feat: 完善题目列表查询接口，支持搜索、多维筛选和排序

- 新增关键词搜索（同时匹配题干 stem 和选项 distractors）
- 新增按难度(difficulty)、来源(source)筛选
- 新增动态排序：支持 createdAt/updatedAt/difficulty，可选 asc/desc
- 路由层增加 sortBy/sortOrder 白名单校验

docs/api-reference.md

@@ -1047,8 +1047,13 @@
 **查询参数**:
 - `page`: 页码 (默认: 1)
 - `limit`: 每页数量 (默认: 20)
-- `status`: draft | reviewing | published | archived (可选)
+- `status`: draft | reviewing | published | archived (可选，按状态筛选)
 - `categoryId`: 分类 ID (可选)
+- `keyword`: 关键词搜索，匹配题干(stem)和选项(distractors)内容 (可选)
+- `difficulty`: 难度值 1-5，精确匹配 (可选)
+- `source`: system | ugc，按来源筛选 (可选)
+- `sortBy`: 排序字段，createdAt | updatedAt | difficulty (默认: createdAt)
+- `sortOrder`: asc | desc (默认: desc)
 
 **响应**:
 ```json

src/routes/admin/questions.ts

@@ -45,12 +45,26 @@ const batchIdsSchema = z.object({ ids: z.array(z.string().uuid()).min(1).max(200
 
 export async function adminQuestionsRoutes(app: FastifyInstance): Promise<void> {
   app.get('/', async (request) => {
-    const { page = '1', limit = '20', status, categoryId } = request.query as Record<string, string>;
+    const query = request.query as Record<string, string>;
+    const { page = '1', limit = '20', status, categoryId, keyword, difficulty, source, sortBy, sortOrder } = query;
+
+    if (sortBy && !['createdAt', 'updatedAt', 'difficulty'].includes(sortBy)) {
+      return { success: false, data: null, error: { code: 'VALIDATION_ERROR', message: 'sortBy 仅支持 createdAt / updatedAt / difficulty' } };
+    }
+    if (sortOrder && !['asc', 'desc'].includes(sortOrder)) {
+      return { success: false, data: null, error: { code: 'VALIDATION_ERROR', message: 'sortOrder 仅支持 asc / desc' } };
+    }
+
     const result = await questionService.listQuestions({
       page: Number(page),
       limit: Number(limit),
       status,
       categoryId,
+      keyword,
+      difficulty: difficulty !== undefined ? Number(difficulty) : undefined,
+      source,
+      sortBy: sortBy as 'createdAt' | 'updatedAt' | 'difficulty' | undefined,
+      sortOrder: sortOrder as 'asc' | 'desc' | undefined,
     });
     return { success: true, data: result.items, pagination: result.pagination, error: null };
   });

src/services/admin/question-service.ts

@@ -1,6 +1,6 @@
 import { db } from '../../db/client.js';
 import { questions, knowledgeCards, categories } from '../../db/schema.js';
-import { eq, and, sql, inArray } from 'drizzle-orm';
+import { eq, and, or, sql, inArray } from 'drizzle-orm';
 import { v4 as uuid } from 'uuid';
 
 /** 单条导入数据的输入结构 */
@@ -124,19 +124,55 @@ function parseCsvRow(line: string): string[] {
   return fields;
 }
 
+type SortField = 'createdAt' | 'updatedAt' | 'difficulty';
+type SortOrder = 'asc' | 'desc';
+
 interface ListOptions {
   page?: number;
   limit?: number;
   status?: string;
   categoryId?: string;
+  keyword?: string;
+  difficulty?: number;
+  source?: string;
+  sortBy?: SortField;
+  sortOrder?: SortOrder;
 }
 
-export async function listQuestions({ page = 1, limit = 20, status, categoryId }: ListOptions) {
+/** 排序字段名映射（Drizzle 列 → SQL 列名） */
+const SORT_COLUMN_MAP: Record<SortField, string> = {
+  createdAt: 'created_at',
+  updatedAt: 'updated_at',
+  difficulty: 'difficulty',
+};
+
+export async function listQuestions({
+  page = 1,
+  limit = 20,
+  status,
+  categoryId,
+  keyword,
+  difficulty,
+  source,
+  sortBy = 'createdAt',
+  sortOrder = 'desc',
+}: ListOptions) {
   const offset = (page - 1) * limit;
   const conditions = [];
 
   if (status) conditions.push(eq(questions.status, status as 'draft' | 'reviewing' | 'published' | 'archived'));
   if (categoryId) conditions.push(eq(questions.categoryId, categoryId));
+  if (difficulty !== undefined) conditions.push(eq(questions.difficulty, difficulty));
+  if (source) conditions.push(eq(questions.source, source as 'system' | 'ugc'));
+  if (keyword) {
+    const like = `%${keyword}%`;
+    conditions.push(
+      or(
+        sql`CAST(${questions.stem} AS CHAR) LIKE ${like}`,
+        sql`CAST(${questions.distractors} AS CHAR) LIKE ${like}`,
+      )!,
+    );
+  }
 
   const where = conditions.length > 0 ? and(...conditions) : undefined;
 
@@ -146,11 +182,14 @@ export async function listQuestions({ page = 1, limit = 20, status, categoryId }
     .where(where);
 
   const total = Number(rows?.count ?? 0);
+
+  const column = SORT_COLUMN_MAP[sortBy] ?? 'created_at';
+  const direction = sortOrder === 'asc' ? 'ASC' : 'DESC';
   const items = await db
     .select()
     .from(questions)
     .where(where)
-    .orderBy(sql`created_at DESC`)
+    .orderBy(sql`${sql.raw(column)} ${sql.raw(direction)}`)
     .limit(limit)
     .offset(offset);