fix import

Both interfaces had identical structures, so unified them into a single
CalendarEventSubscriptionData interface that is used for both REST API
responses and WebSocket subscription data.

Changes:
- Removed CalendarEventRestData interface
- Updated fetchCalendarEvents to use CalendarEventSubscriptionData
- Added documentation clarifying the interface is used for both APIs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/data/calendar.ts

@@ -53,6 +53,9 @@ export const enum CalendarEntityFeature {
   UPDATE_EVENT = 4,
 }
 
+/** Type for date values that can come from REST API or subscription */
+type CalendarDateValue = string | { dateTime: string } | { date: string };
+
 export const fetchCalendarEvents = async (
   hass: HomeAssistant,
   start: Date,
@@ -65,11 +68,11 @@ export const fetchCalendarEvents = async (
 
   const calEvents: CalendarEvent[] = [];
   const errors: string[] = [];
-  const promises: Promise<CalendarEvent[]>[] = [];
+  const promises: Promise<CalendarEventApiData[]>[] = [];
 
   calendars.forEach((cal) => {
     promises.push(
-      hass.callApi<CalendarEvent[]>(
+      hass.callApi<CalendarEventApiData[]>(
         "GET",
         `calendars/${cal.entity_id}${params}`
       )
@@ -77,7 +80,7 @@ export const fetchCalendarEvents = async (
   });
 
   for (const [idx, promise] of promises.entries()) {
-    let result: CalendarEvent[];
+    let result: CalendarEventApiData[];
     try {
       // eslint-disable-next-line no-await-in-loop
       result = await promise;
@@ -87,53 +90,16 @@ export const fetchCalendarEvents = async (
     }
     const cal = calendars[idx];
     result.forEach((ev) => {
-      const eventStart = getCalendarDate(ev.start);
-      const eventEnd = getCalendarDate(ev.end);
-      if (!eventStart || !eventEnd) {
-        return;
+      const normalized = normalizeSubscriptionEventData(ev, cal);
+      if (normalized) {
+        calEvents.push(normalized);
       }
-      const eventData: CalendarEventData = {
-        uid: ev.uid,
-        summary: ev.summary,
-        description: ev.description,
-        dtstart: eventStart,
-        dtend: eventEnd,
-        recurrence_id: ev.recurrence_id,
-        rrule: ev.rrule,
-      };
-      const event: CalendarEvent = {
-        start: eventStart,
-        end: eventEnd,
-        title: ev.summary,
-        backgroundColor: cal.backgroundColor,
-        borderColor: cal.backgroundColor,
-        calendar: cal.entity_id,
-        eventData: eventData,
-      };
-
-      calEvents.push(event);
     });
   }
 
   return { events: calEvents, errors };
 };
 
-const getCalendarDate = (dateObj: any): string | undefined => {
-  if (typeof dateObj === "string") {
-    return dateObj;
-  }
-
-  if (dateObj.dateTime) {
-    return dateObj.dateTime;
-  }
-
-  if (dateObj.date) {
-    return dateObj.date;
-  }
-
-  return undefined;
-};
-
 export const getCalendars = (hass: HomeAssistant): Calendar[] =>
   Object.keys(hass.states)
     .filter(
@@ -191,3 +157,89 @@ export const deleteCalendarEvent = (
     recurrence_id,
     recurrence_range,
   });
+
+/**
+ * Calendar event data from both REST API and WebSocket subscription.
+ * Both APIs use the same data format.
+ */
+export interface CalendarEventApiData {
+  summary: string;
+  start: CalendarDateValue;
+  end: CalendarDateValue;
+  description?: string | null;
+  location?: string | null;
+  uid?: string | null;
+  recurrence_id?: string | null;
+  rrule?: string | null;
+}
+
+export interface CalendarEventSubscription {
+  events: CalendarEventApiData[] | null;
+}
+
+export const subscribeCalendarEvents = (
+  hass: HomeAssistant,
+  entity_id: string,
+  start: Date,
+  end: Date,
+  callback: (update: CalendarEventSubscription) => void
+) =>
+  hass.connection.subscribeMessage<CalendarEventSubscription>(callback, {
+    type: "calendar/event/subscribe",
+    entity_id,
+    start: start.toISOString(),
+    end: end.toISOString(),
+  });
+
+const getCalendarDate = (dateObj: CalendarDateValue): string | undefined => {
+  if (typeof dateObj === "string") {
+    return dateObj;
+  }
+
+  if ("dateTime" in dateObj) {
+    return dateObj.dateTime;
+  }
+
+  if ("date" in dateObj) {
+    return dateObj.date;
+  }
+
+  return undefined;
+};
+
+/**
+ * Normalize calendar event data from API format to internal format.
+ * Handles both REST API format (with dateTime/date objects) and subscription format (strings).
+ * Converts to internal format with { dtstart, dtend, ... }
+ */
+export const normalizeSubscriptionEventData = (
+  eventData: CalendarEventApiData,
+  calendar: Calendar
+): CalendarEvent | null => {
+  const eventStart = getCalendarDate(eventData.start);
+  const eventEnd = getCalendarDate(eventData.end);
+
+  if (!eventStart || !eventEnd) {
+    return null;
+  }
+
+  const normalizedEventData: CalendarEventData = {
+    summary: eventData.summary,
+    dtstart: eventStart,
+    dtend: eventEnd,
+    description: eventData.description ?? undefined,
+    uid: eventData.uid ?? undefined,
+    recurrence_id: eventData.recurrence_id ?? undefined,
+    rrule: eventData.rrule ?? undefined,
+  };
+
+  return {
+    start: eventStart,
+    end: eventEnd,
+    title: eventData.summary,
+    backgroundColor: calendar.backgroundColor,
+    borderColor: calendar.backgroundColor,
+    calendar: calendar.entity_id,
+    eventData: normalizedEventData,
+  };
+};

src/panels/calendar/ha-panel-calendar.ts

@@ -1,5 +1,6 @@
 import { ResizeController } from "@lit-labs/observers/resize-controller";
 import type { RequestSelectedDetail } from "@material/mwc-list/mwc-list-item";
+import type { UnsubscribeFunc } from "home-assistant-js-websocket";
 import { mdiChevronDown, mdiPlus, mdiRefresh } from "@mdi/js";
 import type { CSSResultGroup, PropertyValues, TemplateResult } from "lit";
 import { LitElement, css, html, nothing } from "lit";
@@ -20,8 +21,17 @@ import "../../components/ha-menu-button";
 import "../../components/ha-state-icon";
 import "../../components/ha-svg-icon";
 import "../../components/ha-two-pane-top-app-bar-fixed";
-import type { Calendar, CalendarEvent } from "../../data/calendar";
-import { fetchCalendarEvents, getCalendars } from "../../data/calendar";
+import type {
+  Calendar,
+  CalendarEvent,
+  CalendarEventSubscription,
+  CalendarEventApiData,
+} from "../../data/calendar";
+import {
+  getCalendars,
+  normalizeSubscriptionEventData,
+  subscribeCalendarEvents,
+} from "../../data/calendar";
 import { fetchIntegrationManifest } from "../../data/integration";
 import { showConfigFlowDialog } from "../../dialogs/config-flow/show-dialog-config-flow";
 import { haStyle } from "../../resources/styles";
@@ -42,6 +52,8 @@ class PanelCalendar extends LitElement {
 
   @state() private _error?: string = undefined;
 
+  @state() private _errorCalendars: string[] = [];
+
   @state()
   @storage({
     key: "deSelectedCalendars",
@@ -53,6 +65,8 @@ class PanelCalendar extends LitElement {
 
   private _end?: Date;
 
+  private _unsubs: Record<string, Promise<UnsubscribeFunc>> = {};
+
   private _showPaneController = new ResizeController(this, {
     callback: (entries) => entries[0]?.contentRect.width > 750,
   });
@@ -78,6 +92,7 @@ class PanelCalendar extends LitElement {
     super.disconnectedCallback();
     this._mql?.removeListener(this._setIsMobile!);
     this._mql = undefined;
+    this._unsubscribeAll();
   }
 
   private _setIsMobile = (ev: MediaQueryListEvent) => {
@@ -194,19 +209,95 @@ class PanelCalendar extends LitElement {
       .map((cal) => cal);
   }
 
-  private async _fetchEvents(
-    start: Date | undefined,
-    end: Date | undefined,
-    calendars: Calendar[]
-  ): Promise<{ events: CalendarEvent[]; errors: string[] }> {
-    if (!calendars.length || !start || !end) {
-      return { events: [], errors: [] };
+  private _subscribeCalendarEvents(calendars: Calendar[]): void {
+    if (!this._start || !this._end || calendars.length === 0) {
+      return;
     }
 
-    return fetchCalendarEvents(this.hass, start, end, calendars);
+    this._error = undefined;
+
+    calendars.forEach((calendar) => {
+      // Unsubscribe existing subscription if any
+      if (calendar.entity_id in this._unsubs) {
+        this._unsubs[calendar.entity_id]
+          .then((unsubFunc) => unsubFunc())
+          .catch(() => {
+            // Subscription may have already been closed
+          });
+      }
+
+      const unsub = subscribeCalendarEvents(
+        this.hass,
+        calendar.entity_id,
+        this._start!,
+        this._end!,
+        (update: CalendarEventSubscription) => {
+          this._handleCalendarUpdate(calendar, update);
+        }
+      );
+      this._unsubs[calendar.entity_id] = unsub;
+    });
   }
 
-  private async _requestSelected(ev: CustomEvent<RequestSelectedDetail>) {
+  private _handleCalendarUpdate(
+    calendar: Calendar,
+    update: CalendarEventSubscription
+  ): void {
+    // Remove events from this calendar
+    this._events = this._events.filter(
+      (event) => event.calendar !== calendar.entity_id
+    );
+
+    if (update.events === null) {
+      // Error fetching events
+      if (!this._errorCalendars.includes(calendar.entity_id)) {
+        this._errorCalendars = [...this._errorCalendars, calendar.entity_id];
+      }
+      this._handleErrors(this._errorCalendars);
+      return;
+    }
+
+    // Remove from error list if successfully loaded
+    this._errorCalendars = this._errorCalendars.filter(
+      (id) => id !== calendar.entity_id
+    );
+    this._handleErrors(this._errorCalendars);
+
+    // Add new events from this calendar
+    const newEvents: CalendarEvent[] = update.events
+      .map((eventData: CalendarEventApiData) =>
+        normalizeSubscriptionEventData(eventData, calendar)
+      )
+      .filter((event): event is CalendarEvent => event !== null);
+
+    this._events = [...this._events, ...newEvents];
+  }
+
+  private async _unsubscribeAll(): Promise<void> {
+    await Promise.all(
+      Object.values(this._unsubs).map((unsub) =>
+        unsub
+          .then((unsubFunc) => unsubFunc())
+          .catch(() => {
+            // Subscription may have already been closed
+          })
+      )
+    );
+    this._unsubs = {};
+  }
+
+  private _unsubscribeCalendar(entityId: string): void {
+    if (entityId in this._unsubs) {
+      this._unsubs[entityId]
+        .then((unsubFunc) => unsubFunc())
+        .catch(() => {
+          // Subscription may have already been closed
+        });
+      delete this._unsubs[entityId];
+    }
+  }
+
+  private _requestSelected(ev: CustomEvent<RequestSelectedDetail>) {
     ev.stopPropagation();
     const entityId = (ev.target as HaListItem).value;
     if (ev.detail.selected) {
@@ -223,13 +314,10 @@ class PanelCalendar extends LitElement {
       if (!calendar) {
         return;
       }
-      const result = await this._fetchEvents(this._start, this._end, [
-        calendar,
-      ]);
-      this._events = [...this._events, ...result.events];
-      this._handleErrors(result.errors);
+      this._subscribeCalendarEvents([calendar]);
     } else {
       this._deSelectedCalendars = [...this._deSelectedCalendars, entityId];
+      this._unsubscribeCalendar(entityId);
       this._events = this._events.filter(
         (event) => event.calendar !== entityId
       );
@@ -254,23 +342,15 @@ class PanelCalendar extends LitElement {
   ): Promise<void> {
     this._start = ev.detail.start;
     this._end = ev.detail.end;
-    const result = await this._fetchEvents(
-      this._start,
-      this._end,
-      this._selectedCalendars
-    );
-    this._events = result.events;
-    this._handleErrors(result.errors);
+    await this._unsubscribeAll();
+    this._events = [];
+    this._subscribeCalendarEvents(this._selectedCalendars);
   }
 
   private async _handleRefresh(): Promise<void> {
-    const result = await this._fetchEvents(
-      this._start,
-      this._end,
-      this._selectedCalendars
-    );
-    this._events = result.events;
-    this._handleErrors(result.errors);
+    await this._unsubscribeAll();
+    this._events = [];
+    this._subscribeCalendarEvents(this._selectedCalendars);
   }
 
   private _handleErrors(error_entity_ids: string[]) {

src/panels/lovelace/cards/hui-calendar-card.ts

@@ -1,3 +1,4 @@
+import type { UnsubscribeFunc } from "home-assistant-js-websocket";
 import type { PropertyValues } from "lit";
 import { css, html, LitElement, nothing } from "lit";
 import { classMap } from "lit/directives/class-map";
@@ -7,8 +8,16 @@ import { applyThemesOnElement } from "../../../common/dom/apply_themes_on_elemen
 import type { HASSDomEvent } from "../../../common/dom/fire_event";
 import { debounce } from "../../../common/util/debounce";
 import "../../../components/ha-card";
-import type { Calendar, CalendarEvent } from "../../../data/calendar";
-import { fetchCalendarEvents } from "../../../data/calendar";
+import type {
+  Calendar,
+  CalendarEvent,
+  CalendarEventSubscription,
+  CalendarEventApiData,
+} from "../../../data/calendar";
+import {
+  normalizeSubscriptionEventData,
+  subscribeCalendarEvents,
+} from "../../../data/calendar";
 import type {
   CalendarViewChanged,
   FullCalendarView,
@@ -65,12 +74,16 @@ export class HuiCalendarCard extends LitElement implements LovelaceCard {
 
   @state() private _error?: string = undefined;
 
+  @state() private _errorCalendars: string[] = [];
+
   private _startDate?: Date;
 
   private _endDate?: Date;
 
   private _resizeObserver?: ResizeObserver;
 
+  private _unsubs: Record<string, Promise<UnsubscribeFunc>> = {};
+
   public setConfig(config: CalendarCardConfig): void {
     if (!config.entities?.length) {
       throw new Error("Entities must be specified");
@@ -86,7 +99,8 @@ export class HuiCalendarCard extends LitElement implements LovelaceCard {
     }));
 
     if (this._config?.entities !== config.entities) {
-      this._fetchCalendarEvents();
+      this._unsubscribeAll();
+      // Subscription will happen when view-changed event fires
     }
 
     this._config = { initial_view: "dayGridMonth", ...config };
@@ -115,6 +129,7 @@ export class HuiCalendarCard extends LitElement implements LovelaceCard {
     if (this._resizeObserver) {
       this._resizeObserver.disconnect();
     }
+    this._unsubscribeAll();
   }
 
   protected render() {
@@ -170,31 +185,85 @@ export class HuiCalendarCard extends LitElement implements LovelaceCard {
     }
   }
 
-  private _handleViewChanged(ev: HASSDomEvent<CalendarViewChanged>): void {
+  private async _handleViewChanged(
+    ev: HASSDomEvent<CalendarViewChanged>
+  ): Promise<void> {
     this._startDate = ev.detail.start;
     this._endDate = ev.detail.end;
-    this._fetchCalendarEvents();
+    await this._unsubscribeAll();
+    this._subscribeCalendarEvents();
   }
 
-  private async _fetchCalendarEvents(): Promise<void> {
-    if (!this._startDate || !this._endDate) {
+  private _subscribeCalendarEvents(): void {
+    if (!this.hass || !this._startDate || !this._endDate) {
       return;
     }
 
     this._error = undefined;
-    const result = await fetchCalendarEvents(
-      this.hass!,
-      this._startDate,
-      this._endDate,
-      this._calendars
-    );
-    this._events = result.events;
 
-    if (result.errors.length > 0) {
+    this._calendars.forEach((calendar) => {
+      const unsub = subscribeCalendarEvents(
+        this.hass!,
+        calendar.entity_id,
+        this._startDate!,
+        this._endDate!,
+        (update: CalendarEventSubscription) => {
+          this._handleCalendarUpdate(calendar, update);
+        }
+      );
+      this._unsubs[calendar.entity_id] = unsub;
+    });
+  }
+
+  private _handleCalendarUpdate(
+    calendar: Calendar,
+    update: CalendarEventSubscription
+  ): void {
+    // Remove events from this calendar
+    this._events = this._events.filter(
+      (event) => event.calendar !== calendar.entity_id
+    );
+
+    if (update.events === null) {
+      // Error fetching events
+      if (!this._errorCalendars.includes(calendar.entity_id)) {
+        this._errorCalendars = [...this._errorCalendars, calendar.entity_id];
+      }
       this._error = `${this.hass!.localize(
         "ui.components.calendar.event_retrieval_error"
       )}`;
+      return;
     }
+
+    // Remove from error list if successfully loaded
+    this._errorCalendars = this._errorCalendars.filter(
+      (id) => id !== calendar.entity_id
+    );
+    if (this._errorCalendars.length === 0) {
+      this._error = undefined;
+    }
+
+    // Add new events from this calendar
+    const newEvents: CalendarEvent[] = update.events
+      .map((eventData: CalendarEventApiData) =>
+        normalizeSubscriptionEventData(eventData, calendar)
+      )
+      .filter((event): event is CalendarEvent => event !== null);
+
+    this._events = [...this._events, ...newEvents];
+  }
+
+  private async _unsubscribeAll(): Promise<void> {
+    await Promise.all(
+      Object.values(this._unsubs).map((unsub) =>
+        unsub
+          .then((unsubFunc) => unsubFunc())
+          .catch(() => {
+            // Subscription may have already been closed
+          })
+      )
+    );
+    this._unsubs = {};
   }
 
   private _measureCard() {