fix: Fixes to command stream

server/internal/grpc/server.go

@@ -382,6 +382,17 @@ func (s *vantageServer) CommandStream(stream pb.Vantage_CommandStreamServer) err
 			if beats == 1 {
 				log.Printf("agent %s command stream beating every %s", srv.ServerID, pingInterval)
 			}
+			// A beat the stream accepted is the strongest liveness evidence this
+			// pod has, so it is also used to renew presence. The renewal ticker
+			// proves only that a goroutine still runs; this proves the stream
+			// itself still carries bytes to the agent. A false answer means
+			// another pod has taken the agent over and this stream is a
+			// half-open leftover, which is worth ending here rather than beating
+			// into for as long as the connection survives.
+			if !services.TouchPresence(ctx, srv.ServerID) {
+				log.Printf("agent %s command stream superseded, closing", srv.ServerID)
+				return nil
+			}
 		case cmd, ok := <-ch:
 			if !ok {
 				return nil