Typed Contracts
Document, Chunk, RetrievalResult, and PipelineResult are typed and immutable. Every pipeline stage receives and returns objects whose shape is guaranteed, not assumed.
Explicit Failure Modes
Empty retrieval, score collapse, context truncation, and embedding model mismatch are named, catchable types, not silent quality degradation discovered after the fact.
Cost Accountability
Every result carries a CostReport with tokens, latency, and estimated cost per stage, so quality and cost tradeoffs are visible before the bill arrives.