主要改动：

自动排课接口立即返回 202 + jobId
后台服务独立执行，不受浏览器关闭或前端超时影响
进度、成功、失败状态持久化到数据库
服务重启后自动恢复排队中或中断的任务
同一草稿禁止重复提交后台任务
运行期间禁止编辑、发布或删除该课表
排课结果和任务成功状态在同一事务中提交
前端每秒轮询进度，显示已处理教学班和已规划安排数

src/Jiaowu.Api/Infrastructure/Scheduling/AutomaticScheduleGenerator.cs

@@ -6,8 +6,15 @@ namespace Jiaowu.Api.Infrastructure.Scheduling;
 
 public sealed class AutomaticScheduleGenerator(AppDbContext db)
 {
+    public Task<AutomaticScheduleResult> GenerateAsync(
+        SchedulePlan plan,
+        CancellationToken cancellationToken) =>
+        GenerateAsync(plan, null, true, cancellationToken);
+
     public async Task<AutomaticScheduleResult> GenerateAsync(
         SchedulePlan plan,
+        Func<AutomaticScheduleProgress, CancellationToken, Task>? reportProgress,
+        bool saveChanges,
         CancellationToken cancellationToken)
     {
         var timeSlots = await db.ScheduleTimeSlots.AsNoTracking()
@@ -50,9 +57,18 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
 
         var created = 0;
         var completedTasks = 0;
+        var processedTasks = 0;
         var messages = new List<string>();
+        if (reportProgress is not null)
+        {
+            await reportProgress(
+                new(tasks.Count, 0, 0, 0),
+                cancellationToken);
+        }
+
         foreach (var task in tasks)
         {
+            cancellationToken.ThrowIfCancellationRequested();
             constraints.TryGetValue(task.Id, out var constraint);
             var scheduledHours = entries
                 .Where(x => x.TeachingTaskId == task.Id)
@@ -61,6 +77,13 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
             if (remainingHours == 0)
             {
                 completedTasks++;
+                processedTasks++;
+                if (reportProgress is not null)
+                {
+                    await reportProgress(
+                        new(tasks.Count, processedTasks, created, completedTasks),
+                        cancellationToken);
+                }
                 continue;
             }
 
@@ -74,7 +97,8 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
                     desiredBlock,
                     activePeriods,
                     classrooms,
-                    entries);
+                    entries,
+                    cancellationToken);
                 if (candidate is null && desiredBlock > 1)
                 {
                     candidate = FindBestCandidate(
@@ -84,7 +108,8 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
                         1,
                         activePeriods,
                         classrooms,
-                        entries);
+                        entries,
+                        cancellationToken);
                 }
                 if (candidate is null) break;
 
@@ -103,11 +128,24 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
                 messages.Add(
                     $"{task.TaskNumber} · {task.Name} 仍有 {remainingHours} 学时无法安排，请检查教师/班级冲突或场地与时间约束。");
             }
+
+            processedTasks++;
+            if (reportProgress is not null)
+            {
+                await reportProgress(
+                    new(tasks.Count, processedTasks, created, completedTasks),
+                    cancellationToken);
+            }
         }
 
-        if (created > 0)
+        if (created > 0 && saveChanges)
             await db.SaveChangesAsync(cancellationToken);
-        return new(created, completedTasks, messages);
+        return new(
+            created,
+            completedTasks,
+            messages,
+            tasks.Count,
+            processedTasks);
     }
 
     private static ScheduleEntry? FindBestCandidate(
@@ -117,7 +155,8 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
         int periodCount,
         HashSet<int> activePeriods,
         IReadOnlyList<Classroom> classrooms,
-        IReadOnlyList<ScheduleEntry> entries)
+        IReadOnlyList<ScheduleEntry> entries,
+        CancellationToken cancellationToken)
     {
         var allowedDays = ParseAllowedDays(constraint?.AllowedDayOfWeeks);
         var firstPeriod = constraint?.EarliestPeriod ?? activePeriods.Min();
@@ -129,8 +168,10 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
         var candidates = new List<(ScheduleEntry Entry, int Score)>();
         foreach (var day in allowedDays)
         {
+            cancellationToken.ThrowIfCancellationRequested();
             for (var start = firstPeriod; start + periodCount - 1 <= lastPeriod; start++)
             {
+                cancellationToken.ThrowIfCancellationRequested();
                 if (Enumerable.Range(start, periodCount).Any(period => !activePeriods.Contains(period)))
                     continue;
 
@@ -145,7 +186,6 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
                         TeachingTaskId = task.Id,
                         TeachingTask = task,
                         ClassroomId = room?.Id,
-                        Classroom = room,
                         DayOfWeek = day,
                         StartPeriod = start,
                         PeriodCount = periodCount,
@@ -216,4 +256,12 @@ public sealed class AutomaticScheduleGenerator(AppDbContext db)
 public sealed record AutomaticScheduleResult(
     int CreatedEntries,
     int CompletedTasks,
-    IReadOnlyList<string> Messages);
+    IReadOnlyList<string> Messages,
+    int TotalTasks = 0,
+    int ProcessedTasks = 0);
+
+public sealed record AutomaticScheduleProgress(
+    int TotalTasks,
+    int ProcessedTasks,
+    int CreatedEntries,
+    int CompletedTasks);