Eou Preemption Analysis

Offline viability check for synthesized PREFLIGHT_TRANSCRIPT.

For each assistant turn that has eou_probability_samples recorded, asks: when did Smart Turn v3 first cross threshold, vs. when did the STT final transcript arrive? If Smart Turn fires reliably before the STT final, it's a viable trigger for speculative LLM kickoff in languages that don't have Flux's native eager-EOT (Spanish, etc.).

Sources considered as "smart turn": smart_turn_v3 and smart_turn_v3_shadow (the shadow-mode label).

Returned per language:

• turns: total turns with any smart-turn samples
• crossed_count: turns where Smart Turn ever crossed threshold
• crossed_pct: 100 * crossed_count / turns
• early_advantage_ms: how many ms Smart Turn's first crossing preceded the STT final (positive = useful; negative = too late). Reported as p10/p50/p90.
• false_cross_count: number of times the signal crossed threshold then dropped back below before the final crossing. Reported as mean/p50/p90.
• crossing_count_total: total threshold crossings per turn (mean).