Function prefill_codispatch_enabled 

pub fn prefill_codispatch_enabled() -> bool

2026-09-25: Whether cross-request co-dispatch of fresh prompts is on: --prefill-codispatch, else METRALE_PREFILL_CODISPATCH (1 or true, any case); off when neither is set. The scheduler’s levers and prefill_batched_first_chunk_enabled both read it.