Bind Only Under Pressure: Diagnosing Evidence Identity in Visual PDF Retrieval

Conjunctive PDF retrieval imposes constraints on evidence identity: clauses may require different pages, whereas table predicates may require the same row. However, aggregate retrieval gains do not isolate the contribution of these constraints. We define binding pressure as a violation of a typed relation by independently optimal evidence assignments. We prove that per-role maxima alone cannot identify relational cost, that maximum-product binding preserves feasible independent assignments, and that the fraction of queries with score changes bounds the aggregate metric change. These results motivate PRESSUREAUDIT, a component-matched evaluation protocol, and PRESSUREBIND, an exact, training-free assignment layer. On n-Clue v1, conditionwise scoring with a frozen 4B encoder improves gold nDCG@10 from .4004 to .4802, but distinct-page binding contributes only +0.000001; 3.43% of candidates exhibit pressure. A fresh, checksum-verified n-Clue v2 evaluation yields first-stage, unary, and bound scores of .3183, .3587, and .3591, with 2.44% candidate pressure. On TCR selection queries, same-row scoring preserves Top-1 and MRR on 113 of 127 queries without positive pressure and improves Top-1 from .429 to .643 on the 14 pressured queries. These findings distinguish improvements in unary evidence processing from relational effects and motivate reporting pressure alongside matched ablations and aggregate performance.