diff --git a/localtypings/pxteditor.d.ts b/localtypings/pxteditor.d.ts
index 59845ba17139..77b5595b934f 100644
--- a/localtypings/pxteditor.d.ts
+++ b/localtypings/pxteditor.d.ts
@@ -66,6 +66,7 @@ declare namespace pxt.editor {
         | "renderxml"
         | "renderbyblockid"
         | "setscale"
+        | "updatefilters"
         | "startactivity"
         | "saveproject"
         | "compile"
@@ -1028,6 +1029,7 @@ declare namespace pxt.editor {
         handleExtensionRequest(request: pxt.editor.ExtensionRequest): void;
 
         fireResize(): void;
+        updateFilters(filters?: pxt.editor.ProjectFilters): void;
         updateEditorLogo(left: number, rgba?: string): number;
 
         loadBlocklyAsync(): Promise<void>;
diff --git a/pxteditor/editorcontroller.ts b/pxteditor/editorcontroller.ts
index fb5f9d7c4346..55524047f6a6 100644
--- a/pxteditor/editorcontroller.ts
+++ b/pxteditor/editorcontroller.ts
@@ -95,6 +95,15 @@ export function bindEditorMessages(getEditorAsync: () => Promise<IProjectView>)
                                 return Promise.resolve()
                                     .then(() => projectView.editor.setScale(zoommsg.scale));
                             }
+                            case "updatefilters": return Promise.resolve()
+                                .then(() => {
+                                    // Restored from LBOS-1046 (lost in the v12 upstream merge).
+                                    // p2-studio CodingCanvas sends { type: 'pxteditor', action: 'updatefilters',
+                                    // filters: {...} } when active bits change, so the toolbox can be restricted
+                                    // to blocks/namespaces appropriate for the connected codeBit / BLE bit.
+                                    const filters = (data as any).filters as pxt.editor.ProjectFilters;
+                                    projectView.updateFilters(filters);
+                                });
                             case "stopsimulator": {
                                 const stop = data as pxt.editor.EditorMessageStopRequest;
                                 return Promise.resolve()