fix(backup): 修复差异/清单设计评审发现的三处问题 (#92)

1) DeleteRecord 拒绝删除仍被成功差异依赖的全量（+CountDependentDifferentials），堵住手动删除孤立差异链的数据完整性缺口；2) 列表查询 Omit(Manifest)，差异基线改按需 FindByID 加载，避免清单大列拖累热路径；3) FileRunner.Run 每文件即时关闭句柄，杜绝大目录 FD 泄漏。含仓储层单测。

server/internal/repository/backup_record_manifest_test.go

@@ -0,0 +1,68 @@
+package repository
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"backupx/server/internal/model"
+)
+
+// 列表查询应省略 Manifest 列（避免拖出大 JSON），而 FindByID 仍保留（内容浏览/差异基线需要）。
+func TestListSuccessfulByTaskOmitsManifest(t *testing.T) {
+	ctx := context.Background()
+	repo := newBackupRecordTestRepository(t)
+	rec := &model.BackupRecord{TaskID: 1, StorageTargetID: 1, Status: "success", BackupKind: model.BackupKindFull, Manifest: `{"entries":[{"p":"x"}]}`, StartedAt: time.Now().UTC()}
+	if err := repo.Create(ctx, rec); err != nil {
+		t.Fatalf("create: %v", err)
+	}
+
+	items, err := repo.ListSuccessfulByTask(ctx, 1)
+	if err != nil {
+		t.Fatalf("ListSuccessfulByTask: %v", err)
+	}
+	if len(items) == 0 {
+		t.Fatal("expected at least one record")
+	}
+	for _, it := range items {
+		if it.Manifest != "" {
+			t.Fatalf("ListSuccessfulByTask must omit Manifest, got %q", it.Manifest)
+		}
+	}
+
+	full, err := repo.FindByID(ctx, rec.ID)
+	if err != nil || full == nil {
+		t.Fatalf("FindByID: %v / %v", full, err)
+	}
+	if full.Manifest == "" {
+		t.Fatal("FindByID must retain Manifest (browse/diff depend on it)")
+	}
+}
+
+// 仅统计「成功且依赖给定全量」的差异备份：失败的或依赖其他全量的不计入。
+func TestCountDependentDifferentials(t *testing.T) {
+	ctx := context.Background()
+	repo := newBackupRecordTestRepository(t)
+	now := time.Now().UTC()
+	base := &model.BackupRecord{TaskID: 1, StorageTargetID: 1, Status: "success", BackupKind: model.BackupKindFull, StartedAt: now}
+	if err := repo.Create(ctx, base); err != nil {
+		t.Fatalf("create base: %v", err)
+	}
+	mk := func(status, kind string, baseID uint) {
+		if err := repo.Create(ctx, &model.BackupRecord{TaskID: 1, StorageTargetID: 1, Status: status, BackupKind: kind, BaseRecordID: baseID, StartedAt: now}); err != nil {
+			t.Fatalf("create dependent: %v", err)
+		}
+	}
+	mk(model.BackupRecordStatusSuccess, model.BackupKindDifferential, base.ID) // 计入
+	mk(model.BackupRecordStatusSuccess, model.BackupKindDifferential, base.ID) // 计入
+	mk(model.BackupRecordStatusFailed, model.BackupKindDifferential, base.ID)  // 失败 → 不计
+	mk(model.BackupRecordStatusSuccess, model.BackupKindDifferential, 99999)   // 依赖其他全量 → 不计
+
+	n, err := repo.CountDependentDifferentials(ctx, base.ID)
+	if err != nil {
+		t.Fatalf("CountDependentDifferentials: %v", err)
+	}
+	if n != 2 {
+		t.Fatalf("want 2 dependent successful differentials, got %d", n)
+	}
+}

server/internal/repository/backup_record_repository.go

@@ -40,6 +40,7 @@ type BackupRecordRepository interface {
 	ListRecent(context.Context, int) ([]model.BackupRecord, error)
 	ListByTask(context.Context, uint) ([]model.BackupRecord, error)
 	ListSuccessfulByTask(context.Context, uint) ([]model.BackupRecord, error)
+	CountDependentDifferentials(context.Context, uint) (int64, error)
 	Count(context.Context) (int64, error)
 	CountSince(context.Context, time.Time) (int64, error)
 	CountSuccessSince(context.Context, time.Time) (int64, error)
@@ -57,7 +58,8 @@ func NewBackupRecordRepository(db *gorm.DB) *GormBackupRecordRepository {
 }
 
 func (r *GormBackupRecordRepository) List(ctx context.Context, options BackupRecordListOptions) ([]model.BackupRecord, error) {
-	query := r.db.WithContext(ctx).Model(&model.BackupRecord{}).Preload("Task").Preload("Task.StorageTarget").Order("started_at desc")
+	// Omit("Manifest")：列表不需要可能很大的清单 JSON，避免每行拖出该 TEXT 列。
+	query := r.db.WithContext(ctx).Model(&model.BackupRecord{}).Omit("Manifest").Preload("Task").Preload("Task.StorageTarget").Order("started_at desc")
 	if options.TaskID != nil {
 		query = query.Where("task_id = ?", *options.TaskID)
 	}
@@ -125,7 +127,7 @@ func (r *GormBackupRecordRepository) ListRecent(ctx context.Context, limit int)
 		limit = 10
 	}
 	var items []model.BackupRecord
-	if err := r.db.WithContext(ctx).Preload("Task").Preload("Task.StorageTarget").Order("started_at desc").Limit(limit).Find(&items).Error; err != nil {
+	if err := r.db.WithContext(ctx).Omit("Manifest").Preload("Task").Preload("Task.StorageTarget").Order("started_at desc").Limit(limit).Find(&items).Error; err != nil {
 		return nil, err
 	}
 	return items, nil
@@ -133,7 +135,7 @@ func (r *GormBackupRecordRepository) ListRecent(ctx context.Context, limit int)
 
 func (r *GormBackupRecordRepository) ListByTask(ctx context.Context, taskID uint) ([]model.BackupRecord, error) {
 	var items []model.BackupRecord
-	if err := r.db.WithContext(ctx).Where("task_id = ?", taskID).Order("id desc").Find(&items).Error; err != nil {
+	if err := r.db.WithContext(ctx).Omit("Manifest").Where("task_id = ?", taskID).Order("id desc").Find(&items).Error; err != nil {
 		return nil, err
 	}
 	return items, nil
@@ -141,12 +143,21 @@ func (r *GormBackupRecordRepository) ListByTask(ctx context.Context, taskID uint
 
 func (r *GormBackupRecordRepository) ListSuccessfulByTask(ctx context.Context, taskID uint) ([]model.BackupRecord, error) {
 	var items []model.BackupRecord
-	if err := r.db.WithContext(ctx).Where("task_id = ? AND status = ?", taskID, "success").Order("completed_at desc, id desc").Find(&items).Error; err != nil {
+	if err := r.db.WithContext(ctx).Omit("Manifest").Where("task_id = ? AND status = ?", taskID, "success").Order("completed_at desc, id desc").Find(&items).Error; err != nil {
 		return nil, err
 	}
 	return items, nil
 }
 
+// CountDependentDifferentials 统计依赖某全量记录（作为基线）的成功差异备份数量。
+func (r *GormBackupRecordRepository) CountDependentDifferentials(ctx context.Context, baseID uint) (int64, error) {
+	var count int64
+	err := r.db.WithContext(ctx).Model(&model.BackupRecord{}).
+		Where("base_record_id = ? AND backup_kind = ? AND status = ?", baseID, model.BackupKindDifferential, model.BackupRecordStatusSuccess).
+		Count(&count).Error
+	return count, err
+}
+
 func (r *GormBackupRecordRepository) Count(ctx context.Context) (int64, error) {
 	var count int64
 	if err := r.db.WithContext(ctx).Model(&model.BackupRecord{}).Count(&count).Error; err != nil {