🐛 fix(vscode): 改动 tab 默认统一视图并保留阅读位置

vscode/webview-ui/src/components/prFiles/FileDiffPane.tsx

@@ -6,13 +6,14 @@
  * - 主题跟随 VS Code(body 的 vscode-light/dark class),MutationObserver 监听切换。
  * - 语法高亮用库自带(diffViewHighlight),色彩取库的 light/dark 主题——不会和 VS Code
  *   主题 100% 一致,是本方案已知且可接受的小瑕疵。
+ * - 分栏/统一模式由父级持有(workspace 级);本组件只按 path 记 scrollTop,换文件可回位。
  */
 
 import type { FileDiff } from '../../hooks/usePrFiles'
 import { generateDiffFile } from '@git-diff-view/file'
 import { DiffModeEnum, DiffView } from '@git-diff-view/react'
 import { Check, Loader2, Sparkles } from 'lucide-react'
-import { useEffect, useMemo, useState } from 'react'
+import { useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react'
 import { statusBadge, statusColorVar } from './fileTree'
 import '@git-diff-view/react/styles/diff-view.css'
 
@@ -33,6 +34,10 @@ interface FileDiffPaneProps {
   generating: boolean
   /** 触发 deepseek 生成当前文件说明。 */
   onGenerate: () => void
+  /** 统一 / 分栏;由父级从 workspaceState 拉并持久化。 */
+  mode: DiffModeEnum
+  /** 用户切换模式。 */
+  onModeChange: (mode: DiffModeEnum) => void
 }
 
 /** 读当前 VS Code 主题明暗:body 带 vscode-light / vscode-high-contrast-light 即浅色,否则深色。 */
@@ -53,9 +58,22 @@ function Centered({ children }: { children: React.ReactNode }) {
   )
 }
 
-export function FileDiffPane({ path, status, diff, confirmed, onToggleConfirm, summary, generating, onGenerate }: FileDiffPaneProps) {
-  const [mode, setMode] = useState<DiffModeEnum>(DiffModeEnum.Split)
+export function FileDiffPane({
+  path,
+  status,
+  diff,
+  confirmed,
+  onToggleConfirm,
+  summary,
+  generating,
+  onGenerate,
+  mode,
+  onModeChange,
+}: FileDiffPaneProps) {
   const [theme, setTheme] = useState<'light' | 'dark'>(() => readThemeKind())
+  const scrollRef = useRef<HTMLDivElement | null>(null)
+  // 按文件路径记 scrollTop;随组件生命周期(key=issueNumber)重置。
+  const scrollByPath = useRef<Record<string, number>>({})
 
   // 主题随 VS Code 实时切换。
   useEffect(() => {
@@ -88,6 +106,20 @@ export function FileDiffPane({ path, status, diff, confirmed, onToggleConfirm, s
     return file
   }, [path, diff, mode, theme])
 
+  // path / 内容就绪后恢复该文件上次的滚动位置;DiffView 异步出高时再 rAF 补一次。
+  useLayoutEffect(() => {
+    const el = scrollRef.current
+    if (!el || !path)
+      return
+    const top = scrollByPath.current[path] ?? 0
+    el.scrollTop = top
+    const id = requestAnimationFrame(() => {
+      if (scrollRef.current)
+        scrollRef.current.scrollTop = top
+    })
+    return () => cancelAnimationFrame(id)
+  }, [path, diffFile])
+
   if (!path)
     return <Centered>选择左侧文件查看改动</Centered>
 
@@ -141,7 +173,7 @@ export function FileDiffPane({ path, status, diff, confirmed, onToggleConfirm, s
               <button
                 key={label}
                 type="button"
-                onClick={() => setMode(m)}
+                onClick={() => onModeChange(m)}
                 className={`px-1.5 py-0.5 transition-colors ${
                   mode === m
                     ? 'bg-[var(--vscode-button-background)] text-[var(--vscode-button-foreground)]'
@@ -160,8 +192,15 @@ export function FileDiffPane({ path, status, diff, confirmed, onToggleConfirm, s
         )}
       </div>
 
-      {/* 内容区 */}
-      <div className="min-h-0 flex-1 overflow-auto bg-[var(--vscode-editor-background)] text-xs">
+      {/* 内容区:按 path 记 scrollTop,换文件再回来可恢复 */}
+      <div
+        ref={scrollRef}
+        className="min-h-0 flex-1 overflow-auto bg-[var(--vscode-editor-background)] text-xs"
+        onScroll={(e) => {
+          if (path)
+            scrollByPath.current[path] = e.currentTarget.scrollTop
+        }}
+      >
         {diff === undefined
           ? <Centered>加载中…</Centered>
           : diff.error