feat(video-pipeline): 重构转场与字幕系统，提取公用辅助函数

- 优化转场策略：仅首尾段跳过转场，rhythm模式下支持directorRef和keyword驱动的动态转场
- 提取 `applyAnimationProps` 和 `distributeSegments` 公用辅助函数，减少重复代码
- 支持按导演风格 (`tarantino`/`kitano`/`fincher`) 自动选择入场动画
- 重构字幕与配音段的时长分配逻辑，提高精确性
- 修复多处 `writeFileSync` 为 `saveManifest` 以统一清单写入入口

.claude/skills/video-from-script/scripts/capcut_assemble.js

@@ -17,7 +17,7 @@ const path = require('path')
 const fs = require('fs')
 const { execFile } = require('child_process')
 const { syncDraft, registerDraft, triggerDirectoryScan } = require('./sync-to-jianying')
-const { splitTextIntoSentences } = require('./lib/pipeline-utils')
+const { splitTextIntoSentences, loadAccountConfig: loadAccountConfigFromUtils, saveManifest } = require('./lib/pipeline-utils')
 
 // ============================================================================
 // 配置
@@ -113,15 +113,18 @@ async function uploadToOSS(filePath) {
 // 转场选择策略
 // ============================================================================
 
-function getTransition(item, index, totalCount, transitionConfig) {
+function getTransition(item, index, totalCount, transitionConfig, allItems) {
   // 无配置 → 不加转场
   if (!transitionConfig) return { name: '', duration: 0 }
 
   const defaultT = transitionConfig.default || { name: '闪白', duration: 150000 }
   const strategy = transitionConfig.strategy || 'fixed'
 
-  // 前两段不加转场（避免开头黑屏/闪烁）
+  // 第一段不加转场（避免开头黑屏/闪烁）
-  if (index <= 1) return { name: '', duration: 0 }
+  if (index === 0) return { name: '', duration: 0 }
+
+  // 最后一段不需要转场（没有下一段可过渡）
+  if (index >= totalCount - 1) return { name: '', duration: 0 }
 
   switch (strategy) {
     case 'director': {
@@ -132,10 +135,22 @@ function getTransition(item, index, totalCount, transitionConfig) {
     }
 
     case 'rhythm': {
-      // 按位置选择转场：只在 keypoint / closing 加转场，其余不加
+      // 按位置选择转场：hook/keypoint/closing 加转场，body 段隔 3 段加一次
       const rules = transitionConfig.byPosition || {}
+      // 收尾段
       if (index >= totalCount - 2) return rules.closing || defaultT
-      if (index % 4 === 0) return rules.keypoint || defaultT
+      // 内容结构变化检测：directorRef 变化处、keyword 标记处加转场
+      if (allItems && index > 0) {
+        const prev = allItems[index - 1]
+        if (item.directorRef && prev.directorRef && item.directorRef !== prev.directorRef) {
+          return rules.keypoint || defaultT
+        }
+        if (item.keyword && !prev.keyword) {
+          return rules.keypoint || defaultT
+        }
+      }
+      // 固定间隔兜底（每 3 段）
+      if (index % 3 === 0) return rules.body || defaultT
       return { name: '', duration: 0 }
     }
 
@@ -375,8 +390,8 @@ async function assemble(args) {
           if (manifestFile) {
             try {
               const m = JSON.parse(fs.readFileSync(manifestFile, 'utf-8'))
-              const mi = m.items.find(i => i.id === item.id || i.script === item.script || i.text === item.text)
+              const mi = m.items.find(i => i.id === item.id)
-              if (mi) { mi.videoUrl = url; fs.writeFileSync(manifestFile, JSON.stringify(m, null, 2)) }
+              if (mi) { mi.videoUrl = url; saveManifest(manifestFile, m) }
             } catch (_) {}
           }
         } catch (err) {
@@ -411,7 +426,7 @@ async function assemble(args) {
             }
           }
         }
-        if (changed) fs.writeFileSync(manifestFile, JSON.stringify(manifest, null, 2))
+        if (changed) saveManifest(manifestFile, manifest)
       }
     } catch (err) {
       console.log(`   OSS 上传失败，将尝试本地路径: ${err.message}\n`)
@@ -512,12 +527,24 @@ async function assemble(args) {
 // 添加图片（自动上传到 OSS）
 // ============================================================================
 
+// 按 directorRef 映射不同动画风格
+const DIRECTOR_ANIMATIONS = {
+  tarantino: '缩放',       // 快速冲击感缩放
+  kitano: '回弹伸缩',      // 缓慢静谧的弹性平移
+  fincher: '缩放 II',      // 精确微距推进
+}
+
+function getAnimationForDirector(directorRef, defaultAnimation) {
+  if (!directorRef) return defaultAnimation
+  return DIRECTOR_ANIMATIONS[directorRef.toLowerCase()] || defaultAnimation
+}
+
 async function addImages(draftUrl, items, imgUrls, timeline, width, height, animation = '', transitionConfig = null) {
   const imageInfos = items.map((item, i) => {
     const url = imgUrls[item.file]
     if (!url) throw new Error(`图片 ${item.file} 未上传成功，无法添加`)
     const tl = timeline[i]
-    const t = getTransition(item, i, items.length, transitionConfig)
+    const t = getTransition(item, i, items.length, transitionConfig, items)
 
     // animation 解析：支持 "缩放" (group), "放大" (in), "渐显+缩小" (in+out)
     const info = {
@@ -531,12 +558,13 @@ async function addImages(draftUrl, items, imgUrls, timeline, width, height, anim
       transition_duration: t.duration,
     }
 
-    // animation 解析：循环动画 → loop_animation，其余 → in_animation
+    // animation 解析：按 directorRef 选择风格，循环动画 → loop_animation
     // GroupAnimationType（循环）：缩放, 缩放 II, 回弹伸缩, 旋转伸缩, ...
     // IntroType（入场）：渐显, 放大, 缩小, 向右滑动, 轻微放大, ...
     // OutroType（出场）：渐隐, 缩小, 放大, 向左滑动, ...
-    if (animation) {
+    const itemAnimation = getAnimationForDirector(item.directorRef, animation)
-      const parts = animation.split('+').map(p => p.trim()).filter(Boolean)
+    if (itemAnimation) {
+      const parts = itemAnimation.split('+').map(p => p.trim()).filter(Boolean)
       const loopNames = ['缩放', '缩放 II', '回弹伸缩', '旋转伸缩']
       const loopAnims = parts.filter(p => loopNames.includes(p))
       const inAnims = parts.filter(p => !loopNames.includes(p))
@@ -594,8 +622,8 @@ async function adjustVideoSpeed(videoPath, targetDurationSec) {
         const atempo = Math.min(speed, 2.0) // atempo 单次上限 2.0
         execFile('ffmpeg', [
           '-y', '-i', videoPath,
-          '-filter_complex', `setpts=PTS/${speed}${videoPath.endsWith('.mp4') ? `,atempo=${atempo}` : ''}`,
+          '-filter_complex', `setpts=PTS/${speed}`,
-          '-an', // 去掉音频（视频模式不需要原始音轨）
+          '-an',
           outPath
         ], { timeout: 30000 }, (err) => {
           if (err) { console.log(`     调速失败，使用原始视频: ${err.message}`); resolve(videoPath); return }
@@ -750,27 +778,17 @@ async function addVoiceover(draftUrl, inputDir, items, timeline, audioUrls = {})
 
     if (segments) {
       // 多段音频：按 segment 逐段添加，使用精确时长
-      const totalSegDur = segments.reduce((sum, s) => sum + s.duration * US, 0)
+      const slots = distributeSegments(tl, segments)
-      const tlDuration = tl.end - tl.start
-      let currentTime = tl.start
-
-      for (let j = 0; j < segments.length; j++) {
-        const seg = segments[j]
-        const segDurUs = Math.round(seg.duration * US)
-        let duration = Math.round(tlDuration * (segDurUs / totalSegDur))
-        if (j === segments.length - 1) duration = tl.end - currentTime
-        duration = Math.max(duration, 100000)
-
-        const audioUrl = resolveAudio(seg.audio)
 
+      for (const slot of slots) {
+        const audioUrl = resolveAudio(slot.audio)
         audioInfos.push({
           audio_url: audioUrl,
-          start: currentTime,
+          start: slot.start,
-          end: currentTime + duration,
+          end: slot.end,
-          duration,
+          duration: slot.duration,
           volume: 1.0,
         })
-        currentTime += duration
       }
     } else if (item.audio) {
       // 单段音频
@@ -830,12 +848,35 @@ async function addBGM(draftUrl, bgmUrl, totalDurationUs) {
 // 读取账号配置
 // ============================================================================
 
+// 动画属性注入（DRY helper）
+function applyAnimationProps(cap, style = {}) {
+  if (style.inAnimation) cap.in_animation = style.inAnimation
+  if (style.outAnimation) cap.out_animation = style.outAnimation
+  if (style.inAnimDuration) cap.in_animation_duration = style.inAnimDuration
+  if (style.outAnimDuration) cap.out_animation_duration = style.outAnimDuration
+}
+
+// segments 按比例分配到时间线（DRY helper）
+function distributeSegments(tl, segments) {
+  const totalSegDur = segments.reduce((sum, s) => sum + (s.duration || 0) * US, 0)
+  if (totalSegDur <= 0) return []
+  const tlDuration = tl.end - tl.start
+  let currentTime = tl.start
+  return segments.map((seg, idx) => {
+    const segDurUs = Math.round((seg.duration || 0) * US)
+    let duration = Math.round(tlDuration * (segDurUs / totalSegDur))
+    if (idx === segments.length - 1) duration = tl.end - currentTime
+    duration = Math.max(duration, 100000)
+    const entry = { start: currentTime, end: currentTime + duration, duration, text: seg.text, audio: seg.audio }
+    currentTime += duration
+    return entry
+  })
+}
+
 function loadAccountConfig(manifest) {
   const account = manifest.account
   if (!account) return {}
-  const accountFile = path.join(__dirname, '..', '..', '..', '..', 'accounts', account, 'account.json')
+  try { return loadAccountConfigFromUtils(account) } catch { return {} }
-  if (!fs.existsSync(accountFile)) return {}
-  try { return JSON.parse(fs.readFileSync(accountFile, 'utf-8')) } catch { return {} }
 }
 
 function loadSubtitleStyle(manifest) {
@@ -868,10 +909,7 @@ async function addKeywordOverlays(draftUrl, items, timeline, style = {}) {
       end: tl.end,
       text: item.keyword,
     }
-    if (style.inAnimation) cap.in_animation = style.inAnimation
+    applyAnimationProps(cap, style)
-    if (style.outAnimation) cap.out_animation = style.outAnimation
-    if (style.inAnimDuration) cap.in_animation_duration = style.inAnimDuration
-    if (style.outAnimDuration) cap.out_animation_duration = style.outAnimDuration
 
     captions.push(cap)
   }
@@ -915,10 +953,12 @@ async function addSubtitles(draftUrl, items, timeline, style = {}, split = false
   const captions = []
 
   // 从账号配置读取动画参数
-  const inAnimation = style.inAnimation || ''
+  const animStyle = {
-  const outAnimation = style.outAnimation || ''
+    inAnimation: style.inAnimation || '',
-  const inAnimDuration = style.inAnimationDuration || null
+    outAnimation: style.outAnimation || '',
-  const outAnimDuration = style.outAnimationDuration || null
+    inAnimDuration: style.inAnimationDuration || null,
+    outAnimDuration: style.outAnimationDuration || null,
+  }
 
   for (let i = 0; i < items.length; i++) {
     const item = items[i]
@@ -933,33 +973,13 @@ async function addSubtitles(draftUrl, items, timeline, style = {}, split = false
 
       if (segments) {
         // 精确模式：用 segments 的实际音频时长
-        const totalSegDur = segments.reduce((sum, s) => sum + s.duration * US, 0)
+        const slots = distributeSegments(tl, segments)
-        const tlDuration = tl.end - tl.start
-        let currentTime = tl.start
-
-        segments.forEach((seg, idx) => {
-          const segDurUs = Math.round(seg.duration * US)
-          // 按实际时长占比映射到时间线（处理 ffprobe 重新测量的差异）
-          let duration = Math.round(tlDuration * (segDurUs / totalSegDur))
-          if (idx === segments.length - 1) {
-            duration = tl.end - currentTime
-          }
-          duration = Math.max(duration, 1000000)
-
-          const cap = {
-            start: currentTime,
-            end: currentTime + duration,
-            text: seg.text,
-          }
-
-          if (inAnimation) cap.in_animation = inAnimation
-          if (outAnimation) cap.out_animation = outAnimation
-          if (inAnimDuration) cap.in_animation_duration = inAnimDuration
-          if (outAnimDuration) cap.out_animation_duration = outAnimDuration
 
+        for (const slot of slots) {
+          const cap = { start: slot.start, end: slot.end, text: slot.text }
+          applyAnimationProps(cap, animStyle)
           captions.push(cap)
-          currentTime += duration
+        }
-        })
       } else {
         // 回退：字数权重估算
         const sentences = splitTextIntoSentences(text)
@@ -985,11 +1005,7 @@ async function addSubtitles(draftUrl, items, timeline, style = {}, split = false
             text: sentence,
           }
 
-          if (inAnimation) cap.in_animation = inAnimation
+          applyAnimationProps(cap, animStyle)
-          if (outAnimation) cap.out_animation = outAnimation
-          if (inAnimDuration) cap.in_animation_duration = inAnimDuration
-          if (outAnimDuration) cap.out_animation_duration = outAnimDuration
-
           captions.push(cap)
           currentTime += duration
         })
@@ -1002,11 +1018,7 @@ async function addSubtitles(draftUrl, items, timeline, style = {}, split = false
         text,
       }
 
-      if (inAnimation) cap.in_animation = inAnimation
+      applyAnimationProps(cap, animStyle)
-      if (outAnimation) cap.out_animation = outAnimation
-      if (inAnimDuration) cap.in_animation_duration = inAnimDuration
-      if (outAnimDuration) cap.out_animation_duration = outAnimDuration
-
       captions.push(cap)
     }
   }
@@ -1043,7 +1055,7 @@ async function addSubtitles(draftUrl, items, timeline, style = {}, split = false
     style_text: 0,
   })
 
-  console.log(`   已添加 ${captions.length} 条字幕${split ? ' (分句模式)' : ''} (字体: ${style.font || '默认'}, 动画: ${inAnimation || '无'} → ${outAnimation || '无'})`)
+  console.log(`   已添加 ${captions.length} 条字幕${split ? ' (分句模式)' : ''} (字体: ${style.font || '默认'}, 动画: ${animStyle.inAnimation || '无'} → ${animStyle.outAnimation || '无'})`)
 }
 
 // ============================================================================