diff --git a/frontend/src/api/event-service/event-service.api.ts b/frontend/src/api/event-service/event-service.api.ts
index 3e7a42666b..7464480d5c 100644
--- a/frontend/src/api/event-service/event-service.api.ts
+++ b/frontend/src/api/event-service/event-service.api.ts
@@ -5,7 +5,6 @@ import type {
   ConfirmationResponseRequest,
   ConfirmationResponseResponse,
 } from "./event-service.types";
-import { openHands } from "../open-hands-axios";
 
 class EventService {
   /**
@@ -38,11 +37,27 @@ class EventService {
     return data;
   }
 
-  static async getEventCount(conversationId: string): Promise<number> {
-    const params = new URLSearchParams();
-    params.append("conversation_id__eq", conversationId);
-    const { data } = await openHands.get<number>(
-      `/api/v1/events/count?${params.toString()}`,
+  /**
+   * Get event count for a V1 conversation
+   * @param conversationId The conversation ID
+   * @param conversationUrl The conversation URL (e.g., "http://localhost:54928/api/conversations/...")
+   * @param sessionApiKey Session API key for authentication (required for V1)
+   * @returns The event count
+   */
+  static async getEventCount(
+    conversationId: string,
+    conversationUrl: string,
+    sessionApiKey?: string | null,
+  ): Promise<number> {
+    // Build the runtime URL using the conversation URL
+    const runtimeUrl = buildHttpBaseUrl(conversationUrl);
+
+    // Build session headers for authentication
+    const headers = buildSessionHeaders(sessionApiKey);
+
+    const { data } = await axios.get<number>(
+      `${runtimeUrl}/api/conversations/${conversationId}/events/count`,
+      { headers },
     );
     return data;
   }
diff --git a/frontend/src/contexts/conversation-websocket-context.tsx b/frontend/src/contexts/conversation-websocket-context.tsx
index 68c50f9499..8a8a205cd6 100644
--- a/frontend/src/contexts/conversation-websocket-context.tsx
+++ b/frontend/src/contexts/conversation-websocket-context.tsx
@@ -578,9 +578,13 @@ export function ConversationWebSocketProvider({
         removeErrorMessage(); // Clear any previous error messages on successful connection
 
         // Fetch expected event count for history loading detection
-        if (conversationId) {
+        if (conversationId && conversationUrl) {
           try {
-            const count = await EventService.getEventCount(conversationId);
+            const count = await EventService.getEventCount(
+              conversationId,
+              conversationUrl,
+              sessionApiKey,
+            );
             setExpectedEventCountMain(count);
 
             // If no events expected, mark as loaded immediately
@@ -618,6 +622,7 @@ export function ConversationWebSocketProvider({
     removeErrorMessage,
     sessionApiKey,
     conversationId,
+    conversationUrl,
   ]);
 
   // Separate WebSocket options for planning agent connection
@@ -642,10 +647,15 @@ export function ConversationWebSocketProvider({
         removeErrorMessage(); // Clear any previous error messages on successful connection
 
         // Fetch expected event count for history loading detection
-        if (planningAgentConversation?.id) {
+        if (
+          planningAgentConversation?.id &&
+          planningAgentConversation.conversation_url
+        ) {
           try {
             const count = await EventService.getEventCount(
               planningAgentConversation.id,
+              planningAgentConversation.conversation_url,
+              planningAgentConversation.session_api_key,
             );
             setExpectedEventCountPlanning(count);