core::det], so every detector inherits order-independent, reproducible reductions.