SP+ is the paper's first-use extension of the strict-parity (SP) contract that additionally allows a learned reranker on top of the matched encoder, dense candidate pool, cutoff, split, and matching rule. SP+ results are reported separately from SP so that any reranker-driven gain is not conflated with the graph-traversal effect that SP is designed to isolate. In practice, SP fixes the retrieval interface across compared systems, and SP+ layers a reranker onto that same interface as an explicitly labeled diagnostic.