diff --git a/apps/client/src/services/bundle.ts b/apps/client/src/services/bundle.ts
index e925253ce2..e1c38d0d09 100644
--- a/apps/client/src/services/bundle.ts
+++ b/apps/client/src/services/bundle.ts
@@ -1,10 +1,12 @@
+import BasicWidget from "../widgets/basic_widget.js";
+import RightPanelWidget from "../widgets/right_panel_widget.js";
+import froca from "./froca.js";
+import type { Entity, WidgetDefinition } from "./frontend_script_api.js";
+import { t } from "./i18n.js";
 import ScriptContext from "./script_context.js";
 import server from "./server.js";
 import toastService, { showError } from "./toast.js";
-import froca from "./froca.js";
 import utils from "./utils.js";
-import { t } from "./i18n.js";
-import type { Entity } from "./frontend_script_api.js";
 
 // TODO: Deduplicate with server.
 export interface Bundle {
@@ -14,9 +16,10 @@ export interface Bundle {
     allNoteIds: string[];
 }
 
-interface Widget {
+type LegacyWidget = (BasicWidget | RightPanelWidget) & {
     parentWidget?: string;
-}
+};
+type Widget = LegacyWidget | WidgetDefinition;
 
 async function getAndExecuteBundle(noteId: string, originEntity = null, script = null, params = null) {
     const bundle = await server.post<Bundle>(`script/bundle/${noteId}`, {
@@ -52,7 +55,7 @@ export async function executeBundle(bundle: Bundle, originEntity?: Entity | null
 
 async function executeStartupBundles() {
     const isMobile = utils.isMobile();
-    const scriptBundles = await server.get<Bundle[]>("script/startup" + (isMobile ? "?mobile=true" : ""));
+    const scriptBundles = await server.get<Bundle[]>(`script/startup${  isMobile ? "?mobile=true" : ""}`);
 
     for (const bundle of scriptBundles) {
         await executeBundle(bundle);
@@ -67,13 +70,16 @@ export class WidgetsByParent {
     }
 
     add(widget: Widget) {
-        if (!widget.parentWidget) {
+        if ("parent" in widget) {
+            // React-based script.
+            this.byParent[widget.parent] = this.byParent[widget.parent] || [];
+            this.byParent[widget.parent].push(widget);
+        } else if (widget.parentWidget) {
+            this.byParent[widget.parentWidget] = this.byParent[widget.parentWidget] || [];
+            this.byParent[widget.parentWidget].push(widget);
+        } else {
             console.log(`Custom widget does not have mandatory 'parentWidget' property defined`);
-            return;
         }
-
-        this.byParent[widget.parentWidget] = this.byParent[widget.parentWidget] || [];
-        this.byParent[widget.parentWidget].push(widget);
     }
 
     get(parentName: string) {
diff --git a/apps/client/src/services/frontend_script_api.ts b/apps/client/src/services/frontend_script_api.ts
index e16670d38d..9fe5504ce5 100644
--- a/apps/client/src/services/frontend_script_api.ts
+++ b/apps/client/src/services/frontend_script_api.ts
@@ -1,26 +1,28 @@
-import server from "./server.js";
-import utils from "./utils.js";
-import toastService from "./toast.js";
-import linkService from "./link.js";
+import { dayjs } from "@triliumnext/commons";
+import { formatLogMessage } from "@triliumnext/commons";
+import { VNode } from "preact";
+
+import appContext from "../components/app_context.js";
+import type Component from "../components/component.js";
+import type NoteContext from "../components/note_context.js";
+import type FNote from "../entities/fnote.js";
+import BasicWidget, { ReactWrappedWidget } from "../widgets/basic_widget.js";
+import NoteContextAwareWidget from "../widgets/note_context_aware_widget.js";
+import RightPanelWidget from "../widgets/right_panel_widget.js";
+import dateNotesService from "./date_notes.js";
+import dialogService from "./dialog.js";
 import froca from "./froca.js";
+import { t } from "./i18n.js";
+import linkService from "./link.js";
 import noteTooltipService from "./note_tooltip.js";
 import protectedSessionService from "./protected_session.js";
-import dateNotesService from "./date_notes.js";
 import searchService from "./search.js";
-import RightPanelWidget from "../widgets/right_panel_widget.js";
-import ws from "./ws.js";
-import appContext from "../components/app_context.js";
-import NoteContextAwareWidget from "../widgets/note_context_aware_widget.js";
-import BasicWidget, { ReactWrappedWidget } from "../widgets/basic_widget.js";
-import SpacedUpdate from "./spaced_update.js";
+import server from "./server.js";
 import shortcutService from "./shortcuts.js";
-import dialogService from "./dialog.js";
-import type FNote from "../entities/fnote.js";
-import { t } from "./i18n.js";
-import { dayjs } from "@triliumnext/commons";
-import type NoteContext from "../components/note_context.js";
-import type Component from "../components/component.js";
-import { formatLogMessage } from "@triliumnext/commons";
+import SpacedUpdate from "./spaced_update.js";
+import toastService from "./toast.js";
+import utils from "./utils.js";
+import ws from "./ws.js";
 
 /**
  * A whole number
@@ -464,6 +466,18 @@ export interface Api {
      * Log given message to the log pane in UI
      */
     log(message: string | object): void;
+
+    /**
+     * Method that must be run for widget scripts that run on Preact, using JSX. The method just returns the same definition, reserved for future typechecking and perhaps validation purposes.
+     *
+     * @param definition the widget definition.
+     */
+    defineWidget(definition: WidgetDefinition): void;
+}
+
+export interface WidgetDefinition {
+    parent: "right-pane",
+    render: () => VNode
 }
 
 /**
@@ -533,9 +547,9 @@ function FrontendScriptApi(this: Api, startNote: FNote, currentNote: FNote, orig
         return params.map((p) => {
             if (typeof p === "function") {
                 return `!@#Function: ${p.toString()}`;
-            } else {
-                return p;
             }
+            return p;
+
         });
     }
 
@@ -562,9 +576,9 @@ function FrontendScriptApi(this: Api, startNote: FNote, currentNote: FNote, orig
             await ws.waitForMaxKnownEntityChangeId();
 
             return ret.executionResult;
-        } else {
-            throw new Error(`server error: ${ret.error}`);
         }
+        throw new Error(`server error: ${ret.error}`);
+
     };
 
     this.runOnBackend = async (func, params = []) => {
@@ -721,6 +735,9 @@ function FrontendScriptApi(this: Api, startNote: FNote, currentNote: FNote, orig
         this.logMessages[noteId].push(message);
         this.logSpacedUpdates[noteId].scheduleUpdate();
     };
+    this.defineWidget = (definition) => {
+        module.exports = definition;
+    };
 }
 
 export default FrontendScriptApi as any as {