diff --git a/src/views/customerservice/workbench/composables/useConversationStore.ts b/src/views/customerservice/workbench/composables/useConversationStore.ts
index c5fa4dae..6eacb992 100644
--- a/src/views/customerservice/workbench/composables/useConversationStore.ts
+++ b/src/views/customerservice/workbench/composables/useConversationStore.ts
@@ -28,6 +28,15 @@ import type {
 
 const PAGE_SIZE = 50;
 
+/**
+ * Cap on in-memory messages for the currently opened conversation.
+ * Long-lived sessions (8h shift on a chatty customer) would otherwise grow
+ * unbounded — every SSE INCOMING + every loadMore prepend keeps adding.
+ * When exceeded we drop the oldest half and reopen the loadMore door, so
+ * the user can scroll up to fetch them back from the server.
+ */
+const MAX_MESSAGES_IN_MEMORY = 500;
+
 /**
  * Workbench store: holds the two left-rail lists (mine / unassigned),
  * the currently opened conversation + ascending message stream, and the
@@ -88,7 +97,7 @@ export const useConversationStore = defineStore('customerservice-conversation',
   async function sendReply(body: ReplyMessageRequest) {
     if (!openedConversation.value) return;
     const res = await apiSendMessage(openedConversation.value.id, body);
-    messages.value.push(res.data as any);
+    appendMessage(res.data as any);
   }
 
   async function retry(messageId: number) {
@@ -114,10 +123,20 @@ export const useConversationStore = defineStore('customerservice-conversation',
     agents.value = ((res.data as any).rows ?? []) as AgentVO[];
   }
 
+  function appendMessage(msg: Message) {
+    messages.value.push(msg);
+    if (messages.value.length > MAX_MESSAGES_IN_MEMORY) {
+      // Keep only the latest half; mark loadMore re-openable so user can
+      // scroll up to refetch the dropped older slice if needed.
+      messages.value = messages.value.slice(-MAX_MESSAGES_IN_MEMORY / 2);
+      noMoreMessages.value = false;
+    }
+  }
+
   // ===== SSE handlers =====
   function onIncomingMessage(p: IncomingMessagePayload) {
     if (openedConversation.value?.id === p.conversationId) {
-      messages.value.push(p.message);
+      appendMessage(p.message);
     }
     refreshLists();
   }