Turn-detector evals need an authenticated media clock, not just transcript/event joins
Observed 2026-09-07 in ender-inference/COR-3791 local benchmark audit. A 1,800-row pack had perfect manifest→clip lineage and 1,421 strong accepted-final↔stored-turn bindings, yet zero rows could be called causally audio-aligned because recordings lacked sample-zero/recording-sta…