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

tests/Jiaowu.Api.Tests/AutomaticScheduleGeneratorTests.cs

@@ -26,6 +26,7 @@ public sealed class AutomaticScheduleGeneratorTests
         await migrator.MigrateAsync();
 
         Assert.True(await db.ScheduleTimeSlots.CountAsync() == 0);
+        Assert.True(await db.AutomaticScheduleJobs.CountAsync() == 0);
         Assert.True(await db.Database
             .SqlQueryRaw<int>(
                 """
@@ -112,15 +113,167 @@ public sealed class AutomaticScheduleGeneratorTests
         });
         await db.SaveChangesAsync();
 
+        var progressUpdates = new List<AutomaticScheduleProgress>();
         var result = await new AutomaticScheduleGenerator(db)
-            .GenerateAsync(plan, CancellationToken.None);
+            .GenerateAsync(
+                plan,
+                (progress, _) =>
+                {
+                    progressUpdates.Add(progress);
+                    return Task.CompletedTask;
+                },
+                true,
+                CancellationToken.None);
         var entry = await db.ScheduleEntries.SingleAsync();
 
         Assert.Equal(1, result.CreatedEntries);
         Assert.Empty(result.Messages);
+        Assert.Collection(
+            progressUpdates,
+            progress =>
+            {
+                Assert.Equal(1, progress.TotalTasks);
+                Assert.Equal(0, progress.ProcessedTasks);
+            },
+            progress =>
+            {
+                Assert.Equal(1, progress.TotalTasks);
+                Assert.Equal(1, progress.ProcessedTasks);
+                Assert.Equal(1, progress.CreatedEntries);
+            });
         Assert.Equal(3, entry.DayOfWeek);
         Assert.Equal(1, entry.StartPeriod);
         Assert.Equal(2, entry.PeriodCount);
         Assert.Null(entry.ClassroomId);
     }
+
+    [Fact]
+    public async Task Generator_does_not_attach_duplicate_buildings_from_untracked_classrooms()
+    {
+        await using var connection = new SqliteConnection("Data Source=:memory:");
+        await connection.OpenAsync();
+        var options = new DbContextOptionsBuilder<AppDbContext>()
+            .UseSqlite(connection)
+            .Options;
+        await using var db = new AppDbContext(options);
+        await db.Database.EnsureCreatedAsync();
+
+        var term = new AcademicTerm
+        {
+            Code = "2026-B",
+            Name = "2026 秋季",
+            AcademicYear = "2026-2027",
+            Season = TermSeason.Autumn,
+            StartDate = new DateOnly(2026, 9, 1),
+            EndDate = new DateOnly(2027, 1, 15)
+        };
+        var campus = new Campus { Code = "MAIN", Name = "主校区" };
+        var building = new Building
+        {
+            Code = "A",
+            Name = "教学楼 A",
+            Campus = campus
+        };
+        var smallRoom = new Classroom
+        {
+            Code = "A101",
+            Name = "A101",
+            Building = building,
+            Capacity = 20
+        };
+        var largeRoom = new Classroom
+        {
+            Code = "A102",
+            Name = "A102",
+            Building = building,
+            Capacity = 30
+        };
+        var college = new College { Code = "CS", Name = "计算机学院" };
+        var course = new Course
+        {
+            Code = "CS-01",
+            Name = "程序设计",
+            College = college,
+            Credits = 2,
+            TotalHours = 32,
+            LectureHours = 32
+        };
+        var smallTask = new TeachingTask
+        {
+            TaskNumber = "TASK-SMALL",
+            Name = "小班教学任务",
+            AcademicTerm = term,
+            Course = course,
+            Capacity = 20,
+            StartWeek = 1,
+            EndWeek = 16,
+            WeeklyHours = 2,
+            Status = TeachingTaskStatus.Published
+        };
+        var largeTask = new TeachingTask
+        {
+            TaskNumber = "TASK-LARGE",
+            Name = "大班教学任务",
+            AcademicTerm = term,
+            Course = course,
+            Capacity = 30,
+            StartWeek = 1,
+            EndWeek = 16,
+            WeeklyHours = 2,
+            Status = TeachingTaskStatus.Published
+        };
+        var plan = new SchedulePlan
+        {
+            AcademicTerm = term,
+            Name = "同楼多教室排课",
+            Version = "V1"
+        };
+        db.AddRange(
+            term,
+            campus,
+            building,
+            smallRoom,
+            largeRoom,
+            college,
+            course,
+            smallTask,
+            largeTask,
+            plan);
+        db.ScheduleTimeSlots.AddRange(
+            new ScheduleTimeSlot
+            {
+                AcademicTerm = term,
+                PeriodNumber = 1,
+                Name = "第 1 节",
+                StartsAt = new TimeOnly(8, 0),
+                EndsAt = new TimeOnly(8, 45)
+            },
+            new ScheduleTimeSlot
+            {
+                AcademicTerm = term,
+                PeriodNumber = 2,
+                Name = "第 2 节",
+                StartsAt = new TimeOnly(8, 55),
+                EndsAt = new TimeOnly(9, 40)
+            });
+        await db.SaveChangesAsync();
+
+        db.ChangeTracker.Clear();
+        plan = await db.SchedulePlans.SingleAsync();
+
+        var result = await new AutomaticScheduleGenerator(db)
+            .GenerateAsync(plan, CancellationToken.None);
+        var entries = await db.ScheduleEntries
+            .OrderBy(x => x.TeachingTaskId)
+            .ToListAsync();
+
+        Assert.Equal(2, result.CreatedEntries);
+        Assert.Empty(result.Messages);
+        Assert.Equal(2, entries.Count);
+        Assert.True(
+            new HashSet<Guid> { smallRoom.Id, largeRoom.Id }
+                .SetEquals(entries.Select(x => x.ClassroomId!.Value)));
+        Assert.Equal(1, await db.Buildings.CountAsync());
+        Assert.Equal(2, await db.Classrooms.CountAsync());
+    }
 }