“教学班成绩分析”页面新增“定时刷新设置”，支持启停、刷新间隔、单次处理上限、查看上次/下次扫描时间。

配置保存在独立数据库表 CourseGradeStatisticsRefreshSettings，不是修改 appsettings.json。
后台每 10 秒读取配置，仅到期扫描；成绩录入、导入、审批时不再立即创建统计任务。
扫描发现过期数据后，仍通过持久任务、Outbox 和 RabbitMQ 执行；Redis统计缓存由处理任务统一刷新。

src/Jiaowu.Api/Controllers/ApprovalsController.cs

@@ -251,13 +251,6 @@ public sealed class ApprovalsController(AppDbContext db, ICurrentUserDataScope s
         // Auto-apply: update grade record
         gm.GradeRecord!.TotalScore = gm.RequestedScore;
         gm.GradeRecord.GradePoint = GradeCalculator.CalculateGradePoint(gm.RequestedScore);
-        var statisticsJob = new CourseGradeStatisticsRefreshJob
-        {
-            GradeSheetId = gm.GradeRecord.GradeSheetId
-        };
-        db.CourseGradeStatisticsRefreshJobs.Add(statisticsJob);
-        db.BackgroundJobOutboxMessages.Add(BackgroundJobOutboxMessage.Create(
-            BackgroundJobKind.CourseGradeStatisticsRefresh, statisticsJob.Id));
         await db.SaveChangesAsync(ct);
         await NotificationService.SendAsync(
             db,

src/Jiaowu.Api/Controllers/GradeAnalyticsController.cs

@@ -25,6 +25,69 @@ public sealed class GradeAnalyticsController(
         SystemRoles.CollegeAdmin + "," +
         SystemRoles.Leader + "," +
         SystemRoles.Teacher;
+    private const string ScheduleManagers =
+        SystemRoles.SuperAdmin + "," + SystemRoles.AcademicAdmin;
+
+    [HttpGet("refresh-schedule")]
+    [Authorize(Roles = ScheduleManagers)]
+    public async Task<ActionResult> GetRefreshSchedule(CancellationToken cancellationToken)
+    {
+        var setting = await db.CourseGradeStatisticsRefreshSettings.AsNoTracking()
+            .SingleOrDefaultAsync(
+                x => x.Key == CourseGradeStatisticsRefreshSetting.DefaultKey,
+                cancellationToken);
+        var defaults = new CourseGradeStatisticsRefreshSetting();
+        var enabled = setting?.IsEnabled ?? defaults.IsEnabled;
+        var intervalSeconds = setting?.IntervalSeconds ?? defaults.IntervalSeconds;
+        var batchSize = setting?.BatchSize ?? defaults.BatchSize;
+        var lastRunAt = setting?.LastRunAt;
+        return Ok(new
+        {
+            IsEnabled = enabled,
+            IntervalSeconds = intervalSeconds,
+            BatchSize = batchSize,
+            LastRunAt = lastRunAt,
+            NextRunAt = enabled && lastRunAt.HasValue
+                ? lastRunAt.Value.AddSeconds(intervalSeconds)
+                : null as DateTime?
+        });
+    }
+
+    [HttpPut("refresh-schedule")]
+    [Authorize(Roles = ScheduleManagers)]
+    public async Task<ActionResult> SaveRefreshSchedule(
+        SaveGradeStatisticsRefreshScheduleRequest request,
+        CancellationToken cancellationToken)
+    {
+        if (request.IntervalSeconds is < 10 or > 86400)
+            return BadRequest(new ProblemDetails
+            {
+                Title = "刷新间隔应在 10 秒到 24 小时之间。",
+                Status = StatusCodes.Status400BadRequest
+            });
+        if (request.BatchSize is < 1 or > 5000)
+            return BadRequest(new ProblemDetails
+            {
+                Title = "单次刷新批量应在 1 到 5000 之间。",
+                Status = StatusCodes.Status400BadRequest
+            });
+
+        var setting = await db.CourseGradeStatisticsRefreshSettings
+            .SingleOrDefaultAsync(
+                x => x.Key == CourseGradeStatisticsRefreshSetting.DefaultKey,
+                cancellationToken);
+        if (setting is null)
+        {
+            setting = new CourseGradeStatisticsRefreshSetting();
+            db.CourseGradeStatisticsRefreshSettings.Add(setting);
+        }
+
+        setting.IsEnabled = request.IsEnabled;
+        setting.IntervalSeconds = request.IntervalSeconds;
+        setting.BatchSize = request.BatchSize;
+        await db.SaveChangesAsync(cancellationToken);
+        return NoContent();
+    }
 
     [HttpGet("teaching-classes")]
     public async Task<ActionResult> GetTeachingClasses(
@@ -526,3 +589,8 @@ public sealed class GradeAnalyticsController(
         IReadOnlyList<HistoricalComparison> History,
         ComparisonDelta? UniversityDelta);
 }
+
+public sealed record SaveGradeStatisticsRefreshScheduleRequest(
+    bool IsEnabled,
+    int IntervalSeconds,
+    int BatchSize);

src/Jiaowu.Api/Controllers/GradesController.cs

@@ -508,7 +508,6 @@ public sealed class GradesController(
         }
         targetItem.SourceType = GradeItemSourceType.ExperimentSummary;
         targetItem.SourceSnapshotAt = DateTime.UtcNow;
-        QueueCourseStatisticsRefresh(sheet.Id);
         await db.SaveChangesAsync(cancellationToken);
         return Ok(new
         {
@@ -668,7 +667,6 @@ public sealed class GradesController(
             return ConflictProblem("只有审核通过的成绩单可以发布。");
         sheet.Status = GradeSheetStatus.Published;
         sheet.PublishedAt = DateTime.UtcNow;
-        QueueCourseStatisticsRefresh(sheet.Id);
 
         // The grade sheet roster is authoritative at publication time. This also
         // covers students added through approved roster corrections.
@@ -918,7 +916,6 @@ public sealed class GradesController(
         if (errors.Count > 0)
             return ImportValidationProblem(errors);
 
-        QueueCourseStatisticsRefresh(sheet.Id);
         await db.SaveChangesAsync(cancellationToken);
         return Ok(new { updated, total = rows.Count });
     }
@@ -1161,7 +1158,6 @@ public sealed class GradesController(
     {
         try
         {
-            QueueCourseStatisticsRefresh(id);
             await db.SaveChangesAsync(cancellationToken);
             return created ? Created(string.Empty, new { id }) : NoContent();
         }
@@ -1171,14 +1167,6 @@ public sealed class GradesController(
         }
     }
 
-    private void QueueCourseStatisticsRefresh(Guid gradeSheetId)
-    {
-        var job = new CourseGradeStatisticsRefreshJob { GradeSheetId = gradeSheetId };
-        db.CourseGradeStatisticsRefreshJobs.Add(job);
-        db.BackgroundJobOutboxMessages.Add(BackgroundJobOutboxMessage.Create(
-            BackgroundJobKind.CourseGradeStatisticsRefresh, job.Id));
-    }
-
     private ActionResult ConflictProblem(string detail) =>
         Conflict(new ProblemDetails
         {