Function retrieve_context_multi 

pub fn retrieve_context_multi(
    conn: &Connection,
    repo_root: &str,
    weights: &BrokerWeights,
    request: ContextRequest,
    extra_memory_conns: &[&Connection],
) -> KimetsuResult<ContextBundle>

v0.4.1: multi-conn variant. extra_memory_conns is searched for memory candidates only (repo files + manifests stay project-local). The candidate stream is concatenated BEFORE normalization so the blended set is normalized together — keeping a user-brain capsule and a project-brain capsule comparable on the same raw_relevance scale.

Today extra_memory_conns carries at most one entry (the user brain at ~/.kimetsu/brain.db); the slice shape leaves room for future scope tiers (team brain, org brain) without breaking the signature.

v0.4.2: uses embeddings::open_default_embedder for the cosine term. Pre-v0.4.3 the default is NoopEmbedder, which short- circuits the cosine path so retrieval stays FTS-only — exact v0.4.1 behavior. v0.4.3 swaps the default to a real embedder.