Function compose_detector_corpus 

pub fn compose_detector_corpus(
    embedded: Vec<DetectorSpec>,
    custom: Vec<DetectorSpec>,
    mode: DetectorCorpusMode,
) -> Result<Vec<DetectorSpec>, DetectorCorpusError>

Compose an effective detector corpus without implicit merging.

Replace mode returns the custom vector directly and does not clone either corpus. Overlay mode preserves each input’s order, rejects every identifier shared by the embedded and custom sets, and then moves the custom specs onto the end of the embedded vector.