refactor(MessageManager): enhance conversation list handling and integrate local source fallback

- Update MessageManager to support both remote and local conversation list sources, improving data retrieval and offline capabilities.
- Refactor hooks and components to utilize the new MessageManager structure, ensuring seamless integration of cursor pagination and local caching.
- Introduce new types and methods for better management of conversation data and loading states.
- Modify MessageListScreen to leverage the updated hooks for fetching conversations, enhancing user experience with improved loading and pagination handling.

src/stores/conversationListSources.ts

@@ -0,0 +1,133 @@
+/**
+ * 会话列表数据源抽象：游标、常规页码、SQLite 等实现同一契约，MessageManager 只依赖接口。
+ */
+
+import { ConversationResponse } from '../types/dto';
+import { messageService } from '../services/messageService';
+import { getConversationListCache } from '../services/database';
+
+export const CONVERSATION_LIST_PAGE_SIZE = 20;
+
+/** 单次拉取结果（一页或一批） */
+export interface ConversationListPage {
+  items: ConversationResponse[];
+  /** 在当前源上是否还能再 loadNext 一页 */
+  hasMore: boolean;
+}
+
+/**
+ * 分页式会话列表源：restart 后开始新序列；首次 loadNext 为第一页，之后为后续页。
+ */
+export interface IConversationListPagedSource {
+  restart(): void;
+  loadNext(): Promise<ConversationListPage>;
+  /** 至少成功 loadNext 过一次且仍有下一页时为 true */
+  readonly hasMore: boolean;
+}
+
+/** 远端常规分页：GET /conversations?page=&page_size=（始终请求网络，避免走 getConversations 的本地短路） */
+export class NetworkOffsetConversationListPagedSource implements IConversationListPagedSource {
+  private nextPage = 1;
+  private hasMoreAfterLastLoad = false;
+  private loadedOnce = false;
+  private readonly pageSize: number;
+
+  constructor(pageSize: number = CONVERSATION_LIST_PAGE_SIZE) {
+    this.pageSize = pageSize;
+  }
+
+  restart(): void {
+    this.nextPage = 1;
+    this.hasMoreAfterLastLoad = false;
+    this.loadedOnce = false;
+  }
+
+  get hasMore(): boolean {
+    return this.loadedOnce && this.hasMoreAfterLastLoad;
+  }
+
+  async loadNext(): Promise<ConversationListPage> {
+    const response = await messageService.getConversations(this.nextPage, this.pageSize, true);
+    const items = response.list || [];
+    const totalPages = Math.max(0, response.total_pages ?? 0);
+    const currentPage = response.page ?? this.nextPage;
+    this.hasMoreAfterLastLoad = totalPages > 0 && currentPage < totalPages;
+    this.nextPage = currentPage + 1;
+    this.loadedOnce = true;
+    return { items, hasMore: this.hasMoreAfterLastLoad };
+  }
+}
+
+/** 远端游标接口 */
+export class NetworkCursorConversationListPagedSource implements IConversationListPagedSource {
+  private nextCursor: string | null = null;
+  private hasMoreAfterLastLoad = false;
+  private loadedOnce = false;
+  private readonly pageSize: number;
+
+  constructor(pageSize: number = CONVERSATION_LIST_PAGE_SIZE) {
+    this.pageSize = pageSize;
+  }
+
+  restart(): void {
+    this.nextCursor = null;
+    this.hasMoreAfterLastLoad = false;
+    this.loadedOnce = false;
+  }
+
+  get hasMore(): boolean {
+    return this.loadedOnce && this.hasMoreAfterLastLoad;
+  }
+
+  async loadNext(): Promise<ConversationListPage> {
+    const response = await messageService.getConversationsCursor(
+      this.nextCursor == null
+        ? { page_size: this.pageSize }
+        : { cursor: this.nextCursor, page_size: this.pageSize }
+    );
+    const items = response.list || [];
+    this.nextCursor = response.next_cursor ?? null;
+    this.hasMoreAfterLastLoad = Boolean(response.has_more && response.next_cursor != null);
+    this.loadedOnce = true;
+    return { items, hasMore: this.hasMoreAfterLastLoad };
+  }
+}
+
+/** SQLite 会话列表缓存（单批，无后续页） */
+export class SqliteConversationListPagedSource implements IConversationListPagedSource {
+  private consumed = false;
+
+  restart(): void {
+    this.consumed = false;
+  }
+
+  get hasMore(): boolean {
+    return false;
+  }
+
+  async loadNext(): Promise<ConversationListPage> {
+    if (this.consumed) {
+      return { items: [], hasMore: false };
+    }
+    this.consumed = true;
+    try {
+      const items = await getConversationListCache();
+      return { items, hasMore: false };
+    } catch (e) {
+      console.warn('[SqliteConversationListPagedSource] 读取会话列表缓存失败:', e);
+      return { items: [], hasMore: false };
+    }
+  }
+}
+
+/** 未注入 remote 时，按类型创建默认远端源 */
+export type RemoteConversationListSourceKind = 'cursor' | 'offset';
+
+export function createRemoteConversationListSource(
+  kind: RemoteConversationListSourceKind,
+  pageSize: number = CONVERSATION_LIST_PAGE_SIZE
+): IConversationListPagedSource {
+  return kind === 'offset'
+    ? new NetworkOffsetConversationListPagedSource(pageSize)
+    : new NetworkCursorConversationListPagedSource(pageSize);
+}