Loader steps one refinement pass keeps in flight at once (B9c). The serial
loop left the network idle while each step decoded, projected and committed,
so a scene of many small laddered nodes (a partition's parts) refined one
round trip at a time. Four overlaps those round trips without letting
refinement crowd the fetch gate: its reads queue in the refinement priority
class, behind every demand read (see utils/fetch-concurrency.ts).
Loader steps one refinement pass keeps in flight at once (B9c). The serial loop left the network idle while each step decoded, projected and committed, so a scene of many small laddered nodes (a partition's parts) refined one round trip at a time. Four overlaps those round trips without letting refinement crowd the fetch gate: its reads queue in the
refinementpriority class, behind everydemandread (seeutils/fetch-concurrency.ts).