libtmux:outcome-phase

Return retained dispatch evidence, without I/O. Raw process phases are :PREPARED, :LAUNCHING, :DISPATCHED and :EXITED. Named operations may also report :PREFLIGHT or :GUARD-REJECTED before payload dispatch. Explicit server termination reports :SERVER-TERMINATED only after retained pidfd readiness proves exit. Phase is separate from OUTCOME-STATUS; an exited queue can have partially completed effects even when it reported failure.