TRIDENT: Post-Selection Evidence Accountability for Token-Efficient RAG

RAG systems often verify citations only after retrieval and shortlisting have selected which passages will be tested. A verifier calibrated on random passage--claim pairs is therefore applied to a different population: shortlisted pairs chosen by the retrieval policy. This makes support verification a post-selection inference problem. We introduce TRIDENT, a contract-scoped framework for post-selection evidence accountability. Safe-Cover emits structural-facet support certificates with query-level Bonferroni FWER control, or abstains when the logged contract cannot certify support. Pareto-Knapsack relaxes certification and uses the same frozen facet table as a token-efficient multi-hop QA selector. Across HotpotQA, 2Wiki, and MuSiQue, TRIDENT controls false certificates under deployed contracts, identifies higher-quality answer-linked slices when certificates are emitted, and improves the matched-budget multi-hop QA frontier. The accountable unit is therefore not a retrieved passage or generated citation, but a support claim calibrated under the policy that selected it.