open_server

Start an isolated foreground tmux daemon with an empty configuration and a unique private socket directory. Validate its reported PID against the spawned child before returning an OwnedServer . Environment entries are copied and validated; inherited TMUX and TMUX_PANE are removed. No ambient server is contacted. The temporary directory must permit a socket path under 104 bytes.

open_server(; tmux="tmux", env=ENV, timeout=0.9, cancel=nothing)

timeout bounds startup using a monotonic clock; cancel applies only until startup finishes. Both failure paths reap the daemon. Daemon stderr retains at most 64 KiB; startup and cleanup errors indicate truncated diagnostics. Close the returned handle explicitly, or use with_server for scoped ownership.