A peer actor multiplexes socket reads with its mailbox on one thread: tick()
reads the socket while outgoing messages (e.g. a queued QueueUpload that starts
a download) are delivered through the mailbox between ticks. Inbound
connections accepted by the listener were left in blocking mode, so once such a
peer went idle tick() parked inside read() and never drained the mailbox — a
download queued against that peer never sent its QueueUpload and hung. Outbound
connections already set non-blocking; do the same for inbound P connections.
Covered by a new server-optional e2e test that downloads a file end to end from
an in-process mock peer over real P (control) and F (transfer) connections,
asserting the bytes written match the source. The mock speaks the library's own
public Message wire format, so no dependencies are added.
michel
06cd638736