diff --git a/umap/static/umap/js/modules/sync/updaters.js b/umap/static/umap/js/modules/sync/updaters.js
index a37ee0b9..915b7788 100644
--- a/umap/static/umap/js/modules/sync/updaters.js
+++ b/umap/static/umap/js/modules/sync/updaters.js
@@ -41,7 +41,7 @@ export class MapUpdater extends BaseUpdater {
   update({ key, value }) {
     console.log(key, value)
     this.updateObjectValue(this.map, key, value)
-    this.map.render([key.replace('options.', '')])
+    this.map.render([key])
   }
 }
 
@@ -50,8 +50,7 @@ export class DatalayerUpdater extends BaseUpdater {
     const datalayer = this.getLayerFromID(metadata.id)
     console.log(datalayer, key, value)
     this.updateObjectValue(datalayer, key, value)
-    const property = key.replace('options.', '')
-    datalayer.render([property])
+    datalayer.render([key])
   }
 }
 
diff --git a/umap/static/umap/js/umap.features.js b/umap/static/umap/js/umap.features.js
index 1a42d724..0f151cff 100644
--- a/umap/static/umap/js/umap.features.js
+++ b/umap/static/umap/js/umap.features.js
@@ -3,6 +3,7 @@ U.FeatureMixin = {
 
   getSyncMetadata: function () {
     return {
+      engine: this.map.sync,
       subject: 'feature',
       metadata: {
         id: this.id,
@@ -12,14 +13,9 @@ U.FeatureMixin = {
     }
   },
 
-  getSyncEngine: function () {
-    // FIXME use a get property / defineProperty
-    return this.map.sync
-  },
-
   onCommit: function () {
-    const { subject, metadata } = this.getSyncMetadata()
-    this.map.sync.upsert(subject, metadata, {
+    const { subject, metadata, engine } = this.getSyncMetadata()
+    engine.upsert(subject, metadata, {
       geometry: this.getGeometry(),
     })
   },
@@ -30,14 +26,14 @@ U.FeatureMixin = {
 
   syncUpdatedProperties: function (properties) {
     if ('latlng'.includes(properties)) {
-      const { subject, metadata } = this.getSyncMetadata()
-      this.map.sync.update(subject, metadata, 'geometry', this.getGeometry())
+      const { subject, metadata, engine } = this.getSyncMetadata()
+      engine.update(subject, metadata, 'geometry', this.getGeometry())
     }
   },
 
   syncDelete: function () {
-    let { subject, metadata } = this.getSyncMetadata()
-    this.map.sync.delete(subject, metadata)
+    let { subject, metadata, engine } = this.getSyncMetadata()
+    engine.delete(subject, metadata)
   },
 
   initialize: function (map, latlng, options, id) {
diff --git a/umap/static/umap/js/umap.forms.js b/umap/static/umap/js/umap.forms.js
index ca2d4ab1..1a0ec375 100644
--- a/umap/static/umap/js/umap.forms.js
+++ b/umap/static/umap/js/umap.forms.js
@@ -1186,9 +1186,10 @@ U.FormBuilder = L.FormBuilder.extend({
     L.FormBuilder.prototype.setter.call(this, field, value)
     this.obj.isDirty = true
     if ('render' in this.obj) this.obj.render([field], this)
-    const syncEngine = this.obj.getSyncEngine()
-    const { subject, metadata } = this.obj.getSyncMetadata()
-    syncEngine.update(subject, metadata, field, value)
+    console.log('setter', field, value)
+    const { subject, metadata, engine } = this.obj.getSyncMetadata()
+    console.log('metadata', metadata)
+    engine.update(subject, metadata, field, value)
   },
 
   finish: function () {
diff --git a/umap/static/umap/js/umap.js b/umap/static/umap/js/umap.js
index fbd98a58..102d78cc 100644
--- a/umap/static/umap/js/umap.js
+++ b/umap/static/umap/js/umap.js
@@ -266,14 +266,11 @@ U.Map = L.Map.extend({
 
   getSyncMetadata: function () {
     return {
+      engine: this.sync,
       subject: 'map',
     }
   },
 
-  getSyncEngine: function () {
-    return this.sync
-  },
-
   render: function (fields) {
     let impacts = U.Utils.getImpactsFromSchema(fields)
 
diff --git a/umap/static/umap/js/umap.layer.js b/umap/static/umap/js/umap.layer.js
index d3c6d671..10320578 100644
--- a/umap/static/umap/js/umap.layer.js
+++ b/umap/static/umap/js/umap.layer.js
@@ -597,6 +597,16 @@ U.DataLayer = L.Evented.extend({
     this.on('datachanged', this.map.onDataLayersChanged, this.map)
   },
 
+  getSyncMetadata: function () {
+    return {
+      engine: this.map.sync,
+      subject: 'datalayer',
+      metadata: {
+        id: this.umap_id, // XXX: should we specify it's the layerID here?
+      },
+    }
+  },
+
   render: function (fields, builder) {
     let impacts = U.Utils.getImpactsFromSchema(fields)
 
diff --git a/umap/ws.py b/umap/ws.py
index a6a51cfd..646017f0 100644
--- a/umap/ws.py
+++ b/umap/ws.py
@@ -33,7 +33,7 @@ class JoinMessage(BaseModel):
 
 
 class Geometry(BaseModel):
-    type: Literal["Point",]
+    type: Literal["Point", "Polygon"]
     coordinates: list
 
 
@@ -43,13 +43,15 @@ class GeometryValue(BaseModel):
 
 # FIXME better define the different messages
 # to ensure only relying valid ones.
+# This would mean having different kind of validation types
+# based on the kind and verb.
 class OperationMessage(BaseModel):
     kind: str = "operation"
     verb: str = Literal["upsert", "update", "delete"]
     subject: str = Literal["map", "layer", "feature"]
     metadata: Optional[dict] = None
     key: Optional[str] = None
-    value: Optional[str | bool | int | GeometryValue]
+    value: Optional[str | bool | int | GeometryValue] = None
 
 
 async def join_and_listen(
@@ -90,8 +92,7 @@ async def handler(websocket):
     signed = TimestampSigner().unsign_object(message.token, max_age=30)
     user, map_id, permissions = signed.values()
 
-    # We trust the signed info from the server to give access
-    # If the user can edit the map, let her in
+    # Check if permissions for this map have been granted by the server
     if "edit" in signed["permissions"]:
         await join_and_listen(map_id, permissions, user, websocket)