feat: 新增备课模块并修复全模块 P0/P1/P2 缺陷

主要变更:

- 新增 lesson-preparation 模块: 备课编辑器、节点编辑、AI 建议、知识点选择、版本历史、作业发布

- 新增 shared 通用组件: charts/question-bank-filters/schedule-list/ui (chip-nav/filter-bar/page-header/stat-card/stat-item)

- 新增 student/admin 端 loading.tsx 与 error.tsx, 优化加载与错误态体验

- 新增 teacher/lesson-plans 页面 (列表/新建/编辑)

- 新增 drizzle 迁移 0002_tiny_lionheart 及 snapshot

- 新增 textbooks/schema.ts 与 exams/utils/normalize-structure.ts

- 修复 Tiptap v3 SSR hydration 崩溃 (rich-text-block immediatelyRender: false)

- 重构多模块 data-access/actions/组件, 修复权限校验与类型规范

- 同步架构文档 004/005 反映新增模块、导出、依赖关系

- 归档 bugs/* 测试报告与 e2e 测试脚本 (admin/parent/student/teacher web_test)

src/app/(dashboard)/student/attendance/loading.tsx

@@ -0,0 +1,25 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+      <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-4">
+        {Array.from({ length: 4 }).map((_, i) => (
+          <Card key={i}>
+            <CardHeader className="pb-2">
+              <Skeleton className="h-4 w-24" />
+            </CardHeader>
+            <CardContent>
+              <Skeleton className="h-8 w-16" />
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/student/attendance/page.tsx

@@ -2,7 +2,7 @@ import { getAuthContext } from "@/shared/lib/auth-guard"
 import { getStudentAttendanceSummary } from "@/modules/attendance/data-access-stats"
 import { StudentAttendanceView } from "@/modules/attendance/components/student-attendance-view"
 import { EmptyState } from "@/shared/components/ui/empty-state"
-import { CalendarCheck } from "lucide-react"
+import { UserX } from "lucide-react"
 
 export const dynamic = "force-dynamic"
 
@@ -21,7 +21,7 @@ export default async function StudentAttendancePage() {
         <EmptyState
           title="No user found"
           description="Unable to load your student profile."
-          icon={CalendarCheck}
+          icon={UserX}
           className="border-none shadow-none"
         />
       </div>

src/app/(dashboard)/student/dashboard/page.tsx

@@ -3,27 +3,31 @@ import { getStudentClasses, getStudentSchedule } from "@/modules/classes/data-ac
 import { getStudentDashboardGrades, getStudentHomeworkAssignments } from "@/modules/homework/data-access"
 import { getCurrentStudentUser } from "@/modules/users/data-access"
 import { EmptyState } from "@/shared/components/ui/empty-state"
-import { Inbox } from "lucide-react"
+import { UserX } from "lucide-react"
+import type { StudentHomeworkProgressStatus } from "@/modules/homework/types"
 
 export const dynamic = "force-dynamic"
 
 const toWeekday = (d: Date): 1 | 2 | 3 | 4 | 5 | 6 | 7 => {
+  // getDay() 返回 0(周日)-6(周六)，转换为 1-7（周一为 1）
+  const WEEKDAY_MAP = [7, 1, 2, 3, 4, 5, 6] as const
   const day = d.getDay()
-  return (day === 0 ? 7 : day) as 1 | 2 | 3 | 4 | 5 | 6 | 7
+  if (day < 0 || day > 6) {
+    throw new Error(`Invalid day from getDay(): ${day}`)
+  }
+  return WEEKDAY_MAP[day]
 }
 
 export default async function StudentDashboardPage() {
   const student = await getCurrentStudentUser()
   if (!student) {
     return (
-      <div className="flex h-full flex-col items-center justify-center">
-        <EmptyState
-          title="No user found"
-          description="Create a student user to see dashboard."
-          icon={Inbox}
-          className="border-none shadow-none h-auto"
-        />
-      </div>
+      <EmptyState
+        title="No user found"
+        description="Create a student user to see dashboard."
+        icon={UserX}
+        className="border-none shadow-none h-auto"
+      />
     )
   }
 
@@ -38,19 +42,24 @@ export default async function StudentDashboardPage() {
   const in7Days = new Date(now)
   in7Days.setDate(in7Days.getDate() + 7)
 
-  const dueSoonCount = assignments.filter((a) => {
-    if (!a.dueAt) return false
+  // 单次遍历统计，避免重复 filter（PERF-04）
+  let dueSoonCount = 0
+  let overdueCount = 0
+  let gradedCount = 0
+  for (const a of assignments) {
+    const status: StudentHomeworkProgressStatus = a.progressStatus
+    if (status === "graded") {
+      gradedCount++
+      continue
+    }
+    if (!a.dueAt) continue
     const due = new Date(a.dueAt)
-    return due >= now && due <= in7Days && a.progressStatus !== "graded"
-  }).length
-
-  const overdueCount = assignments.filter((a) => {
-    if (!a.dueAt) return false
-    const due = new Date(a.dueAt)
-    return due < now && a.progressStatus !== "graded"
-  }).length
-
-  const gradedCount = assignments.filter((a) => a.progressStatus === "graded").length
+    if (due >= now && due <= in7Days) {
+      dueSoonCount++
+    } else if (due < now) {
+      overdueCount++
+    }
+  }
 
   const todayWeekday = toWeekday(now)
   const todayScheduleItems = schedule
@@ -75,15 +84,21 @@ export default async function StudentDashboardPage() {
     .slice(0, 6)
 
   return (
-    <StudentDashboard
-      studentName={student.name}
-      enrolledClassCount={classes.length}
-      dueSoonCount={dueSoonCount}
-      overdueCount={overdueCount}
-      gradedCount={gradedCount}
-      todayScheduleItems={todayScheduleItems}
-      upcomingAssignments={upcomingAssignments}
-      grades={grades}
-    />
+    <div className="space-y-8">
+      <div>
+        <h2 className="text-2xl font-bold tracking-tight">Dashboard</h2>
+        <p className="text-muted-foreground">Welcome back, {student.name}.</p>
+      </div>
+      <StudentDashboard
+        studentName={student.name}
+        enrolledClassCount={classes.length}
+        dueSoonCount={dueSoonCount}
+        overdueCount={overdueCount}
+        gradedCount={gradedCount}
+        todayScheduleItems={todayScheduleItems}
+        upcomingAssignments={upcomingAssignments}
+        grades={grades}
+      />
+    </div>
   )
 }

src/app/(dashboard)/student/diagnostic/loading.tsx

@@ -0,0 +1,35 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-72" />
+      </div>
+      <div className="grid gap-4 md:grid-cols-2">
+        <Card>
+          <CardHeader>
+            <Skeleton className="h-5 w-40" />
+          </CardHeader>
+          <CardContent className="space-y-3">
+            {Array.from({ length: 4 }).map((_, i) => (
+              <Skeleton key={i} className="h-12 w-full" />
+            ))}
+          </CardContent>
+        </Card>
+        <Card>
+          <CardHeader>
+            <Skeleton className="h-5 w-44" />
+          </CardHeader>
+          <CardContent className="space-y-3">
+            {Array.from({ length: 4 }).map((_, i) => (
+              <Skeleton key={i} className="h-12 w-full" />
+            ))}
+          </CardContent>
+        </Card>
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/student/elective/loading.tsx

@@ -0,0 +1,26 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+      <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-3">
+        {Array.from({ length: 6 }).map((_, i) => (
+          <Card key={i}>
+            <CardHeader className="pb-2">
+              <Skeleton className="h-5 w-32" />
+              <Skeleton className="mt-2 h-4 w-24" />
+            </CardHeader>
+            <CardContent>
+              <Skeleton className="h-9 w-28" />
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/student/elective/page.tsx

@@ -15,7 +15,7 @@ export default async function StudentElectivePage() {
   ])
 
   return (
-    <div className="flex h-full flex-col space-y-8 p-8">
+    <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
       <div>
         <h2 className="text-2xl font-bold tracking-tight">Elective Courses</h2>
         <p className="text-muted-foreground">

src/app/(dashboard)/student/error.tsx

@@ -0,0 +1,21 @@
+"use client"
+
+import { EmptyState } from "@/shared/components/ui/empty-state"
+import { AlertTriangle } from "lucide-react"
+
+export default function StudentError({
+  error,
+  reset,
+}: {
+  error: Error & { digest?: string }
+  reset: () => void
+}) {
+  return (
+    <EmptyState
+      icon={AlertTriangle}
+      title="Something went wrong"
+      description={error.message || "An unexpected error occurred. Please try again."}
+      action={{ label: "Try again", onClick: reset }}
+    />
+  )
+}

src/app/(dashboard)/student/grades/loading.tsx

@@ -0,0 +1,23 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-40" />
+        <Skeleton className="h-4 w-56" />
+      </div>
+      <Card>
+        <CardHeader>
+          <Skeleton className="h-5 w-48" />
+        </CardHeader>
+        <CardContent className="space-y-3">
+          {Array.from({ length: 5 }).map((_, i) => (
+            <Skeleton key={i} className="h-10 w-full" />
+          ))}
+        </CardContent>
+      </Card>
+    </div>
+  )
+}

src/app/(dashboard)/student/grades/page.tsx

@@ -2,7 +2,7 @@ import { getAuthContext } from "@/shared/lib/auth-guard"
 import { getStudentGradeSummary } from "@/modules/grades/data-access"
 import { StudentGradeSummary } from "@/modules/grades/components/student-grade-summary"
 import { EmptyState } from "@/shared/components/ui/empty-state"
-import { GraduationCap } from "lucide-react"
+import { UserX } from "lucide-react"
 
 export const dynamic = "force-dynamic"
 
@@ -21,7 +21,7 @@ export default async function StudentGradesPage() {
         <EmptyState
           title="No user found"
           description="Unable to load your student profile."
-          icon={GraduationCap}
+          icon={UserX}
           className="border-none shadow-none"
         />
       </div>

src/app/(dashboard)/student/learning/assignments/[assignmentId]/loading.tsx

@@ -0,0 +1,13 @@
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-4">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-64" />
+        <Skeleton className="h-4 w-48" />
+      </div>
+      <Skeleton className="h-96 w-full" />
+    </div>
+  )
+}

src/app/(dashboard)/student/learning/assignments/[assignmentId]/page.tsx

@@ -24,7 +24,7 @@ export default async function StudentAssignmentTakePage({
   const status = data.submission?.status
   if (status === "graded" || status === "submitted") {
     return (
-      <div className="flex h-full flex-col space-y-4 p-6">
+      <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
         <div className="flex flex-col gap-1">
           <h2 className="text-2xl font-bold tracking-tight">{data.assignment.title}</h2>
           <div className="text-sm text-muted-foreground">
@@ -43,7 +43,7 @@ export default async function StudentAssignmentTakePage({
         <h2 className="text-2xl font-bold tracking-tight">{data.assignment.title}</h2>
         <div className="text-sm text-muted-foreground">
           <span>Due: {data.assignment.dueAt ? formatDate(data.assignment.dueAt) : "-"}</span>
-          <span className="mx-2">•</span>
+          <span className="mx-2" aria-hidden="true">•</span>
           <span>Max Attempts: {data.assignment.maxAttempts}</span>
         </div>
       </div>

src/app/(dashboard)/student/learning/assignments/loading.tsx

@@ -0,0 +1,33 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-6">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+      <div className="space-y-3">
+        <Skeleton className="h-4 w-32" />
+        <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
+          {Array.from({ length: 6 }).map((_, i) => (
+            <Card key={i}>
+              <CardHeader className="gap-2 pb-3">
+                <div className="flex items-start justify-between gap-3">
+                  <Skeleton className="h-5 w-40" />
+                  <Skeleton className="h-5 w-16 rounded-full" />
+                </div>
+                <Skeleton className="h-3 w-48" />
+              </CardHeader>
+              <CardContent className="flex items-center justify-between">
+                <Skeleton className="h-8 w-16" />
+                <Skeleton className="h-9 w-20" />
+              </CardContent>
+            </Card>
+          ))}
+        </div>
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/student/learning/assignments/page.tsx

@@ -7,46 +7,109 @@ import { Card, CardContent, CardHeader, CardTitle } from "@/shared/components/ui
 import { formatDate } from "@/shared/lib/utils"
 import { getStudentHomeworkAssignments } from "@/modules/homework/data-access"
 import { getCurrentStudentUser } from "@/modules/users/data-access"
-import { Inbox } from "lucide-react"
+import { Inbox, UserX } from "lucide-react"
+import type {
+  StudentHomeworkAssignmentListItem,
+  StudentHomeworkProgressStatus,
+} from "@/modules/homework/types"
 
 export const dynamic = "force-dynamic"
 
-const getStatusVariant = (status: string): "default" | "secondary" | "outline" => {
-  if (status === "graded") return "default"
-  if (status === "submitted") return "secondary"
-  if (status === "in_progress") return "secondary"
-  return "outline"
+const getStatusVariant = (
+  status: StudentHomeworkProgressStatus
+): "default" | "secondary" | "outline" => {
+  switch (status) {
+    case "graded":
+      return "default"
+    case "submitted":
+      return "secondary"
+    case "in_progress":
+      return "outline"
+    default:
+      return "outline"
+  }
 }
 
-const getStatusLabel = (status: string) => {
-  if (status === "graded") return "Graded"
-  if (status === "submitted") return "Submitted"
-  if (status === "in_progress") return "In progress"
-  return "Not started"
+const getStatusLabel = (status: StudentHomeworkProgressStatus): string => {
+  switch (status) {
+    case "graded":
+      return "Graded"
+    case "submitted":
+      return "Submitted"
+    case "in_progress":
+      return "In progress"
+    default:
+      return "Not started"
+  }
 }
 
-const getActionLabel = (status: string) => {
-  if (status === "graded") return "Review"
-  if (status === "submitted") return "View"
-  if (status === "in_progress") return "Continue"
-  return "Start"
+const getActionLabel = (status: StudentHomeworkProgressStatus): string => {
+  switch (status) {
+    case "graded":
+      return "Review"
+    case "submitted":
+      return "View"
+    case "in_progress":
+      return "Continue"
+    default:
+      return "Start"
+  }
 }
 
-const getActionVariant = (status: string): "default" | "secondary" | "outline" => {
-  if (status === "graded" || status === "submitted") return "outline"
-  return "default"
+const getActionVariant = (
+  status: StudentHomeworkProgressStatus
+): "default" | "secondary" | "outline" => {
+  return status === "graded" || status === "submitted" ? "outline" : "default"
 }
 
-const isAnswered = (status: string) => status === "submitted" || status === "graded"
+const isAnswered = (status: StudentHomeworkProgressStatus): boolean =>
+  status === "submitted" || status === "graded"
+
+function AssignmentCard({ assignment: a }: { assignment: StudentHomeworkAssignmentListItem }) {
+  return (
+    <Card className="flex h-full flex-col overflow-hidden transition-all hover:shadow-md">
+      <CardHeader className="gap-2 pb-3">
+        <div className="flex items-start justify-between gap-3">
+          <CardTitle className="text-base">
+            <Link href={`/student/learning/assignments/${a.id}`} className="hover:underline">
+              {a.title}
+            </Link>
+          </CardTitle>
+          <Badge variant={getStatusVariant(a.progressStatus)} className="capitalize">
+            {getStatusLabel(a.progressStatus)}
+          </Badge>
+        </div>
+        <div className="text-xs text-muted-foreground">
+          <span>Due {a.dueAt ? formatDate(a.dueAt) : "-"}</span>
+          <span className="px-2" aria-hidden="true">
+            •
+          </span>
+          <span>
+            Attempts {a.attemptsUsed}/{a.maxAttempts}
+          </span>
+        </div>
+      </CardHeader>
+      <CardContent className="mt-auto flex items-center justify-between">
+        <div className="text-sm">
+          <div className="text-muted-foreground">Score</div>
+          <div className="font-medium tabular-nums">{a.latestScore ?? "-"}</div>
+        </div>
+        <Button asChild size="sm" variant={getActionVariant(a.progressStatus)}>
+          <Link href={`/student/learning/assignments/${a.id}`}>
+            {getActionLabel(a.progressStatus)}
+          </Link>
+        </Button>
+      </CardContent>
+    </Card>
+  )
+}
 
 export default async function StudentAssignmentsPage() {
   const student = await getCurrentStudentUser()
 
   if (!student) {
     return (
-      <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
-        <EmptyState title="No user found" description="Create a student user to see assignments." icon={Inbox} />
-      </div>
+      <EmptyState title="No user found" description="Create a student user to see assignments." icon={UserX} />
     )
   }
 
@@ -61,108 +124,61 @@ export default async function StudentAssignmentsPage() {
       acc.set(subject, [assignment])
     }
     return acc
-  }, new Map<string, typeof assignments>())
-  const subjectEntries = Array.from(assignmentsBySubject.entries()).sort((a, b) => a[0].localeCompare(b[0]))
+  }, new Map<string, StudentHomeworkAssignmentListItem[]>())
+  const subjectEntries = Array.from(assignmentsBySubject.entries()).sort((a, b) =>
+    a[0].localeCompare(b[0])
+  )
 
   return (
-    <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
+    <>
       {!hasAssignments ? (
         <EmptyState title="No assignments" description="You have no assigned homework right now." icon={Inbox} />
       ) : (
         <div className="space-y-6">
           {subjectEntries.map(([subject, items]) => {
-            const answeredItems = items.filter((a) => isAnswered(a.progressStatus))
-            const unansweredItems = items.filter((a) => !isAnswered(a.progressStatus))
+            // 单次遍历分桶，避免重复 filter（PERF-05）
+            const answered: StudentHomeworkAssignmentListItem[] = []
+            const unanswered: StudentHomeworkAssignmentListItem[] = []
+            for (const a of items) {
+              if (isAnswered(a.progressStatus)) {
+                answered.push(a)
+              } else {
+                unanswered.push(a)
+              }
+            }
 
             return (
               <div key={subject} className="space-y-3">
-              <div className="text-sm font-semibold text-muted-foreground">{subject}</div>
-              {unansweredItems.length > 0 && (
-                <div className="space-y-3">
-                  <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">未答题</div>
-                  <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
-                    {unansweredItems.map((a) => (
-                      <Card key={a.id} className="flex h-full flex-col overflow-hidden transition-all hover:shadow-md">
-                        <CardHeader className="gap-2 pb-3">
-                          <div className="flex items-start justify-between gap-3">
-                            <CardTitle className="text-base">
-                              <Link href={`/student/learning/assignments/${a.id}`} className="hover:underline">
-                                {a.title}
-                              </Link>
-                            </CardTitle>
-                            <Badge variant={getStatusVariant(a.progressStatus)} className="capitalize">
-                              {getStatusLabel(a.progressStatus)}
-                            </Badge>
-                          </div>
-                          <div className="text-xs text-muted-foreground">
-                            <span>Due {a.dueAt ? formatDate(a.dueAt) : "-"}</span>
-                            <span className="px-2">•</span>
-                            <span>
-                              Attempts {a.attemptsUsed}/{a.maxAttempts}
-                            </span>
-                          </div>
-                        </CardHeader>
-                        <CardContent className="mt-auto flex items-center justify-between">
-                          <div className="text-sm">
-                            <div className="text-muted-foreground">Score</div>
-                            <div className="font-medium tabular-nums">{a.latestScore ?? "-"}</div>
-                          </div>
-                          <Button asChild size="sm" variant={getActionVariant(a.progressStatus)}>
-                            <Link href={`/student/learning/assignments/${a.id}`}>
-                              {getActionLabel(a.progressStatus)}
-                            </Link>
-                          </Button>
-                        </CardContent>
-                      </Card>
-                    ))}
+                <div className="text-sm font-semibold text-muted-foreground">{subject}</div>
+                {unanswered.length > 0 && (
+                  <div className="space-y-3">
+                    <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">
+                      Pending
+                    </div>
+                    <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
+                      {unanswered.map((a) => (
+                        <AssignmentCard key={a.id} assignment={a} />
+                      ))}
+                    </div>
                   </div>
-                </div>
-              )}
-              {answeredItems.length > 0 && (
-                <div className="space-y-3">
-                  <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">已答题</div>
-                  <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
-                    {answeredItems.map((a) => (
-                      <Card key={a.id} className="flex h-full flex-col overflow-hidden transition-all hover:shadow-md">
-                        <CardHeader className="gap-2 pb-3">
-                          <div className="flex items-start justify-between gap-3">
-                            <CardTitle className="text-base">
-                              <Link href={`/student/learning/assignments/${a.id}`} className="hover:underline">
-                                {a.title}
-                              </Link>
-                            </CardTitle>
-                            <Badge variant={getStatusVariant(a.progressStatus)} className="capitalize">
-                              {getStatusLabel(a.progressStatus)}
-                            </Badge>
-                          </div>
-                          <div className="text-xs text-muted-foreground">
-                            <span>Due {a.dueAt ? formatDate(a.dueAt) : "-"}</span>
-                            <span className="px-2">•</span>
-                            <span>
-                              Attempts {a.attemptsUsed}/{a.maxAttempts}
-                            </span>
-                          </div>
-                        </CardHeader>
-                        <CardContent className="mt-auto flex items-center justify-between">
-                          <div className="text-sm">
-                            <div className="text-muted-foreground">Score</div>
-                            <div className="font-medium tabular-nums">{a.latestScore ?? "-"}</div>
-                          </div>
-                          <Button asChild size="sm" variant={getActionVariant(a.progressStatus)}>
-                            <Link href={`/student/learning/assignments/${a.id}`}>
-                              {getActionLabel(a.progressStatus)}
-                            </Link>
-                          </Button>
-                        </CardContent>
-                      </Card>
-                    ))}
+                )}
+                {answered.length > 0 && (
+                  <div className="space-y-3">
+                    <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">
+                      Completed
+                    </div>
+                    <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
+                      {answered.map((a) => (
+                        <AssignmentCard key={a.id} assignment={a} />
+                      ))}
+                    </div>
                   </div>
-                </div>
-              )}
-            </div>
-          )})}
+                )}
+              </div>
+            )
+          })}
         </div>
       )}
-    </div>
+    </>
   )
 }

src/app/(dashboard)/student/learning/courses/page.tsx

@@ -1,4 +1,4 @@
-import { Inbox } from "lucide-react"
+import { UserX } from "lucide-react"
 
 import { getStudentClasses } from "@/modules/classes/data-access"
 import { getCurrentStudentUser } from "@/modules/users/data-access"
@@ -11,7 +11,7 @@ export default async function StudentCoursesPage() {
   const student = await getCurrentStudentUser()
   if (!student) {
     return (
-      <div className="flex h-full flex-col space-y-8 p-8">
+      <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
         <div>
           <h2 className="text-2xl font-bold tracking-tight">Courses</h2>
           <p className="text-muted-foreground">Your enrolled classes.</p>
@@ -19,7 +19,7 @@ export default async function StudentCoursesPage() {
         <EmptyState
           title="No user found"
           description="Create a student user to see courses."
-          icon={Inbox}
+          icon={UserX}
         />
       </div>
     )

src/app/(dashboard)/student/learning/textbooks/[id]/loading.tsx

@@ -0,0 +1,17 @@
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="flex h-[calc(100vh-4rem)] flex-col overflow-hidden">
+      <div className="flex items-center justify-between border-b py-3 px-6 shrink-0">
+        <div className="flex items-center gap-3">
+          <Skeleton className="h-6 w-48" />
+          <Skeleton className="h-5 w-16 rounded-full" />
+        </div>
+      </div>
+      <div className="flex-1 p-6">
+        <Skeleton className="h-full w-full" />
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/student/learning/textbooks/[id]/page.tsx

@@ -1,6 +1,6 @@
 import { notFound } from "next/navigation"
 
-import { BookOpen, Inbox } from "lucide-react"
+import { BookOpen } from "lucide-react"
 
 import { getTextbookById, getChaptersByTextbookId, getKnowledgePointsByTextbookId } from "@/modules/textbooks/data-access"
 import { TextbookReader } from "@/modules/textbooks/components/textbook-reader"
@@ -16,19 +16,7 @@ export default async function StudentTextbookDetailPage({
   params: Promise<{ id: string }>
 }) {
   const student = await getCurrentStudentUser()
-  if (!student) {
-    return (
-      <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
-        <div className="flex items-center justify-between space-y-2">
-          <div>
-            <h2 className="text-2xl font-bold tracking-tight">Textbook</h2>
-            <p className="text-muted-foreground">Read chapters and review content.</p>
-          </div>
-        </div>
-        <EmptyState title="No user found" description="Create a student user to read textbooks." icon={Inbox} />
-      </div>
-    )
-  }
+  if (!student) return notFound()
 
   const { id } = await params
 
@@ -46,7 +34,7 @@ export default async function StudentTextbookDetailPage({
         <div className="flex items-center gap-3 min-w-0">
           <h1 className="text-lg font-bold tracking-tight truncate">{textbook.title}</h1>
           <div className="flex items-center gap-2 text-sm text-muted-foreground">
-             <span className="hidden sm:inline-block w-px h-4 bg-border" />
+             <span className="hidden sm:inline-block w-px h-4 bg-border" aria-hidden="true" />
              <Badge variant="outline" className="font-normal text-xs">{textbook.subject}</Badge>
              {textbook.grade && (
                <Badge variant="secondary" className="font-normal text-xs">{textbook.grade}</Badge>

src/app/(dashboard)/student/learning/textbooks/loading.tsx

@@ -0,0 +1,18 @@
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-40" />
+        <Skeleton className="h-4 w-56" />
+      </div>
+      <Skeleton className="h-10 w-full max-w-md" />
+      <div className="grid grid-cols-1 gap-6 sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-4">
+        {Array.from({ length: 8 }).map((_, i) => (
+          <Skeleton key={i} className="h-48 w-full" />
+        ))}
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/student/learning/textbooks/page.tsx

@@ -1,4 +1,4 @@
-import { BookOpen, Inbox } from "lucide-react"
+import { BookOpen, UserX } from "lucide-react"
 
 import { getTextbooks } from "@/modules/textbooks/data-access"
 import { TextbookCard } from "@/modules/textbooks/components/textbook-card"
@@ -25,7 +25,7 @@ export default async function StudentTextbooksPage({
   if (!student) {
     return (
       <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
-        <EmptyState title="No user found" description="Create a student user to see textbooks." icon={Inbox} />
+        <EmptyState title="No user found" description="Create a student user to see textbooks." icon={UserX} />
       </div>
     )
   }
@@ -39,15 +39,10 @@ export default async function StudentTextbooksPage({
 
   return (
     <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
-      {/* <div className="flex flex-col gap-4 md:flex-row md:items-center md:justify-between">
-        <div>
-          <h2 className="text-2xl font-bold tracking-tight">Textbooks</h2>
-          <p className="text-muted-foreground">Browse your course textbooks.</p>
-        </div>
-        <Button asChild variant="outline">
-          <Link href="/student/dashboard">Back</Link>
-        </Button>
-      </div> */}
+      <div>
+        <h2 className="text-2xl font-bold tracking-tight">Textbooks</h2>
+        <p className="text-muted-foreground">Browse your course textbooks.</p>
+      </div>
 
       <TextbookFilters />
 

src/app/(dashboard)/student/schedule/page.tsx

@@ -1,4 +1,4 @@
-import { Inbox } from "lucide-react"
+import { UserX } from "lucide-react"
 
 import { getStudentClasses, getStudentSchedule } from "@/modules/classes/data-access"
 import { getCurrentStudentUser } from "@/modules/users/data-access"
@@ -18,12 +18,12 @@ export default async function StudentSchedulePage({
   const student = await getCurrentStudentUser()
   if (!student) {
     return (
-      <div className="flex h-full flex-col space-y-8 p-8">
+      <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
         <div>
           <h2 className="text-2xl font-bold tracking-tight">Schedule</h2>
           <p className="text-muted-foreground">Your weekly timetable.</p>
         </div>
-        <EmptyState title="No user found" description="Create a student user to see schedule." icon={Inbox} />
+        <EmptyState title="No user found" description="Create a student user to see schedule." icon={UserX} />
       </div>
     )
   }
@@ -35,9 +35,14 @@ export default async function StudentSchedulePage({
   ])
 
   const classIdParam = sp.classId
-  const classId = typeof classIdParam === "string" ? classIdParam : Array.isArray(classIdParam) ? classIdParam[0] : "all"
+  const resolveClassId = (param: string | string[] | undefined): string => {
+    if (typeof param === "string") return param
+    if (Array.isArray(param)) return param[0] ?? "all"
+    return "all"
+  }
+  const classId = resolveClassId(classIdParam)
   const filteredItems =
-    classId && classId !== "all" ? schedule.filter((s) => s.classId === classId) : schedule
+    classId !== "all" ? schedule.filter((s) => s.classId === classId) : schedule
 
   return (
     <div className="flex h-full flex-col space-y-8 p-8">