学年学期页面新增“设为当前”“归档”“撤销归档”，当前学期不能归档、删除或直接取消；已归档学期需先撤销才能重新设为当前。[BaseDataController.cs (line 286)](/E:/jiaowu/src/Jiaowu.Api/Controllers/BaseDataController.cs:286)

切换后，其他学期自动变为历史态；已归档学期进一步弱化。所有主要学期选择器统一默认当前，并显示“当前 / 历史 / 已归档”。[academicTerms.ts (line 1)](/E:/jiaowu/web/src/utils/academicTerms.ts:1)
桌面使用分层表格，390px 手机端改为独立学期卡片，操作不会再挤压表格。[BaseDataView.vue (line 211)](/E:/jiaowu/web/src/views/BaseDataView.vue:211)
归档定义为“历史显示状态”，不是成绩冻结：补考成绩仍可录入并回写，已发布成绩仍可走成绩更正审批。
已加入 SQLite 开发迁移、MySQL 正式迁移和切换/归档/撤销测试。[20260726143000_AcademicTermArchiving.cs (line 1)](/E:/jiaowu/src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/20260726143000_AcademicTermArchiving.cs:1)

src/Jiaowu.Api/Controllers/BaseDataController.cs

@@ -287,7 +287,9 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
     public async Task<ActionResult<IReadOnlyCollection<AcademicTerm>>> GetTerms(
         CancellationToken cancellationToken) =>
         await db.AcademicTerms.AsNoTracking()
-            .OrderByDescending(x => x.StartDate)
+            .OrderByDescending(x => x.IsCurrent)
+            .ThenBy(x => x.IsArchived)
+            .ThenByDescending(x => x.StartDate)
             .ToListAsync(cancellationToken);
 
     [HttpPost("terms")]
@@ -298,11 +300,20 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
     {
         if (request.EndDate <= request.StartDate)
             return ValidationProblem("学期结束日期必须晚于开始日期。");
+        if (request.IsCurrent && !request.IsEnabled)
+            return ValidationProblem("当前学期必须保持启用。");
 
-        if (request.IsCurrent)
-            await db.AcademicTerms.ExecuteUpdateAsync(
-                setters => setters.SetProperty(x => x.IsCurrent, false),
-                cancellationToken);
+        var hasCurrentTerm = await db.AcademicTerms
+            .AnyAsync(x => x.IsCurrent, cancellationToken);
+        var shouldBeCurrent = request.IsCurrent || (!hasCurrentTerm && request.IsEnabled);
+        if (shouldBeCurrent)
+        {
+            var currentTerms = await db.AcademicTerms
+                .Where(x => x.IsCurrent)
+                .ToListAsync(cancellationToken);
+            foreach (var currentTerm in currentTerms)
+                currentTerm.IsCurrent = false;
+        }
 
         var entity = new AcademicTerm
         {
@@ -312,7 +323,7 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
             Season = request.Season,
             StartDate = request.StartDate,
             EndDate = request.EndDate,
-            IsCurrent = request.IsCurrent,
+            IsCurrent = shouldBeCurrent,
             IsEnabled = request.IsEnabled
         };
         return await CreateAsync(entity, "GetTerms", cancellationToken);
@@ -327,10 +338,22 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
     {
         var entity = await db.AcademicTerms.FindAsync([id], cancellationToken);
         if (entity is null) return NotFound();
+        if (request.EndDate <= request.StartDate)
+            return ValidationProblem("学期结束日期必须晚于开始日期。");
+        if (entity.IsCurrent && !request.IsCurrent)
+            return ConflictProblem("不能直接取消当前学期，请将另一个学期设为当前。");
+        if (request.IsCurrent && entity.IsArchived)
+            return ConflictProblem("已归档学期不能直接设为当前，请先撤销归档。");
+        if (request.IsCurrent && !request.IsEnabled)
+            return ValidationProblem("当前学期必须保持启用。");
         if (request.IsCurrent)
-            await db.AcademicTerms.Where(x => x.Id != id).ExecuteUpdateAsync(
-                setters => setters.SetProperty(x => x.IsCurrent, false),
-                cancellationToken);
+        {
+            var currentTerms = await db.AcademicTerms
+                .Where(x => x.Id != id && x.IsCurrent)
+                .ToListAsync(cancellationToken);
+            foreach (var currentTerm in currentTerms)
+                currentTerm.IsCurrent = false;
+        }
         ApplyCatalog(entity, request);
         entity.AcademicYear = request.AcademicYear.Trim();
         entity.Season = request.Season;
@@ -341,6 +364,64 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
         return entity;
     }
 
+    [HttpPost("terms/{id:guid}/set-current")]
+    [Authorize(Roles = Administrators)]
+    public async Task<ActionResult<AcademicTerm>> SetCurrentTerm(
+        Guid id,
+        CancellationToken cancellationToken)
+    {
+        var entity = await db.AcademicTerms.FindAsync([id], cancellationToken);
+        if (entity is null) return NotFound();
+        if (entity.IsArchived)
+            return ConflictProblem("已归档学期不能直接设为当前，请先撤销归档。");
+        if (!entity.IsEnabled)
+            return ConflictProblem("停用学期不能设为当前，请先启用。");
+        if (entity.IsCurrent) return entity;
+
+        var currentTerms = await db.AcademicTerms
+            .Where(x => x.Id != id && x.IsCurrent)
+            .ToListAsync(cancellationToken);
+        foreach (var currentTerm in currentTerms)
+            currentTerm.IsCurrent = false;
+        entity.IsCurrent = true;
+        await db.SaveChangesAsync(cancellationToken);
+        return entity;
+    }
+
+    [HttpPost("terms/{id:guid}/archive")]
+    [Authorize(Roles = Administrators)]
+    public async Task<ActionResult<AcademicTerm>> ArchiveTerm(
+        Guid id,
+        CancellationToken cancellationToken)
+    {
+        var entity = await db.AcademicTerms.FindAsync([id], cancellationToken);
+        if (entity is null) return NotFound();
+        if (entity.IsCurrent)
+            return ConflictProblem("当前学期不能归档，请先切换到新的当前学期。");
+        if (entity.IsArchived) return entity;
+
+        entity.IsArchived = true;
+        entity.ArchivedAt = DateTime.UtcNow;
+        await db.SaveChangesAsync(cancellationToken);
+        return entity;
+    }
+
+    [HttpPost("terms/{id:guid}/unarchive")]
+    [Authorize(Roles = Administrators)]
+    public async Task<ActionResult<AcademicTerm>> UnarchiveTerm(
+        Guid id,
+        CancellationToken cancellationToken)
+    {
+        var entity = await db.AcademicTerms.FindAsync([id], cancellationToken);
+        if (entity is null) return NotFound();
+        if (!entity.IsArchived) return entity;
+
+        entity.IsArchived = false;
+        entity.ArchivedAt = null;
+        await db.SaveChangesAsync(cancellationToken);
+        return entity;
+    }
+
     [HttpGet("classrooms")]
     public async Task<ActionResult<object>> GetClassrooms(CancellationToken cancellationToken) =>
         Ok(await db.Classrooms.AsNoTracking()
@@ -447,6 +528,8 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
         };
 
         if (entity is null) return NotFound();
+        if (entity is AcademicTerm { IsCurrent: true })
+            return ConflictProblem("当前学期不能删除，请先切换到其他学期。");
         db.Remove(entity);
         try
         {
@@ -508,6 +591,14 @@ public sealed class BaseDataController(AppDbContext db) : ControllerBase
         entity.SortOrder = request.SortOrder;
         entity.IsEnabled = request.IsEnabled;
     }
+
+    private ObjectResult ConflictProblem(string detail) =>
+        Conflict(new ProblemDetails
+        {
+            Title = "当前操作无法完成",
+            Detail = detail,
+            Status = StatusCodes.Status409Conflict
+        });
 }
 
 public record CatalogRequest(