diff --git a/umap/static/umap/js/modules/sync/undo.js b/umap/static/umap/js/modules/sync/undo.js
index f973febe..57826495 100644
--- a/umap/static/umap/js/modules/sync/undo.js
+++ b/umap/static/umap/js/modules/sync/undo.js
@@ -22,12 +22,41 @@ export class UndoManager {
     this.toggleState()
   }
 
-  cleanOperation(operation, redo) {
-    const syncOperation = Utils.CopyJSON(operation)
-    delete syncOperation.oldValue
-    delete syncOperation.newValue
-    syncOperation.value = redo ? operation.newValue : operation.oldValue
-    return syncOperation
+  markSaved() {
+    if (this._undoStack.length > 0) {
+      const lastOperation = this._undoStack[this._undoStack.length - 1]
+      lastOperation.saved_marker = true
+    }
+  }
+
+  /**
+   * Returns the list of changed "subjects" from the undo stack,
+   * since the last time we marked "saved"
+   **/
+  getChangedObjects() {
+    // Get operations in the undo stack since the last save
+    let last_save_index = this._undoStack.findLastIndex(
+      (op) => op.saved_marker === true
+    )
+    if (last_save_index === -1) {
+      last_save_index = 0
+    }
+
+    console.log('last save index', last_save_index)
+    const operations_since_last_saved = this._undoStack.slice(last_save_index)
+
+    return operations_since_last_saved.reduce((acc, op) => {
+      const metadata = { subject: op.subject, metadata: op.metadata }
+      const obj = this._getSaveTargetFromOperation(op)
+      if (!acc.includes(obj)) {
+        acc.push(obj)
+      }
+      return acc
+    }, [])
+  }
+
+  _getSaveTargetFromOperation({ subject, metadata }) {
+    return this._getUpdater(subject, metadata).getSaveTarget(metadata)
   }
 
   undo(redo = false) {
@@ -37,10 +66,10 @@ export class UndoManager {
     if (!operation) return
     if (operation.verb === 'batch') {
       for (const op of operation.operations) {
-        this.applyOperation(this.cleanOperation(op, redo))
+        this._applyOperation(this._cleanOperation(op, redo))
       }
     } else {
-      this.applyOperation(this.cleanOperation(operation, redo))
+      this._applyOperation(this._cleanOperation(operation, redo))
     }
     toStack.push(operation)
     this.toggleState()
@@ -50,7 +79,15 @@ export class UndoManager {
     this.undo(true)
   }
 
-  applyOperation(syncOperation) {
+  _cleanOperation(operation, redo) {
+    const syncOperation = Utils.CopyJSON(operation)
+    delete syncOperation.oldValue
+    delete syncOperation.newValue
+    syncOperation.value = redo ? operation.newValue : operation.oldValue
+    return syncOperation
+  }
+
+  _applyOperation(syncOperation) {
     const updater = this._getUpdater(syncOperation.subject, syncOperation.metadata)
     switch (syncOperation.verb) {
       case 'update':
diff --git a/umap/static/umap/js/modules/sync/updaters.js b/umap/static/umap/js/modules/sync/updaters.js
index 0ea66d2e..32471934 100644
--- a/umap/static/umap/js/modules/sync/updaters.js
+++ b/umap/static/umap/js/modules/sync/updaters.js
@@ -31,8 +31,8 @@ class BaseUpdater {
     }
   }
 
-  getDataLayerFromID(layerId) {
-    return this._umap.getDataLayerByUmapId(layerId)
+  getDataLayerFromMetadata({ id }) {
+    return this._umap.getDataLayerByUmapId(id)
   }
 
   applyMessage(payload) {
@@ -51,6 +51,10 @@ export class MapUpdater extends BaseUpdater {
     this._umap.onPropertiesUpdated([key])
     this._umap.render([key])
   }
+
+  getSaveTarget(metadata) {
+    return this._umap
+  }
 }
 
 export class DataLayerUpdater extends BaseUpdater {
@@ -60,7 +64,7 @@ export class DataLayerUpdater extends BaseUpdater {
       console.log(
         'found datalayer with id',
         value.id,
-        this.getDataLayerFromID(value.id)
+        this.getDataLayerFromMetadata(value)
       )
     } catch {
       console.log('we are the fucking catch', value)
@@ -72,7 +76,7 @@ export class DataLayerUpdater extends BaseUpdater {
   }
 
   update({ key, metadata, value }) {
-    const datalayer = this.getDataLayerFromID(metadata.id)
+    const datalayer = this.getDataLayerFromMetadata(metadata)
     if (fieldInSchema(key)) {
       this.updateObjectValue(datalayer, key, value)
     } else {
@@ -85,17 +89,21 @@ export class DataLayerUpdater extends BaseUpdater {
   }
 
   delete({ metadata }) {
-    const datalayer = this.getDataLayerFromID(metadata.id)
+    const datalayer = this.getDataLayerFromMetadata(metadata)
     if (datalayer) {
       datalayer.del(false)
       datalayer.commitDelete()
     }
   }
+
+  getSaveTarget(metadata) {
+    return this.getDataLayerFromMetadata(metadata)
+  }
 }
 
 export class FeatureUpdater extends BaseUpdater {
   getFeatureFromMetadata({ id, layerId }) {
-    const datalayer = this.getDataLayerFromID(layerId)
+    const datalayer = this.getDataLayerFromMetadata({ id: layerId })
     return datalayer.getFeatureById(id)
   }
 
@@ -103,7 +111,7 @@ export class FeatureUpdater extends BaseUpdater {
   upsert({ metadata, value }) {
     console.log('updater.upsert for', metadata, value)
     const { id, layerId } = metadata
-    const datalayer = this.getDataLayerFromID(layerId)
+    const datalayer = this.getDataLayerFromMetadata({ id: layerId })
     const feature = this.getFeatureFromMetadata(metadata)
     console.log('feature', feature)
 
@@ -139,4 +147,8 @@ export class FeatureUpdater extends BaseUpdater {
     const feature = this.getFeatureFromMetadata(metadata)
     if (feature) feature.del(false)
   }
+
+  getSaveTarget({ layerId }) {
+    return this.getDataLayerFromMetadata({ id: layerId })
+  }
 }