major changes

pkg/actor/grpc_server.go

@@ -107,19 +107,27 @@ func (s *ControlServer[V]) AnnounceOwnership(ctx context.Context, req *messages.
 	}, nil
 }
 
+func toAny[V any](grain V) (*anypb.Any, error) {
+	data, err := json.Marshal(grain)
+	if err != nil {
+		return nil, err
+	}
+	return &anypb.Any{
+		Value: data,
+	}, nil
+}
+
 func (s *ControlServer[V]) Get(ctx context.Context, req *messages.GetRequest) (*messages.GetReply, error) {
 	grain, err := s.pool.Get(ctx, req.Id)
 	if err != nil {
 		return nil, err
 	}
-	data, err := json.Marshal(grain)
+	grainAny, err := toAny(grain)
 	if err != nil {
 		return nil, err
 	}
 	return &messages.GetReply{
-		Grain: &anypb.Any{
-			Value: data,
-		},
+		Grain: grainAny,
 	}, nil
 }
 
@@ -163,16 +171,40 @@ func (s *ControlServer[V]) Apply(ctx context.Context, in *messages.ApplyRequest)
 	for i, anyMsg := range in.Messages {
 		msg, err := anyMsg.UnmarshalNew()
 		if err != nil {
-			return &messages.ApplyResult{Accepted: false}, fmt.Errorf("failed to unmarshal message: %w", err)
+			return nil, fmt.Errorf("failed to unmarshal message: %w", err)
 		}
 		msgs[i] = msg
 	}
-	_, err := s.pool.Apply(ctx, in.Id, msgs...)
+	r, err := s.pool.Apply(ctx, in.Id, msgs...)
 	if err != nil {
-		return &messages.ApplyResult{Accepted: false}, err
+		return nil, err
+	}
+	grainAny, err := toAny(r)
+	if err != nil {
+		return nil, err
+	}
+	mutList := make([]*messages.MutationResult, len(in.Messages))
+	for i, msg := range r.Mutations {
+		mut, err := anypb.New(msg.Mutation)
+		if err != nil {
+			return nil, err
+		}
+		var errString *string
+		if msg.Error != nil {
+			s := msg.Error.Error()
+			errString = &s
+		}
+		mutList[i] = &messages.MutationResult{
+			Type:    msg.Type,
+			Message: mut,
+			Error:   errString,
+		}
 	}
 
-	return &messages.ApplyResult{Accepted: true}, nil
+	return &messages.ApplyResult{
+		State:     grainAny,
+		Mutations: mutList,
+	}, nil
 }
 
 // ControlPlane: Negotiate (merge host views)