diff --git a/core/backend/apps/projects/tests.py b/core/backend/apps/projects/tests.py
index 88f78fb..8a4f74e 100644
--- a/core/backend/apps/projects/tests.py
+++ b/core/backend/apps/projects/tests.py
@@ -402,6 +402,74 @@ class ProjectApiTests(TestCase):
             {"cast": [], "scenes": [], "cast_prompts": {}, "scene_prompts": {}},
         )
 
+    def test_adopt_script_syncs_video_segments_to_shot_count(self):
+        """采用脚本时把视频片段数对齐到分镜数:用户在「采用前」删掉一镜(4→3),
+        采用后视频步骤的片段数必须跟着变 3,而不是停在项目创建固定铺的 4 段。"""
+        # 项目创建 → 固定 4 段视频片段
+        project = Project.objects.create(team=self.team, created_by=self.user, product=self.product, name="P")
+        for i in range(4):
+            VideoSegment.objects.create(project=project, sort_order=i, target_duration_seconds=15)
+        # 草稿脚本只剩 3 镜(模拟用户建了 4 镜又删 1,且尚未采用)
+        script = ScriptVersion.objects.create(project=project, is_adopted=False)
+        for i in range(3):
+            ScriptSegment.objects.create(script_version=script, sort_order=i, narration=f"n{i}", visual_prompt=f"v{i}")
+        self.assertEqual(project.video_segments.count(), 4)
+
+        response = self.client.post(
+            f"/api/projects/{project.id}/adopt-script/",
+            {"script_version_id": str(script.id)},
+            format="json",
+        )
+
+        self.assertEqual(response.status_code, 200)
+        # 采用后:多出的「从未生成过」尾段被裁掉,片段数 = 分镜数
+        self.assertEqual(project.video_segments.count(), 3)
+
+    def test_retrieve_self_heals_stale_video_segment_count(self):
+        """历史脏项目(已在视频阶段、片段数比采用版分镜多)在详情加载时自愈到分镜数。"""
+        project = Project.objects.create(
+            team=self.team, created_by=self.user, product=self.product, name="P",
+            current_stage=ProjectStage.Stage.VIDEO,
+        )
+        for i in range(4):
+            VideoSegment.objects.create(project=project, sort_order=i, target_duration_seconds=15)
+        script = ScriptVersion.objects.create(project=project, is_adopted=True)
+        for i in range(3):
+            ScriptSegment.objects.create(script_version=script, sort_order=i, narration=f"n{i}", visual_prompt=f"v{i}")
+
+        response = self.client.get(f"/api/projects/{project.id}/")
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(project.video_segments.count(), 3)
+        self.assertEqual(len(response.data["video_segments"]), 3)
+
+    def test_adopt_script_keeps_generated_segment_even_if_excess(self):
+        """收口绝不动已生成的段:即便采用版分镜少于已出片的片段数,已采用版本的尾段保留。"""
+        project = Project.objects.create(team=self.team, created_by=self.user, product=self.product, name="P")
+        segs = [VideoSegment.objects.create(project=project, sort_order=i, target_duration_seconds=15) for i in range(2)]
+        # 第 2 段(sort_order=1)已出片(有 adopted_version)→ 不可裁
+        asset = Asset.objects.create(
+            team=self.team, created_by=self.user, name="clip",
+            asset_type=Asset.Type.VIDEO, source=Asset.Source.AI_GENERATED, category=Asset.Category.VIDEO_CLIP,
+        )
+        ver = VideoSegmentVersion.objects.create(video_segment=segs[1], asset=asset, is_adopted=True)
+        segs[1].adopted_version = ver
+        segs[1].status = VideoSegment.Status.SUCCEEDED
+        segs[1].save(update_fields=["adopted_version", "status"])
+        # 采用版只有 1 镜
+        script = ScriptVersion.objects.create(project=project, is_adopted=False)
+        ScriptSegment.objects.create(script_version=script, sort_order=0, narration="n", visual_prompt="v")
+
+        response = self.client.post(
+            f"/api/projects/{project.id}/adopt-script/",
+            {"script_version_id": str(script.id)},
+            format="json",
+        )
+
+        self.assertEqual(response.status_code, 200)
+        # 已出片的尾段保留 → 不裁到 1,停在 2
+        self.assertEqual(project.video_segments.count(), 2)
+
     def test_adopt_video_version_remaps_timeline_draft(self):
         """切换采用版本后,时间线草稿里引用本场旧版本资产的片段必须跟随换成新资产(剪辑台/导出都读草稿)。"""
         project = Project.objects.create(team=self.team, created_by=self.user, product=self.product, name="P")
diff --git a/core/backend/apps/projects/views.py b/core/backend/apps/projects/views.py
index 21ac532..a057543 100644
--- a/core/backend/apps/projects/views.py
+++ b/core/backend/apps/projects/views.py
@@ -140,6 +140,22 @@ class ProjectViewSet(TeamScopedViewSetMixin, ModelViewSet):
         # 列表用轻量序列化(只给列表/仪表盘/侧栏要的字段);详情/写操作用全量 ProjectSerializer
         return ProjectListSerializer if self.action == "list" else ProjectSerializer
 
+    def retrieve(self, request, *args, **kwargs):
+        # 详情加载(=进入流水线页)时自愈视频片段数:历史项目在「采用前增删分镜」未同步,
+        # 或项目创建固定铺的 4 段从未被收口,会让视频步骤的片段数与故事板/采用版分镜对不上。
+        # 按采用版分镜数收口一次(幂等;只裁从未生成过的尾段,生成中/已出片的段绝不动)。
+        # 用轻量查询判定 + 同步,再交给 super 做重 prefetch 序列化(避免重查询跑两遍)。
+        proj = (
+            Project.objects.filter(pk=kwargs.get("pk"), **{self.team_field: self.get_team()})
+            .only("id", "current_stage")
+            .first()
+        )
+        if proj is not None and proj.current_stage == ProjectStage.Stage.VIDEO:
+            adopted_script = proj.script_versions.filter(is_adopted=True).order_by("-created_at").first()
+            if adopted_script is not None:
+                self._sync_video_segments_to_script(proj, adopted_script)
+        return super().retrieve(request, *args, **kwargs)
+
     def get_queryset(self):
         # 列表:轻查询(只 select_related product + 计数注解),不做详情那串 12 个重 prefetch
         # ——原列表把每个项目的 阶段/片段/故事板/时间线/资产文件全拉出,20 个项目实测 ~2s。
@@ -285,6 +301,10 @@ class ProjectViewSet(TeamScopedViewSetMixin, ModelViewSet):
         ScriptVersion.objects.filter(project=project).update(is_adopted=False)
         script.is_adopted = True
         script.save(update_fields=["is_adopted", "updated_at"])
+        # 采用脚本时把视频片段数对齐到这版分镜数:用户常在「采用前」就增删分镜,
+        # 那些编辑因 _sync 的 is_adopted 闸而未同步到 VideoSegment(项目创建时固定铺了 4 段),
+        # 不在此收口的话视频步骤会一直停在 4 段,与故事板/分镜数对不上。已生成的段绝不动。
+        self._sync_video_segments_to_script(project, script)
         stage, _ = ProjectStage.objects.get_or_create(project=project, stage=ProjectStage.Stage.SCRIPT)
         stage.status = ProjectStage.Status.SUCCEEDED
         stage.save(update_fields=["status", "updated_at"])
@@ -631,6 +651,10 @@ class ProjectViewSet(TeamScopedViewSetMixin, ModelViewSet):
             stage, _ = ProjectStage.objects.get_or_create(project=project, stage=ProjectStage.Stage.STORYBOARD)
             stage.status = ProjectStage.Status.SUCCEEDED
             stage.save(update_fields=["status", "updated_at"])
+            # 进入视频阶段前再收口一次视频片段数,确保与采用版分镜数一致(已生成的段不动)
+            adopted_script = project.script_versions.filter(is_adopted=True).order_by("-created_at").first()
+            if adopted_script is not None:
+                self._sync_video_segments_to_script(project, adopted_script)
             project.current_stage = ProjectStage.Stage.VIDEO
             project.status = Project.Status.VIDEOING
             project.save(update_fields=["current_stage", "status", "updated_at"])
@@ -644,6 +668,10 @@ class ProjectViewSet(TeamScopedViewSetMixin, ModelViewSet):
         stage, _ = ProjectStage.objects.get_or_create(project=project, stage=ProjectStage.Stage.STORYBOARD)
         stage.status = ProjectStage.Status.SKIPPED
         stage.save(update_fields=["status", "updated_at"])
+        # 跳过故事板直接进视频时,同样把视频片段数对齐到采用版分镜数(已生成的段不动)
+        adopted_script = project.script_versions.filter(is_adopted=True).order_by("-created_at").first()
+        if adopted_script is not None:
+            self._sync_video_segments_to_script(project, adopted_script)
         project.current_stage = ProjectStage.Stage.VIDEO
         project.status = Project.Status.VIDEOING
         project.save(update_fields=["current_stage", "status", "updated_at"])