Save default panel in user data

src/data/frontend.ts

@@ -14,6 +14,7 @@ declare global {
   interface FrontendUserData {
     core: CoreFrontendUserData;
     sidebar: SidebarFrontendUserData;
+    default_panel: string;
   }
 }
 

src/state/connection-mixin.ts

@@ -30,7 +30,7 @@ import { translationMetadata } from "../resources/translations-metadata";
 import type { Constructor, HomeAssistant, ServiceCallResponse } from "../types";
 import { getLocalLanguage } from "../util/common-translation";
 import { fetchWithAuth } from "../util/fetch-with-auth";
-import { getState } from "../util/ha-pref-storage";
+import { getState, storeState } from "../util/ha-pref-storage";
 import hassCallApi, { hassCallApiRaw } from "../util/hass-call-api";
 import type { HassBaseEl } from "./hass-base-mixin";
 import { computeStateName } from "../common/entity/compute_state_name";
@@ -285,6 +285,14 @@ export const connectionMixin = <T extends Constructor<HassBaseEl>>(
       subscribeFrontendUserData(conn, "core", ({ value: userData }) => {
         this._updateHass({ userData });
       });
+      subscribeFrontendUserData(
+        conn,
+        "default_panel",
+        ({ value: defaultPanel }) => {
+          this._updateHass({ defaultPanel: defaultPanel || DEFAULT_PANEL });
+          storeState(this.hass!);
+        }
+      );
 
       clearInterval(this.__backendPingInterval);
       this.__backendPingInterval = setInterval(() => {

src/state/sidebar-mixin.ts

@@ -1,4 +1,5 @@
 import type { HASSDomEvent } from "../common/dom/fire_event";
+import { saveFrontendUserData } from "../data/frontend";
 import type { Constructor, HomeAssistant } from "../types";
 import { storeState } from "../util/ha-pref-storage";
 import type { HassBaseEl } from "./hass-base-mixin";
@@ -33,8 +34,19 @@ export default <T extends Constructor<HassBaseEl>>(superClass: T) =>
         storeState(this.hass!);
       });
       this.addEventListener("hass-default-panel", (ev) => {
-        this._updateHass({ defaultPanel: ev.detail.defaultPanel });
+        const defaultPanel = ev.detail.defaultPanel;
+        this._updateHass({ defaultPanel });
         storeState(this.hass!);
+        try {
+          saveFrontendUserData(
+            this.hass!.connection,
+            "default_panel",
+            defaultPanel
+          );
+        } catch (err) {
+          // eslint-disable-next-line no-console
+          console.error("Failed to save default panel", err);
+        }
       });
     }
   };