Unified composite transfer type produced by CompositeTransferBuilder.
Input capability flags (Pushable, PollingProxy, AsyncPushable, AsyncPollingProxy)
are extracted from the start transfer. Output capability flags (Pullable, Subscribable,
AsyncPullable) are extracted from the finish transfer. Triggerable, AsyncTriggerable,
and Gate are extracted from options or the start/finish transfers (same priority logic
as UniversalCompositeTransfer).
The result is a Transfer<TInput, TOutput, [...Flags]> — the same computed type used
by all transfer factories, with compile-time literal flags guaranteeing method existence.
Unified composite transfer type produced by CompositeTransferBuilder.
Input capability flags (Pushable, PollingProxy, AsyncPushable, AsyncPollingProxy) are extracted from the start transfer. Output capability flags (Pullable, Subscribable, AsyncPullable) are extracted from the finish transfer. Triggerable, AsyncTriggerable, and Gate are extracted from options or the start/finish transfers (same priority logic as UniversalCompositeTransfer).
The result is a
Transfer<TInput, TOutput, [...Flags]>— the same computed type used by all transfer factories, with compile-time literal flags guaranteeing method existence.