选课批次：时间窗口、退课截止、学分上限、开放/关闭。

教学班投放：容量、班级范围、全校开放。
学生选退课：容量、重复课程、学分上限、课表冲突校验。
教学班实时名单。
校级、学院级、学生角色分级操作。
SQLite 本地增量升级及演示数据。
MySQL 正式 EF Core 迁移。
Vue 已编译进 wwwroot，单服务运行无需 npm run dev。
学生端和管理端均完成桌面、手机响应式检查。

src/Jiaowu.Api/Infrastructure/Persistence/AppDbContext.cs

@@ -28,6 +28,11 @@ public sealed class AppDbContext(DbContextOptions<AppDbContext> options)
     public DbSet<TeachingTaskClass> TeachingTaskClasses => Set<TeachingTaskClass>();
     public DbSet<SchedulePlan> SchedulePlans => Set<SchedulePlan>();
     public DbSet<ScheduleEntry> ScheduleEntries => Set<ScheduleEntry>();
+    public DbSet<CourseSelectionRound> CourseSelectionRounds =>
+        Set<CourseSelectionRound>();
+    public DbSet<CourseSelectionOffering> CourseSelectionOfferings =>
+        Set<CourseSelectionOffering>();
+    public DbSet<CourseEnrollment> CourseEnrollments => Set<CourseEnrollment>();
     public DbSet<AuditLog> AuditLogs => Set<AuditLog>();
 
     protected override void OnModelCreating(ModelBuilder builder)
@@ -267,6 +272,51 @@ public sealed class AppDbContext(DbContextOptions<AppDbContext> options)
                 .OnDelete(DeleteBehavior.Restrict);
         });
 
+        builder.Entity<CourseSelectionRound>(entity =>
+        {
+            entity.Property(x => x.Name).HasMaxLength(120);
+            entity.Property(x => x.MaxCredits).HasPrecision(6, 1);
+            entity.Property(x => x.Notes).HasMaxLength(500);
+            entity.HasIndex(x => new { x.AcademicTermId, x.Status });
+            entity.HasOne(x => x.AcademicTerm)
+                .WithMany()
+                .HasForeignKey(x => x.AcademicTermId)
+                .OnDelete(DeleteBehavior.Restrict);
+        });
+
+        builder.Entity<CourseSelectionOffering>(entity =>
+        {
+            entity.Property(x => x.Notes).HasMaxLength(500);
+            entity.HasIndex(x => new
+            {
+                x.CourseSelectionRoundId,
+                x.TeachingTaskId
+            }).IsUnique();
+            entity.HasOne(x => x.CourseSelectionRound)
+                .WithMany(x => x.Offerings)
+                .HasForeignKey(x => x.CourseSelectionRoundId)
+                .OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne(x => x.TeachingTask)
+                .WithMany()
+                .HasForeignKey(x => x.TeachingTaskId)
+                .OnDelete(DeleteBehavior.Restrict);
+        });
+
+        builder.Entity<CourseEnrollment>(entity =>
+        {
+            entity.HasIndex(x => new { x.CourseSelectionOfferingId, x.StudentId })
+                .IsUnique();
+            entity.HasIndex(x => new { x.StudentId, x.Status });
+            entity.HasOne(x => x.CourseSelectionOffering)
+                .WithMany(x => x.Enrollments)
+                .HasForeignKey(x => x.CourseSelectionOfferingId)
+                .OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne(x => x.Student)
+                .WithMany()
+                .HasForeignKey(x => x.StudentId)
+                .OnDelete(DeleteBehavior.Restrict);
+        });
+
         builder.Entity<AuditLog>(entity =>
         {
             entity.Property(x => x.Method).HasMaxLength(10);