chore: Simplify reply message lookup with store-based fetching

app/javascript/dashboard/store/modules/conversations/index.js

@@ -74,9 +74,17 @@ export const mutations = {
   [types.SET_PREVIOUS_CONVERSATIONS](_state, { id, data }) {
     if (data.length) {
       const [chat] = _state.allConversations.filter(c => c.id === id);
-      chat.messages.unshift(...data);
+      if (chat) {
+        // Duplicate check: only add messages that don't already exist
+        const existingIds = new Set(chat.messages.map(m => m.id));
+        const newMessages = data.filter(m => !existingIds.has(m.id));
+        if (newMessages.length) {
+          chat.messages.unshift(...newMessages);
+        }
+      }
     }
   },
+
   [types.SET_ALL_ATTACHMENTS](_state, { id, data }) {
     _state.attachments[id] = [...data];
   },

app/javascript/dashboard/store/modules/specs/conversations/mutations.spec.js

@@ -615,6 +615,29 @@ describe('#mutations', () => {
       mutations[types.SET_PREVIOUS_CONVERSATIONS](state, payload);
       expect(state.allConversations[0].messages).toEqual([{ id: 'msg2' }]);
     });
+
+    it('should filter out duplicate messages', () => {
+      const state = {
+        allConversations: [{ id: 1, messages: [{ id: 'msg2' }] }],
+      };
+      const payload = { id: 1, data: [{ id: 'msg1' }, { id: 'msg2' }] };
+
+      mutations[types.SET_PREVIOUS_CONVERSATIONS](state, payload);
+      expect(state.allConversations[0].messages).toEqual([
+        { id: 'msg1' },
+        { id: 'msg2' },
+      ]);
+    });
+
+    it('should do nothing if conversation is not found', () => {
+      const state = {
+        allConversations: [{ id: 2, messages: [{ id: 'msg2' }] }],
+      };
+      const payload = { id: 1, data: [{ id: 'msg1' }] };
+
+      mutations[types.SET_PREVIOUS_CONVERSATIONS](state, payload);
+      expect(state.allConversations[0].messages).toEqual([{ id: 'msg2' }]);
+    });
   });
 
   describe('#SET_MISSING_MESSAGES', () => {