fix(agent): bound Wait on abandoned stdout/stderr pipes (session leak)#5
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A daemonizing exec (sh -c 'task &') leaves the background child holding the session's stdout/stderr pipe write-ends; cmd.Wait blocks until that child dies, pinning the handler goroutine, the vsock conn, and the pipe fds indefinitely. WaitDelay force-closes the pipes 2s after the command itself exits; ErrWaitDelay is mapped to the child's real exit code.
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The leak
vm exec -- sh -c 'task &': the shell exits instantly, but the daemonized child inherits the session's stdout/stderr pipe write-ends.cmd.Waitblocks until pipe EOF — i.e. until the background child dies, which for a real daemon is never. Each such exec pins: the handler goroutine, the vsock conn, the internal pipe fds, and the host-sidecocoon vm exechangs with it.Same family as the stdin-reader hang fixed in 7f796c5 (session join blocked), other side of the plumbing: stdout/stderr drain instead of stdin decode.
Fix
cmd.WaitDelay = 2s— after the command itself exits, abandoned pipes are force-closed and Wait returns (exec.ErrWaitDelay)ErrWaitDelaymapped to the command's real exit code fromProcessState— MsgExit semantics unchangedVerification
TestServerExecBackgroundChildDoesNotPinSession(sh -c 'sleep 6 & echo started'): without fix FAIL 6.29s (pinned), with fix PASS 2.01s (= WaitDelay signature) — negative-tested both waysmake lint0 issues × {linux, darwin, windows}; full test suite green (agent 83.6%, client 21.2%)