Function long_prompt_path 

pub async fn long_prompt_path(
    handle: &PluginHandle,
    short: Value,
    long: Value,
    want: &(dyn Fn(&str) -> bool + Sync),
    timeout: Duration,
) -> Cell

2026-09-26: The same image and question, short and with a large block of filler text prepended; both replies must satisfy want.

With METRALE_VISION_CODISPATCH on, phase_start_prefills admits an image request to the batched encode only when its prompt fits max_prefill_tokens; a longer prompt encodes its own images (prepare_vision_embed), so the two prompts take different paths.