✨ feat(vscode): 「改动」面板加审查勾 + deepseek 增量生成文件改动说明

右栏 diff 头部加一组按钮:
- 审查对勾:与左树同一状态源,勾上则文件路径标题置灰
- ✨ 一键调 deepseek 生成该文件「一句话改动目的」

增量复用会话:首个文件开新 cc 会话并把 sessionId 记到
.spx/pr-file-summaries.json,后续文件 --resume 接上去,省去每次重新
理解 PR 的开销;resume 失败则丢弃旧 id 重开一次。说明也落盘(跨 push
保留),重载后仍显示。

- spawnClaude 增 resumeSessionId(--resume)
- 新增 prFileSummaryStore;handler handleGeneratePrFileSummary
  用 jsdiff 拼 unified diff 喂模型
- 依赖 diff(jsdiff)

vscode/webview-ui/src/hooks/usePrFiles.ts

@@ -31,8 +31,13 @@ export interface UsePrFilesResult {
   confirmed: string[]
   /** key ∈ diffByPath 即「已请求/已到」；值为内容。仅 key 在但值 undefined 不会出现。 */
   diffByPath: Record<string, FileDiff>
+  /** 路径 → 已生成的一句话改动说明（deepseek 增量生成、跨 push 保留）。 */
+  summariesByPath: Record<string, string>
+  /** 正在生成说明的文件路径；null 表示无生成中。 */
+  generatingPath: string | null
   getFileDiff: (path: string, previousPath?: string) => void
   setConfirmed: (paths: string[]) => void
+  generateSummary: (path: string, previousPath?: string) => void
 }
 
 export function usePrFiles(issueNumber: number | undefined): UsePrFilesResult {
@@ -42,6 +47,8 @@ export function usePrFiles(issueNumber: number | undefined): UsePrFilesResult {
   const [loading, setLoading] = useState(false)
   const [confirmed, setConfirmedState] = useState<string[]>([])
   const [diffByPath, setDiffByPath] = useState<Record<string, FileDiff>>({})
+  const [summariesByPath, setSummariesByPath] = useState<Record<string, string>>({})
+  const [generatingPath, setGeneratingPath] = useState<string | null>(null)
 
   // issueNumber / headSha 装进 ref，让订阅闭包与回调始终读到当前值。
   const issueRef = useRef<number | undefined>(issueNumber)
@@ -60,10 +67,20 @@ export function usePrFiles(issueNumber: number | undefined): UsePrFilesResult {
         setFiles(msg.files)
         setHeadSha(msg.headSha)
         setConfirmedState(msg.confirmed ?? [])
+        setSummariesByPath(msg.summaries ?? {})
         setFilesError(msg.error)
         setLoading(false)
         return
       }
+      if (msg.type === 'pr-file-summary/show') {
+        if (msg.issueNumber !== issueRef.current)
+          return
+        // 生成结束（成功带 summary / 失败带 error）都解除该文件的 loading；失败的 error 已由扩展侧 toast。
+        setGeneratingPath(p => (p === msg.path ? null : p))
+        if (msg.summary)
+          setSummariesByPath(prev => ({ ...prev, [msg.path]: msg.summary! }))
+        return
+      }
       if (msg.type === 'pr-file-diff/show') {
         if (msg.issueNumber !== issueRef.current)
           return
@@ -89,6 +106,8 @@ export function usePrFiles(issueNumber: number | undefined): UsePrFilesResult {
     setFilesError(undefined)
     setConfirmedState([])
     setDiffByPath({})
+    setSummariesByPath({})
+    setGeneratingPath(null)
     requestedRef.current = new Set()
     if (issueNumber === undefined) {
       setLoading(false)
@@ -117,6 +136,15 @@ export function usePrFiles(issueNumber: number | undefined): UsePrFilesResult {
     postMessage({ type: 'pr-review/set', issueNumber: num, headSha: headShaRef.current, confirmed: paths })
   }, [])
 
+  // 触发 deepseek 增量生成该文件的改动说明；置 loading，结果经 pr-file-summary/show 回来。
+  const generateSummary = useCallback((path: string, previousPath?: string): void => {
+    const num = issueRef.current
+    if (num === undefined)
+      return
+    setGeneratingPath(path)
+    postMessage({ type: 'pr-file-summary/generate', issueNumber: num, path, previousPath })
+  }, [])
+
   return {
     files,
     headSha,
@@ -124,7 +152,10 @@ export function usePrFiles(issueNumber: number | undefined): UsePrFilesResult {
     loading,
     confirmed,
     diffByPath,
+    summariesByPath,
+    generatingPath,
     getFileDiff,
     setConfirmed,
+    generateSummary,
   }
 }