The per-command fan-out loop, generic over the selection member, the resolved
per-target plan, and the inner envelope type. Mirrors the original
retrieveGroup worker exactly: resolve each member (a resolve failure becomes
an inner error envelope, never a throw out of the batch); run the resolved
request through runWithRetry (a retryable transient drop is retried,
everything else recovers to an inner error envelope). Results are returned in
input (record-index) order via runBoundedPool.
The per-command fan-out loop, generic over the selection member, the resolved per-target plan, and the inner envelope type. Mirrors the original
retrieveGroupworker exactly: resolve each member (a resolve failure becomes an inner error envelope, never a throw out of the batch); run the resolved request through runWithRetry (a retryable transient drop is retried, everything else recovers to an inner error envelope). Results are returned in input (record-index) order via runBoundedPool.