feat: exam actions and data safety fixes

2025-12-30 17:48:22 +08:00
parent e7c902e8e1
commit f7ff018490
27 changed files with 896 additions and 194 deletions
--- a/docs/design/005_exam_module_implementation.md
+++ b/docs/design/005_exam_module_implementation.md
@@ -12,7 +12,7 @@
 - **SubmissionAnswers**: 链接到特定题目的单个答案。

 ### 2.2 `structure` 字段
-为了支持层级布局（如章节/分组），我们在 `exams` 表中引入了一个 JSON 列 `structure`。这作为考试布局的“单一事实来源”（Source of Truth）。
+为了支持层级布局（如章节/分组），我们在 `exams` 表中引入了一个 JSON 列 `structure`。它作为“布局/呈现层”的单一事实来源（Source of Truth），用于渲染分组与排序；而 `exam_questions` 仍然承担题目关联、外键完整性与索引查询职责。

 **JSON Schema:**
 ```typescript
@@ -26,6 +26,9 @@ type ExamNode = {
 }
 ```

+### 2.3 `description` 元数据字段（当前实现）
+当前版本将部分元数据（如 `subject/grade/difficulty/totalScore/durationMin/tags/scheduledAt`）以 JSON 字符串形式存入 `exams.description`，并在数据访问层解析后提供给列表页展示与筛选。
+
 ## 3. 组件架构

 ### 3.1 组卷（构建器）
@@ -52,6 +55,13 @@ type ExamNode = {
  - **状态**: 在提交前管理本地更改。
 - **Actions**: `gradeSubmissionAction` 更新 `submissionAnswers` 并将总分聚合到 `examSubmissions`。

+### 3.3 列表页（All Exams）
+位于 `/teacher/exams/all`。
+
+- **Page (RSC)**: 负责解析 query（`q/status/difficulty`）并调用数据访问层获取 exams。
+- **`ExamFilters` (客户端组件)**: 使用 URL query 驱动筛选条件。
+- **`ExamDataTable` (客户端组件)**: 基于 TanStack Table 渲染列表，并在 actions 列中渲染 `ExamActions`。
+
 ## 4. 关键工作流

 ### 4.1 创建与构建考试
@@ -72,6 +82,27 @@ type ExamNode = {
    - 教师输入分数（上限为满分）和反馈。
 4.  **提交**: 服务器更新单个答案记录并重新计算提交总分。

+### 4.3 考试管理（All Exams Actions）
+位于 `/teacher/exams/all` 的表格行级菜单。
+
+1. **Publish / Move to Draft / Archive**
+   - 客户端组件 `ExamActions` 触发 `updateExamAction`，传入 `examId` 与目标 `status`。
+   - 服务器更新 `exams.status`，并对 `/teacher/exams/all` 执行缓存再验证。
+
+2. **Duplicate**
+   - 客户端组件 `ExamActions` 触发 `duplicateExamAction`，传入 `examId`。
+   - 服务器复制 `exams` 记录并复制关联的 `exam_questions`。
+   - 新考试以 `draft` 状态创建，复制结构（`exams.structure`），并清空排期信息（`startTime/endTime`，以及 description 中的 `scheduledAt`）。
+   - 成功后跳转到新考试的构建页 `/teacher/exams/[id]/build`。
+
+3. **Delete**
+   - 客户端组件 `ExamActions` 触发 `deleteExamAction`，传入 `examId`。
+   - 服务器删除 `exams` 记录；相关表（如 `exam_questions`、`exam_submissions`、`submission_answers`）通过外键级联删除。
+   - 成功后刷新列表。
+
+4. **Edit / Build**
+   - 当前统一跳转到 `/teacher/exams/[id]/build`。
+
 ## 5. 技术决策

 ### 5.1 混合存储策略
@@ -87,4 +118,46 @@ type ExamNode = {
 - 面向未来（现代 React Hooks 模式）。

 ### 5.3 Server Actions
-所有变更操作（保存草稿、发布、评分）均使用 Next.js Server Actions，以确保类型安全并自动重新验证缓存。
+所有变更操作（保存草稿、发布、复制、删除、评分）均使用 Next.js Server Actions，以确保类型安全并自动重新验证缓存。
+
+已落地的 Server Actions：
+- `createExamAction`
+- `updateExamAction`
+- `duplicateExamAction`
+- `deleteExamAction`
+- `gradeSubmissionAction`
+
+## 6. 接口与数据影响
+
+### 6.1 `updateExamAction`
+- **入参（FormData）**: `examId`（必填），`status`（可选：draft/published/archived），`questionsJson`（可选），`structureJson`（可选）
+- **行为**:
+  - 若传入 `questionsJson`：先清空 `exam_questions` 再批量写入，`order` 由数组顺序决定；未传入则不触碰 `exam_questions`
+  - 若传入 `structureJson`：写入 `exams.structure`；未传入则不更新该字段
+  - 若传入 `status`：写入 `exams.status`
+- **缓存**: `revalidatePath("/teacher/exams/all")`
+
+### 6.2 `duplicateExamAction`
+- **入参（FormData）**: `examId`（必填）
+- **行为**:
+  - 复制一条 `exams`（新 id、新 title：追加 “(Copy)”、`status` 强制为 `draft`）
+  - `startTime/endTime` 置空；同时尝试从 `description` JSON 中移除 `scheduledAt`
+  - 复制 `exam_questions`（保留 questionId/score/order）
+  - 复制 `exams.structure`
+- **缓存**: `revalidatePath("/teacher/exams/all")`
+
+### 6.3 `deleteExamAction`
+- **入参（FormData）**: `examId`（必填）
+- **行为**:
+  - 删除 `exams` 记录
+  - 依赖外键级联清理关联数据：`exam_questions`、`exam_submissions`、`submission_answers`
+- **缓存**:
+  - `revalidatePath("/teacher/exams/all")`
+  - `revalidatePath("/teacher/exams/grading")`
+
+### 6.4 数据访问层（Data Access）
+位于 `src/modules/exams/data-access.ts`，对外提供与页面/组件解耦的查询函数。
+
+- `getExams(params)`: 支持按 `q/status` 在数据库侧过滤；`difficulty` 因当前存储在 `description` JSON 中，采用内存过滤
+- `getExamById(id)`: 查询 exam 及其 `exam_questions`，并返回 `structure` 以用于构建器 Hydrate
+- `getExamSubmissions()`: 为阅卷列表提供 submissions 数据
--- a/docs/scripts/reset-db.ts
+++ b/docs/scripts/reset-db.ts
@@ -16,8 +16,18 @@ async function reset() {
  `)

  // Drop each table
-  for (const row of (tables[0] as unknown as any[])) {
-    const tableName = row.TABLE_NAME || row.table_name
+  const rows = (tables as unknown as [unknown])[0]
+  if (!Array.isArray(rows)) return
+
+  for (const row of rows) {
+    const record = row as Record<string, unknown>
+    const tableName =
+      typeof record.TABLE_NAME === "string"
+        ? record.TABLE_NAME
+        : typeof record.table_name === "string"
+          ? record.table_name
+          : null
+    if (!tableName) continue
    console.log(`Dropping table: ${tableName}`)
    await db.execute(sql.raw(`DROP TABLE IF EXISTS \`${tableName}\`;`))
  }
--- a/docs/scripts/seed-exams.ts
+++ b/docs/scripts/seed-exams.ts
@@ -80,7 +80,12 @@ async function seed() {
    const qId = createId()
    questionIds.push(qId)
    
-    const type = faker.helpers.arrayElement(["single_choice", "multiple_choice", "text", "judgment"])
+    const type = faker.helpers.arrayElement([
+      "single_choice",
+      "multiple_choice",
+      "text",
+      "judgment",
+    ] as const)
    
    await db.insert(questions).values({
      id: qId,
@@ -93,7 +98,7 @@ async function seed() {
          { id: "D", text: faker.lorem.sentence(), isCorrect: false },
        ] : undefined
      },
-      type: type as any,
+      type,
      difficulty: faker.helpers.arrayElement(DIFFICULTY),
      authorId: teacherId,
    })
@@ -105,7 +110,7 @@ async function seed() {
    const examId = createId()
    const subject = faker.helpers.arrayElement(SUBJECTS)
    const grade = faker.helpers.arrayElement(GRADES)
-    const status = faker.helpers.arrayElement(["draft", "published", "archived"])
+    const status = faker.helpers.arrayElement(["draft", "published", "archived"] as const)
    
    const scheduledAt = faker.date.soon({ days: 30 })

@@ -126,7 +131,7 @@ async function seed() {
      description: JSON.stringify(meta),
      creatorId: teacherId,
      startTime: scheduledAt,
-      status: status as any,
+      status,
    })

    // Link some questions to this exam (random 5 questions)
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -5,6 +5,11 @@ import nextTs from "eslint-config-next/typescript";
 const eslintConfig = defineConfig([
  ...nextVitals,
  ...nextTs,
+  {
+    rules: {
+      "react-hooks/incompatible-library": "off",
+    },
+  },
  // Override default ignores of eslint-config-next.
  globalIgnores([
    // Default ignores of eslint-config-next:
--- a/scripts/seed.ts
+++ b/scripts/seed.ts
@@ -211,7 +211,7 @@ async function seed() {
    creatorId: "user_teacher_math",
    status: "published",
    startTime: new Date(),
-    structure: examStructure as any // Bypass strict typing for seed
+    structure: examStructure as unknown
  });

  // Link questions physically (Source of Truth)
--- a/src/app/(dashboard)/teacher/exams/[id]/build/page.tsx
+++ b/src/app/(dashboard)/teacher/exams/[id]/build/page.tsx
@@ -16,38 +16,93 @@ export default async function BuildExamPage({ params }: { params: Promise<{ id:
  // In a real app, this might be paginated or filtered by exam subject/grade
  const { data: questionsData } = await getQuestions({ pageSize: 100 })
  
-  const questionOptions: Question[] = questionsData.map((q) => ({
-    id: q.id,
-    content: q.content as any,
-    type: q.type as any,
-    difficulty: q.difficulty ?? 1,
-    createdAt: new Date(q.createdAt),
-    updatedAt: new Date(q.updatedAt),
-    author: q.author ? {
-      id: q.author.id,
-      name: q.author.name || "Unknown",
-      image: q.author.image || null
-    } : null,
-    knowledgePoints: (q.questionsToKnowledgePoints || []).map((kp) => ({
-      id: kp.knowledgePoint.id,
-      name: kp.knowledgePoint.name
-    }))
-  }))
-
  const initialSelected = (exam.questions || []).map(q => ({
    id: q.id,
    score: q.score || 0
  }))

-  // Prepare initialStructure on server side to avoid hydration mismatch with random IDs
-  let initialStructure: ExamNode[] = exam.structure as ExamNode[] || []
+  const selectedQuestionIds = initialSelected.map((s) => s.id)
+  const { data: selectedQuestionsData } = selectedQuestionIds.length
+    ? await getQuestions({ ids: selectedQuestionIds, pageSize: Math.max(10, selectedQuestionIds.length) })
+    : { data: [] as typeof questionsData }
+
+  type RawQuestion = (typeof questionsData)[number]
+
+  const toQuestionOption = (q: RawQuestion): Question => ({
+    id: q.id,
+    content: q.content as Question["content"],
+    type: q.type as Question["type"],
+    difficulty: q.difficulty ?? 1,
+    createdAt: new Date(q.createdAt),
+    updatedAt: new Date(q.updatedAt),
+    author: q.author
+      ? {
+          id: q.author.id,
+          name: q.author.name || "Unknown",
+          image: q.author.image || null,
+        }
+      : null,
+    knowledgePoints:
+      q.questionsToKnowledgePoints?.map((kp) => ({
+        id: kp.knowledgePoint.id,
+        name: kp.knowledgePoint.name,
+      })) ?? [],
+  })
+
+  const questionOptionsById = new Map<string, Question>()
+  for (const q of questionsData) questionOptionsById.set(q.id, toQuestionOption(q))
+  for (const q of selectedQuestionsData) questionOptionsById.set(q.id, toQuestionOption(q))
+  const questionOptions = Array.from(questionOptionsById.values())
+
+  const normalizeStructure = (nodes: unknown): ExamNode[] => {
+    const seen = new Set<string>()
+    const isRecord = (v: unknown): v is Record<string, unknown> =>
+      typeof v === "object" && v !== null
+
+    const normalize = (raw: unknown[]): ExamNode[] => {
+      return raw
+        .map((n) => {
+          if (!isRecord(n)) return null
+          const type = n.type
+          if (type !== "group" && type !== "question") return null
+
+          let id = typeof n.id === "string" && n.id.length > 0 ? n.id : createId()
+          while (seen.has(id)) id = createId()
+          seen.add(id)
+
+          if (type === "group") {
+            return {
+              id,
+              type: "group",
+              title: typeof n.title === "string" ? n.title : undefined,
+              children: normalize(Array.isArray(n.children) ? n.children : []),
+            } satisfies ExamNode
+          }
+
+          if (typeof n.questionId !== "string" || n.questionId.length === 0) return null
+
+          return {
+            id,
+            type: "question",
+            questionId: n.questionId,
+            score: typeof n.score === "number" ? n.score : undefined,
+          } satisfies ExamNode
+        })
+        .filter(Boolean) as ExamNode[]
+    }
+
+    if (!Array.isArray(nodes)) return []
+    return normalize(nodes)
+  }
+
+  let initialStructure: ExamNode[] = normalizeStructure(exam.structure)
  
  if (initialStructure.length === 0 && initialSelected.length > 0) {
-    initialStructure = initialSelected.map(s => ({
-      id: createId(), // Generate stable ID on server
-      type: 'question',
+    initialStructure = initialSelected.map((s) => ({
+      id: createId(),
+      type: "question",
      questionId: s.id,
-      score: s.score
+      score: s.score,
    }))
  }

--- a/src/app/(dashboard)/teacher/exams/all/page.tsx
+++ b/src/app/(dashboard)/teacher/exams/all/page.tsx
@@ -1,24 +1,137 @@
 import { Suspense } from "react"
 import Link from "next/link"
 import { Button } from "@/shared/components/ui/button"
+import { Badge } from "@/shared/components/ui/badge"
+import { EmptyState } from "@/shared/components/ui/empty-state"
+import { Skeleton } from "@/shared/components/ui/skeleton"
 import { ExamDataTable } from "@/modules/exams/components/exam-data-table"
 import { examColumns } from "@/modules/exams/components/exam-columns"
 import { ExamFilters } from "@/modules/exams/components/exam-filters"
 import { getExams } from "@/modules/exams/data-access"
+import { FileText, PlusCircle } from "lucide-react"
+
+type SearchParams = { [key: string]: string | string[] | undefined }
+
+const getParam = (params: SearchParams, key: string) => {
+  const v = params[key]
+  return Array.isArray(v) ? v[0] : v
+}
+
+async function ExamsResults({ searchParams }: { searchParams: Promise<SearchParams> }) {
+  const params = await searchParams
+
+  const q = getParam(params, "q")
+  const status = getParam(params, "status")
+  const difficulty = getParam(params, "difficulty")
+
+  const exams = await getExams({
+    q,
+    status,
+    difficulty,
+  })
+
+  const hasFilters = Boolean(q || (status && status !== "all") || (difficulty && difficulty !== "all"))
+
+  const counts = exams.reduce(
+    (acc, e) => {
+      acc.total += 1
+      if (e.status === "draft") acc.draft += 1
+      if (e.status === "published") acc.published += 1
+      if (e.status === "archived") acc.archived += 1
+      return acc
+    },
+    { total: 0, draft: 0, published: 0, archived: 0 }
+  )
+
+  return (
+    <div className="space-y-4">
+      <div className="flex flex-col gap-3 rounded-md border bg-card px-4 py-3 md:flex-row md:items-center md:justify-between">
+        <div className="flex flex-wrap items-center gap-2">
+          <span className="text-sm text-muted-foreground">Showing</span>
+          <span className="text-sm font-medium">{counts.total}</span>
+          <span className="text-sm text-muted-foreground">exams</span>
+          <Badge variant="outline" className="ml-0 md:ml-2">
+            Draft {counts.draft}
+          </Badge>
+          <Badge variant="outline">Published {counts.published}</Badge>
+          <Badge variant="outline">Archived {counts.archived}</Badge>
+        </div>
+        <div className="flex items-center gap-2">
+          <Button asChild variant="outline" size="sm">
+            <Link href="/teacher/exams/grading">Go to Grading</Link>
+          </Button>
+          <Button asChild size="sm">
+            <Link href="/teacher/exams/create" className="inline-flex items-center gap-2">
+              <PlusCircle className="h-4 w-4" />
+              Create Exam
+            </Link>
+          </Button>
+        </div>
+      </div>
+
+      {exams.length === 0 ? (
+        <EmptyState
+          icon={FileText}
+          title={hasFilters ? "No exams match your filters" : "No exams yet"}
+          description={
+            hasFilters
+              ? "Try clearing filters or adjusting keywords."
+              : "Create your first exam to start assigning and grading."
+          }
+          action={
+            hasFilters
+              ? {
+                  label: "Clear filters",
+                  href: "/teacher/exams/all",
+                }
+              : {
+                  label: "Create Exam",
+                  href: "/teacher/exams/create",
+                }
+          }
+          className="h-[360px] bg-card"
+        />
+      ) : (
+        <ExamDataTable columns={examColumns} data={exams} />
+      )}
+    </div>
+  )
+}
+
+function ExamsResultsFallback() {
+  return (
+    <div className="space-y-4">
+      <div className="flex flex-col gap-3 rounded-md border bg-card px-4 py-3 md:flex-row md:items-center md:justify-between">
+        <div className="flex flex-wrap items-center gap-2">
+          <Skeleton className="h-4 w-[160px]" />
+          <Skeleton className="h-5 w-[92px]" />
+          <Skeleton className="h-5 w-[112px]" />
+          <Skeleton className="h-5 w-[106px]" />
+        </div>
+        <div className="flex items-center gap-2">
+          <Skeleton className="h-9 w-[120px]" />
+          <Skeleton className="h-9 w-[132px]" />
+        </div>
+      </div>
+      <div className="rounded-md border bg-card">
+        <div className="p-4">
+          <Skeleton className="h-8 w-full" />
+        </div>
+        <div className="space-y-2 p-4 pt-0">
+          {Array.from({ length: 6 }).map((_, idx) => (
+            <Skeleton key={idx} className="h-10 w-full" />
+          ))}
+        </div>
+      </div>
+    </div>
+  )
+}

 export default async function AllExamsPage({
  searchParams,
 }: {
-  searchParams: Promise<{ [key: string]: string | string[] | undefined }>
+  searchParams: Promise<SearchParams>
 }) {
-  const params = await searchParams
-  
-  const exams = await getExams({
-    q: params.q as string,
-    status: params.status as string,
-    difficulty: params.difficulty as string,
-  })
-
  return (
    <div className="flex h-full flex-col space-y-8 p-8">
      <div className="flex flex-col justify-between space-y-4 md:flex-row md:items-center md:space-y-0">
@@ -26,11 +139,6 @@ export default async function AllExamsPage({
          <h2 className="text-2xl font-bold tracking-tight">All Exams</h2>
          <p className="text-muted-foreground">View and manage all your exams.</p>
        </div>
-        <div className="flex items-center space-x-2">
-          <Button asChild>
-            <Link href="/teacher/exams/create">Create Exam</Link>
-          </Button>
-        </div>
      </div>

      <div className="space-y-4">
@@ -38,9 +146,9 @@ export default async function AllExamsPage({
          <ExamFilters />
        </Suspense>

-        <div className="rounded-md border bg-card">
-          <ExamDataTable columns={examColumns} data={exams} />
-        </div>
+        <Suspense fallback={<ExamsResultsFallback />}>
+          <ExamsResults searchParams={searchParams} />
+        </Suspense>
      </div>
    </div>
  )
--- a/src/modules/auth/components/login-form.tsx
+++ b/src/modules/auth/components/login-form.tsx
@@ -8,7 +8,7 @@ import { Label } from "@/shared/components/ui/label"
 import { cn } from "@/shared/lib/utils"
 import { Loader2, Github } from "lucide-react"

-interface LoginFormProps extends React.HTMLAttributes<HTMLDivElement> {}
+type LoginFormProps = React.HTMLAttributes<HTMLDivElement>

 export function LoginForm({ className, ...props }: LoginFormProps) {
  const [isLoading, setIsLoading] = React.useState<boolean>(false)
--- a/src/modules/auth/components/register-form.tsx
+++ b/src/modules/auth/components/register-form.tsx
@@ -8,7 +8,7 @@ import { Label } from "@/shared/components/ui/label"
 import { cn } from "@/shared/lib/utils"
 import { Loader2, Github } from "lucide-react"

-interface RegisterFormProps extends React.HTMLAttributes<HTMLDivElement> {}
+type RegisterFormProps = React.HTMLAttributes<HTMLDivElement>

 export function RegisterForm({ className, ...props }: RegisterFormProps) {
  const [isLoading, setIsLoading] = React.useState<boolean>(false)
--- a/src/modules/dashboard/components/teacher-schedule.tsx
+++ b/src/modules/dashboard/components/teacher-schedule.tsx
@@ -40,9 +40,9 @@ export function TeacherSchedule() {
  const hasSchedule = MOCK_SCHEDULE.length > 0;

  return (
-    <Card className="col-span-3">
+      <Card className="col-span-3">
      <CardHeader>
-        <CardTitle>Today's Schedule</CardTitle>
+        <CardTitle>Today&apos;s Schedule</CardTitle>
      </CardHeader>
      <CardContent>
        {!hasSchedule ? (
--- a/src/modules/exams/actions.ts
+++ b/src/modules/exams/actions.ts
@@ -101,8 +101,8 @@ const ExamUpdateSchema = z.object({
        score: z.coerce.number().int().min(0),
      })
    )
-    .default([]),
-  structure: z.any().optional(), // Accept structure JSON
+    .optional(),
+  structure: z.unknown().optional(),
  status: z.enum(["draft", "published", "archived"]).optional(),
 })

@@ -110,13 +110,15 @@ export async function updateExamAction(
  prevState: ActionState<string> | null,
  formData: FormData
 ): Promise<ActionState<string>> {
-  const rawQuestions = formData.get("questionsJson") as string | null
-  const rawStructure = formData.get("structureJson") as string | null
+  const rawQuestions = formData.get("questionsJson")
+  const rawStructure = formData.get("structureJson")
+  const hasQuestions = typeof rawQuestions === "string"
+  const hasStructure = typeof rawStructure === "string"
  
  const parsed = ExamUpdateSchema.safeParse({
    examId: formData.get("examId"),
-    questions: rawQuestions ? JSON.parse(rawQuestions) : [],
-    structure: rawStructure ? JSON.parse(rawStructure) : undefined,
+    questions: hasQuestions ? JSON.parse(rawQuestions) : undefined,
+    structure: hasStructure ? JSON.parse(rawStructure) : undefined,
    status: formData.get("status") ?? undefined,
  })

@@ -131,22 +133,24 @@ export async function updateExamAction(
  const { examId, questions, structure, status } = parsed.data

  try {
-    await db.delete(examQuestions).where(eq(examQuestions.examId, examId))
-    if (questions.length > 0) {
-      await db.insert(examQuestions).values(
-        questions.map((q, idx) => ({
-          examId,
-          questionId: q.id,
-          score: q.score ?? 0,
-          order: idx,
-        }))
-      )
+    if (questions) {
+      await db.delete(examQuestions).where(eq(examQuestions.examId, examId))
+      if (questions.length > 0) {
+        await db.insert(examQuestions).values(
+          questions.map((q, idx) => ({
+            examId,
+            questionId: q.id,
+            score: q.score ?? 0,
+            order: idx,
+          }))
+        )
+      }
    }
    
    // Prepare update object
-    const updateData: any = {}
+    const updateData: Partial<typeof exams.$inferInsert> = {}
    if (status) updateData.status = status
-    if (structure) updateData.structure = structure
+    if (structure !== undefined) updateData.structure = structure
    
    if (Object.keys(updateData).length > 0) {
      await db.update(exams).set(updateData).where(eq(exams.id, examId))
@@ -169,6 +173,143 @@ export async function updateExamAction(
  }
 }

+const ExamDeleteSchema = z.object({
+  examId: z.string().min(1),
+})
+
+export async function deleteExamAction(
+  prevState: ActionState<string> | null,
+  formData: FormData
+): Promise<ActionState<string>> {
+  const parsed = ExamDeleteSchema.safeParse({
+    examId: formData.get("examId"),
+  })
+
+  if (!parsed.success) {
+    return {
+      success: false,
+      message: "Invalid delete data",
+      errors: parsed.error.flatten().fieldErrors,
+    }
+  }
+
+  const { examId } = parsed.data
+
+  try {
+    await db.delete(exams).where(eq(exams.id, examId))
+  } catch (error) {
+    console.error("Failed to delete exam:", error)
+    return {
+      success: false,
+      message: "Database error: Failed to delete exam",
+    }
+  }
+
+  revalidatePath("/teacher/exams/all")
+  revalidatePath("/teacher/exams/grading")
+
+  return {
+    success: true,
+    message: "Exam deleted",
+    data: examId,
+  }
+}
+
+const ExamDuplicateSchema = z.object({
+  examId: z.string().min(1),
+})
+
+const omitScheduledAtFromDescription = (description: string | null) => {
+  if (!description) return null
+  try {
+    const parsed: unknown = JSON.parse(description)
+    if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return description
+    const meta = parsed as Record<string, unknown>
+    if ("scheduledAt" in meta) delete meta.scheduledAt
+    return JSON.stringify(meta)
+  } catch {
+    return description
+  }
+}
+
+export async function duplicateExamAction(
+  prevState: ActionState<string> | null,
+  formData: FormData
+): Promise<ActionState<string>> {
+  const parsed = ExamDuplicateSchema.safeParse({
+    examId: formData.get("examId"),
+  })
+
+  if (!parsed.success) {
+    return {
+      success: false,
+      message: "Invalid duplicate data",
+      errors: parsed.error.flatten().fieldErrors,
+    }
+  }
+
+  const { examId } = parsed.data
+
+  const source = await db.query.exams.findFirst({
+    where: eq(exams.id, examId),
+    with: {
+      questions: {
+        orderBy: (examQuestions, { asc }) => [asc(examQuestions.order)],
+      },
+    },
+  })
+
+  if (!source) {
+    return {
+      success: false,
+      message: "Exam not found",
+    }
+  }
+
+  const newExamId = createId()
+  const user = await getCurrentUser()
+
+  try {
+    await db.transaction(async (tx) => {
+      await tx.insert(exams).values({
+        id: newExamId,
+        title: `${source.title} (Copy)`,
+        description: omitScheduledAtFromDescription(source.description),
+        creatorId: user?.id ?? "user_teacher_123",
+        startTime: null,
+        endTime: null,
+        status: "draft",
+        structure: source.structure,
+      })
+
+      if (source.questions.length > 0) {
+        await tx.insert(examQuestions).values(
+          source.questions.map((q) => ({
+            examId: newExamId,
+            questionId: q.questionId,
+            score: q.score ?? 0,
+            order: q.order ?? 0,
+          }))
+        )
+      }
+    })
+  } catch (error) {
+    console.error("Failed to duplicate exam:", error)
+    return {
+      success: false,
+      message: "Database error: Failed to duplicate exam",
+    }
+  }
+
+  revalidatePath("/teacher/exams/all")
+
+  return {
+    success: true,
+    message: "Exam duplicated",
+    data: newExamId,
+  }
+}
+
 const GradingSchema = z.object({
  submissionId: z.string().min(1),
  answers: z.array(z.object({
--- a/src/modules/exams/components/assembly/exam-paper-preview.tsx
+++ b/src/modules/exams/components/assembly/exam-paper-preview.tsx
@@ -0,0 +1,141 @@
+"use client"
+
+import React from "react"
+import { ScrollArea } from "@/shared/components/ui/scroll-area"
+import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogTrigger } from "@/shared/components/ui/dialog"
+import { Button } from "@/shared/components/ui/button"
+import { Eye, Printer } from "lucide-react"
+import type { ExamNode } from "./selected-question-list"
+
+type ChoiceOption = {
+  id: string
+  text: string
+}
+
+type QuestionContent = {
+  text?: string
+  options?: ChoiceOption[]
+}
+
+type ExamPaperPreviewProps = {
+  title: string
+  subject: string
+  grade: string
+  durationMin: number
+  totalScore: number
+  nodes: ExamNode[]
+}
+
+export function ExamPaperPreview({ title, subject, grade, durationMin, totalScore, nodes }: ExamPaperPreviewProps) {
+  // Helper to flatten questions for continuous numbering
+  let questionCounter = 0
+
+  const renderNode = (node: ExamNode, depth: number = 0) => {
+    if (node.type === 'group') {
+      return (
+        <div key={node.id} className="space-y-4 mb-6">
+          <div className="flex items-center gap-2">
+            <h3 className={`font-bold ${depth === 0 ? 'text-lg' : 'text-md'} text-foreground/90`}>
+              {node.title || "Section"}
+            </h3>
+            {/* Optional: Show section score if needed */}
+          </div>
+          <div className="pl-0">
+            {node.children?.map(child => renderNode(child, depth + 1))}
+          </div>
+        </div>
+      )
+    }
+
+    if (node.type === 'question' && node.question) {
+      questionCounter++
+      const q = node.question
+      const content = q.content as QuestionContent
+      
+      return (
+        <div key={node.id} className="mb-6 break-inside-avoid">
+          <div className="flex gap-2">
+            <span className="font-semibold text-foreground min-w-[24px]">{questionCounter}.</span>
+            <div className="flex-1 space-y-2">
+              <div className="text-foreground/90 leading-relaxed whitespace-pre-wrap">
+                {content.text ?? ""} 
+                <span className="text-muted-foreground text-sm ml-2">({node.score}分)</span>
+              </div>
+              
+              {/* Options for Choice Questions */}
+              {(q.type === 'single_choice' || q.type === 'multiple_choice') && content.options && (
+                <div className="grid grid-cols-1 md:grid-cols-2 gap-y-2 gap-x-4 mt-2 pl-2">
+                  {content.options.map((opt) => (
+                    <div key={opt.id} className="flex gap-2 text-sm text-muted-foreground hover:text-foreground transition-colors">
+                      <span className="font-medium">{opt.id}.</span>
+                      <span>{opt.text}</span>
+                    </div>
+                  ))}
+                </div>
+              )}
+
+              {/* Space for written answers */}
+              {q.type === 'text' && (
+                <div className="mt-4 h-24 border-b border-dashed border-muted-foreground/30 w-full"></div>
+              )}
+            </div>
+          </div>
+        </div>
+      )
+    }
+    return null
+  }
+
+  return (
+    <Dialog>
+      <DialogTrigger asChild>
+        <Button variant="secondary" size="sm" className="gap-2">
+          <Eye className="h-4 w-4" />
+          Preview Exam
+        </Button>
+      </DialogTrigger>
+      <DialogContent className="max-w-4xl h-[90vh] flex flex-col p-0 gap-0">
+        <DialogHeader className="p-6 pb-2 border-b shrink-0">
+          <div className="flex items-center justify-between">
+            <DialogTitle>Exam Preview</DialogTitle>
+            <Button variant="outline" size="sm" onClick={() => window.print()} className="hidden">
+              <Printer className="h-4 w-4 mr-2" />
+              Print
+            </Button>
+          </div>
+        </DialogHeader>
+        
+        <ScrollArea className="flex-1 p-8 bg-white/50 dark:bg-zinc-950/50">
+          <div className="max-w-3xl mx-auto bg-card shadow-sm border p-12 min-h-[1000px] print:shadow-none print:border-none">
+            {/* Header */}
+            <div className="text-center space-y-4 mb-12 border-b-2 border-primary/20 pb-8">
+              <h1 className="text-3xl font-black tracking-tight text-foreground">{title}</h1>
+              <div className="flex justify-center gap-8 text-sm text-muted-foreground font-medium uppercase tracking-wide">
+                <span>Subject: {subject}</span>
+                <span>Grade: {grade}</span>
+                <span>Time: {durationMin} mins</span>
+                <span>Total: {totalScore} pts</span>
+              </div>
+              <div className="flex justify-center gap-12 text-sm pt-4">
+                <div className="w-32 border-b border-foreground/20 text-left px-1">Class:</div>
+                <div className="w-32 border-b border-foreground/20 text-left px-1">Name:</div>
+                <div className="w-32 border-b border-foreground/20 text-left px-1">No.:</div>
+              </div>
+            </div>
+
+            {/* Content */}
+            <div className="space-y-2">
+              {nodes.length === 0 ? (
+                <div className="text-center py-20 text-muted-foreground">
+                  Empty Exam Paper
+                </div>
+              ) : (
+                nodes.map(node => renderNode(node))
+              )}
+            </div>
+          </div>
+        </ScrollArea>
+      </DialogContent>
+    </Dialog>
+  )
+}
--- a/src/modules/exams/components/assembly/structure-editor.tsx
+++ b/src/modules/exams/components/assembly/structure-editor.tsx
@@ -5,7 +5,6 @@ import {
  DndContext,
  pointerWithin,
  rectIntersection,
-  getFirstCollision,
  CollisionDetection,
  KeyboardSensor,
  PointerSensor,
@@ -34,7 +33,6 @@ import { Collapsible, CollapsibleContent, CollapsibleTrigger } from "@/shared/co
 import { Trash2, GripVertical, ChevronDown, ChevronRight, Calculator } from "lucide-react"
 import { cn } from "@/shared/lib/utils"
 import type { ExamNode } from "./selected-question-list"
-import type { Question } from "@/modules/questions/types"

 // --- Types ---

@@ -47,6 +45,15 @@ type StructureEditorProps = {
  onAddGroup: () => void
 }

+function cloneExamNodes(nodes: ExamNode[]): ExamNode[] {
+  return nodes.map((node) => {
+    if (node.type === "group") {
+      return { ...node, children: cloneExamNodes(node.children || []) }
+    }
+    return { ...node }
+  })
+}
+
 // --- Components ---

 function SortableItem({ 
@@ -201,10 +208,20 @@ function StructureRenderer({ nodes, ...props }: {
  onScoreChange: (id: string, score: number) => void
  onGroupTitleChange: (id: string, title: string) => void
 }) {
+  // Deduplicate nodes to prevent React key errors
+  const uniqueNodes = useMemo(() => {
+    const seen = new Set()
+    return nodes.filter(n => {
+      if (seen.has(n.id)) return false
+      seen.add(n.id)
+      return true
+    })
+  }, [nodes])
+
  return (
-    <SortableContext items={nodes.map(n => n.id)} strategy={verticalListSortingStrategy}>
-      {nodes.map(node => (
-        <React.Fragment key={node.id}>
+    <SortableContext items={uniqueNodes.map(n => n.id)} strategy={verticalListSortingStrategy}>
+      {uniqueNodes.map(node => (
+        <div key={node.id}>
           {node.type === 'group' ? (
             <SortableGroup 
               id={node.id} 
@@ -232,7 +249,7 @@ function StructureRenderer({ nodes, ...props }: {
               onScoreChange={(val) => props.onScoreChange(node.id, val)} 
             />
           )}
-        </React.Fragment>
+        </div>
      ))}
    </SortableContext>
  )
@@ -362,7 +379,7 @@ export function StructureEditor({ items, onChange, onScoreChange, onGroupTitleCh
      if (activeContainerId !== overNode.id) {
          // ... implementation continues ...
          
-          const newItems = JSON.parse(JSON.stringify(items)) as ExamNode[]
+          const newItems = cloneExamNodes(items)
          
          // Remove active from old location
          const removeRecursive = (list: ExamNode[]): ExamNode | null => {
@@ -386,7 +403,10 @@ export function StructureEditor({ items, onChange, onScoreChange, onGroupTitleCh
             for (const node of list) {
               if (node.id === overId) {
                 if (!node.children) node.children = []
-                 node.children.push(movedItem)
+                 // Extra safety: Check if movedItem.id is already in children
+                 if (!node.children.some(c => c.id === movedItem.id)) {
+                    node.children.push(movedItem)
+                 }
                 return true
               }
               if (node.children) {
@@ -404,8 +424,12 @@ export function StructureEditor({ items, onChange, onScoreChange, onGroupTitleCh

    // Scenario 2: Moving between different lists (e.g. from Root to Group A, or Group A to Group B)
    if (activeContainerId !== overContainerId) {
+      // FIX: If we are already inside the group we are hovering (i.e. activeContainerId IS overId), 
+      // do not try to move "next to" the group (which would move us out).
+      if (activeContainerId === overId) return
+
      // Standard Sortable Move
-      const newItems = JSON.parse(JSON.stringify(items)) as ExamNode[]
+      const newItems = cloneExamNodes(items)
      
      const removeRecursive = (list: ExamNode[]): ExamNode | null => {
        const idx = list.findIndex(i => i.id === activeId)
@@ -484,7 +508,7 @@ export function StructureEditor({ items, onChange, onScoreChange, onGroupTitleCh

    if (activeContainerId === overContainerId) {
      // Same container reorder
-      const newItems = JSON.parse(JSON.stringify(items)) as ExamNode[]
+      const newItems = cloneExamNodes(items)
      
      const getMutableList = (groupId?: string): ExamNode[] => {
        if (groupId === 'root') return newItems
@@ -560,7 +584,9 @@ export function StructureEditor({ items, onChange, onScoreChange, onGroupTitleCh
           ) : (
             <div className="rounded-md border bg-background p-3 shadow-lg opacity-80 w-[300px] flex items-center gap-3">
               <GripVertical className="h-4 w-4" />
-               <p className="text-sm line-clamp-1">{(activeItem.question?.content as any)?.text || "Question"}</p>
+               <p className="text-sm line-clamp-1">
+                 {(activeItem.question?.content as { text?: string } | undefined)?.text || "Question"}
+               </p>
             </div>
           )
        ) : null}
--- a/src/modules/exams/components/exam-actions.tsx
+++ b/src/modules/exams/components/exam-actions.tsx
@@ -32,6 +32,7 @@ import {
  DialogTitle,
 } from "@/shared/components/ui/dialog"

+import { deleteExamAction, duplicateExamAction, updateExamAction } from "../actions"
 import { Exam } from "../types"

 interface ExamActionsProps {
@@ -42,31 +43,70 @@ export function ExamActions({ exam }: ExamActionsProps) {
  const router = useRouter()
  const [showViewDialog, setShowViewDialog] = useState(false)
  const [showDeleteDialog, setShowDeleteDialog] = useState(false)
+  const [isWorking, setIsWorking] = useState(false)

  const copyId = () => {
    navigator.clipboard.writeText(exam.id)
    toast.success("Exam ID copied to clipboard")
  }

-  const publishExam = async () => {
-    toast.success("Exam published")
+  const setStatus = async (status: Exam["status"]) => {
+    setIsWorking(true)
+    try {
+      const formData = new FormData()
+      formData.set("examId", exam.id)
+      formData.set("status", status)
+      const result = await updateExamAction(null, formData)
+      if (result.success) {
+        toast.success(status === "published" ? "Exam published" : status === "archived" ? "Exam archived" : "Exam moved to draft")
+        router.refresh()
+      } else {
+        toast.error(result.message || "Failed to update exam")
+      }
+    } catch {
+      toast.error("Failed to update exam")
+    } finally {
+      setIsWorking(false)
+    }
  }

-  const unpublishExam = async () => {
-    toast.success("Exam moved to draft")
-  }
-
-  const archiveExam = async () => {
-    toast.success("Exam archived")
+  const duplicateExam = async () => {
+    setIsWorking(true)
+    try {
+      const formData = new FormData()
+      formData.set("examId", exam.id)
+      const result = await duplicateExamAction(null, formData)
+      if (result.success && result.data) {
+        toast.success("Exam duplicated")
+        router.push(`/teacher/exams/${result.data}/build`)
+        router.refresh()
+      } else {
+        toast.error(result.message || "Failed to duplicate exam")
+      }
+    } catch {
+      toast.error("Failed to duplicate exam")
+    } finally {
+      setIsWorking(false)
+    }
  }

  const handleDelete = async () => {
+    setIsWorking(true)
    try {
-      await new Promise((r) => setTimeout(r, 800))
-      toast.success("Exam deleted successfully")
-      setShowDeleteDialog(false)
-    } catch (e) {
+      const formData = new FormData()
+      formData.set("examId", exam.id)
+      const result = await deleteExamAction(null, formData)
+      if (result.success) {
+        toast.success("Exam deleted successfully")
+        setShowDeleteDialog(false)
+        router.refresh()
+      } else {
+        toast.error(result.message || "Failed to delete exam")
+      }
+    } catch {
      toast.error("Failed to delete exam")
+    } finally {
+      setIsWorking(false)
    }
  }

@@ -88,25 +128,39 @@ export function ExamActions({ exam }: ExamActionsProps) {
          <DropdownMenuItem onClick={() => setShowViewDialog(true)}>
            <Eye className="mr-2 h-4 w-4" /> View
          </DropdownMenuItem>
-          <DropdownMenuItem>
+          <DropdownMenuItem onClick={() => router.push(`/teacher/exams/${exam.id}/build`)}>
            <Pencil className="mr-2 h-4 w-4" /> Edit
          </DropdownMenuItem>
          <DropdownMenuItem onClick={() => router.push(`/teacher/exams/${exam.id}/build`)}>
            <MoreHorizontal className="mr-2 h-4 w-4" /> Build
          </DropdownMenuItem>
          <DropdownMenuSeparator />
-          <DropdownMenuItem onClick={publishExam}>
+          <DropdownMenuItem onClick={duplicateExam} disabled={isWorking}>
+            <Copy className="mr-2 h-4 w-4" /> Duplicate
+          </DropdownMenuItem>
+          <DropdownMenuSeparator />
+          <DropdownMenuItem
+            onClick={() => setStatus("published")}
+            disabled={isWorking || exam.status === "published"}
+          >
            <UploadCloud className="mr-2 h-4 w-4" /> Publish
          </DropdownMenuItem>
-          <DropdownMenuItem onClick={unpublishExam}>
+          <DropdownMenuItem
+            onClick={() => setStatus("draft")}
+            disabled={isWorking || exam.status === "draft"}
+          >
            <Undo2 className="mr-2 h-4 w-4" /> Move to Draft
          </DropdownMenuItem>
-          <DropdownMenuItem onClick={archiveExam}>
+          <DropdownMenuItem
+            onClick={() => setStatus("archived")}
+            disabled={isWorking || exam.status === "archived"}
+          >
            <Archive className="mr-2 h-4 w-4" /> Archive
          </DropdownMenuItem>
          <DropdownMenuItem
            className="text-destructive focus:text-destructive"
            onClick={() => setShowDeleteDialog(true)}
+            disabled={isWorking}
          >
            <Trash className="mr-2 h-4 w-4" /> Delete
          </DropdownMenuItem>
@@ -159,6 +213,7 @@ export function ExamActions({ exam }: ExamActionsProps) {
                e.preventDefault()
                handleDelete()
              }}
+              disabled={isWorking}
            >
              Delete
            </AlertDialogAction>
--- a/src/modules/exams/components/exam-assembly.tsx
+++ b/src/modules/exams/components/exam-assembly.tsx
@@ -1,6 +1,6 @@
 "use client"

-import { useMemo, useState } from "react"
+import { useDeferredValue, useMemo, useState } from "react"
 import { useFormStatus } from "react-dom"
 import { useRouter } from "next/navigation"
 import { toast } from "sonner"
@@ -19,6 +19,7 @@ import { updateExamAction } from "@/modules/exams/actions"
 import { StructureEditor } from "./assembly/structure-editor"
 import { QuestionBankList } from "./assembly/question-bank-list"
 import type { ExamNode } from "./assembly/selected-question-list"
+import { ExamPaperPreview } from "./assembly/exam-paper-preview"
 import { createId } from "@paralleldrive/cuid2"

 type ExamAssemblyProps = {
@@ -48,17 +49,20 @@ export function ExamAssembly(props: ExamAssemblyProps) {
  const [search, setSearch] = useState("")
  const [typeFilter, setTypeFilter] = useState<string>("all")
  const [difficultyFilter, setDifficultyFilter] = useState<string>("all")
+  const deferredSearch = useDeferredValue(search)
  
  // Initialize structure state
  const [structure, setStructure] = useState<ExamNode[]>(() => {
-    // Hydrate structure with full question objects
+    const questionById = new Map<string, Question>()
+    for (const q of props.questionOptions) questionById.set(q.id, q)
+
    const hydrate = (nodes: ExamNode[]): ExamNode[] => {
-      return nodes.map(node => {
-        if (node.type === 'question') {
-          const q = props.questionOptions.find(opt => opt.id === node.questionId)
+      return nodes.map((node) => {
+        if (node.type === "question") {
+          const q = node.questionId ? questionById.get(node.questionId) : undefined
          return { ...node, question: q }
        }
-        if (node.type === 'group') {
+        if (node.type === "group") {
          return { ...node, children: hydrate(node.children || []) }
        }
        return node
@@ -77,8 +81,8 @@ export function ExamAssembly(props: ExamAssemblyProps) {
  const filteredQuestions = useMemo(() => {
    let list: Question[] = [...props.questionOptions]
    
-    if (search) {
-      const lower = search.toLowerCase()
+    if (deferredSearch) {
+      const lower = deferredSearch.toLowerCase()
      list = list.filter(q => {
        const content = q.content as { text?: string }
        return content.text?.toLowerCase().includes(lower)
@@ -93,7 +97,7 @@ export function ExamAssembly(props: ExamAssemblyProps) {
      list = list.filter((q) => q.difficulty === d)
    }
    return list
-  }, [search, typeFilter, difficultyFilter, props.questionOptions])
+  }, [deferredSearch, typeFilter, difficultyFilter, props.questionOptions])

  // Recursively calculate total score
  const assignedTotal = useMemo(() => {
@@ -109,17 +113,40 @@ export function ExamAssembly(props: ExamAssemblyProps) {

  const progress = Math.min(100, Math.max(0, (assignedTotal / props.totalScore) * 100))

-  const handleAdd = (question: Question) => {
-    setStructure(prev => [
-      ...prev, 
-      { 
-        id: createId(), 
-        type: 'question', 
-        questionId: question.id, 
-        score: 10, 
-        question 
+  const addedQuestionIds = useMemo(() => {
+    const ids = new Set<string>()
+    const walk = (nodes: ExamNode[]) => {
+      for (const n of nodes) {
+        if (n.type === "question" && n.questionId) ids.add(n.questionId)
+        if (n.type === "group" && n.children) walk(n.children)
      }
-    ])
+    }
+    walk(structure)
+    return ids
+  }, [structure])
+
+  const handleAdd = (question: Question) => {
+    setStructure((prev) => {
+      const has = (nodes: ExamNode[]): boolean => {
+        return nodes.some((n) => {
+          if (n.type === "question") return n.questionId === question.id
+          if (n.type === "group" && n.children) return has(n.children)
+          return false
+        })
+      }
+      if (has(prev)) return prev
+
+      return [
+        ...prev,
+        {
+          id: createId(),
+          type: "question",
+          questionId: question.id,
+          score: 10,
+          question,
+        },
+      ]
+    })
  }

  const handleAddGroup = () => {
@@ -171,10 +198,14 @@ export function ExamAssembly(props: ExamAssemblyProps) {
  // Helper to extract flat list for DB examQuestions table
  const getFlatQuestions = () => {
    const list: Array<{ id: string; score: number }> = []
+    const seen = new Set<string>()
    const traverse = (nodes: ExamNode[]) => {
      nodes.forEach(n => {
        if (n.type === 'question' && n.questionId) {
-          list.push({ id: n.questionId, score: n.score || 0 })
+          if (!seen.has(n.questionId)) {
+            seen.add(n.questionId)
+            list.push({ id: n.questionId, score: n.score || 0 })
+          }
        }
        if (n.type === 'group') {
          traverse(n.children || [])
@@ -187,9 +218,12 @@ export function ExamAssembly(props: ExamAssemblyProps) {
  
  // Helper to strip runtime question objects for DB structure storage
  const getCleanStructure = () => {
-    const clean = (nodes: ExamNode[]): any[] => {
+    type CleanExamNode = Omit<ExamNode, "question"> & { children?: CleanExamNode[] }
+
+    const clean = (nodes: ExamNode[]): CleanExamNode[] => {
      return nodes.map(n => {
        const { question, ...rest } = n
+        void question
        if (n.type === 'group') {
          return { ...rest, children: clean(n.children || []) }
        }
@@ -233,7 +267,17 @@ export function ExamAssembly(props: ExamAssemblyProps) {
      <Card className="lg:col-span-3 flex flex-col overflow-hidden border-2 border-primary/10">
        <CardHeader className="bg-muted/30 pb-4">
          <div className="flex items-center justify-between">
-            <CardTitle>Exam Structure</CardTitle>
+            <div className="flex items-center gap-3">
+              <CardTitle>Exam Structure</CardTitle>
+              <ExamPaperPreview 
+                title={props.title}
+                subject={props.subject}
+                grade={props.grade}
+                durationMin={props.durationMin}
+                totalScore={props.totalScore}
+                nodes={structure}
+              />
+            </div>
            <div className="flex items-center gap-4 text-sm">
              <div className="flex flex-col items-end">
                <span className="font-medium">{assignedTotal} / {props.totalScore}</span>
@@ -324,17 +368,7 @@ export function ExamAssembly(props: ExamAssemblyProps) {
          <QuestionBankList 
            questions={filteredQuestions}
            onAdd={handleAdd}
-            isAdded={(id) => {
-               // Check if question is added anywhere in the structure
-               const isAddedRecursive = (nodes: ExamNode[]): boolean => {
-                 return nodes.some(n => {
-                   if (n.type === 'question' && n.questionId === id) return true
-                   if (n.type === 'group' && n.children) return isAddedRecursive(n.children)
-                   return false
-                 })
-               }
-               return isAddedRecursive(structure)
-            }}
+            isAdded={(id) => addedQuestionIds.has(id)}
          />
        </ScrollArea>
      </Card>
--- a/src/modules/exams/components/exam-columns.tsx
+++ b/src/modules/exams/components/exam-columns.tsx
@@ -2,7 +2,7 @@

 import { ColumnDef } from "@tanstack/react-table"
 import { Checkbox } from "@/shared/components/ui/checkbox"
-import { Badge } from "@/shared/components/ui/badge"
+import { Badge, type BadgeProps } from "@/shared/components/ui/badge"
 import { cn, formatDate } from "@/shared/lib/utils"
 import { Exam } from "../types"
 import { ExamActions } from "./exam-actions"
@@ -36,8 +36,8 @@ export const examColumns: ColumnDef<Exam>[] = [
        <span className="font-medium">{row.original.title}</span>
        {row.original.tags && row.original.tags.length > 0 && (
          <div className="flex flex-wrap gap-1">
-            {row.original.tags.slice(0, 2).map((t) => (
-              <Badge key={t} variant="outline" className="text-xs">
+            {row.original.tags.slice(0, 2).map((t, idx) => (
+              <Badge key={`${t}-${idx}`} variant="outline" className="text-xs">
                {t}
              </Badge>
            ))}
@@ -65,9 +65,14 @@ export const examColumns: ColumnDef<Exam>[] = [
    header: "Status",
    cell: ({ row }) => {
      const status = row.original.status
-      const variant = status === "published" ? "secondary" : status === "archived" ? "destructive" : "outline"
+      const variant: BadgeProps["variant"] =
+        status === "published"
+          ? "secondary"
+          : status === "archived"
+          ? "destructive"
+          : "outline"
      return (
-        <Badge variant={variant as any} className="capitalize">
+        <Badge variant={variant} className="capitalize">
          {status}
        </Badge>
      )
@@ -134,4 +139,3 @@ export const examColumns: ColumnDef<Exam>[] = [
    cell: ({ row }) => <ExamActions exam={row.original} />,
  },
 ]
-
--- a/src/modules/exams/components/grading-view.tsx
+++ b/src/modules/exams/components/grading-view.tsx
@@ -13,13 +13,17 @@ import { ScrollArea } from "@/shared/components/ui/scroll-area"
 import { Separator } from "@/shared/components/ui/separator"
 import { gradeSubmissionAction } from "../actions"

+const isRecord = (v: unknown): v is Record<string, unknown> => typeof v === "object" && v !== null
+
+type QuestionContent = { text?: string } & Record<string, unknown>
+
 type Answer = {
  id: string
  questionId: string
-  questionContent: any
+  questionContent: QuestionContent | null
  questionType: string
  maxScore: number
-  studentAnswer: any
+  studentAnswer: unknown
  score: number | null
  feedback: string | null
  order: number
@@ -105,7 +109,7 @@ export function GradingView({
                <div className="rounded-md bg-muted/50 p-4">
                  <Label className="mb-2 block text-xs text-muted-foreground">Student Answer</Label>
                  <p className="text-sm font-medium">
-                    {typeof ans.studentAnswer?.answer === 'string' 
+                    {isRecord(ans.studentAnswer) && typeof ans.studentAnswer.answer === "string"
                      ? ans.studentAnswer.answer
                      : JSON.stringify(ans.studentAnswer)}
                  </p>
--- a/src/modules/exams/components/submission-columns.tsx
+++ b/src/modules/exams/components/submission-columns.tsx
@@ -32,7 +32,7 @@ export const submissionColumns: ColumnDef<ExamSubmission>[] = [
    cell: ({ row }) => {
      const status = row.original.status
      const variant = status === "graded" ? "secondary" : "outline"
-      return <Badge variant={variant as any} className="capitalize">{status}</Badge>
+      return <Badge variant={variant} className="capitalize">{status}</Badge>
    },
  },
  {
@@ -60,4 +60,3 @@ export const submissionColumns: ColumnDef<ExamSubmission>[] = [
    ),
  },
 ]
-
--- a/src/modules/exams/data-access.ts
+++ b/src/modules/exams/data-access.ts
@@ -1,9 +1,9 @@
 import { db } from "@/shared/db"
-import { exams, examQuestions, examSubmissions, submissionAnswers, users } from "@/shared/db/schema"
+import { exams, examQuestions, examSubmissions, submissionAnswers } from "@/shared/db/schema"
 import { eq, desc, like, and, or } from "drizzle-orm"
 import { cache } from "react"

-import type { ExamStatus } from "./types"
+import type { Exam, ExamDifficulty, ExamStatus } from "./types"

 export type GetExamsParams = {
  q?: string
@@ -13,6 +13,40 @@ export type GetExamsParams = {
  pageSize?: number
 }

+const isRecord = (v: unknown): v is Record<string, unknown> => typeof v === "object" && v !== null
+
+const parseExamMeta = (description: string | null): Record<string, unknown> => {
+  if (!description) return {}
+  try {
+    const parsed: unknown = JSON.parse(description)
+    return isRecord(parsed) ? parsed : {}
+  } catch {
+    return {}
+  }
+}
+
+const getString = (obj: Record<string, unknown>, key: string): string | undefined => {
+  const v = obj[key]
+  return typeof v === "string" ? v : undefined
+}
+
+const getNumber = (obj: Record<string, unknown>, key: string): number | undefined => {
+  const v = obj[key]
+  return typeof v === "number" ? v : undefined
+}
+
+const getStringArray = (obj: Record<string, unknown>, key: string): string[] | undefined => {
+  const v = obj[key]
+  if (!Array.isArray(v)) return undefined
+  const items = v.filter((x): x is string => typeof x === "string")
+  return items.length === v.length ? items : undefined
+}
+
+const toExamDifficulty = (n: number | undefined): ExamDifficulty => {
+  if (n === 1 || n === 2 || n === 3 || n === 4 || n === 5) return n
+  return 1
+}
+

 export const getExams = cache(async (params: GetExamsParams) => {
  const conditions = []
@@ -23,7 +57,7 @@ export const getExams = cache(async (params: GetExamsParams) => {
  }

  if (params.status && params.status !== "all") {
-    conditions.push(eq(exams.status, params.status as any))
+    conditions.push(eq(exams.status, params.status))
  }

  // Note: Difficulty is stored in JSON description field in current schema, 
@@ -37,25 +71,23 @@ export const getExams = cache(async (params: GetExamsParams) => {
  })

  // Transform and Filter (especially for JSON fields)
-  let result = data.map((exam) => {
-    let meta: any = {}
-    try {
-      meta = JSON.parse(exam.description || "{}")
-    } catch { }
+  let result: Exam[] = data.map((exam) => {
+    const meta = parseExamMeta(exam.description || null)

    return {
      id: exam.id,
      title: exam.title,
      status: (exam.status as ExamStatus) || "draft",
-      subject: meta.subject || "General",
-      grade: meta.grade || "General",
-      difficulty: meta.difficulty || 1,
-      totalScore: meta.totalScore || 100,
-      durationMin: meta.durationMin || 60,
-      questionCount: meta.questionCount || 0,
+      subject: getString(meta, "subject") || "General",
+      grade: getString(meta, "grade") || "General",
+      difficulty: toExamDifficulty(getNumber(meta, "difficulty")),
+      totalScore: getNumber(meta, "totalScore") || 100,
+      durationMin: getNumber(meta, "durationMin") || 60,
+      questionCount: getNumber(meta, "questionCount") || 0,
      scheduledAt: exam.startTime?.toISOString(),
      createdAt: exam.createdAt.toISOString(),
-      tags: meta.tags || [],
+      updatedAt: exam.updatedAt?.toISOString(),
+      tags: getStringArray(meta, "tags") || [],
    }
  })

@@ -82,30 +114,27 @@ export const getExamById = cache(async (id: string) => {

  if (!exam) return null

-  let meta: any = {}
-  try {
-    meta = JSON.parse(exam.description || "{}")
-  } catch { }
+  const meta = parseExamMeta(exam.description || null)

  return {
    id: exam.id,
    title: exam.title,
    status: (exam.status as ExamStatus) || "draft",
-    subject: meta.subject || "General",
-    grade: meta.grade || "General",
-    difficulty: meta.difficulty || 1,
-    totalScore: meta.totalScore || 100,
-    durationMin: meta.durationMin || 60,
+    subject: getString(meta, "subject") || "General",
+    grade: getString(meta, "grade") || "General",
+    difficulty: toExamDifficulty(getNumber(meta, "difficulty")),
+    totalScore: getNumber(meta, "totalScore") || 100,
+    durationMin: getNumber(meta, "durationMin") || 60,
    scheduledAt: exam.startTime?.toISOString(),
    createdAt: exam.createdAt.toISOString(),
-    tags: meta.tags || [],
-    structure: exam.structure as any, // Return structure
-    questions: exam.questions.map(eq => ({
-        id: eq.questionId,
-        score: eq.score,
-        order: eq.order,
-        // ... include question details if needed
-    }))
+    updatedAt: exam.updatedAt?.toISOString(),
+    tags: getStringArray(meta, "tags") || [],
+    structure: exam.structure as unknown,
+    questions: exam.questions.map((eqRel) => ({
+      id: eqRel.questionId,
+      score: eqRel.score ?? 0,
+      order: eqRel.order ?? 0,
+    })),
  }
 })

@@ -154,13 +183,20 @@ export const getSubmissionDetails = cache(async (submissionId: string) => {
    orderBy: [desc(examQuestions.order)],
  })

+  type QuestionContent = { text?: string } & Record<string, unknown>
+
+  const toQuestionContent = (v: unknown): QuestionContent | null => {
+    if (!isRecord(v)) return null
+    return v as QuestionContent
+  }
+
  // Map answers with question details
  const answersWithDetails = answers.map(ans => {
    const eqRel = examQ.find(q => q.questionId === ans.questionId)
    return {
      id: ans.id,
      questionId: ans.questionId,
-      questionContent: ans.question.content,
+      questionContent: toQuestionContent(ans.question.content),
      questionType: ans.question.type,
      maxScore: eqRel?.score || 0,
      studentAnswer: ans.answerContent,
--- a/src/modules/layout/config/navigation.ts
+++ b/src/modules/layout/config/navigation.ts
@@ -2,7 +2,6 @@ import {
  BarChart,
  BookOpen,
  Calendar,
-  GraduationCap,
  LayoutDashboard,
  Settings,
  Users,
@@ -15,10 +14,11 @@ import {
  Library,
  PenTool
 } from "lucide-react"
+import type { LucideIcon } from "lucide-react"

 export type NavItem = {
  title: string
-  icon: any
+  icon: LucideIcon
  href: string
  items?: { title: string; href: string }[]
 }
--- a/src/modules/questions/actions.ts
+++ b/src/modules/questions/actions.ts
@@ -5,8 +5,6 @@ import { questions, questionsToKnowledgePoints } from "@/shared/db/schema";
 import { CreateQuestionInput, CreateQuestionSchema } from "./schema";
 import { ActionState } from "@/shared/types/action-state";
 import { revalidatePath } from "next/cache";
-import { ZodError } from "zod";
-import { eq } from "drizzle-orm";
 import { createId } from "@paralleldrive/cuid2";

 // --- Mock Auth Helper (Replace with actual Auth.js call) ---
@@ -29,8 +27,10 @@ async function ensureTeacher() {

 // --- Recursive Insert Helper ---
 // We pass 'tx' to ensure all operations run within the same transaction
+type Tx = Parameters<Parameters<typeof db.transaction>[0]>[0]
+
 async function insertQuestionWithRelations(
-  tx: any, // using any or strict Drizzle Transaction type if imported
+  tx: Tx,
  input: CreateQuestionInput,
  authorId: string,
  parentId: string | null = null
@@ -81,14 +81,14 @@ export async function createNestedQuestion(
    // If formData is actual FormData, we need to convert it. 
    // For complex nested structures, frontend usually sends JSON string or pure JSON object if using `useServerAction` with arguments.
    // Here we assume the client might send a raw object (if using direct function call) or we parse FormData.
-    let rawInput: any = formData;
+    let rawInput: unknown = formData;
    
    if (formData instanceof FormData) {
       // Parsing complex nested JSON from FormData is messy. 
       // We assume one field 'data' contains the JSON, or we expect direct object usage (common in modern Next.js RPC).
       const jsonString = formData.get("json");
       if (typeof jsonString === "string") {
-         rawInput = JSON.parse(jsonString);
+         rawInput = JSON.parse(jsonString) as unknown;
       } else {
         return { success: false, message: "Invalid submission format. Expected JSON." };
       }
--- a/src/modules/questions/data-access.ts
+++ b/src/modules/questions/data-access.ts
@@ -9,6 +9,7 @@ import { cache } from "react";
 export type GetQuestionsParams = {
  page?: number;
  pageSize?: number;
+  ids?: string[];
  knowledgePointId?: string;
  difficulty?: number;
 };
@@ -18,6 +19,7 @@ export type GetQuestionsParams = {
 export const getQuestions = cache(async ({
  page = 1,
  pageSize = 10,
+  ids,
  knowledgePointId,
  difficulty,
 }: GetQuestionsParams = {}) => {
@@ -26,6 +28,10 @@ export const getQuestions = cache(async ({
  // Build Where Conditions
  const conditions = [];

+  if (ids && ids.length > 0) {
+    conditions.push(inArray(questions.id, ids));
+  }
+
  if (difficulty) {
    conditions.push(eq(questions.difficulty, difficulty));
  }
@@ -40,9 +46,9 @@ export const getQuestions = cache(async ({
    conditions.push(inArray(questions.id, subQuery));
  }

-  // Only fetch top-level questions (parent questions)
-  // Assuming we only want to list "root" questions, not sub-questions
-  conditions.push(sql`${questions.parentId} IS NULL`);
+  if (!ids || ids.length === 0) {
+    conditions.push(sql`${questions.parentId} IS NULL`)
+  }

  const whereClause = conditions.length > 0 ? and(...conditions) : undefined;

--- a/src/modules/textbooks/components/textbook-content-layout.tsx
+++ b/src/modules/textbooks/components/textbook-content-layout.tsx
@@ -40,8 +40,7 @@ export function TextbookContentLayout({ chapters, knowledgePoints, textbookId }:
    if (result.success) {
      toast.success(result.message)
      setIsEditing(false)
-      // Update local state to reflect change immediately (optimistic-like)
-      selectedChapter.content = editContent
+      setSelectedChapter((prev) => (prev ? { ...prev, content: editContent } : prev))
    } else {
      toast.error(result.message)
    }
--- a/src/modules/textbooks/components/textbook-form-dialog.tsx
+++ b/src/modules/textbooks/components/textbook-form-dialog.tsx
@@ -61,7 +61,7 @@ export function TextbookFormDialog() {
        <DialogHeader>
          <DialogTitle>Add New Textbook</DialogTitle>
          <DialogDescription>
-            Create a new digital textbook. Click save when you're done.
+            Create a new digital textbook. Click save when you&apos;re done.
          </DialogDescription>
        </DialogHeader>
        <form action={handleSubmit}>
--- a/src/modules/textbooks/data-access.ts
+++ b/src/modules/textbooks/data-access.ts
@@ -65,7 +65,7 @@ let MOCK_KNOWLEDGE_POINTS: KnowledgePoint[] = [

 export async function getTextbooks(query?: string, subject?: string, grade?: string): Promise<Textbook[]> {
  await new Promise((resolve) => setTimeout(resolve, 500));
-  let results = [...MOCK_TEXTBOOKS];
+  const results = [...MOCK_TEXTBOOKS];
  // ... (filtering logic)
  return results;
 }
--- a/src/shared/components/ui/form.tsx
+++ b/src/shared/components/ui/form.tsx
@@ -28,7 +28,7 @@ const FormFieldContext = React.createContext<FormFieldContextValue>(
 const FormField = <
  TFieldValues extends FieldValues = FieldValues,
  TName extends FieldPath<TFieldValues> = FieldPath<TFieldValues>,
-  TTransformedValues = any
+  TTransformedValues = unknown
 >({
  ...props
 }: ControllerProps<TFieldValues, TName, TTransformedValues>) => {
--- a/tailwind.config.ts
+++ b/tailwind.config.ts
@@ -1,4 +1,5 @@
 import type { Config } from "tailwindcss";
+import tailwindcssAnimate from "tailwindcss-animate";

 const config: Config = {
  darkMode: "class",
@@ -70,7 +71,7 @@ const config: Config = {
      },
    },
  },
-  plugins: [require("tailwindcss-animate")],
+  plugins: [tailwindcssAnimate],
 };

 export default config;