pub const RRF_K: f64 = 30.0;Expand description
G9 — Reciprocal Rank Fusion constant. IR-C (2026-06-10b,
performance-output-and-compare.md) found the standard k≈60 slightly too
high: the recall gain is concentrated at the top of the list, where a lower
k sharpens rank-1/2 contributions. k=30 is the validated operating point
(k10 > k30 > k60 > k100 on the sweep, 30 the conservative middle).
Fusion is on rank, never raw score.