[Init] Initial commit - NetMesh terminal manager

docs/research/sftp-shared-channel-cancellation.md

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+# Shared SSH connection cancellation audit
+
+Cancelling a transfer while its isolated SFTP channel is opening calls the
+bounded-open abort path. Previously that path ended/destroyed the physical SSH
+transport. Production pooled SFTP sessions normally share a terminal SSH
+connection, so cancelling one transfer can disconnect terminals, browsing and
+other transfers. The same teardown happened on the channel-open deadline.
+
+The real startTransfer/cancelTransfer path reproduces physical end/destroy calls;
+its old test double lacked those methods and could not detect the problem.
+
+The repair rejects the abandoned caller promptly, retains the shared transport,
+closes a channel arriving after abandonment, and blocks further channel-open
+allocation on that transport while any abandoned request remains unresolved.
+This bounds retry accumulation without queuing controls behind a transfer.
+Healthy parallel opens remain allowed; callback settlement or transport closure
+releases the abandoned-open bookkeeping. Existing active channels remain usable.
+
+This separately reproduced mechanism is relevant to the connection-loss themes
+in #2973 and #2832, but does not establish the cause of their VPN/jump-host reports.