nx_drbench.nx

nx_drbench.nx -- HotpotQA distractor val[0..99]: the FIRST public-benchmark measurement of the Nishi researcher (census axis [BEN]). Protocol = published distractor eval (10 paras: 2 gold + 8 distractors); retrieve + extract; scored by SQuAD word-F1/EM (nx_qa_score_lib, integer permille) + gold-para recall@2. MODES: mode0 single-hop lexical (IDF-weighted para retrieval + span-heuristic extraction); mode1 mechanical multi-hop (hop-1 best para/sentence -> bridge entities -> expanded second retrieval). TEETH: T1 parse integrity, T2 gold-title resolution, T3 rotated-gold NEG-CONTROL (~0), T4 retrieval floor. MEASURED 2026-07-07 (100-row p0): MODE0 F1=172 EM=13 r@2=640 / MODE1 F1=155 EM=11 r@2=660 -- the honest mechanical ceiling (bridge-not-answer-target failure mode; the climb is census R1/R3). DEBT EATEN 2026-07-07: the ~1100-line engine that lived here moved to nx_qabench_engine.nx (shared with nx_qabench's multi-benchmark ladder) -- this file is now IMPORT + main only, zero duplication, one fix point. ctx slots + engine docs live in nx_qabench_engine.nx. expect_exit: 0 license_tier: ORIGINAL