Policy-Conditioned Constrained Decoding for Column-Level Access Control in Text-to-SQL

PCC-SQL achieves 0% Leakage Rate and coverage up to 88.7% on Spider-CU by applying a per-token logits mask that deterministically eliminates column-use violations during text-to-SQL decoding. The system formalizes column-use policies across semantic roles—output, filter condition, and aggregation argument—aligning each with grammar productions tracked by the decoder. It operates in a single decoding pass with overhead within +10% tokens of direct prompting.