diff --git a/pkg/acl/acltree/acltree.go b/pkg/acl/acltree/acltree.go
index 9761e545..90bf337a 100644
--- a/pkg/acl/acltree/acltree.go
+++ b/pkg/acl/acltree/acltree.go
@@ -38,6 +38,7 @@ type ACLTree interface {
 	ACLState() *ACLState
 	AddContent(ctx context.Context, f func(builder ChangeBuilder) error) (*Change, error)
 	AddChanges(ctx context.Context, changes ...*Change) (AddResult, error)
+	AddRawChanges(ctx context.Context, changes ...*aclpb.RawChange) (AddResult, error)
 	Heads() []string
 	Root() *Change
 	Iterate(func(change *Change) bool)
@@ -245,6 +246,20 @@ func (a *aclTree) AddContent(ctx context.Context, build func(builder ChangeBuild
 	return ch, nil
 }
 
+func (a *aclTree) AddRawChanges(ctx context.Context, rawChanges ...*aclpb.RawChange) (AddResult, error) {
+	var aclChanges []*Change
+	for _, ch := range rawChanges {
+		change, err := NewFromRawChange(ch)
+		// TODO: think what if we will have incorrect signatures on rawChanges, how everything will work
+		if err != nil {
+			continue
+		}
+		aclChanges = append(aclChanges, change)
+	}
+
+	return a.AddChanges(ctx, aclChanges...)
+}
+
 func (a *aclTree) AddChanges(ctx context.Context, changes ...*Change) (AddResult, error) {
 	a.Lock()
 	// TODO: make proper error handling, because there are a lot of corner cases where this will break
diff --git a/service/sync/requesthandler.go b/service/sync/requesthandler.go
new file mode 100644
index 00000000..c935885a
--- /dev/null
+++ b/service/sync/requesthandler.go
@@ -0,0 +1,43 @@
+package sync
+
+import (
+	"context"
+	"github.com/anytypeio/go-anytype-infrastructure-experiments/pkg/acl/acltree"
+	"github.com/anytypeio/go-anytype-infrastructure-experiments/service/sync/syncpb"
+	"github.com/anytypeio/go-anytype-infrastructure-experiments/service/treecache"
+	"github.com/anytypeio/go-anytype-infrastructure-experiments/util/slice"
+)
+
+type requestHander struct {
+	treeCache treecache.Service
+	client    SyncClient
+}
+
+func (r *requestHander) HandleHeadUpdate(ctx context.Context, senderId string, update *syncpb.SyncHeadUpdate) error {
+	err := r.treeCache.Do(ctx, update.TreeId, func(tree acltree.ACLTree) error {
+		_, err := tree.AddRawChanges(ctx, update.Changes...)
+		if err != nil {
+			return err
+		}
+		shouldFullSync := !r.compareHeads(update.Heads, tree.Heads())
+
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (r *requestHander) compareHeads(syncHeads []*syncpb.SyncHead, heads []string) bool {
+	for _, head := range syncHeads {
+		if slice.FindPos(heads, head.Id) == -1 {
+			return false
+		}
+	}
+	return true
+}
+
+func (r *requestHander) prepareFullSyncRequest(tree acltree.ACLTree) (*syncpb.SyncFullRequest, error) {
+	
+}
diff --git a/service/sync/syncclient.go b/service/sync/syncclient.go
new file mode 100644
index 00000000..95354982
--- /dev/null
+++ b/service/sync/syncclient.go
@@ -0,0 +1,8 @@
+package sync
+
+import "github.com/anytypeio/go-anytype-infrastructure-experiments/service/sync/syncpb"
+
+type SyncClient interface {
+	NotifyHeadsChanged(update *syncpb.SyncHeadUpdate) error
+	RequestFullSync(id string, request *syncpb.SyncFullRequest) error
+}