Extend the clipboard target boundary with ordered prefix delivery.
Pass up to four queued LGMP stream records to the Helper ring in one
operation, apply state only to the accepted prefix, and retain the
remaining suffix for exact retries.
The channel holds its write lock across the prefix and emits one pipe
doorbell per stream window instead of one per record.
Keep inbound stream payloads in the bounded stream-target window while
the Helper channel is busy and publish directly from those buffers.
Retain the pending target only for LGMP queue controls. Their credits
remain outstanding across retries.
This removes one full payload copy per client-to-Helper record without
changing delivery order, backpressure, or reset behavior.
Drive adaptive clipboard stream polling with a high-resolution waitable
timer instead of rounding microsecond delays into coarse wait-function
timeouts.
Preserve the explicit stop and local wake events while avoiding a clock-tick
stall at each file-transfer window.
Carry DATA and FILE_DATA only through the duplex SPSC streams. Keep LGMP
queues for control and status. Remove grants, commits, ACKs, and
queue-payload transport negotiation.
Poll adaptively while ownership or release is active. Preserve FIFO
release and graceful draining. Quarantine payloads crossed by a newer
OFFER or CLEAR, and retire data-plane state on detach.
Create one reliable four-slot lane in each direction and advertise the
stream data plane for clipboard protocol v4.
Bind both lanes to the accepted owner generation, stage incoming data
within a fixed window, and apply backpressure when Helper delivery is
full.
Drain reliable records before releasing an owner. Force stale or
unresponsive bindings after a bounded deadline while preserving the
existing cancellation and clipboard-clear cleanup.
