refactor(modules): update existing module implementations across attendance, audit, auth, classes, course-plans, exams, files, homework, layout, proctoring, questions, scheduling, textbooks, users

- Update attendance components and data-access for record management

- Update audit log views, filters, and data-access

- Update auth login and register forms

- Update classes actions, components, and data-access (admin, schedule, stats)

- Update course-plans actions, form, list, progress, and schema

- Update exams actions, AI pipeline, preview components, and hooks

- Update files components (icon, list, preview, upload) and data-access

- Update homework assignment form, review view, auto-save hook, and stats-service

- Update layout sidebar, header, and navigation config

- Update proctoring actions, anti-cheat monitor, and data-access

- Update questions actions, components (dialog, actions, columns, filters), and data-access

- Update scheduling actions, auto-scheduler, components, and schema

- Update textbooks constants and text-selection hook

- Update users class-registration, import-dialog, data-access, and user-service

src/modules/homework/hooks/use-debounced-auto-save.ts

@@ -70,27 +70,40 @@ export function useDebouncedAutoSave({
     savingRef.current = true
     setStatus("saving")
 
-    let allOk = true
-    for (const [questionId, answer] of pending) {
-      const fd = new FormData()
-      fd.set("submissionId", submissionId)
-      fd.set("questionId", questionId)
-      fd.set("answerJson", JSON.stringify({ answer }))
-      const res = await saveHomeworkAnswerAction(null, fd)
-      if (!res.success) {
-        allOk = false
-      }
-    }
+    // 并行保存所有待保存答案，单个失败不影响其他答案
+    const results = await Promise.allSettled(
+      pending.map(([questionId, answer]) => {
+        const fd = new FormData()
+        fd.set("submissionId", submissionId)
+        fd.set("questionId", questionId)
+        fd.set("answerJson", JSON.stringify({ answer }))
+        return saveHomeworkAnswerAction(null, fd)
+      })
+    )
 
     savingRef.current = false
 
-    if (allOk) {
+    // 收集失败的 questionId 以便重试
+    const failedQuestionIds: string[] = []
+    results.forEach((res, idx) => {
+      if (res.status !== "fulfilled" || !res.value.success) {
+        failedQuestionIds.push(pending[idx][0])
+      }
+    })
+
+    if (failedQuestionIds.length === 0) {
       pendingRef.current.clear()
       setStatus("saved")
       setLastSavedAt(Date.now())
     } else {
       setStatus("error")
-      // Keep pending items for retry on next change or manual flush
+      // 仅保留失败的项用于重试，移除已成功的项
+      const newPending = new Map<string, unknown>()
+      for (const qid of failedQuestionIds) {
+        const ans = pendingRef.current.get(qid)
+        if (ans !== undefined) newPending.set(qid, ans)
+      }
+      pendingRef.current = newPending
     }
   }, [submissionId])
 
@@ -135,7 +148,12 @@ export function useDebouncedAutoSave({
       if (timerRef.current) {
         clearTimeout(timerRef.current)
       }
-      // Fire-and-forget final save
+      // 注意：此处无法使用 navigator.sendBeacon，因为保存逻辑调用的是
+      // Next.js Server Action（基于 fetch 的 RPC），而非简单的 POST 请求。
+      // sendBeacon 仅支持发送原始 body，无法携带 Server Action 所需的
+      // 特定 headers 和编码格式。因此采用 fire-and-forget 方式触发最后的
+      // 保存，并依赖 localStorage 离线缓存作为兜底（下次进入页面会恢复）。
+      // 真正的可靠 flush 由 handleSubmit 在提交前调用 autoSave.flush() 保证。
       void savePending()
     }
   }, [savePending])