Patch release. The CLI and MCP entrypoints now default to the bm25 retriever, matching pre-registered decision D3 of study c36 (Finding More, Fusing Less, doi:10.5281/zenodo.21969901), which retired the fused default. Previous releases shipped surfaces that still defaulted to fused while the library documentation claimed bm25-primary. A regression test now asserts no surface reintroduces the fused default. No other behavior changes.