重构聊天会话管理，支持会话历史和存储

src/components/chat/GlobalChatbox.utils.ts

@@ -1,8 +1,7 @@
-import type { BranchGroup, Message, PersistedChatState } from "./GlobalChatbox.types";
+import type { BranchGroup, Message } from "./GlobalChatbox.types";
 
 export const createId = () =>
   `${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
-export const CHAT_STORAGE_KEY = "tjwater_agent_chat_state_v1";
 export const PRESET_PROMPTS = [
   "分析当前管网中的水力瓶颈管道，并给出改造建议。",
   "帮我分析当前管网压力异常点，并按风险等级排序。",
@@ -29,34 +28,6 @@ export const stripMarkdown = (md: string): string =>
     .replace(/<[^>]+>/g, "")
     .trim();
 
-export const getInitialChatState = (): PersistedChatState => {
-  if (typeof window === "undefined") {
-    return { messages: [], sessionId: undefined };
-  }
-  try {
-    const storedRaw = window.localStorage.getItem(CHAT_STORAGE_KEY);
-    if (!storedRaw) return { messages: [], sessionId: undefined };
-    const parsed = JSON.parse(storedRaw) as PersistedChatState;
-    if (!Array.isArray(parsed.messages)) {
-      console.error("[GlobalChatbox] Invalid persisted messages format.");
-      window.localStorage.removeItem(CHAT_STORAGE_KEY);
-      return { messages: [], sessionId: undefined };
-    }
-    return {
-      messages: Array.isArray(parsed.messages) ? parsed.messages : [],
-      sessionId: parsed.sessionId,
-      branchGroups: Array.isArray(parsed.branchGroups) ? parsed.branchGroups : [],
-    };
-  } catch (error) {
-    console.error(
-      "[GlobalChatbox] Failed to read persisted chat state:",
-      error,
-    );
-    window.localStorage.removeItem(CHAT_STORAGE_KEY);
-    return { messages: [], sessionId: undefined };
-  }
-};
-
 export const cloneMessage = (message: Message): Message => ({
   ...message,
   progress: message.progress ? [...message.progress] : undefined,