Function dispatch_generic_frame 

pub fn dispatch_generic_frame(
    frame: &Frame,
    authenticated: bool,
    session: ParticipantSession,
    context: ParticipantConnectionContext,
    conversations: &mut ParticipantConnectionConversations,
    handler: &dyn ParticipantSemanticHandler,
) -> ParticipantDispatch

Gates, decodes, semantically applies, and encodes one participant frame.

Transport rejection values originate in liminal-protocol; semantic values originate only in handler. No lifecycle outcome is constructed here.