同步传播链编辑并保护模板切换

- 修改激活模板时，如果当前项目已有 mask，先提示确认并清空所有本地 mask 和已保存后端标注；无 mask 项目可直接切换。

- 模板库详情页将“+ 新建分类”改为带编辑图标的“编辑模板”，并打开完整模板编辑弹窗。

- 区域合并会按 propagation lineage 找到其它传播帧的对应主区域和参与区域，逐帧执行 union，只删除实际参与合并的对应 mask。

- 重叠区域去除会按 propagation lineage 同步到其它传播帧的对应区域，保留参与扣除 mask，不再只改当前帧。

- 当前帧清空遮罩会同步删除这些 mask 的关联自动传播结果，并新增左侧工具栏清空入口。

- 传播链同步编辑保留 source、source_annotation_id、source_mask_id、propagation_seed_key 等 metadata，避免时间轴帧属性变色。

- 补充模板切换确认、模板编辑按钮、左侧清空入口、传播链合并/去除和清空传播链的前端回归测试。

- 更新 AGENTS、接口契约、冻结需求、设计冻结和测试计划文档。

src/components/VideoWorkspace.tsx

@@ -280,6 +280,61 @@ const isPropagatedMask = (mask: Mask) => {
     || mask.metadata?.propagation_seed_key !== undefined;
 };
 
+const metadataNumber = (value: unknown): number | null => {
+  const parsed = Number(value);
+  return Number.isFinite(parsed) && parsed > 0 ? parsed : null;
+};
+
+const propagationSourceMaskTokens = (value: unknown): string[] => {
+  if (typeof value !== 'string' || value.length === 0) return [];
+  const tokens = [`mask:${value}`];
+  const annotationMatch = value.match(/^annotation-(\d+)$/);
+  if (annotationMatch) tokens.push(`annotation:${annotationMatch[1]}`);
+  return tokens;
+};
+
+const propagationLineageTokens = (mask: Mask): Set<string> => {
+  const metadata = mask.metadata || {};
+  const tokens = new Set<string>([`mask:${mask.id}`]);
+  if (mask.annotationId) tokens.add(`annotation:${mask.annotationId}`);
+  const sourceAnnotationId = metadataNumber(metadata.source_annotation_id);
+  if (sourceAnnotationId !== null) tokens.add(`annotation:${sourceAnnotationId}`);
+  propagationSourceMaskTokens(metadata.source_mask_id).forEach((token) => tokens.add(token));
+  if (typeof metadata.propagation_seed_key === 'string' && metadata.propagation_seed_key.length > 0) {
+    tokens.add(`seed-key:${metadata.propagation_seed_key}`);
+  }
+  return tokens;
+};
+
+const findPropagationChainMaskIds = (selectedIds: string[], allMasks: Mask[]): Set<string> => {
+  const selectedMasks = selectedIds
+    .map((id) => allMasks.find((mask) => mask.id === id))
+    .filter((mask): mask is Mask => Boolean(mask));
+  const selectedTokens = new Set<string>();
+  selectedMasks.forEach((mask) => {
+    propagationLineageTokens(mask).forEach((token) => selectedTokens.add(token));
+  });
+  if (selectedTokens.size === 0) return new Set(selectedIds);
+  return new Set(
+    allMasks
+      .filter((mask) => {
+        const candidateTokens = propagationLineageTokens(mask);
+        return [...candidateTokens].some((token) => selectedTokens.has(token));
+      })
+      .map((mask) => mask.id),
+  );
+};
+
+const expandedPropagationDeletionMaskIds = (selectedIds: string[], allMasks: Mask[]): Set<string> => {
+  const selectedIdSet = new Set(selectedIds);
+  const chainIds = findPropagationChainMaskIds(selectedIds, allMasks);
+  return new Set(
+    allMasks
+      .filter((mask) => selectedIdSet.has(mask.id) || (chainIds.has(mask.id) && isPropagatedMask(mask)))
+      .map((mask) => mask.id),
+  );
+};
+
 const persistentMaskMetadata = (metadata?: Record<string, unknown>) => {
   if (!metadata) return {};
   const {
@@ -732,25 +787,30 @@ export function VideoWorkspace({ onNavigateToAI }: { onNavigateToAI?: () => void
   const handleClearCurrentFrameMasks = useCallback(async () => {
     if (!currentFrame) return;
     const frameMasks = masks.filter((mask) => mask.frameId === currentFrame.id);
-    const annotationIds = frameMasks
-      .map((mask) => mask.annotationId)
-      .filter((annotationId): annotationId is string => Boolean(annotationId));
+    const maskIdsToClear = expandedPropagationDeletionMaskIds(frameMasks.map((mask) => mask.id), masks);
+    const masksToClear = masks.filter((mask) => maskIdsToClear.has(mask.id));
+    const annotationIds = Array.from(new Set(
+      masksToClear
+        .map((mask) => mask.annotationId)
+        .filter((annotationId): annotationId is string => Boolean(annotationId)),
+    ));
 
     setIsSaving(true);
-    setStatusMessage(annotationIds.length > 0 ? '正在删除已保存标注...' : '正在清空本帧遮罩...');
+    setStatusMessage(annotationIds.length > 0 ? '正在删除已保存标注和关联传播帧...' : '正在清空本帧遮罩和关联传播帧...');
     try {
       await deleteAnnotationsIfExist(annotationIds);
-      setMasks(masks.filter((mask) => mask.frameId !== currentFrame.id));
+      setMasks(masks.filter((mask) => !maskIdsToClear.has(mask.id)));
+      setSelectedMaskIds(useStore.getState().selectedMaskIds.filter((id) => !maskIdsToClear.has(id)));
       setStatusMessage(annotationIds.length > 0
-        ? `已删除 ${annotationIds.length} 个后端标注`
-        : '已清空本帧未保存遮罩');
+        ? `已删除 ${annotationIds.length} 个后端标注，已同步清空关联传播帧`
+        : '已清空本帧未保存遮罩和关联传播帧');
     } catch (err) {
       console.error('Delete annotations failed:', err);
       setStatusMessage('删除失败，请检查后端服务');
     } finally {
       setIsSaving(false);
     }
-  }, [currentFrame, masks, setMasks]);
+  }, [currentFrame, masks, setMasks, setSelectedMaskIds]);
 
   const executeClearFrameRange = useCallback(async (request: ClearRangeConfirmState) => {
     const frameIdsToClear = new Set(request.frameIdsToClear);
@@ -1844,6 +1904,7 @@ export function VideoWorkspace({ onNavigateToAI }: { onNavigateToAI?: () => void
           setActiveTool={setActiveTool}
           onTriggerAI={onNavigateToAI}
           onImportGtMask={() => gtMaskInputRef.current?.click()}
+          onClearMasks={handleClearCurrentFrameMasks}
           canImportGtMask={Boolean(currentProject?.id && currentFrame?.id) && !isSaving && !isExporting && !isPropagating}
           isImportingGtMask={isImportingGt}
         />