Chroma vectors

@mayurajs/vector-chroma implements the RAG contracts. Install it alongside mayura. Construction performs no I/O, credential discovery, provisioning or background work. All operations require an explicit host permission and a nonnegative costMicros ceiling. Offline tests and package checks passed locally. Real service behavior remains unqualified; see release validation status.

chromaVectorStore accepts endpoint, headers, collection, dimensions, costMicros, permissions, timeoutMs, maxConcurrent and optional test fetch. Grant rag:transport:chroma. Credentials go in host-owned headers, never URLs. HTTPS is required except explicit loopback development. There are no automatic retries or redirects. Response bodies and concurrency are bounded. A timed-out callback retains its slot until settlement.

Provision the collection/index before ingestion and configure cosine similarity, self-provided vectors and matching dimensions. The adapter binds every operation to a hash of project, principal and index space, and validates returned chunk metadata. Staging is not a cross-service transaction: the authoritative catalog decides which revision may be disclosed. Partial writes remain hidden and require reconciliation.

Also pass the explicit tenant and database and the collection ID as collection; provision a cosine collection.

Protocol reference, reviewed 2026-10-20: chroma documentation.