✨ feat(vscode): 代码阅读预览按侧栏筛选算代码差异（未提交的更改对比上一次提交、审查对比 PR 目标分支；兄弟块按名字 / 相似度对齐，卡片内按行 / 值 / 词比对），算好后补发给预览

vscode/src/codeReader/editor/previewEditor.ts

@@ -1,7 +1,8 @@
-import type { CustomTextEditorProvider, Disposable, TextDocument, TextDocumentShowOptions, Uri, WebviewPanel } from 'vscode'
+import type { CustomTextEditorProvider, Disposable, Event, TextDocument, TextDocumentShowOptions, Uri, WebviewPanel } from 'vscode'
 import type { ClaudeImage } from '../../cc/spawnClaude'
-import type { BlockView } from '../blockView'
 import type { BlockKind, LocalSymbol, RuleLocation, RuleReference, WorkspaceIndex } from '../contract'
+import type { DiffBase } from '../diff/diffBase'
+import type { OldDocument, SentDocument } from '../diff/previewDiff'
 import type { DefinitionStart, IndexedName, NameSources } from '../nameResolution'
 import type { CodeQa } from '../qa/codeQa'
 import type { CodeReaderRegistry } from '../registry'
@@ -15,6 +16,7 @@ import { commands, Range, window, workspace, WorkspaceEdit } from 'vscode'
 import { logger } from '../../logging/logger'
 import { webviewHtml, webviewUiRoot } from '../../webview/html'
 import { DocumentCallees } from '../calleeKinds'
+import { PreviewDiff } from '../diff/previewDiff'
 import { blockReplacement } from '../editText'
 import { locate } from '../folderStore'
 import { definitionFor, symbolAt, symbolOccurrences } from '../localSymbols'
@@ -33,6 +35,12 @@ export const PREVIEW_VIEW_TYPE = 'superpowers.codeReader.preview'
 /** 连续输入时合并成一次重新解析。 */
 const REFRESH_DELAY_MS = 150
 
+/** 预览对比什么：侧栏开着的筛选定（TreeFilters），换了筛选、基准变了发 onDidChangeDiffBase。 */
+export interface DiffBases {
+  diffBase: (uri: Uri) => DiffBase | undefined
+  onDidChangeDiffBase: Event<void>
+}
+
 /**
  * 「代码阅读预览」自定义编辑器。预览和普通编辑器共用同一个 TextDocument：
  * 块内修改走 WorkspaceEdit，未保存标记、⌘S、⌘Z 都是 VS Code 原生行为。
@@ -57,6 +65,8 @@ export class PreviewEditorProvider implements CustomTextEditorProvider {
     readonly indexedNames: (languageId: string, name: string) => Promise<IndexedName[]>,
     /** 库规则的工作区索引里键是 key 的各项（规则查名字的定义时用，见 ruleLookups.ts） */
     readonly indexed: (index: WorkspaceIndex, key: string) => Promise<IndexedEntry[]>,
+    /** 预览标差异时对比什么 */
+    readonly diffBases: DiffBases,
   ) {}
 
   resolveCustomTextEditor(document: TextDocument, panel: WebviewPanel): void {
@@ -127,8 +137,8 @@ class Preview {
   private readonly definitions: DefinitionSources<FoundLocation>
   /** webview 报来的视口顶部那块的起始行 */
   visibleLine: number | undefined
-  /** 最近一次发出去的块树和它的源码：问 AI 时按块的记号在里面找那块代码 */
-  private sent: { blocks: BlockView[], source: string } | undefined
+  /** 最近一次发出去的文档（版本、块树、源码）：问 AI 时按块的记号在里面找那块代码，对比基准变了时拿它重新比 */
+  private sent: SentDocument | undefined
   /** 最近一次发出去的文档里语言插件自己认得出的名字（LanguageAdapter.symbols）：语言扩展查不到定义、各处出现时用 */
   private symbols: { version: number, list: LocalSymbol[] } | undefined
   /** 这份文档各版本显示成中文名的名字 */
@@ -137,6 +147,8 @@ class Preview {
   private readonly lookups: DocumentLookups
   /** 调用的名字定义成哪种块（分新建还是调用）：查到的变了就重发文档 */
   private readonly callees: DocumentCallees
+  /** 这份文件相比对比基准改了什么：发完文档再算、补发 */
+  private readonly diff: PreviewDiff
 
   constructor(
     private readonly document: TextDocument,
@@ -164,7 +176,20 @@ class Preview {
     })
     this.lookups = new DocumentLookups(() => this.schedulePush())
     this.callees = new DocumentCallees(() => this.schedulePush())
+    this.diff = new PreviewDiff(
+      () => owner.diffBases.diffBase(document.uri),
+      source => this.readOld(source),
+      (diff) => {
+        if (this.ready)
+          this.post({ type: 'diff', diff })
+      },
+      text => logger.add({ level: 'warn', source: 'codeReader', message: `${document.uri.fsPath}：${text}` }),
+    )
     this.disposables = [
+      owner.diffBases.onDidChangeDiffBase(() => {
+        if (this.ready && this.sent)
+          void this.diff.update(this.sent)
+      }),
       panel.webview.onDidReceiveMessage((msg: WebviewToExtension) => this.handleMessage(msg)),
       panel.onDidChangeViewState(() => {
         if (panel.visible)
@@ -240,11 +265,14 @@ class Preview {
     if (request !== this.latest || !this.ready)
       return
     this.definitions.remember(message.version, message.blocks)
-    this.sent = { blocks: message.blocks, source }
+    // 解析失败的文档没有块：问 AI 找不到块，也不拿它比差异
+    this.sent = message.error === undefined ? { version: message.version, blocks: message.blocks, source } : undefined
     this.symbols = { version, list: symbols }
     const reveal = this.pendingReveal
     this.pendingReveal = undefined
     this.post({ ...message, names: this.names.known(version), ...(reveal && { reveal }) })
+    if (this.sent)
+      void this.diff.update(this.sent)
     // 文档在解析期间又改了的，等下一次发文档再查
     if (version === this.document.version) {
       this.names.resolve(version, report => resolveNames(displayNames, message.blocks, this.nameSources(), report))
@@ -253,6 +281,22 @@ class Preview {
     }
   }
 
+  /**
+   * 对比基准里的旧版本排成视图数据：和这份文档同一种语言、同一个翻译插件和库规则；规则查定义、调用的种类用这份文档眼下查到的答案，
+   * 两边同样的写法翻得一样，不会因为答案晚到被当成改了。旧版本里规则出的错不记（记的是现在这份的）。
+   */
+  private async readOld(source: string): Promise<OldDocument | undefined> {
+    const { message } = await documentMessage(
+      { languageId: this.document.languageId, version: this.document.version, getText: () => source },
+      this.registry,
+      this.runtime,
+      () => {},
+      this.lookups.session().lookup,
+      this.callees.session().calleeKind,
+    )
+    return message.error === undefined ? { blocks: message.blocks, attributes: message.attributes } : undefined
+  }
+
   /** 这份文档里 offset 处名字的定义是哪种块：语言扩展查到的几处定义里第一处认得出的；语言扩展没答是 undefined。 */
   private async calleeKind(offset: number): Promise<BlockKind | null | undefined> {
     const { document } = this
@@ -360,7 +404,7 @@ class Preview {
    */
   private async ask(askId: string, anchor: string, question: string, images: ClaudeImage[]): Promise<void> {
     const at = locate(this.document.uri)
-    const subject = at && this.sent && { path: at.key, languageId: this.document.languageId, ...this.sent, anchor }
+    const subject = at && this.sent && { path: at.key, languageId: this.document.languageId, blocks: this.sent.blocks, source: this.sent.source, anchor }
     const prompt = subject && askPrompt(subject, question)
     const followUp = subject && followUpPrompt(subject, question)
     const refused = prompt === undefined || followUp === undefined