1. 教室容量按 1/2 计算

- ExamArrangementService.cs: SelectRooms() 使用 Capacity / 2 选择房间、计算剩余座位和总容量
  - MakeupExamArrangementService.cs: 数据库查询用 x.Capacity >= enrolledCount * 2（等价于 Capacity/2 >=
  enrolledCount），消息显示有效座位数

  2. 教学楼限制多选

  - Domain: ExamSession 和 MakeupExamSession 新增 RequiredBuildingIds (JSON string)，保留旧 RequiredBuildingId 向后兼容
  - Service: RoomGroupKey 改为字符串键确保值相等；GroupKey() 合并新旧字段
  - Controller: 请求 DTO 增加 RequiredBuildingIds (Guid 数组)，响应包含该字段
  - DB: MySQL 迁移 + SQLite migrator 添加新列
  - Frontend: <el-select> 改为 multiple，新增 parseBuildingIds() 解析服务器返回的 JSON

  3. 导出签名单后台任务

  - 新增: ExamSignInExportJob 实体、ExamSignInExportJobProcessor、ExamSignInExportJobStatus 枚举
  - BackgroundJobKind: 新增 ExamSignInExport = 5
  - RabbitMQ: routing key exam.sign-in-export，队列 jiaowu.background-jobs.exam.sign-in-export
  - API: POST /sign-in-export 创建任务返回 202；GET /sign-in-exports/{jobId} 查询状态；GET
  /sign-in-exports/{jobId}/download 下载文件
  - Frontend: 导出改为异步任务 + 轮询 + 自动下载，显示进度条
  - 恢复: OutboxPublisher 启动时恢复未完成的任务，重试超限自动标记失败

web/src/views/ExamsView.vue

@@ -35,6 +35,10 @@ const arrangementProgress = computed(() =>
     : arrangementJob.value?.status === 'Running' ? 60
       : arrangementJob.value?.status === 'Succeeded' ? 100 : 0)
 const exportLoading = ref(false)
+const exportJob = ref<any | null>(null)
+let exportPollTimer: ReturnType<typeof setTimeout> | null = null
+const exportJobRunning = computed(() =>
+  ['Queued', 'Running'].includes(exportJob.value?.status))
 const removeLoading = ref(false)
 const deletePlanLoading = ref(false)
 const planDialog = ref(false)
@@ -136,6 +140,8 @@ async function load() {
 }
 async function selectPlan(id: string) {
   stopArrangementPolling()
+  stopExportPolling()
+  exportJob.value = null
   sessionPage.value = 1
   selectedSessionIds.value = []
   await loadSelectedPlan(id)
@@ -243,6 +249,7 @@ async function openSession(existing?: any) {
     startPeriod: existing?.startPeriod ?? (firstSlot?.periodNumber ?? 1),
     periodCount: existing?.periodCount ?? 2,
     requiredBuildingId: existing?.requiredBuildingId ?? undefined,
+    requiredBuildingIds: parseBuildingIds(existing?.requiredBuildingIds),
     requiredInvigilatorCount: existing?.requiredInvigilatorCount ?? 2,
     invigilatorIds: existing?.invigilatorIds ?? [],
     notes: existing?.notes ?? '',
@@ -265,6 +272,7 @@ async function saveSession() {
         startPeriod: payload.startPeriod,
         periodCount: payload.periodCount,
         requiredBuildingId: payload.requiredBuildingId,
+        requiredBuildingIds: payload.requiredBuildingIds,
         requiredInvigilatorCount: payload.requiredInvigilatorCount,
         notes: payload.notes,
       })
@@ -478,17 +486,61 @@ async function exportSignInSheets() {
   if (!selected.value) return
   exportLoading.value = true
   try {
-    await downloadApiFile(
-      `/exams/plans/${selected.value.id}/sign-in-sheets.xlsx`,
-      `考场签名单-${selected.value.name}.xlsx`,
-    )
-    ElMessage.success('考场签名单已导出')
+    const res = await http.post(`/exams/plans/${selected.value.id}/sign-in-export`)
+    exportJob.value = {
+      id: res.data.jobId,
+      planId: selected.value.id,
+      status: res.data.status,
+      currentStep: '等待后台生成',
+    }
+    scheduleExportPoll(true)
   } catch (error) {
     ElMessage.error(apiErrorMessage(error))
   } finally {
     exportLoading.value = false
   }
 }
+function scheduleExportPoll(notifyTerminal: boolean) {
+  stopExportPolling()
+  exportPollTimer = setTimeout(
+    () => pollExportJob(notifyTerminal),
+    2000,
+  )
+}
+async function pollExportJob(notifyTerminal: boolean) {
+  if (!exportJob.value?.id) return
+  const jobId = exportJob.value.id
+  const planId = selected.value?.id
+  try {
+    const { data: job } = await http.get(`/exams/sign-in-exports/${jobId}`)
+    if (selected.value?.id !== planId || exportJob.value?.id !== jobId) return
+    exportJob.value = job
+    if (['Queued', 'Running'].includes(job.status)) {
+      scheduleExportPoll(notifyTerminal)
+      return
+    }
+    stopExportPolling()
+    if (job.status === 'Succeeded') {
+      await downloadApiFile(
+        `/exams/sign-in-exports/${jobId}/download`,
+        job.fileName || `考场签名单.xlsx`,
+      )
+      if (notifyTerminal) ElMessage.success('考场签名单已导出')
+    } else if (notifyTerminal) {
+      ElMessage.error(job.errorMessage || '考场签名单导出失败')
+    }
+  } catch {
+    if (selected.value?.id === planId && exportJob.value?.id === jobId) {
+      scheduleExportPoll(notifyTerminal)
+    }
+  }
+}
+function stopExportPolling() {
+  if (exportPollTimer) {
+    clearTimeout(exportPollTimer)
+    exportPollTimer = null
+  }
+}
 async function showRoster(row: any) {
   try {
     roster.value = (await http.get(`/exams/sessions/${row.id}/roster`)).data
@@ -506,8 +558,12 @@ function classroomLabel(room: any) {
   return `${room.name} · ${room.capacity}座 · ${room.buildingName}`
 }
 function filteredRooms() {
-  if (!sessionForm.requiredBuildingId) return rooms.value
-  return rooms.value.filter((r: any) => r.buildingId === sessionForm.requiredBuildingId)
+  if (!sessionForm.requiredBuildingIds || sessionForm.requiredBuildingIds.length === 0) return rooms.value
+  return rooms.value.filter((r: any) => sessionForm.requiredBuildingIds.includes(r.buildingId))
+}
+function parseBuildingIds(raw: string | undefined | null): string[] {
+  if (!raw) return []
+  try { return JSON.parse(raw) } catch { return [] }
 }
 
 onMounted(async () => {
@@ -527,7 +583,10 @@ onMounted(async () => {
     await load()
   } catch (error) { ElMessage.error(apiErrorMessage(error)) }
 })
-onBeforeUnmount(stopArrangementPolling)
+onBeforeUnmount(() => {
+  stopArrangementPolling()
+  stopExportPolling()
+})
 </script>
 
 <template>
@@ -598,6 +657,25 @@ onBeforeUnmount(stopArrangementPolling)
             />
           </template>
         </el-alert>
+        <el-alert
+          v-if="exportJob"
+          :title="exportJob.status === 'Failed' ? '签名单导出失败' : exportJob.status === 'Succeeded' ? '签名单导出完成' : '正在生成考场签名单'"
+          :type="exportJob.status === 'Failed' ? 'error' : exportJob.status === 'Succeeded' ? 'success' : 'info'"
+          :closable="false"
+          show-icon
+          style="margin-bottom: 16px"
+        >
+          <template #default>
+            <p>{{ exportJob.errorMessage || exportJob.currentStep || '等待后台任务处理' }}</p>
+            <el-progress
+              v-if="exportJobRunning"
+              :percentage="exportJob.status === 'Running' ? 60 : 10"
+              :show-text="false"
+              :stroke-width="6"
+              :indeterminate="exportJob.status === 'Running'"
+            />
+          </template>
+        </el-alert>
         <div class="exam-filter-bar">
           <el-input
             v-model="sessionFilter.keyword"
@@ -799,7 +877,7 @@ onBeforeUnmount(stopArrangementPolling)
         </div>
         <div class="form-grid">
           <el-form-item label="教学楼限制">
-            <el-select v-model="sessionForm.requiredBuildingId" clearable placeholder="不限教学楼">
+            <el-select v-model="sessionForm.requiredBuildingIds" multiple clearable placeholder="不限教学楼">
               <el-option v-for="x in buildings" :key="x.id" :label="x.name" :value="x.id" />
             </el-select>
           </el-form-item>

web/src/views/MakeupExamsView.vue

@@ -171,6 +171,7 @@ function openSession(existing?: any) {
     startPeriod: existing?.startPeriod ?? (firstSlot?.periodNumber ?? 1),
     periodCount: existing?.periodCount ?? 2,
     requiredBuildingId: existing?.requiredBuildingId ?? undefined,
+    requiredBuildingIds: parseBuildingIds(existing?.requiredBuildingIds),
     requiredInvigilatorCount: existing?.requiredInvigilatorCount ?? 2,
     invigilatorIds: existing?.invigilatorIds ?? [],
     notes: existing?.notes ?? '',
@@ -193,6 +194,7 @@ async function saveSession() {
         startPeriod: payload.startPeriod,
         periodCount: payload.periodCount,
         requiredBuildingId: payload.requiredBuildingId,
+        requiredBuildingIds: payload.requiredBuildingIds,
         requiredInvigilatorCount: payload.requiredInvigilatorCount,
         notes: payload.notes,
       })
@@ -357,8 +359,12 @@ function classroomLabel(room: any) {
   return `${room.name} · ${room.capacity}座 · ${room.buildingName}`
 }
 function filteredRooms() {
-  if (!sessionForm.requiredBuildingId) return rooms.value
-  return rooms.value.filter((r: any) => r.buildingId === sessionForm.requiredBuildingId)
+  if (!sessionForm.requiredBuildingIds || sessionForm.requiredBuildingIds.length === 0) return rooms.value
+  return rooms.value.filter((r: any) => sessionForm.requiredBuildingIds.includes(r.buildingId))
+}
+function parseBuildingIds(raw: string | undefined | null): string[] {
+  if (!raw) return []
+  try { return JSON.parse(raw) } catch { return [] }
 }
 
 function openEnrollment(session: any) {
@@ -782,7 +788,7 @@ onBeforeUnmount(() => {
         </div>
         <div class="form-grid">
           <el-form-item label="教学楼限制">
-            <el-select v-model="sessionForm.requiredBuildingId" clearable placeholder="不限教学楼">
+            <el-select v-model="sessionForm.requiredBuildingIds" multiple clearable placeholder="不限教学楼">
               <el-option v-for="x in buildings" :key="x.id" :label="x.name" :value="x.id" />
             </el-select>
           </el-form-item>