Interface RerankCodec

nodedb-vector/src/rerank/codec.rs:48–75

Object-safe trait for asymmetric rerank codecs. Each impl wraps an existing `nodedb-codec::VectorCodec` and exposes a uniform shape so the sidecar can hold `Arc ` regardless of the underlying associated-type machinery.

/// hold `Arc<dyn RerankCodec>` regardless of the underlying associated-type
/// machinery.
pub trait RerankCodec: Send + Sync {
    /// Encode a full-precision vector. Returns fixed-width bytes for this codec.
    fn encode(&self, v: &[f32]) -> Result<Vec<u8>, RerankError>;

    /// Prepare a query once before repeated distance calls.
    fn prepare_query(&self, q: &[f32]) -> Result<PreparedQuery, RerankError>;

    /// Compute asymmetric distance from a prepared query to an encoded vector.
    fn distance_prepared(
        &self,
        prepared: &PreparedQuery,
        encoded: &[u8],
    ) -> Result<f32, RerankError>;

    /// Identity tag for mismatch detection.
    fn name(&self) -> CodecName;

    /// Train from a sample of vectors. Default no-op for codecs that don't need
    /// training (e.g. Binary). Specific codec impls override this when needed.
    fn train(&mut self, _samples: &[&[f32]]) -> Result<(), RerankError> {
        Ok(())
    }

    /// Serialize trained state to bytes. Each codec uses its own magic header
    /// (NDSQ / NDBIN / NDPQ / NDRBQ / NDBBQ). The bytes are codec-specific;
    /// `rerank_codec_from_bytes` is used for restore, paired with `name()`.
    fn to_bytes(&self) -> Result<Vec<u8>, RerankError>;
}

/// Reconstruct a `RerankCodec` from its byte form. The `name` tag tells us
/// which wrapper to dispatch into; the bytes are the codec's own format.