Per-field accept/review with selective risk at most alpha is the trust contract document-extraction systems need. The paper shows that the natural procedure silently violates this contract on real documents: on 13,859 genuine claude-sonnet-5 fields from 800 CORD receipts (49.0% correct), coverage 0.416 at risk 0.127 violates nominal alpha=0.10 in 95% of resplits. This is new because prior work assumed that per-field conditional calibration suffices; here it does not.1
The diagnosis identifies three failure modes: document clustering (design effect 1.84–2.45), score-refit leakage, and a tie-mass pathology in which a degenerate score collapses the threshold grid (0.030 to 0.001). Each failure mode corresponds to an unstated assumption in the standard protocol: sample independence, use of the same data for scoring and threshold selection, and continuous non-degenerate scores.1
The validity ladder organizes guarantee forms by tier. A fit/val split restores expected-selective-risk control for a learned fusion: coverage 0.318 at risk 0.096 at nominal alpha=0.10, but the realized risk exceeds alpha in 47.5% of resplits, so it is an on-average point, not a certificate. The only tier matched to documents is Mondrian Learn-then-Test with exact binomial tails, yielding per-group PAC certificates (field-iid 0.171 at risk 0.068, cluster-corrected 0.140, doc-iid 0.060), honestly near-vacuous today.1
The constraint that moves is the target of inference: from expected selective risk over resplits to per-group certificates that hold simultaneously. Concurrently, the paper asks when conditioning pays. The pre-specified support-bin taxonomy wins every rigor tier on the sonnet CORD capture (Bonferroni-corrected p<1e-4), yet the win does not replicate on the same documents under haiku or qwen, and pooled thresholds win on higher-accuracy corpora. The evidence thus suggests conditioning helps exactly where pooled cannot certify.1
A frozen-configuration confirmation on selection-untouched claude-haiku-4-5 held at both risk levels, and a blind three-annotator human-gold audit verifies the practical tier's accepted-set risk at 1.3% against its 10% budget (Fleiss' kappa=0.83). What would change our mind: a demonstration on multiple model families and corpora that the validity ladder transfers, or a failure of the frozen-configuration confirmation under larger scale.1
Context
The paper is a methodological study in selective prediction, evaluated on a real document-extraction task. The dataset comprises 800 CORD receipts with fields extracted by claude-sonnet-5. The three failure modes are defined by contrast with the assumptions of the standard selective-risk estimator, and the validity ladder is the paper's organizing contribution: each rung adds a stricter guarantee form, from in-sample to PAC.1
Caveats
The central caveat is that the primary guarantee is only expected-selective-risk, and the realized risk exceeds alpha in 47.5% of resplits; the PAC certificates, while valid, are near-vacuous. The support-bin win does not replicate on other model families, and the entire evaluation rests on a single corpus. A change of mind would require diverse replication and a certificate tier that is not vacuous in practice.1



