diff --git a/src/features/subject-images/model.ts b/src/features/subject-images/model.ts
index c750956..715599e 100644
--- a/src/features/subject-images/model.ts
+++ b/src/features/subject-images/model.ts
@@ -19,6 +19,33 @@ export function coverImage(form: SubjectFormAsset): SubjectImage | undefined {
     return primaryImage(form.images) ?? form.images.find(image => image.status === 'completed' && image.imageUrl)
 }
 
+/** 当前主体正在使用的 Identity Anchor ID。 */
+export function currentIdentityAnchorId(form: SubjectFormAsset): string | undefined {
+    return form.subject.identity?.images[0]?.id
+}
+
+/** 读取形态图生成时实际使用的 Identity Anchor ID。 */
+export function imageIdentityAnchorId(image: SubjectImage | undefined): string | undefined {
+    if (!image?.rawJson) return undefined
+    try {
+        const raw = JSON.parse(image.rawJson) as { identityAnchorImageId?: unknown }
+        return typeof raw.identityAnchorImageId === 'string' ? raw.identityAnchorImageId : undefined
+    } catch {
+        return undefined
+    }
+}
+
+/**
+ * 当前主形态图是否由旧 Identity Anchor 生成。
+ * 有当前 Anchor 但旧图没有追溯 ID，也按过期处理，避免历史图片继续进入后续 Keyframe。
+ */
+export function isPrimaryIdentityStale(form: SubjectFormAsset): boolean {
+    const anchorId = currentIdentityAnchorId(form)
+    const primary = primaryImage(form.images)
+    if (!anchorId || !primary) return false
+    return imageIdentityAnchorId(primary) !== anchorId
+}
+
 /** 查询发现后台仍在运行时也阻止重复提交，不只依赖本地 loading。 */
 export function hasRunningImages(images: Pick<SubjectImage, 'status'>[]): boolean {
     return images.some(image => image.status === 'pending' || image.status === 'generating')