diff --git a/internal/model/street_snap.go b/internal/model/street_snap.go
index 0601cd6..2ce3ccb 100644
--- a/internal/model/street_snap.go
+++ b/internal/model/street_snap.go
@@ -38,6 +38,11 @@ type StreetSnapImage struct {
 	Phash       sql.NullString `gorm:"column:phash;type:vector(64)" json:"phash"`
 	IsDuplicate uint8          `gorm:"column:is_duplicate;not null;default:0" json:"is_duplicate"`
 	DupOf       string         `gorm:"column:dup_of;type:varchar(32);not null;default:''" json:"dup_of"`
+
+	// 主副图分组（列由 db/migrations/2026-09-21-01-street-main-detail.sql 添加）：
+	// is_detail=0 为主图（parent_image_id=0）；=1 为副图，parent_image_id 指向同专辑内主图的行 id。
+	IsDetail      uint8  `gorm:"column:is_detail;not null;default:0" json:"is_detail"`
+	ParentImageID uint32 `gorm:"column:parent_image_id;not null;default:0" json:"parent_image_id"`
 }
 
 // TableName 指定图片明细表名。
diff --git a/internal/repository/review_repository.go b/internal/repository/review_repository.go
index 35f1743..f579d25 100644
--- a/internal/repository/review_repository.go
+++ b/internal/repository/review_repository.go
@@ -449,22 +449,74 @@ func (r *reviewRepository) SaveStreetSnapFromDraft(ctx context.Context, draftID
 			return dErr
 		}
 		if len(imgs) > 0 {
-			rows := make([]model.StreetSnapImage, 0, len(imgs))
-			for i, im := range imgs {
-			rows = append(rows, model.StreetSnapImage{
-				SnapID:      snapID,
-				Image:       im.Image,
-				Name:        im.Name,
-				SortOrder:   uint32(i + 1),
-				Phash:       im.Phash,
-				IsDuplicate: im.IsDuplicate,
-				DupOf:       im.DupOf,
-				CreatedAt:   now,
-				UpdatedAt:   now,
-			})
+			// 第一遍：插入主图（is_detail=0），并记下「草稿行 id → 新正式行 id」的映射。
+			//
+			// 必须两遍插入：副图的 parent_image_id 存的是**草稿表**的行 id，
+			// 而这里插入的正式行拿到的是全新 id。若先插副图，父引用就会指向草稿表的旧 id，
+			// 详情页折叠结构随之错乱（见计划「任务 2」标题下的说明）。
+			newIDByDraftID := make(map[uint32]uint32, len(imgs))
+			mains := make([]model.StreetSnapImage, 0, len(imgs))
+			for _, im := range imgs {
+				if im.IsDetail == 1 {
+					continue
+				}
+				mains = append(mains, model.StreetSnapImage{
+					SnapID:      snapID,
+					Image:       im.Image,
+					Name:        im.Name,
+					SortOrder:   uint32(len(mains) + 1),
+					IsDetail:    0,
+					Phash:       im.Phash,
+					IsDuplicate: im.IsDuplicate,
+					DupOf:       im.DupOf,
+					CreatedAt:   now,
+					UpdatedAt:   now,
+				})
 			}
-			if cErr := tx.Create(&rows).Error; cErr != nil {
-				return cErr
+			for i := range mains {
+				if cErr := tx.Create(&mains[i]).Error; cErr != nil {
+					return cErr
+				}
+			}
+			mainIdx := 0
+			for _, im := range imgs {
+				if im.IsDetail == 1 {
+					continue
+				}
+				newIDByDraftID[im.ID] = mains[mainIdx].ID
+				mainIdx++
+			}
+
+			// 第二遍：插入副图，把父引用改写成新主图行 id。
+			details := make([]model.StreetSnapImage, 0, len(imgs)-len(mains))
+			for _, im := range imgs {
+				if im.IsDetail != 1 {
+					continue
+				}
+				newParent, ok := newIDByDraftID[im.ParentImageID]
+				row := model.StreetSnapImage{
+					SnapID:      snapID,
+					Image:       im.Image,
+					Name:        im.Name,
+					SortOrder:   uint32(len(mains) + len(details) + 1),
+					IsDetail:    1,
+					Phash:       im.Phash,
+					IsDuplicate: im.IsDuplicate,
+					DupOf:       im.DupOf,
+					CreatedAt:   now,
+					UpdatedAt:   now,
+				}
+				if ok {
+					row.ParentImageID = newParent
+				} else {
+					row.IsDetail = 0 // 父行缺失：按主图渲染，与读侧容错口径一致
+				}
+				details = append(details, row)
+			}
+			if len(details) > 0 {
+				if cErr := tx.Create(&details).Error; cErr != nil {
+					return cErr
+				}
 			}
 		}
 		return nil
diff --git a/internal/repository/street_main_detail_integration_test.go b/internal/repository/street_main_detail_integration_test.go
index 7b69871..c949e9c 100644
--- a/internal/repository/street_main_detail_integration_test.go
+++ b/internal/repository/street_main_detail_integration_test.go
@@ -159,3 +159,50 @@ func TestStreetMainDetailReparentGrandchildren(t *testing.T) {
 		}
 	}
 }
+
+// TestStreetPromoteRebuildsParentRef 晋升时必须把副图的父引用从「草稿行 id」改写为「新正式行 id」。
+func TestStreetPromoteRebuildsParentRef(t *testing.T) {
+	repo := NewReviewRepository(testDB(t))
+	ctx := context.Background()
+
+	draftID := seedStreetDraft(t, repo)
+	m1 := seedStreetDraftImage(t, repo, draftID, "main", 1)
+	d2 := seedStreetDraftImage(t, repo, draftID, "detail-a", 2)
+	d3 := seedStreetDraftImage(t, repo, draftID, "detail-b", 3)
+	if err := repo.AttachStreetDraftImages(ctx, draftID, m1, []uint32{d2, d3}); err != nil {
+		t.Fatalf("预置主副图失败: %v", err)
+	}
+
+	snapID, err := repo.SaveStreetSnapFromDraft(ctx, draftID)
+	if err != nil {
+		t.Fatalf("晋升失败: %v", err)
+	}
+	t.Cleanup(func() {
+		db := repo.(*reviewRepository).db
+		db.Exec("DELETE FROM street_snap_images WHERE snap_id = ?", snapID)
+		db.Exec("DELETE FROM street_snaps WHERE id = ?", snapID)
+	})
+
+	db := repo.(*reviewRepository).db
+	var rows []model.StreetSnapImage
+	if err := db.WithContext(ctx).Where("snap_id = ? AND is_deleted = 0", snapID).
+		Order("sort_order ASC, id ASC").Find(&rows).Error; err != nil {
+		t.Fatalf("读正式图失败: %v", err)
+	}
+	if len(rows) != 3 {
+		t.Fatalf("期望 3 行正式图，实际 %d", len(rows))
+	}
+
+	mainRow := rows[0]
+	if mainRow.IsDetail != 0 || mainRow.ParentImageID != 0 {
+		t.Fatalf("首行应是主图，实际 is_detail=%d parent=%d", mainRow.IsDetail, mainRow.ParentImageID)
+	}
+	for _, row := range rows[1:] {
+		if row.IsDetail != 1 {
+			t.Fatalf("第 %d 行应是副图", row.ID)
+		}
+		if row.ParentImageID != mainRow.ID {
+			t.Fatalf("副图 parent 应指向新主图行 id %d，实际 %d", mainRow.ID, row.ParentImageID)
+		}
+	}
+}