diff --git a/src/features/production/components/KeyframeDialog.vue b/src/features/production/components/KeyframeDialog.vue
index 04512af..61f98f0 100644
--- a/src/features/production/components/KeyframeDialog.vue
+++ b/src/features/production/components/KeyframeDialog.vue
@@ -4,8 +4,14 @@ import { AppDialog } from '../../../components/ui'
 import { validOptionalSize } from '../model'
 import type { GenerateKeyframeInput, ShotKeyframe } from '../types'
 
-/** 单镜头首帧表单；是否替换主首帧必须由用户明确选择。 */
-const props = defineProps<{ shotId: string; shotTitle: string; keyframes: ShotKeyframe[]; disabled: boolean }>()
+/** 单镜头首帧表单；普通候选仍由用户明确选择，过期主首帧默认替换为新图。 */
+const props = defineProps<{
+    shotId: string
+    shotTitle: string
+    keyframes: ShotKeyframe[]
+    disabled: boolean
+    replacePrimary?: boolean
+}>()
 const open = defineModel<boolean>('open', { default: false })
 const emit = defineEmits<{ generate: [input: GenerateKeyframeInput] }>()
 const width = ref<number | ''>('')
@@ -16,11 +22,11 @@ const hasPrimary = computed(() => props.keyframes.some(item => item.isPrimary &&
 const sizeValid = computed(() => validOptionalSize(width.value, height.value))
 const canSubmit = computed(() => !props.disabled && sizeValid.value && confirmed.value)
 
-/** 切换镜头或重新打开时清空费用确认，避免沿用上个镜头的覆盖选择。 */
+/** 切换镜头或重新打开时清空费用确认；过期首帧默认让新结果成为 Primary。 */
 function reset() {
     width.value = ''
     height.value = ''
-    setPrimary.value = !hasPrimary.value
+    setPrimary.value = !!props.replacePrimary || !hasPrimary.value
     confirmed.value = false
 }
 watch([() => props.shotId, open], reset, { immediate: true })
@@ -41,9 +47,12 @@ function submit() {
 <template>
     <AppDialog
         v-model:open="open"
-        :title="`生成首帧 · ${shotTitle}`"
+        :title="`${replacePrimary ? '重新生成主首帧' : '生成首帧'} · ${shotTitle}`"
         description="依据视觉风格、GenerationSpec 和主体主参考图编译首帧提示词，并调用 Seedream。"
     >
+        <p v-if="replacePrimary" class="alert mt-5 text-xs">
+            当前主首帧使用的主体参考资产已经变化。新图成功后应设为主首帧，旧图会继续保留为历史候选。
+        </p>
         <div class="mt-5 grid grid-cols-2 gap-4">
             <label
                 ><span class="field-label">宽度（可选）</span