perf(ipc): give worker pipes real OS buffers instead of zero-quota rendezvous

docs/WorkerFrameProtocol.md

@@ -164,6 +164,17 @@ class drains both queues to empty, and the heartbeat loop guarantees one
 arrives within a heartbeat interval, so worst-case residency is a few envelope
 references for seconds — not a leak.
 
+## Pipe Buffers
+
+The gateway creates each worker pipe with an explicit 128 KiB kernel buffer per
+direction (`SessionWorkerClientFactory.PipeBufferSizeBytes`) rather than the zero
+quota the short `NamedPipeServerStream` overloads request. A zero-quota byte-mode
+pipe makes every write rendezvous with a pending read, so a writer with no reader
+parked blocks until one arrives — the failure class behind the historical windev
+full-suite wedge. A real quota decouples writer latency from reader scheduling and
+lets the flush coalescing above actually pay off. On Unix hosts, where named pipes
+are Unix domain sockets, the sizes are advisory.
+
 ## Verification
 
 The frame protocol lives in `ZB.MOM.WW.MxGateway.Worker.Ipc` (`WorkerFrameReader`,