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/modules/exams/components/exam-actions.tsx

@@ -2,6 +2,7 @@
 
 import { useState } from "react"
 import { useRouter } from "next/navigation"
+import { useTranslations } from "next-intl"
 import { MoreHorizontal, Eye, Pencil, Trash, Archive, UploadCloud, Undo2, Copy } from "lucide-react"
 import { toast } from "sonner"
 
@@ -43,6 +44,7 @@ interface ExamActionsProps {
 
 export function ExamActions({ exam }: ExamActionsProps) {
   const router = useRouter()
+  const t = useTranslations("examHomework")
   const [showViewDialog, setShowViewDialog] = useState(false)
   const [showDeleteDialog, setShowDeleteDialog] = useState(false)
   const [isWorking, setIsWorking] = useState(false)
@@ -76,11 +78,11 @@ export function ExamActions({ exam }: ExamActionsProps) {
         const nodes = Array.isArray(structure) ? hydrate(structure) : []
         setPreviewNodes(nodes)
       } else {
-        toast.error("Failed to load exam preview")
+        toast.error(t("exam.actions.previewFailed"))
         setShowViewDialog(false)
       }
     } catch {
-      toast.error("Failed to load exam preview")
+      toast.error(t("exam.actions.previewFailed"))
       setShowViewDialog(false)
     } finally {
       setLoadingPreview(false)
@@ -89,7 +91,7 @@ export function ExamActions({ exam }: ExamActionsProps) {
 
   const copyId = () => {
     navigator.clipboard.writeText(exam.id)
-    toast.success("Exam ID copied to clipboard")
+    toast.success(t("exam.actions.idCopied"))
   }
 
   const setStatus = async (status: Exam["status"]) => {
@@ -100,13 +102,13 @@ export function ExamActions({ exam }: ExamActionsProps) {
       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")
+        toast.success(status === "published" ? t("exam.actions.publishSuccess") : status === "archived" ? t("exam.actions.archiveSuccess") : t("exam.actions.draftSuccess"))
         router.refresh()
       } else {
-        toast.error(result.message || "Failed to update exam")
+        toast.error(result.message || t("exam.actions.updateFailed"))
       }
     } catch {
-      toast.error("Failed to update exam")
+      toast.error(t("exam.actions.updateFailed"))
     } finally {
       setIsWorking(false)
     }
@@ -119,14 +121,14 @@ export function ExamActions({ exam }: ExamActionsProps) {
       formData.set("examId", exam.id)
       const result = await duplicateExamAction(null, formData)
       if (result.success && result.data) {
-        toast.success("Exam duplicated")
+        toast.success(t("exam.actions.duplicateSuccess"))
         router.push(`/teacher/exams/${result.data}/build`)
         router.refresh()
       } else {
-        toast.error(result.message || "Failed to duplicate exam")
+        toast.error(result.message || t("exam.actions.duplicateFailed"))
       }
     } catch {
-      toast.error("Failed to duplicate exam")
+      toast.error(t("exam.actions.duplicateFailed"))
     } finally {
       setIsWorking(false)
     }
@@ -139,14 +141,14 @@ export function ExamActions({ exam }: ExamActionsProps) {
       formData.set("examId", exam.id)
       const result = await deleteExamAction(null, formData)
       if (result.success) {
-        toast.success("Exam deleted successfully")
+        toast.success(t("exam.actions.deleteSuccess"))
         setShowDeleteDialog(false)
         router.refresh()
       } else {
-        toast.error(result.message || "Failed to delete exam")
+        toast.error(result.message || t("exam.actions.deleteFailed"))
       }
     } catch {
-      toast.error("Failed to delete exam")
+      toast.error(t("exam.actions.deleteFailed"))
     } finally {
       setIsWorking(false)
     }
@@ -163,75 +165,74 @@ export function ExamActions({ exam }: ExamActionsProps) {
             e.stopPropagation()
             handleView()
           }}
-          title="Preview Exam"
-          aria-label="Preview exam"
+          title={t("exam.actions.preview")}
+          aria-label={t("exam.actions.preview")}
         >
           <Eye className="h-4 w-4" />
         </Button>
         <DropdownMenu>
           <DropdownMenuTrigger asChild>
-            <Button variant="ghost" className="h-8 w-8 p-0" aria-label="Open menu">
-              <span className="sr-only">Open menu</span>
+            <Button variant="ghost" className="h-8 w-8 p-0" aria-label={t("exam.actions.openMenu")}>
+              <span className="sr-only">{t("exam.actions.openMenu")}</span>
               <MoreHorizontal className="h-4 w-4" />
             </Button>
           </DropdownMenuTrigger>
           <DropdownMenuContent align="end">
-            <DropdownMenuLabel>Actions</DropdownMenuLabel>
+            <DropdownMenuLabel>{t("exam.actions.copyId")}</DropdownMenuLabel>
             <DropdownMenuItem onClick={copyId}>
-              <Copy className="mr-2 h-4 w-4" /> Copy ID
+              <Copy className="mr-2 h-4 w-4" /> {t("exam.actions.copyId")}
             </DropdownMenuItem>
             <DropdownMenuSeparator />
             <DropdownMenuItem onClick={() => router.push(`/teacher/exams/${exam.id}/build`)}>
-              <Pencil className="mr-2 h-4 w-4" /> Edit
+              <Pencil className="mr-2 h-4 w-4" /> {t("exam.actions.edit")}
             </DropdownMenuItem>
           <DropdownMenuItem onClick={() => router.push(`/teacher/exams/${exam.id}/build`)}>
-            <MoreHorizontal className="mr-2 h-4 w-4" /> Build
+            <MoreHorizontal className="mr-2 h-4 w-4" /> {t("exam.actions.build")}
           </DropdownMenuItem>
           <DropdownMenuSeparator />
           <DropdownMenuItem onClick={duplicateExam} disabled={isWorking}>
-            <Copy className="mr-2 h-4 w-4" /> Duplicate
+            <Copy className="mr-2 h-4 w-4" /> {t("exam.actions.duplicate")}
           </DropdownMenuItem>
           <DropdownMenuSeparator />
           <DropdownMenuItem
             onClick={() => setStatus("published")}
             disabled={isWorking || exam.status === "published"}
           >
-            <UploadCloud className="mr-2 h-4 w-4" /> Publish
+            <UploadCloud className="mr-2 h-4 w-4" /> {t("exam.actions.publish")}
           </DropdownMenuItem>
           <DropdownMenuItem
             onClick={() => setStatus("draft")}
             disabled={isWorking || exam.status === "draft"}
           >
-            <Undo2 className="mr-2 h-4 w-4" /> Move to Draft
+            <Undo2 className="mr-2 h-4 w-4" /> {t("exam.actions.moveToDraft")}
           </DropdownMenuItem>
           <DropdownMenuItem
             onClick={() => setStatus("archived")}
             disabled={isWorking || exam.status === "archived"}
           >
-            <Archive className="mr-2 h-4 w-4" /> Archive
+            <Archive className="mr-2 h-4 w-4" /> {t("exam.actions.archive")}
           </DropdownMenuItem>
           <DropdownMenuItem
             className="text-destructive focus:text-destructive"
             onClick={() => setShowDeleteDialog(true)}
             disabled={isWorking}
           >
-            <Trash className="mr-2 h-4 w-4" /> Delete
+            <Trash className="mr-2 h-4 w-4" /> {t("exam.actions.delete")}
           </DropdownMenuItem>
         </DropdownMenuContent>
       </DropdownMenu>
       </div>
-      
+
       <AlertDialog open={showDeleteDialog} onOpenChange={setShowDeleteDialog}>
         <AlertDialogContent>
           <AlertDialogHeader>
-            <AlertDialogTitle>Are you absolutely sure?</AlertDialogTitle>
+            <AlertDialogTitle>{t("exam.actions.deleteConfirmTitle")}</AlertDialogTitle>
             <AlertDialogDescription>
-              This action cannot be undone. This will permanently delete the exam
-              &quot;{exam.title}&quot; and remove all associated data.
+              {t("exam.actions.deleteConfirmDescription", { title: exam.title })}
             </AlertDialogDescription>
           </AlertDialogHeader>
           <AlertDialogFooter>
-            <AlertDialogCancel>Cancel</AlertDialogCancel>
+            <AlertDialogCancel>{t("exam.actions.cancel")}</AlertDialogCancel>
             <AlertDialogAction
               className="bg-destructive text-destructive-foreground hover:bg-destructive/90"
               onClick={(e) => {
@@ -240,7 +241,7 @@ export function ExamActions({ exam }: ExamActionsProps) {
               }}
               disabled={isWorking}
             >
-              Delete
+              {t("exam.actions.delete")}
             </AlertDialogAction>
           </AlertDialogFooter>
         </AlertDialogContent>
@@ -253,10 +254,10 @@ export function ExamActions({ exam }: ExamActionsProps) {
             </div>
             <ScrollArea className="flex-1">
                 {loadingPreview ? (
-                    <div className="py-20 text-center text-muted-foreground">Loading preview...</div>
+                    <div className="py-20 text-center text-muted-foreground">{t("exam.actions.loadingPreview")}</div>
                 ) : previewNodes && previewNodes.length > 0 ? (
                     <div className="max-w-3xl mx-auto py-8 px-6">
-                        <ExamPaperPreview 
+                        <ExamPaperPreview
                             title={exam.title}
                             subject={exam.subject}
                             grade={exam.grade}
@@ -267,7 +268,7 @@ export function ExamActions({ exam }: ExamActionsProps) {
                     </div>
                 ) : (
                     <div className="py-20 text-center text-muted-foreground">
-                        No questions in this exam.
+                        {t("exam.actions.noQuestions")}
                     </div>
                 )}
             </ScrollArea>

src/modules/exams/components/exam-columns.tsx

@@ -7,152 +7,154 @@ import { cn, formatDate } from "@/shared/lib/utils"
 import { Exam } from "../types"
 import { ExamActions } from "./exam-actions"
 
-export const examColumns: ColumnDef<Exam>[] = [
-  {
-    id: "select",
-    header: ({ table }) => (
-      <Checkbox
-        checked={table.getIsAllPageRowsSelected()}
-        onCheckedChange={(value) => table.toggleAllPageRowsSelected(!!value)}
-        aria-label="Select all"
-      />
-    ),
-    cell: ({ row }) => (
-      <Checkbox
-        checked={row.getIsSelected()}
-        onCheckedChange={(value) => row.toggleSelected(!!value)}
-        aria-label="Select row"
-      />
-    ),
-    enableSorting: false,
-    enableHiding: false,
-    size: 36,
-  },
-  {
-    accessorKey: "title",
-    header: "Exam Info",
-    cell: ({ row }) => (
-      <div className="flex flex-col gap-1">
-        <div className="flex items-center gap-2">
-          <span className="font-semibold text-base">{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, idx) => (
-                <Badge key={`${t}-${idx}`} variant="secondary" className="h-5 px-1.5 text-[10px]">
-                  {t}
-                </Badge>
-              ))}
-              {row.original.tags.length > 2 && (
-                <Badge variant="secondary" className="h-5 px-1.5 text-[10px]">+{row.original.tags.length - 2}</Badge>
-              )}
-            </div>
-          )}
-        </div>
-        <div className="flex items-center gap-2 text-xs text-muted-foreground">
-          <span className="font-medium text-foreground/80">{row.original.subject}</span>
-          <span>•</span>
-          <span>{row.original.grade}</span>
-        </div>
-      </div>
-    ),
-  },
-  {
-    accessorKey: "status",
-    header: "Status",
-    cell: ({ row }) => {
-      const status = row.original.status
-      // Use 'default' as base for published/success to ensure type safety, 
-      // but override with className below
-      const variant: BadgeProps["variant"] =
-        status === "published"
-          ? "default" 
-          : status === "archived"
-          ? "secondary"
-          : "outline"
-      
-      return (
-        <Badge 
-          variant={variant} 
-          className={cn(
-            "capitalize",
-            status === "published" && "bg-green-600 hover:bg-green-700 border-transparent",
-            status === "draft" && "bg-amber-100 text-amber-800 hover:bg-amber-200 border-amber-200 dark:bg-amber-900/30 dark:text-amber-400 dark:border-amber-800"
-          )}
-        >
-          {status}
-        </Badge>
-      )
+type TranslationFn = (key: string, params?: Record<string, unknown>) => string
+
+export function createExamColumns(t: TranslationFn): ColumnDef<Exam>[] {
+  return [
+    {
+      id: "select",
+      header: ({ table }) => (
+        <Checkbox
+          checked={table.getIsAllPageRowsSelected()}
+          onCheckedChange={(value) => table.toggleAllPageRowsSelected(!!value)}
+          aria-label={t("exam.actions.selectAll")}
+        />
+      ),
+      cell: ({ row }) => (
+        <Checkbox
+          checked={row.getIsSelected()}
+          onCheckedChange={(value) => row.toggleSelected(!!value)}
+          aria-label={t("exam.actions.selectRow")}
+        />
+      ),
+      enableSorting: false,
+      enableHiding: false,
+      size: 36,
     },
-  },
-  {
-    id: "stats",
-    header: "Stats",
-    cell: ({ row }) => (
-      <div className="flex flex-col gap-1 text-xs text-muted-foreground">
-        <div className="flex items-center gap-2">
-          <span className="font-medium text-foreground">{row.original.questionCount} Qs</span>
-          <span>•</span>
-          <span>{row.original.totalScore} Pts</span>
-        </div>
-        <div className="flex items-center gap-1">
-          <span>{row.original.durationMin} min</span>
-        </div>
-      </div>
-    ),
-  },
-  {
-    accessorKey: "difficulty",
-    header: "Difficulty",
-    cell: ({ row }) => {
-      const diff = row.original.difficulty
-      return (
+    {
+      accessorKey: "title",
+      header: t("exam.columns.examInfo"),
+      cell: ({ row }) => (
         <div className="flex flex-col gap-1">
-          <div className="flex gap-0.5">
-            {[1, 2, 3, 4, 5].map((level) => (
-              <div
-                key={level}
-                className={cn(
-                  "h-1.5 w-3 rounded-full",
-                  level <= diff 
-                    ? diff <= 2 ? "bg-green-500" : diff === 3 ? "bg-yellow-500" : "bg-red-500"
-                    : "bg-muted"
+          <div className="flex items-center gap-2">
+            <span className="font-semibold text-base">{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((tag, idx) => (
+                  <Badge key={`${tag}-${idx}`} variant="secondary" className="h-5 px-1.5 text-[10px]">
+                    {tag}
+                  </Badge>
+                ))}
+                {row.original.tags.length > 2 && (
+                  <Badge variant="secondary" className="h-5 px-1.5 text-[10px]">+{row.original.tags.length - 2}</Badge>
                 )}
-              />
-            ))}
+              </div>
+            )}
+          </div>
+          <div className="flex items-center gap-2 text-xs text-muted-foreground">
+            <span className="font-medium text-foreground/80">{row.original.subject}</span>
+            <span>•</span>
+            <span>{row.original.grade}</span>
           </div>
-          <span className="text-[10px] text-muted-foreground font-medium">
-            {diff === 1 ? "Easy" : diff === 2 ? "Easy-Med" : diff === 3 ? "Medium" : diff === 4 ? "Med-Hard" : "Hard"}
-          </span>
         </div>
-      )
+      ),
     },
-  },
-  {
-    id: "dates",
-    header: "Date",
-    cell: ({ row }) => {
-      const scheduled = row.original.scheduledAt
-      const created = row.original.createdAt
-      
-      return (
-        <div className="flex flex-col gap-0.5 text-xs">
-          {scheduled ? (
-             <>
-               <span className="font-medium text-blue-600 dark:text-blue-400">Scheduled</span>
-               <span className="text-muted-foreground">{formatDate(scheduled)}</span>
-             </>
-          ) : (
-             <>
-               <span className="text-muted-foreground">Created</span>
-               <span>{formatDate(created)}</span>
-             </>
-          )}
+    {
+      accessorKey: "status",
+      header: t("exam.columns.status"),
+      cell: ({ row }) => {
+        const status = row.original.status
+        const variant: BadgeProps["variant"] =
+          status === "published"
+            ? "default"
+            : status === "archived"
+            ? "secondary"
+            : "outline"
+
+        return (
+          <Badge
+            variant={variant}
+            className={cn(
+              "capitalize",
+              status === "published" && "bg-green-600 hover:bg-green-700 border-transparent",
+              status === "draft" && "bg-amber-100 text-amber-800 hover:bg-amber-200 border-amber-200 dark:bg-amber-900/30 dark:text-amber-400 dark:border-amber-800"
+            )}
+          >
+            {t(`exam.status.${status}`)}
+          </Badge>
+        )
+      },
+    },
+    {
+      id: "stats",
+      header: t("exam.columns.stats"),
+      cell: ({ row }) => (
+        <div className="flex flex-col gap-1 text-xs text-muted-foreground">
+          <div className="flex items-center gap-2">
+            <span className="font-medium text-foreground">{row.original.questionCount} {t("exam.columns.questions")}</span>
+            <span>•</span>
+            <span>{row.original.totalScore} {t("exam.columns.points")}</span>
+          </div>
+          <div className="flex items-center gap-1">
+            <span>{row.original.durationMin} min</span>
+          </div>
         </div>
-      )
+      ),
     },
-  },
-  {
-    id: "actions",
-    cell: ({ row }) => <ExamActions exam={row.original} />,
-  },
-]
+    {
+      accessorKey: "difficulty",
+      header: t("exam.columns.difficulty"),
+      cell: ({ row }) => {
+        const diff = row.original.difficulty
+        return (
+          <div className="flex flex-col gap-1">
+            <div className="flex gap-0.5">
+              {[1, 2, 3, 4, 5].map((level) => (
+                <div
+                  key={level}
+                  className={cn(
+                    "h-1.5 w-3 rounded-full",
+                    level <= diff
+                      ? diff <= 2 ? "bg-green-500" : diff === 3 ? "bg-yellow-500" : "bg-red-500"
+                      : "bg-muted"
+                  )}
+                />
+              ))}
+            </div>
+            <span className="text-[10px] text-muted-foreground font-medium">
+              {t(`exam.difficulty.${diff}`)}
+            </span>
+          </div>
+        )
+      },
+    },
+    {
+      id: "dates",
+      header: t("exam.columns.date"),
+      cell: ({ row }) => {
+        const scheduled = row.original.scheduledAt
+        const created = row.original.createdAt
+
+        return (
+          <div className="flex flex-col gap-0.5 text-xs">
+            {scheduled ? (
+               <>
+                 <span className="font-medium text-blue-600 dark:text-blue-400">{t("exam.columns.scheduled")}</span>
+                 <span className="text-muted-foreground">{formatDate(scheduled)}</span>
+               </>
+            ) : (
+               <>
+                 <span className="text-muted-foreground">{t("exam.columns.created")}</span>
+                 <span>{formatDate(created)}</span>
+               </>
+            )}
+          </div>
+        )
+      },
+    },
+    {
+      id: "actions",
+      cell: ({ row }) => <ExamActions exam={row.original} />,
+    },
+  ]
+}

src/modules/exams/components/exam-data-table.tsx

@@ -2,7 +2,6 @@
 
 import * as React from "react"
 import {
-  ColumnDef,
   flexRender,
   getCoreRowModel,
   useReactTable,
@@ -12,6 +11,7 @@ import {
   getFilteredRowModel,
   RowSelectionState,
 } from "@tanstack/react-table"
+import { useTranslations } from "next-intl"
 
 import {
   Table,
@@ -23,16 +23,23 @@ import {
 } from "@/shared/components/ui/table"
 import { Button } from "@/shared/components/ui/button"
 import { ChevronLeft, ChevronRight } from "lucide-react"
+import { Exam } from "../types"
+import { createExamColumns } from "./exam-columns"
 
-interface DataTableProps<TData, TValue> {
-  columns: ColumnDef<TData, TValue>[]
-  data: TData[]
+interface DataTableProps {
+  data: Exam[]
 }
 
-export function ExamDataTable<TData, TValue>({ columns, data }: DataTableProps<TData, TValue>) {
+export function ExamDataTable({ data }: DataTableProps) {
+  const t = useTranslations("examHomework")
   const [sorting, setSorting] = React.useState<SortingState>([])
   const [rowSelection, setRowSelection] = React.useState<RowSelectionState>({})
 
+  const columns = React.useMemo(
+    () => createExamColumns((key, params) => t(key, params as Record<string, string | number | Date> | undefined)),
+    [t]
+  )
+
   const table = useReactTable({
     data,
     columns,
@@ -81,7 +88,7 @@ export function ExamDataTable<TData, TValue>({ columns, data }: DataTableProps<T
             ) : (
               <TableRow>
                 <TableCell colSpan={columns.length} className="h-24 text-center">
-                  No results.
+                  {t("common.noResults")}
                 </TableCell>
               </TableRow>
             )}
@@ -90,14 +97,13 @@ export function ExamDataTable<TData, TValue>({ columns, data }: DataTableProps<T
       </div>
       <div className="flex items-center justify-between px-2 py-4">
         <div className="flex-1 text-sm text-muted-foreground">
-          {table.getFilteredSelectedRowModel().rows.length} of {table.getFilteredRowModel().rows.length} row(s)
-          selected.
+          {table.getFilteredSelectedRowModel().rows.length} {t("common.of")} {table.getFilteredRowModel().rows.length} {t("common.rows")} {t("common.selected")}.
         </div>
         <div className="flex items-center space-x-6 lg:space-x-8">
           <div className="flex items-center space-x-2">
-            <p className="text-sm font-medium">Page</p>
+            <p className="text-sm font-medium">{t("common.page")}</p>
             <span className="text-sm font-medium">
-              {table.getState().pagination.pageIndex + 1} of {table.getPageCount()}
+              {table.getState().pagination.pageIndex + 1} {t("common.of")} {table.getPageCount()}
             </span>
           </div>
           <div className="flex items-center space-x-2">
@@ -107,7 +113,7 @@ export function ExamDataTable<TData, TValue>({ columns, data }: DataTableProps<T
               onClick={() => table.previousPage()}
               disabled={!table.getCanPreviousPage()}
             >
-              <span className="sr-only">Go to previous page</span>
+              <span className="sr-only">{t("common.page")}</span>
               <ChevronLeft className="h-4 w-4" />
             </Button>
             <Button
@@ -116,7 +122,7 @@ export function ExamDataTable<TData, TValue>({ columns, data }: DataTableProps<T
               onClick={() => table.nextPage()}
               disabled={!table.getCanNextPage()}
             >
-              <span className="sr-only">Go to next page</span>
+              <span className="sr-only">{t("common.page")}</span>
               <ChevronRight className="h-4 w-4" />
             </Button>
           </div>
@@ -125,4 +131,3 @@ export function ExamDataTable<TData, TValue>({ columns, data }: DataTableProps<T
     </div>
   )
 }
-