frontend/src/store/chatStore.js

import { create } from 'zustand'

export const useChatStore = create((set, get) => ({
  chats: [],
  activeChat: null,
  messages: {},
  
  setActiveChat: (chat) => set({ activeChat: chat }),
  
  addMessage: (chatId, message) => set((state) => ({
    messages: {
      ...state.messages,
      [chatId]: [...(state.messages[chatId] || []), message]
    }
  })),
  
  updateChats: (chats) => set({ chats })
}))