feat(exam-homework): add audit report, i18n, error boundaries, and permission hardening

- Add comprehensive audit report for exam and homework module

- Create exam-homework i18n message files (zh-CN + en) and register namespace

- Add permission check to gradeHomeworkSubmissionAction to prevent horizontal privilege escalation

- Add Error Boundary + loading.tsx for 5 key pages (exam build/proctoring, homework assignment/submissions, student assignment)

- Refactor exam-columns to createExamColumns(t) factory for i18n support

- Refactor exam-data-table to manage columns internally via useTranslations

- Replace hardcoded strings with i18n keys in all exam/homework components and pages

- Add getHomeworkSubmissionForGrading data-access for secure grading flow

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

@@ -1,58 +1,42 @@
 import Link from "next/link"
+import { getTranslations } from "next-intl/server"
 
 import { EmptyState } from "@/shared/components/ui/empty-state"
-import { Badge } from "@/shared/components/ui/badge"
 import { Button } from "@/shared/components/ui/button"
 import { Card, CardContent, CardHeader, CardTitle } from "@/shared/components/ui/card"
-import { formatDate } from "@/shared/lib/utils"
+import { StatusBadge } from "@/shared/components/ui/status-badge"
+import { formatDate, cn } from "@/shared/lib/utils"
 import { getStudentHomeworkAssignments } from "@/modules/homework/data-access"
 import { getCurrentStudentUser } from "@/modules/users/data-access"
-import { Inbox, UserX } from "lucide-react"
+import { AssignmentFilters } from "@/modules/homework/components/assignment-filters"
+import { Inbox, UserX, TriangleAlert } from "lucide-react"
 import type {
   StudentHomeworkAssignmentListItem,
   StudentHomeworkProgressStatus,
 } from "@/modules/homework/types"
+import {
+  STUDENT_HOMEWORK_PROGRESS_VARIANT,
+} from "@/modules/homework/types"
 
 export const dynamic = "force-dynamic"
 
-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"
-  }
+type SearchParams = { [key: string]: string | string[] | undefined }
+
+const getParam = (params: SearchParams, key: string) => {
+  const v = params[key]
+  return Array.isArray(v) ? v[0] : v
 }
 
-const getStatusLabel = (status: StudentHomeworkProgressStatus): string => {
+const getActionLabel = (status: StudentHomeworkProgressStatus, t: (key: string) => string): string => {
   switch (status) {
     case "graded":
-      return "Graded"
+      return t("homework.review.title")
     case "submitted":
-      return "Submitted"
+      return t("common.view")
     case "in_progress":
-      return "In progress"
+      return t("common.continue")
     default:
-      return "Not started"
-  }
-}
-
-const getActionLabel = (status: StudentHomeworkProgressStatus): string => {
-  switch (status) {
-    case "graded":
-      return "Review"
-    case "submitted":
-      return "View"
-    case "in_progress":
-      return "Continue"
-    default:
-      return "Start"
+      return t("homework.take.startAssignment")
   }
 }
 
@@ -65,7 +49,55 @@ const getActionVariant = (
 const isAnswered = (status: StudentHomeworkProgressStatus): boolean =>
   status === "submitted" || status === "graded"
 
-function AssignmentCard({ assignment: a }: { assignment: StudentHomeworkAssignmentListItem }) {
+const matchesStatusFilter = (
+  status: StudentHomeworkProgressStatus,
+  filter: string
+): boolean => {
+  if (filter === "all") return true
+  if (filter === "pending") return status === "not_started" || status === "in_progress"
+  if (filter === "submitted") return status === "submitted"
+  if (filter === "graded") return status === "graded"
+  return true
+}
+
+// Stable color mapping for subjects (hash-based, deterministic)
+const SUBJECT_DOT_COLORS = [
+  "bg-blue-500",
+  "bg-emerald-500",
+  "bg-amber-500",
+  "bg-violet-500",
+  "bg-rose-500",
+  "bg-cyan-500",
+  "bg-orange-500",
+  "bg-pink-500",
+  "bg-indigo-500",
+  "bg-teal-500",
+]
+
+const getSubjectColor = (subject: string): string => {
+  let hash = 0
+  for (let i = 0; i < subject.length; i++) {
+    hash = (hash * 31 + subject.charCodeAt(i)) | 0
+  }
+  const idx = Math.abs(hash) % SUBJECT_DOT_COLORS.length
+  return SUBJECT_DOT_COLORS[idx]
+}
+
+type TranslationFn = (key: string) => string
+
+function AssignmentCard({
+  assignment: a,
+  t,
+  statusLabelMap,
+}: {
+  assignment: StudentHomeworkAssignmentListItem
+  t: TranslationFn
+  statusLabelMap: Record<StudentHomeworkProgressStatus, string>
+}) {
+  const now = new Date()
+  const isOverdue = a.dueAt ? new Date(a.dueAt) < now : false
+  const showOverdueBadge = isOverdue && !isAnswered(a.progressStatus)
+
   return (
     <Card className="flex h-full flex-col overflow-hidden transition-all hover:shadow-md">
       <CardHeader className="gap-2 pb-3">
@@ -75,28 +107,38 @@ function AssignmentCard({ assignment: a }: { assignment: StudentHomeworkAssignme
               {a.title}
             </Link>
           </CardTitle>
-          <Badge variant={getStatusVariant(a.progressStatus)} className="capitalize">
-            {getStatusLabel(a.progressStatus)}
-          </Badge>
+          <StatusBadge
+            status={a.progressStatus}
+            variantMap={STUDENT_HOMEWORK_PROGRESS_VARIANT}
+            labelMap={statusLabelMap}
+          />
         </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 className={cn(
+          "text-xs",
+          showOverdueBadge ? "text-destructive font-medium" : "text-muted-foreground"
+        )}>
+          <span>{t("homework.list.columns.dueAt")} {a.dueAt ? formatDate(a.dueAt) : "-"}</span>
+          <span className="px-2" aria-hidden="true">•</span>
+          <span>{t("homework.take.attempts")} {a.attemptsUsed}/{a.maxAttempts}</span>
+          {showOverdueBadge && (
+            <>
+              <span className="px-2" aria-hidden="true">•</span>
+              <span className="inline-flex items-center gap-1">
+                <TriangleAlert className="h-3 w-3" />
+                {t("homework.take.overdue")}
+              </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="text-muted-foreground">{t("homework.grade.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)}
+            {getActionLabel(a.progressStatus, t)}
           </Link>
         </Button>
       </CardContent>
@@ -104,19 +146,53 @@ function AssignmentCard({ assignment: a }: { assignment: StudentHomeworkAssignme
   )
 }
 
-export default async function StudentAssignmentsPage() {
+export default async function StudentAssignmentsPage({
+  searchParams,
+}: {
+  searchParams: Promise<SearchParams>
+}) {
+  const t = await getTranslations("examHomework")
   const student = await getCurrentStudentUser()
 
+  const statusLabelMap: Record<StudentHomeworkProgressStatus, string> = {
+    not_started: t("homework.status.not_started"),
+    in_progress: t("homework.status.in_progress"),
+    submitted: t("homework.status.submitted"),
+    graded: t("homework.status.graded"),
+  }
+
   if (!student) {
     return (
-      <EmptyState title="No user found" description="Create a student user to see assignments." icon={UserX} />
+      <div className="space-y-8">
+        <div>
+          <h2 className="text-2xl font-bold tracking-tight">{t("homework.list.title")}</h2>
+          <p className="text-muted-foreground">{t("homework.list.description")}</p>
+        </div>
+        <EmptyState title={t("homework.error.notFound")} description={t("homework.error.assignmentNotFound")} icon={UserX} />
+      </div>
     )
   }
 
-  const assignments = await getStudentHomeworkAssignments(student.id)
+  const [sp, assignments] = await Promise.all([
+    searchParams,
+    getStudentHomeworkAssignments(student.id),
+  ])
+
+  const q = (getParam(sp, "q") || "").toLowerCase().trim()
+  const statusFilter = getParam(sp, "status") || "all"
+
+  // 应用筛选
+  const filtered = assignments.filter((a) => {
+    if (q && !a.title.toLowerCase().includes(q)) return false
+    if (!matchesStatusFilter(a.progressStatus, statusFilter)) return false
+    return true
+  })
+
   const hasAssignments = assignments.length > 0
-  const assignmentsBySubject = assignments.reduce((acc, assignment) => {
-    const subject = assignment.subjectName?.trim() || "Other"
+  const hasFiltered = filtered.length > 0
+
+  const assignmentsBySubject = filtered.reduce((acc, assignment) => {
+    const subject = assignment.subjectName?.trim() || t("common.other")
     const existing = acc.get(subject)
     if (existing) {
       existing.push(assignment)
@@ -130,9 +206,22 @@ export default async function StudentAssignmentsPage() {
   )
 
   return (
-    <>
+    <div className="space-y-8">
+      <div>
+        <h2 className="text-2xl font-bold tracking-tight">{t("homework.list.title")}</h2>
+        <p className="text-muted-foreground">{t("homework.list.description")}</p>
+      </div>
+
+      {hasAssignments && <AssignmentFilters />}
+
       {!hasAssignments ? (
-        <EmptyState title="No assignments" description="You have no assigned homework right now." icon={Inbox} />
+        <EmptyState title={t("homework.list.empty")} description={t("homework.list.emptyDescription")} icon={Inbox} />
+      ) : !hasFiltered ? (
+        <EmptyState
+          title={t("homework.list.emptyFiltered")}
+          description={t("homework.list.emptyFilteredDescription")}
+          icon={Inbox}
+        />
       ) : (
         <div className="space-y-6">
           {subjectEntries.map(([subject, items]) => {
@@ -149,15 +238,24 @@ export default async function StudentAssignmentsPage() {
 
             return (
               <div key={subject} className="space-y-3">
-                <div className="text-sm font-semibold text-muted-foreground">{subject}</div>
+                <div className="flex items-center gap-2 text-sm font-semibold">
+                  <span
+                    className={cn("h-2.5 w-2.5 rounded-full", getSubjectColor(subject))}
+                    aria-hidden="true"
+                  />
+                  <span className="text-muted-foreground">{subject}</span>
+                  <span className="text-xs font-normal text-muted-foreground/70">
+                    ({items.length})
+                  </span>
+                </div>
                 {unanswered.length > 0 && (
                   <div className="space-y-3">
                     <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">
-                      Pending
+                      {t("homework.status.not_started")}
                     </div>
                     <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
                       {unanswered.map((a) => (
-                        <AssignmentCard key={a.id} assignment={a} />
+                        <AssignmentCard key={a.id} assignment={a} t={t} statusLabelMap={statusLabelMap} />
                       ))}
                     </div>
                   </div>
@@ -165,11 +263,11 @@ export default async function StudentAssignmentsPage() {
                 {answered.length > 0 && (
                   <div className="space-y-3">
                     <div className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">
-                      Completed
+                      {t("common.completed")}
                     </div>
                     <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
                       {answered.map((a) => (
-                        <AssignmentCard key={a.id} assignment={a} />
+                        <AssignmentCard key={a.id} assignment={a} t={t} statusLabelMap={statusLabelMap} />
                       ))}
                     </div>
                   </div>
@@ -179,6 +277,6 @@ export default async function StudentAssignmentsPage() {
           })}
         </div>
       )}
-    </>
+    </div>
   )
 }