Function ensure_decode_route_servable 

pub fn ensure_decode_route_servable(
    route: MoeLoraRoute,
    path: &str,
) -> Result<()>

SOLID Incr-4 host-side pre-lookup guard for the BATCHED decode entries (decode_batch_compute_main, mixed_forward): a batch containing a row routed to a NON-active adapter (Refuse) cannot be served by the single-active fold — build_moe_row_adapter_decode defensively maps such rows to base, so proceeding would SILENTLY serve base weights for an adapter-routed request. Call BEFORE any graph lookup/capture so captured padded_n graphs stay route-agnostic. Pure (no self, no GPU) so the decision is unit-testable without hardware.