Stateful incremental frame parser. Feed raw decoded text via push;
each call returns zero or more COMPLETE frames (a frame dispatches only on
its terminating blank line, exactly per spec — a frame split across pushes
never double-dispatches or drops data).
Stateful incremental frame parser. Feed raw decoded text via push; each call returns zero or more COMPLETE frames (a frame dispatches only on its terminating blank line, exactly per spec — a frame split across pushes never double-dispatches or drops data).