diff --git a/vscode/webview-ui/src/codeReader/App.test.tsx b/vscode/webview-ui/src/codeReader/App.test.tsx
index de70f1b..a7e3894 100644
--- a/vscode/webview-ui/src/codeReader/App.test.tsx
+++ b/vscode/webview-ui/src/codeReader/App.test.tsx
@@ -9,6 +9,58 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { App } from './App'
 import { createViewStateStore } from './viewState'
 
+/**
+ * 一次次提交里哪些组件真的画了（新挂上的不算）：赶在 react-dom 加载之前挂上 React 开发者工具的钩子，每次提交顺着 fiber 树数。
+ * 跳过重画的整棵子树（fiber 和上一次的共用子节点）不往下数。
+ */
+const renders = vi.hoisted(() => {
+  interface Fiber { type: unknown, elementType: unknown, alternate: Fiber | null, flags: number, child: Fiber | null, sibling: Fiber | null }
+  const counts = new Map<string, number>()
+  let counting = false
+  /** 组件叫什么：memo 包着的看它的 displayName，别的看函数名 */
+  const nameOf = (fiber: Fiber): string | undefined => {
+    const memoName = (fiber.elementType as { displayName?: string } | null)?.displayName
+    return memoName ?? (typeof fiber.type === 'function' ? fiber.type.name : undefined)
+  }
+  const walk = (root: { current: Fiber }): void => {
+    const stack = [root.current]
+    while (stack.length > 0) {
+      const fiber = stack.pop()!
+      const name = nameOf(fiber)
+      // flags 的第 1 位（PerformedWork）：这次真的调用了组件函数
+      if (name && fiber.alternate && (fiber.flags & 1))
+        counts.set(name, (counts.get(name) ?? 0) + 1)
+      if (fiber.alternate && fiber.child === fiber.alternate.child)
+        continue
+      for (let child = fiber.child; child; child = child.sibling)
+        stack.push(child)
+    }
+  }
+  Object.assign(globalThis, {
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: {
+      supportsFiber: true,
+      isDisabled: false,
+      renderers: new Map(),
+      inject: () => 1,
+      checkDCE: () => {},
+      onScheduleFiberRoot: () => {},
+      onCommitFiberRoot: (_id: number, root: { current: Fiber }) => counting && walk(root),
+      onCommitFiberUnmount: () => {},
+      onPostCommitFiberRoot: () => {},
+    },
+  })
+  return {
+    start: () => {
+      counts.clear()
+      counting = true
+    },
+    stop: (): Record<string, number> => {
+      counting = false
+      return Object.fromEntries(counts)
+    },
+  }
+})
+
 /** 扩展端那头：页面发出去的消息、页面挂着的收消息回调，以及 webview 自己存的状态（页面重新加载时还在） */
 const host = vi.hoisted(() => ({
   posted: [] as unknown[],
@@ -171,3 +223,70 @@ describe('代码配色跟着当前颜色主题', () => {
     expect(style.getPropertyValue('--cr-kind-loop')).toBe('#AF00DB')
   })
 })
+
+describe('一条消息只重画受影响的卡片', () => {
+  /** 三张卡片，译文里各有一个带下标的名字（下标 10、20、30） */
+  function named(id: string, name: string, offset: number, text = '调用'): BlockView {
+    return { ...block(id, name), translation: [{ text, role: 'keyword' }, { text: name, role: 'function', offset }] }
+  }
+  const DOC = documentOf(3, [named('0', 'load', 10), named('1', 'save', 20), named('2', 'drop', 30)])
+  /** 扩展端每次发来的都是新对象：深拷一份 */
+  const copy = <T,>(value: T): T => JSON.parse(JSON.stringify(value)) as T
+
+  async function rendered(msg: ExtensionToWebview): Promise<Record<string, number>> {
+    renders.start()
+    await deliver(msg)
+    return renders.stop()
+  }
+
+  it('中文名到了：只重画换了字的那段文字，卡片不动', async () => {
+    await load()
+    await deliver(copy(DOC))
+    const counts = await rendered({ type: 'displayNames', version: 3, names: [{ offset: 20, length: 4, name: '保存' }] })
+    expect(counts).toEqual({ SegmentText: 1 })
+    expect(container.querySelector('[data-offset="20"]')?.textContent).toBe('保存')
+  })
+
+  it('调用树棵数到了：只重画棵数变了的那几块', async () => {
+    await load()
+    await deliver(copy(DOC))
+    const counts = await rendered({ type: 'callTreeCounts', version: 3, counts: { save: 2 } })
+    expect(counts.BlockItem).toBe(1)
+    expect(counts.SegmentText).toBeUndefined()
+    expect(container.querySelector('[data-call-tree="save"]')?.textContent).toBe('2')
+  })
+
+  it('同一版文档重发、只改了一块的新版本：内容没变的卡片不重画', async () => {
+    await load()
+    await deliver(copy(DOC))
+    expect(await rendered(copy(DOC))).not.toHaveProperty('BlockItem')
+    const edited = documentOf(4, [named('0', 'load', 10), named('1', 'save', 20, '调用了'), named('2', 'drop', 30)])
+    const counts = await rendered(copy(edited))
+    expect(counts.BlockItem).toBe(1)
+    expect(container.querySelector('[data-id="1"]')?.textContent).toContain('调用了')
+  })
+
+  it('单击名字高亮：只重画高亮落到的那段文字', async () => {
+    await load()
+    await deliver(copy(DOC))
+    await act(async () => container.querySelector<HTMLElement>('[data-offset="30"]')!.click())
+    const asked = [...host.posted].reverse().find((msg): msg is Extract<WebviewToExtension, { type: 'findOccurrences' }> => (msg as WebviewToExtension).type === 'findOccurrences')!
+    const counts = await rendered({ type: 'occurrencesFound', id: asked.id, occurrences: [{ start: 30, end: 34, kind: 'read' }] })
+    expect(counts.SegmentText).toBe(1)
+    expect(counts.BlockItem).toBeUndefined()
+    expect(container.querySelector('[data-offset="30"]')?.getAttribute('data-occurrence')).toBe('normal')
+  })
+
+  it('没展开、没说过的块下面不画问答区；展开一块只重画那一块', async () => {
+    await load()
+    await deliver({ type: 'qa', available: true, threads: [], path: [], subject: 'file', current: [], rewrites: [], rewriteCurrent: [] })
+    await deliver(copy(DOC))
+    // 顶部那条一直摊开
+    expect(container.querySelectorAll('.cr-qa')).toHaveLength(1)
+    renders.start()
+    await act(async () => container.querySelector<HTMLButtonElement>('[data-id="1"] [aria-label="问 AI"]')!.click())
+    const counts = renders.stop()
+    expect(counts.BlockItem).toBe(1)
+    expect(container.querySelectorAll('.cr-qa')).toHaveLength(2)
+  })
+})
diff --git a/vscode/webview-ui/src/codeReader/App.tsx b/vscode/webview-ui/src/codeReader/App.tsx
index ee58fb5..8ea4c17 100644
--- a/vscode/webview-ui/src/codeReader/App.tsx
+++ b/vscode/webview-ui/src/codeReader/App.tsx
@@ -1,29 +1,32 @@
 import type { ReactElement } from 'react'
-import type { BlockTreeState } from './BlockTree'
-import type { NameMap, VersionNames } from './displayNames'
-import type { BlockView, CallTree, ContractMiss, DocumentDiff, DocumentMessage, Excluded, KindBadge, Reveal } from './types'
+import type { BlockTreeHandle } from './BlockTree'
+import type { OpenCall } from './pageState'
+import type { TextMarks } from './SegmentText'
+import type { BlockView, DocumentMessage } from './types'
 import type { OccurrencePage } from './useOccurrences'
-import type { ViewState } from './viewState'
 import { TriangleAlert } from 'lucide-react'
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { AskThread, FEATURE_THREAD } from './AskThread'
-import { BlockLevel } from './BlockTree'
+import { BlockTree } from './BlockTree'
 import { CallTreeDialog } from './CallTreeDialog'
 import { applyCodeColors } from './codeColors'
 import { DefinitionPeekPopup } from './DefinitionPeekPopup'
 import { DiffBar, NewFileBanner } from './DiffBar'
-import { changeStops, diffTree, foldUnchanged, openedByDiff } from './diffView'
-import { acceptNames, DisplayNameContext, documentNames } from './displayNames'
-import { coveredByEditing, startEditing } from './editing'
-import { applyFilter, excludedBy, keptWhileEditing } from './filter'
+import { nameMap } from './displayNames'
+import { startEditing } from './editing'
+import { keptWhileEditing } from './filter'
 import { FilterBar } from './FilterBar'
 import { OverviewRuler } from './OverviewRuler'
-import { asksOf, historyOf, PATH_ASK_ANCHOR } from './qa'
+import { createPageStore } from './pageState'
+import { chatOf, PATH_ASK_ANCHOR, sameChat } from './qa'
+import { TextMarksContext } from './SegmentText'
+import { shareUnchanged } from './sharing'
 import { StickyLines } from './StickyLines'
+import { createStore, useStore } from './store'
 import { useChangeNav } from './useChangeNav'
 import { useDefinitionLinks } from './useDefinitionLinks'
 import { useDefinitionPeek } from './useDefinitionPeek'
-import { HighlightContext, useOccurrences } from './useOccurrences'
+import { useOccurrences } from './useOccurrences'
 import { useQa } from './useQa'
 import { useRepoImages } from './useRepoImages'
 import { useRepoLinks } from './useRepoLinks'
@@ -31,32 +34,9 @@ import { useReveal } from './useReveal'
 import { useRewrite } from './useRewrite'
 import { useScrollPosition } from './useScrollPosition'
 import { useStickySettings } from './useStickyScroll'
-import { collapsedIds } from './viewState'
 import { onMessage, postMessage, viewState } from './vscode'
 
-type BlockModes = Pick<ViewState, 'editing' | 'folds'>
-
 const NONE: ReadonlySet<string> = new Set()
-const NO_NAMES: NameMap = new Map()
-
-function savedBlockModes(): BlockModes {
-  const { editing, folds } = viewState.get()
-  return { editing, folds }
-}
-
-/** 开着的调用树弹框：哪一版文档的哪一块、选中第几个入口，扩展端发来的树 */
-interface OpenCall {
-  anchor: string
-  version: number
-  entry: number
-  status: 'loading' | 'ready'
-  name: string
-  where: string
-  kind: string
-  badge?: KindBadge
-  trees: CallTree[]
-  contractMiss?: ContractMiss
-}
 
 /** 打开 doc 里 anchor 那块的调用树弹框，先是「正在查」，等扩展端发树来；这块不在了、或者它看不了调用树时是 undefined。 */
 function openingCall(doc: DocumentMessage, anchor: string, entry: number): OpenCall | undefined {
@@ -77,6 +57,10 @@ function blockAt(blocks: readonly BlockView[], anchor: string): BlockView | unde
   return undefined
 }
 
+/**
+ * 代码阅读预览页。页面状态放在一份 store 里（createPageStore），扩展端的消息、用户的点击都改它；
+ * 块树的卡片各自订阅自己那部分（见 BlockTree），一条消息只重画受影响的卡片；这一层重画时，块树顶层各块照 memo 跳过。
+ */
 export function App(): ReactElement | null {
   // 先于下面发 ready 的那个 effect 挂上收消息：ready 后扩展端马上发问答
   const qa = useQa()
@@ -84,54 +68,25 @@ export function App(): ReactElement | null {
   const [pathFocus, setPathFocus] = useState(0)
   /** 按注释规范重写 */
   const rewrite = useRewrite()
-  const [doc, setDoc] = useState<DocumentMessage | null>(null)
-  const [view, setView] = useState<BlockModes>(savedBlockModes)
-  const [focusId, setFocusId] = useState<string | null>(null)
-  /** 等着滚过去的位置：新预览第一份文档带的，或已开着的预览收到的 reveal */
-  const [reveal, setReveal] = useState<Reveal | null>(null)
-  /** 扩展端发来的块筛选（整个工作区共用）；本地不改，改了发给扩展端、等它发回来 */
-  const [excluded, setExcluded] = useState<Excluded>({})
-  /** 跳到定义时临时露出来的块（目标和它的各层祖先），筛选一变、文档一刷新就回到筛选状态 */
-  const [keep, setKeep] = useState<ReadonlySet<string>>(NONE)
-  /** 页面上这个文档版本的中文名：文档带来的，扩展端查到了再换 */
-  const [names, setNames] = useState<VersionNames | undefined>()
-  /** 这份文件相比对比基准改了什么：审查工作副本里的、从「未提交的更改」点开的有改动的文件扩展端算好了补来，不比时是 null */
-  const [diff, setDiff] = useState<DocumentDiff | null>(null)
-  /** 收到消息时读眼下哪些块在编辑（消息回调只在挂载时注册一次） */
-  const editing = useRef(view.editing)
-  /** 页面上这份文档的版本：调用树的回答不是这一版就丢掉 */
-  const docVersion = useRef<number | undefined>(undefined)
-  const [callCounts, setCallCounts] = useState<{ version: number, counts: Record<string, number> }>()
-  const [openCall, setOpenCall] = useState<OpenCall | null>(null)
+  const [page] = useState(() => createPageStore(viewState.get()))
+  /** 页面上文字的标记：这个文档版本的中文名（文档带来的，扩展端查到了再换）和单击高亮的名字；各段文字按自己那几段订阅 */
+  const [marks] = useState(() => createStore<TextMarks>({ names: new Map() }))
   /** 页面重新加载前开着的调用树弹框：第一份文档到了，那块还在就重新打开；到之前记着的不动 */
   const restoreCall = useRef(viewState.get().callTree)
   /** 块树所在的页面内容：钉住卡片时在这里面量 */
   const content = useRef<HTMLDivElement>(null)
-  // 解析失败的文档没有块，不标差异；删掉的块按块筛选同样藏
-  const changes = useMemo(() => doc && doc.error === undefined
-    ? diffTree(doc.blocks, diff, doc.version, removed => !excludedBy(removed.block, excluded))
-    : undefined, [doc, diff, excluded])
-  const collapsed = useMemo(() => collapsedIds(doc?.blocks ?? [], view.folds, openedByDiff(changes)), [doc, view.folds, changes])
-  const filter = useMemo(() => applyFilter(doc?.blocks ?? [], excluded, keep), [doc, excluded, keep])
-  const covered = useMemo(() => coveredByEditing(doc?.blocks ?? [], new Set(view.editing)), [doc, view.editing])
-  /** 「只看改动」开着（整个工作区共用，扩展端记着）；本地不改，改了发给扩展端、等它发回来 */
-  const [onlyChanges, setOnlyChanges] = useState(false)
-  /** 「只看改动」时点开过的几段没变的块（按第一块的 id），筛选一变就重新折 */
-  const [openedRuns, setOpenedRuns] = useState<ReadonlySet<string>>(NONE)
-  const folded = useMemo(() => doc && changes && onlyChanges
-    ? foldUnchanged(doc.blocks, changes, block => !filter.hidden.has(block.id) && !covered.has(block.id), openedRuns, keep)
-    : undefined, [doc, changes, onlyChanges, filter, covered, openedRuns, keep])
-  /** 页面上没画出来的块：被筛掉的，和「只看改动」折起来的 */
-  const unshown = useMemo(() => folded ? new Set([...filter.hidden, ...folded.folded]) : filter.hidden, [filter, folded])
-  const stops = useMemo(() => doc && changes ? changeStops(doc.blocks, changes, filter.hidden) : [], [doc, changes, filter])
+  const { doc, editing, folds, reveal, excluded, diff, onlyChanges, openCall, changes, collapsed, filter, covered, unshown, stops } = useStore(page, current => current)
+  const pathChat = useStore(qa.store, state => chatOf(state, PATH_ASK_ANCHOR), sameChat)
+  const qaAvailable = useStore(qa.store, state => state.available)
+  const qaSubject = useStore(qa.store, state => state.subject)
+
   /** 记下这几块、属性行、子行折叠还是展开，从此不再按默认 */
-  const setFolded = useCallback((ids: string[], folded: boolean) => setView(prev => ({
-    ...prev,
-    folds: { ...prev.folds, ...Object.fromEntries(ids.map(id => [id, folded])) },
-  })), [])
+  const setFolded = useCallback((ids: string[], folded: boolean) => page.update(current => ({
+    folds: { ...current.folds, ...Object.fromEntries(ids.map(id => [id, folded])) },
+  })), [page])
   const expand = useCallback((ids: string[]) => setFolded(ids, false), [setFolded])
-  const show = useCallback((ids: string[]) => setKeep(prev => new Set([...prev, ...ids])), [])
-  const revealed = useCallback(() => setReveal(null), [])
+  const show = useCallback((ids: string[]) => page.update(current => ({ keep: new Set([...current.keep, ...ids]) })), [page])
+  const revealed = useCallback(() => page.update({ reveal: null }), [page])
   useScrollPosition(doc)
   useReveal(doc, reveal, collapsed, unshown, covered, show, expand, revealed)
   useDefinitionLinks(doc?.version)
@@ -143,12 +98,40 @@ export function App(): ReactElement | null {
   const occurrencePage = useMemo((): OccurrencePage | undefined => doc
     ? {
         blocks: doc.blocks,
-        skip: id => unshown.has(id) || covered.has(id) || view.editing.includes(id),
+        skip: id => unshown.has(id) || covered.has(id) || editing.includes(id),
         collapsed,
         expand,
       }
-    : undefined, [doc, unshown, covered, view.editing, collapsed, expand])
-  const { highlight, moveOccurrence } = useOccurrences(doc?.version, doc?.translatorId, occurrencePage)
+    : undefined, [doc, unshown, covered, editing, collapsed, expand])
+  const occurrences = useOccurrences(doc?.version, doc?.translatorId, occurrencePage, marks)
+
+  /** 块树：状态是页面 store 里的 tree，动作改页面 store；整页一份，卡片拿到的回调一直是同一个 */
+  const [tree] = useState((): BlockTreeHandle => ({
+    state: { get: () => page.get().tree, subscribe: page.subscribe },
+    onToggleFold: id => page.update(current => ({ folds: { ...current.folds, [id]: !current.collapsed.has(id) } })),
+    onSetFolds: next => page.update(current => ({ folds: { ...current.folds, ...next } })),
+    onOpenRun: id => page.update(current => ({ openedRuns: new Set([...current.openedRuns, id]) })),
+    edit: {
+      onToggleEdit: id => page.update((current) => {
+        const leaving = current.editing.includes(id)
+        return {
+          focusId: leaving ? null : id,
+          editing: leaving ? current.editing.filter(other => other !== id) : startEditing(current.doc?.blocks ?? [], current.editing, id),
+        }
+      }),
+      onFocused: () => page.update({ focusId: null }),
+    },
+    onOpenCall: (anchor) => {
+      const current = page.get().doc
+      const opening = current && openingCall(current, anchor, 0)
+      if (!opening)
+        return
+      page.update({ openCall: opening })
+      postMessage({ type: 'openCallTree', version: opening.version, anchor })
+    },
+    qa,
+    rewrite,
+  }))
 
   useEffect(() => {
     const off = onMessage((msg) => {
@@ -156,52 +139,53 @@ export function App(): ReactElement | null {
         case 'document': {
           const restoring = restoreCall.current
           restoreCall.current = undefined
-          const reopened = restoring && openingCall(msg, restoring.anchor, restoring.entry)
-          docVersion.current = msg.version
-          setDoc(msg)
-          setNames(documentNames(msg.version, msg.names))
-          setKeep(prev => keptWhileEditing(prev, editing.current))
-          setCallCounts(prev => prev?.version === msg.version ? prev : undefined)
-          setOpenCall(prev => prev?.version === msg.version ? prev : reopened ?? null)
+          // 和上一份内容一样的块还是原来的对象：没变的卡片不重画
+          const next = shareUnchanged(page.get().doc, msg)
+          const reopened = restoring && openingCall(next, restoring.anchor, restoring.entry)
+          marks.set(current => ({ ...current, names: nameMap(msg.names) }))
+          page.update(current => ({
+            doc: next,
+            keep: keptWhileEditing(current.keep, current.editing),
+            callCounts: current.callCounts?.version === msg.version ? current.callCounts : undefined,
+            openCall: current.openCall?.version === msg.version ? current.openCall : reopened ?? null,
+            ...(msg.reveal && { reveal: msg.reveal }),
+          }))
           if (reopened)
             postMessage({ type: 'openCallTree', version: msg.version, anchor: reopened.anchor })
           else if (restoring)
             viewState.update({ callTree: undefined })
-          if (msg.reveal)
-            setReveal(msg.reveal)
           return
         }
         case 'callTreeCounts':
-          if (msg.version !== docVersion.current)
+          if (msg.version !== page.get().doc?.version)
             return
-          setCallCounts({ version: msg.version, counts: msg.counts })
+          page.update({ callCounts: { version: msg.version, counts: msg.counts } })
           return
         case 'callTree':
-          if (msg.version !== docVersion.current)
+          if (msg.version !== page.get().doc?.version)
             return
-          setOpenCall((prev) => {
-            if (!prev || prev.anchor !== msg.anchor || prev.version !== msg.version)
-              return prev
-            return { ...prev, status: 'ready', name: msg.name, where: msg.where, trees: msg.trees, contractMiss: msg.contractMiss }
-          })
+          page.update(({ openCall: prev }) => ({
+            openCall: !prev || prev.anchor !== msg.anchor || prev.version !== msg.version
+              ? prev
+              : { ...prev, status: 'ready', name: msg.name, where: msg.where, trees: msg.trees, contractMiss: msg.contractMiss },
+          }))
           return
         case 'reveal':
-          setReveal({ line: msg.line, definition: msg.definition })
+          page.update({ reveal: { line: msg.line, definition: msg.definition } })
           return
         case 'displayNames':
-          setNames(prev => acceptNames(prev, msg.version, msg.names))
+          // 查到的是页面上这个版本的才换上，迟到的旧版本的不理
+          if (msg.version === page.get().doc?.version)
+            marks.set(current => ({ ...current, names: nameMap(msg.names) }))
           return
         case 'filter':
-          setExcluded(msg.excluded)
-          setOnlyChanges(msg.onlyChanges)
-          setKeep(NONE)
-          setOpenedRuns(NONE)
+          page.update({ excluded: msg.excluded, onlyChanges: msg.onlyChanges, keep: NONE, openedRuns: NONE })
           return
         case 'codeColors':
           applyCodeColors(document.body.style, msg)
           return
         case 'diff':
-          setDiff(msg.diff)
+          page.update(current => ({ diff: shareUnchanged(current.diff, msg.diff) }))
           return
         case 'openedFrom':
           viewState.update({ openedFrom: msg.from })
@@ -214,12 +198,11 @@ export function App(): ReactElement | null {
     const { openedFrom } = viewState.get()
     postMessage({ type: 'ready', ...(openedFrom && { openedFrom }) })
     return off
-  }, [])
+  }, [page, marks])
 
   useEffect(() => {
-    viewState.update(view)
-    editing.current = view.editing
-  }, [view])
+    viewState.update({ editing, folds })
+  }, [editing, folds])
 
   useEffect(() => {
     if (restoreCall.current)
@@ -227,137 +210,92 @@ export function App(): ReactElement | null {
     viewState.update({ callTree: openCall ? { anchor: openCall.anchor, entry: openCall.entry } : undefined })
   }, [openCall])
 
-  const onFocused = useCallback(() => setFocusId(null), [])
-  const onOpenCall = useCallback((anchor: string) => {
-    const opening = doc && openingCall(doc, anchor, 0)
-    if (!opening)
-      return
-    setOpenCall(opening)
-    postMessage({ type: 'openCallTree', version: opening.version, anchor })
-  }, [doc])
-  const kindNames = useMemo(() => new Map(doc?.attributes.find(attribute => attribute.id === 'kind')?.values.map(value => [value.id, value.name])), [doc])
-  const kindName = useCallback((kind: string) => kindNames.get(kind) ?? kind, [kindNames])
-  const tree = useMemo((): BlockTreeState | null => doc && {
-    edit: {
-      version: doc.version,
-      editing: new Set(view.editing),
-      focusId,
-      onFocused,
-      onToggleEdit: (id) => {
-        setFocusId(view.editing.includes(id) ? null : id)
-        setView(prev => ({
-          ...prev,
-          editing: prev.editing.includes(id) ? prev.editing.filter(other => other !== id) : startEditing(doc.blocks, prev.editing, id),
-        }))
-      },
-    },
-    collapsed,
-    hidden: filter.hidden,
-    temporary: filter.temporary,
-    covered,
-    kindName,
-    onToggleFold: id => setFolded([id], !collapsed.has(id)),
-    onSetFolds: folds => setView(prev => ({ ...prev, folds: { ...prev.folds, ...folds } })),
-    ...(qa.state.available && { qa }),
-    ...(rewrite.state.available && { rewrite }),
-    ...(changes && { diff: changes }),
-    ...(folded && { folded }),
-    onOpenRun: id => setOpenedRuns(prev => new Set([...prev, id])),
-    callTree: {
-      counts: callCounts?.version === doc.version ? new Map(Object.entries(callCounts.counts)) : new Map(),
-      ...(openCall?.version === doc.version && { openAnchor: openCall.anchor }),
-      onOpen: onOpenCall,
-    },
-  }, [doc, view, collapsed, filter, covered, kindName, focusId, onFocused, setFolded, rewrite, qa, changes, folded, callCounts, openCall, onOpenCall])
-
-  if (!doc || !tree)
+  if (!doc)
     return null
 
   return (
-    <HighlightContext value={highlight}>
-      <DisplayNameContext value={names?.names ?? NO_NAMES}>
-        <FilterBar
-          attributes={doc.attributes}
-          excluded={excluded}
-          view={filter}
-          highlight={highlight}
-          onMoveOccurrence={moveOccurrence}
-          onChange={next => postMessage({ type: 'setFilter', excluded: next })}
-          translators={doc.translators}
-          translatorId={doc.translatorId}
-          onSelectTranslator={id => postMessage({ type: 'selectTranslator', id })}
-          below={diff && doc.error === undefined && (
-            <DiffBar
-              diff={diff}
-              onlyChanges={onlyChanges}
-              onToggleOnly={() => postMessage({ type: 'setOnlyChanges', on: !onlyChanges })}
-              canMove={stops.length > 0}
-              onMove={nav.move}
-            />
-          )}
-        />
-        {changes && diff && <OverviewRuler stops={stops} lineCount={diff.lineCount} onPick={nav.goTo} />}
-        <div ref={content} className="mx-auto box-content max-w-[880px] px-6 py-5">
-          {qa.state.available && (
-            <div className="mb-4">
-              <AskThread
-                history={historyOf(qa.state, PATH_ASK_ANCHOR)}
-                asks={asksOf(qa.state, PATH_ASK_ANCHOR)}
-                open
-                hint={qa.state.subject === 'folder' ? '这个文件夹' : '这个文件'}
-                {...(qa.state.subject === 'feature' && { wording: FEATURE_THREAD })}
-                autoFocus={false}
-                focusToken={pathFocus}
-                closable={false}
-                profiles={qa.state.profiles}
-                onSelectProfile={qa.onSelectProfile}
-                onAsk={(question, images) => qa.onAsk(PATH_ASK_ANCHOR, question, images)}
-                onStop={qa.onStop}
-                onDelete={entryId => qa.onDelete(PATH_ASK_ANCHOR, entryId)}
-                onClose={() => undefined}
-              />
-            </div>
-          )}
-          {diff?.newFile !== undefined && doc.error === undefined && <NewFileBanner detail={diff.newFile} />}
-          {doc.error !== undefined && (
-            <div className="mb-3 flex items-start gap-2 rounded-lg border border-[var(--vscode-inputValidation-errorBorder)] bg-[var(--vscode-inputValidation-errorBackground)] px-3 py-2">
-              <TriangleAlert size={16} strokeWidth={1.8} className="mt-px shrink-0 text-[var(--vscode-errorForeground)]" />
-              <div className="min-w-0">
-                <div className="break-words">
-                  解析失败：
-                  {doc.error}
-                </div>
-                <div className="mt-0.5 text-xs text-[var(--vscode-descriptionForeground)]">点编辑器右上角的「编辑」查看源码。</div>
-              </div>
-            </div>
-          )}
-          {doc.blocks.length === 0
-            ? doc.error === undefined && qa.state.subject === 'file' && <div className="text-[var(--vscode-descriptionForeground)]">这个文件里没有代码。</div>
-            : doc.blocks.some(block => !filter.hidden.has(block.id))
-              ? <BlockLevel blocks={doc.blocks} tree={tree} />
-              : <div className="text-[var(--vscode-descriptionForeground)]">所有块都被筛选隐藏了。</div>}
-        </div>
-        {sticky?.enabled && <StickyLines content={content} blocks={doc.blocks} settings={sticky} />}
-        <DefinitionPeekPopup shown={peek.shown} onJump={peek.jump} />
-        {openCall && (
-          <CallTreeDialog
-            kind={openCall.kind}
-            badge={openCall.badge}
-            name={openCall.name}
-            where={openCall.where}
-            status={openCall.status === 'loading' ? 'loading' : openCall.trees.length === 0 ? 'empty' : 'ready'}
-            trees={openCall.trees}
-            selected={openCall.entry}
-            contractMiss={openCall.contractMiss}
-            onSelect={entry => setOpenCall(prev => prev && { ...prev, entry })}
-            onClose={() => setOpenCall(null)}
-            onJump={(jump) => {
-              setOpenCall(null)
-              postMessage({ type: 'goToCallNode', ...jump })
-            }}
+    <TextMarksContext value={marks}>
+      <FilterBar
+        attributes={doc.attributes}
+        excluded={excluded}
+        view={filter}
+        highlight={occurrences.highlight}
+        onMoveOccurrence={occurrences.moveOccurrence}
+        onChange={next => postMessage({ type: 'setFilter', excluded: next })}
+        translators={doc.translators}
+        translatorId={doc.translatorId}
+        onSelectTranslator={id => postMessage({ type: 'selectTranslator', id })}
+        below={diff && doc.error === undefined && (
+          <DiffBar
+            diff={diff}
+            onlyChanges={onlyChanges}
+            onToggleOnly={() => postMessage({ type: 'setOnlyChanges', on: !onlyChanges })}
+            canMove={stops.length > 0}
+            onMove={nav.move}
           />
         )}
-      </DisplayNameContext>
-    </HighlightContext>
+      />
+      {changes && diff && <OverviewRuler stops={stops} lineCount={diff.lineCount} onPick={nav.goTo} />}
+      <div ref={content} className="mx-auto box-content max-w-[880px] px-6 py-5">
+        {qaAvailable && (
+          <div className="mb-4">
+            <AskThread
+              history={pathChat.history}
+              asks={pathChat.asks}
+              open
+              hint={qaSubject === 'folder' ? '这个文件夹' : '这个文件'}
+              {...(qaSubject === 'feature' && { wording: FEATURE_THREAD })}
+              autoFocus={false}
+              focusToken={pathFocus}
+              closable={false}
+              profiles={pathChat.profiles}
+              onSelectProfile={qa.onSelectProfile}
+              onAsk={(question, images) => qa.onAsk(PATH_ASK_ANCHOR, question, images)}
+              onStop={qa.onStop}
+              onDelete={entryId => qa.onDelete(PATH_ASK_ANCHOR, entryId)}
+              onClose={() => undefined}
+            />
+          </div>
+        )}
+        {diff?.newFile !== undefined && doc.error === undefined && <NewFileBanner detail={diff.newFile} />}
+        {doc.error !== undefined && (
+          <div className="mb-3 flex items-start gap-2 rounded-lg border border-[var(--vscode-inputValidation-errorBorder)] bg-[var(--vscode-inputValidation-errorBackground)] px-3 py-2">
+            <TriangleAlert size={16} strokeWidth={1.8} className="mt-px shrink-0 text-[var(--vscode-errorForeground)]" />
+            <div className="min-w-0">
+              <div className="break-words">
+                解析失败：
+                {doc.error}
+              </div>
+              <div className="mt-0.5 text-xs text-[var(--vscode-descriptionForeground)]">点编辑器右上角的「编辑」查看源码。</div>
+            </div>
+          </div>
+        )}
+        {doc.blocks.length === 0
+          ? doc.error === undefined && qaSubject === 'file' && <div className="text-[var(--vscode-descriptionForeground)]">这个文件里没有代码。</div>
+          : doc.blocks.some(block => !filter.hidden.has(block.id))
+            ? <BlockTree blocks={doc.blocks} tree={tree} />
+            : <div className="text-[var(--vscode-descriptionForeground)]">所有块都被筛选隐藏了。</div>}
+      </div>
+      {sticky?.enabled && <StickyLines content={content} blocks={doc.blocks} settings={sticky} />}
+      <DefinitionPeekPopup shown={peek.shown} onJump={peek.jump} />
+      {openCall && (
+        <CallTreeDialog
+          kind={openCall.kind}
+          badge={openCall.badge}
+          name={openCall.name}
+          where={openCall.where}
+          status={openCall.status === 'loading' ? 'loading' : openCall.trees.length === 0 ? 'empty' : 'ready'}
+          trees={openCall.trees}
+          selected={openCall.entry}
+          contractMiss={openCall.contractMiss}
+          onSelect={entry => page.update(({ openCall: prev }) => ({ openCall: prev && { ...prev, entry } }))}
+          onClose={() => page.update({ openCall: null })}
+          onJump={(jump) => {
+            page.update({ openCall: null })
+            postMessage({ type: 'goToCallNode', ...jump })
+          }}
+        />
+      )}
+    </TextMarksContext>
   )
 }
diff --git a/vscode/webview-ui/src/codeReader/BlockTree.test.tsx b/vscode/webview-ui/src/codeReader/BlockTree.test.tsx
index 1991a25..be4bf5c 100644
--- a/vscode/webview-ui/src/codeReader/BlockTree.test.tsx
+++ b/vscode/webview-ui/src/codeReader/BlockTree.test.tsx
@@ -1,6 +1,6 @@
 // @vitest-environment happy-dom
 
-import type { BlockTreeState, RewriteTree } from './BlockTree'
+import type { BlockTreeHandle, BlockTreeState, RewriteTree } from './BlockTree'
 import type { Ask, ChatState } from './qa'
 import type { BlockView, KindBadge } from './types'
 import { renderToStaticMarkup } from 'react-dom/server'
@@ -11,17 +11,14 @@ import { createPythonAdapter } from '../../../src/codeReader/languages/python'
 import { fastapiRule } from '../../../src/codeReader/rules/fastapi'
 import { WASM_DIR, withBlocks } from '../../../src/codeReader/testSupport'
 import { pythonZhTranslator } from '../../../src/codeReader/translators/pythonZh'
-import { BlockLevel } from './BlockTree'
+import { BlockTree, treeState } from './BlockTree'
 import { applyFilter } from './filter'
 import { FilterBar } from './FilterBar'
 import { EMPTY_CHAT } from './qa'
+import { staticStore } from './store'
 import { collapsedIds } from './viewState'
 
-// 高亮的上下文所在的模块、编辑框都连着和 VS Code 收发消息的那一套，渲染成 HTML 用不着
-vi.mock('./useOccurrences', async () => {
-  const { createContext } = await import('react')
-  return { HighlightContext: createContext(undefined) }
-})
+// 编辑框连着和 VS Code 收发消息的那一套，渲染成 HTML 用不着
 vi.mock('./vscode', () => ({ postMessage: () => {}, onMessage: () => () => {}, viewState: { get: () => ({ editing: [], folds: {} }), update: () => {} } }))
 
 const BADGE: KindBadge = { label: '卡片', color: { dark: '#61dafb', light: '#0a7ea4' }, icon: 'box' }
@@ -64,32 +61,34 @@ const CARD: BlockView = {
 
 /** 重写注释的状态和动作：动作什么都不做 */
 function rewriteTree(state: ChatState): RewriteTree {
-  return { state, onRewrite: () => {}, onAsk: () => {}, onStop: () => {}, onDelete: () => {}, onOpen: () => {}, onClose: () => {}, onSelectProfile: () => {} }
+  return { store: staticStore(state), onRewrite: () => {}, onAsk: () => {}, onStop: () => {}, onDelete: () => {}, onOpen: () => {}, onClose: () => {}, onSelectProfile: () => {} }
 }
 
-function state(collapsed: ReadonlySet<string>, rewrite: ChatState = { ...EMPTY_CHAT, available: true }): BlockTreeState {
+/** 能编辑、能重写注释的块树，动作什么都不做；view 盖在默认的状态上（什么都没折、没筛掉） */
+function tree(view: Partial<Omit<BlockTreeState, 'folds'>> = {}, rewrite: ChatState = { ...EMPTY_CHAT, available: true }): BlockTreeHandle {
   return {
-    edit: {
-      version: 1,
-      editing: new Set(),
-      focusId: null,
-      onFocused: () => {},
-      onToggleEdit: () => {},
-    },
-    rewrite: rewriteTree(rewrite),
-    collapsed,
-    hidden: new Set(),
-    temporary: new Set(),
-    covered: new Map(),
-    kindName: kind => kind,
+    state: staticStore(treeState({
+      edit: { version: 1, editing: new Set(), focusId: null },
+      collapsed: new Set(),
+      hidden: new Set(),
+      temporary: new Set(),
+      covered: new Map(),
+      ...view,
+    })),
     onToggleFold: () => {},
     onSetFolds: () => {},
     onOpenRun: () => {},
+    edit: { onToggleEdit: () => {}, onFocused: () => {} },
+    rewrite: rewriteTree(rewrite),
   }
 }
 
+function markup(blocks: BlockView[], handle: BlockTreeHandle): string {
+  return renderToStaticMarkup(<BlockTree blocks={blocks} tree={handle} />)
+}
+
 function render(folds: Record<string, boolean>): string {
-  return renderToStaticMarkup(<BlockLevel blocks={[CARD]} tree={state(collapsedIds([CARD], folds))} />)
+  return markup([CARD], tree({ collapsed: collapsedIds([CARD], folds) }))
 }
 
 describe('路由筛选后展开函数体', () => {
@@ -118,11 +117,11 @@ describe('路由筛选后展开函数体', () => {
     const attributes = fileAttributes(blocks, pythonZhTranslator.attributeNames)
     const excluded = { kind: attributes.find(attribute => attribute.id === 'kind')!.values.map(value => value.id).filter(kind => kind !== 'fastapi.route') }
     const filtered = applyFilter(blocks, excluded, new Set())
-    const tree = { ...state(collapsedIds(blocks, {})), ...filtered }
-    const closed = renderToStaticMarkup(<BlockLevel blocks={blocks} tree={tree} />)
+    const view = { collapsed: collapsedIds(blocks, {}), hidden: filtered.hidden, temporary: filtered.temporary }
+    const closed = markup(blocks, tree(view))
     expect(closed).toContain('aria-label="展开子块"')
     expect(closed).not.toContain('enabled-body')
-    const opened = renderToStaticMarkup(<BlockLevel blocks={blocks} tree={{ ...tree, collapsed: new Set() }} />)
+    const opened = markup(blocks, tree({ ...view, collapsed: new Set() }))
     expect(opened).toContain('enabled-body')
     expect(opened).toContain('disabled-body')
     expect(opened).not.toContain('unrelated-body')
@@ -182,14 +181,13 @@ describe('挂在卡片子行上的子块', () => {
 describe('卡片记着块记号', () => {
   it('每张卡片带着它那块的记号（data-anchor）：说明里不带路径的引用靠它认自己写在哪块', () => {
     const method = view('0.1', 'function', '', { anchor: 'class AgentService > function get_default_agent', translation: { markdown: '先看 [get_agent_admitted]' } })
-    const markup = renderToStaticMarkup(<BlockLevel blocks={[method]} tree={state(new Set())} />)
-    expect(markup).toMatch(/<div class="cr-block [^"]*"[^>]*data-anchor="class AgentService &gt; function get_default_agent"[\s\S]*href="symbol:get_agent_admitted"/)
+    expect(markup([method], tree())).toMatch(/<div class="cr-block [^"]*"[^>]*data-anchor="class AgentService &gt; function get_default_agent"[\s\S]*href="symbol:get_agent_admitted"/)
   })
 })
 
 describe('「注释」一行和「重写注释」按钮', () => {
   const comment = { label: '注释', value: { markdown: '按名字找' } }
-  const html = (block: BlockView): string => renderToStaticMarkup(<BlockLevel blocks={[block]} tree={state(new Set())} />)
+  const html = (block: BlockView): string => markup([block], tree())
   /** 按钮只有一个，排在右上角那排按钮（块操作）的最前面 */
   const inToolbar = (markup: string, label: string): void => {
     expect(markup.match(new RegExp(`aria-label="${label}"`, 'g'))).toHaveLength(1)
@@ -216,10 +214,10 @@ describe('「注释」一行和「重写注释」按钮', () => {
     const block = view('5', 'statement', 'save()', { commentTarget: { kind: 'replace', startLine: 0, endLine: 0 } })
     const entry = { id: 'r1', question: '/ecc:writing-code-comments a.py:1-1', answer: '保存。', createdAt: '2026-09-25T10:00:00.000Z' }
     const closed = { ...EMPTY_CHAT, available: true, threads: [{ anchor: block.anchor, entries: [entry] }] }
-    const collapsedMarkup = renderToStaticMarkup(<BlockLevel blocks={[block]} tree={state(new Set(), closed)} />)
+    const collapsedMarkup = markup([block], tree({}, closed))
     expect(collapsedMarkup.replace(/<[^>]*>/g, '')).toContain('重写过 1 次')
     inToolbar(collapsedMarkup, '展开重写记录')
-    const opened = renderToStaticMarkup(<BlockLevel blocks={[block]} tree={state(new Set(), { ...closed, open: [block.anchor] })} />)
+    const opened = markup([block], tree({}, { ...closed, open: [block.anchor] }))
     expect(opened).toMatch(/role="group" aria-label="块操作"><button[^>]*aria-label="按注释规范重写"/)
     expect(opened).toContain('<section class="cr-qa" aria-label="按注释规范重写">')
     expect(opened).toContain('aria-label="对这段注释的修改意见"')
@@ -229,8 +227,7 @@ describe('「注释」一行和「重写注释」按钮', () => {
     const block = view('6', 'statement', 'save()', { commentTarget: { kind: 'replace', startLine: 0, endLine: 0 } })
     const button = (status: Ask['status']): string => {
       const rewrite = { ...EMPTY_CHAT, available: true, open: [block.anchor], asks: [{ askId: 'r1', anchor: block.anchor, question: 'q', text: '', status }] }
-      const markup = renderToStaticMarkup(<BlockLevel blocks={[block]} tree={state(new Set(), rewrite)} />)
-      return /<button[^>]*aria-label="按注释规范重写"[^>]*>/.exec(markup)?.[0] ?? ''
+      return /<button[^>]*aria-label="按注释规范重写"[^>]*>/.exec(markup([block], tree({}, rewrite)))?.[0] ?? ''
     }
     expect(button('running')).toContain('disabled')
     expect(button('queued')).toContain('disabled')
@@ -266,7 +263,7 @@ describe('一行译文下面拆开的各项', () => {
   /** 画成页面（只画这一块），collapsed 是折叠着的 id */
   function page(block: BlockView, collapsed: ReadonlySet<string> = new Set(), diff?: BlockTreeState['diff']): HTMLElement {
     const root = document.createElement('div')
-    root.innerHTML = renderToStaticMarkup(<BlockLevel blocks={[block]} tree={{ ...state(collapsed), ...(diff && { diff }) }} />)
+    root.innerHTML = markup([block], tree({ collapsed, ...(diff && { diff }) }))
     return root
   }
 
diff --git a/vscode/webview-ui/src/codeReader/BlockTree.tsx b/vscode/webview-ui/src/codeReader/BlockTree.tsx
index dffc090..dcbd6c1 100644
--- a/vscode/webview-ui/src/codeReader/BlockTree.tsx
+++ b/vscode/webview-ui/src/codeReader/BlockTree.tsx
@@ -2,11 +2,12 @@ import type { CSSProperties, ReactElement, ReactNode } from 'react'
 import type { RewriteTool } from './BlockTools'
 import type { DiffTree, FoldedRuns, PlacedRemoved } from './diffView'
 import type { GridSlots } from './PropertyGrid'
-import type { ChatState, QaState } from './qa'
+import type { ChatState, ChatView, QaState } from './qa'
 import type { PendingImage } from './qaImages'
-import type { BlockMarks, BlockView } from './types'
+import type { ReadableStore } from './store'
+import type { BlockMarks, BlockView, ChangedBlock } from './types'
 import { ChevronDown, ChevronRight, ChevronsUpDown, EyeOff } from 'lucide-react'
-import { Fragment, useState } from 'react'
+import { createContext, Fragment, memo, useContext, useMemo, useState } from 'react'
 import { AskThread, REWRITE_THREAD } from './AskThread'
 import { BlockTools } from './BlockTools'
 import { CodeEditor } from './CodeEditor'
@@ -14,62 +15,74 @@ import { DiffText } from './DiffText'
 import { removedTitle } from './diffView'
 import { KindIcon } from './kindIcons'
 import { PropertyGrid, PropertyItems, PropertyTable } from './PropertyGrid'
-import { asksOf, historyOf, unfinished } from './qa'
+import { chatOf, EMPTY_CHAT, sameChat, unfinished } from './qa'
+import { shallowEqual, staticStore, useStore } from './store'
 import { TextPreview } from './TextPreview'
-import { listId, tableId } from './viewState'
+import { foldsByCard, listId, tableId } from './viewState'
 
-/**
- * 块树里改代码的那部分：哪些块在编辑、点「编辑」。页面上的块树才有；定义卡片浮窗里的块树没有，
- * 卡片只读，不画右上角的按钮
- */
-export interface EditTree {
+/** 块树里改代码的那部分状态：哪些块在编辑。页面上的块树才有；定义卡片浮窗里的块树没有，卡片只读，不画右上角的按钮 */
+export interface EditState {
   version: number
   editing: ReadonlySet<string>
   /** 刚点了「编辑」、要把光标放进去的块 */
   focusId: string | null
-  onFocused: () => void
-  onToggleEdit: (id: string) => void
 }
 
-/** 函数、类落在几棵调用树里。定义浮窗不传，跟问 AI 一样不画这排按钮。 */
-export interface CallTreeTools {
+/** 函数、类落在几棵调用树里，开着哪一块的弹框。定义浮窗没有，跟问 AI 一样不画这排按钮。 */
+export interface CallTreeState {
   counts: ReadonlyMap<string, number>
   openAnchor?: string
-  onOpen: (anchor: string) => void
 }
 
+/**
+ * 块树要画的、会变的状态：一份不可变的快照，放在 BlockTreeHandle.state 里。每张卡片只订阅自己用到的那部分（useStore），
+ * 一处变了只重画受影响的卡片。
+ */
 export interface BlockTreeState {
   /** 能编辑（页面上的块树）；定义卡片浮窗里没有 */
-  edit?: EditTree
-  /** 调用树。只读的树不传 */
-  callTree?: CallTreeTools
+  edit?: EditState
+  /** 调用树。只读的树没有 */
+  callTree?: CallTreeState
   /** 眼下折叠着的块 id、属性行 id 和子行 id（propertyRowId、propertyItemId）：用户的选择叠在默认上，见 collapsedIds */
   collapsed: ReadonlySet<string>
+  /** collapsed 按卡片分好的（见 foldsByCard）：卡片和它的属性表只看自己那份 */
+  folds: ReadonlyMap<string, ReadonlySet<string>>
   /** 按筛选不画的块（连同子孙），见 applyFilter */
   hidden: ReadonlySet<string>
   /** 本来被筛掉、跳到定义时临时显示的块 */
   temporary: ReadonlySet<string>
   /** 被正在编辑的祖先盖住、不画的块（它们的代码在祖先的编辑框里），见 coveredByEditing */
   covered: ReadonlyMap<string, string>
-  /** 种类叫什么（种类图标的悬停提示和 aria-label）：翻译插件给种类起的名字（库规则的种类是规则给的 badge.label），没给就是 id */
-  kindName: (kind: string) => string
+  /** 代码差异：新增、修改的块和删掉的块；侧栏开着「未提交的更改」或审查工单、基准里有这个文件时才有 */
+  diff?: DiffTree
+  /** 「只看改动」开着时折起来的连着没变的块（见 foldUnchanged） */
+  folded?: FoldedRuns
+}
+
+/**
+ * 一棵块树：会变的状态（state，卡片按自己那部分订阅）和动作。整页一份、不跟着状态变，卡片拿到的回调一直是同一个，
+ * 卡片照 memo 跳过重画。
+ */
+export interface BlockTreeHandle {
+  state: ReadableStore<BlockTreeState>
   onToggleFold: (id: string) => void
   /** 一次记下几块、几行折叠还是展开（点子行展开一块、同一行里别的收起） */
   onSetFolds: (folds: Record<string, boolean>) => void
-  /** 问 AI；文件不在工作区文件夹里（问答没地方存）时没有 */
-  qa?: QaTree
-  /** 按注释规范重写；同问 AI，文件不在工作区文件夹里时没有 */
-  rewrite?: RewriteTree
-  /** 代码差异：新增、修改的块和删掉的块；侧栏开着「未提交的更改」或审查工单、基准里有这个文件时才有 */
-  diff?: DiffTree
-  /** 「只看改动」开着时折起来的连着没变的块（见 foldUnchanged）；onOpenRun 点开一段（按第一块的 id） */
-  folded?: FoldedRuns
+  /** 「只看改动」时点开一段折起来的块（按第一块的 id） */
   onOpenRun: (id: string) => void
+  /** 编辑：点「编辑 / 预览」、光标放进去之后。和 state.edit 同时有 */
+  edit?: { onToggleEdit: (id: string) => void, onFocused: () => void }
+  /** 打开一块的调用树弹框。和 state.callTree 同时有 */
+  onOpenCall?: (anchor: string) => void
+  /** 问 AI；文件不在工作区文件夹里（问答没地方存）时 state 里 available 是 false */
+  qa?: QaTree
+  /** 按注释规范重写；同问 AI */
+  rewrite?: RewriteTree
 }
 
-/** 重写注释的状态和动作，块按自己的记号（anchor）取；profile 下拉是自己的，和问 AI 的互不影响 */
+/** 重写注释的状态（块按自己的记号订阅）和动作；profile 下拉是自己的，和问 AI 的互不影响 */
 export interface RewriteTree {
-  state: ChatState
+  store: ReadableStore<ChatState>
   /** 点了块右上角的按钮：按技能命令重写这块（开新会话），展开它的重写记录 */
   onRewrite: (anchor: string) => void
   /** 在输入框里说的修改意见，接着这块最近一次重写的会话说；images 是贴的图片 */
@@ -82,9 +95,9 @@ export interface RewriteTree {
   onSelectProfile: (id: string) => void
 }
 
-/** 问 AI 的状态和动作，块按自己的记号（anchor）取 */
+/** 问 AI 的状态（块按自己的记号订阅）和动作 */
 export interface QaTree {
-  state: QaState
+  store: ReadableStore<QaState>
   onToggle: (anchor: string) => void
   onClose: (anchor: string) => void
   /** images 是贴进输入框的图片，随问题一起发 */
@@ -95,19 +108,47 @@ export interface QaTree {
   onSelectProfile: (id: string) => void
 }
 
+const BlockTreeContext = createContext<BlockTreeHandle | null>(null)
+
+function useBlockTree(): BlockTreeHandle {
+  const tree = useContext(BlockTreeContext)
+  if (!tree)
+    throw new Error('块树外面没有 BlockTree')
+  return tree
+}
+
+/** 一棵块树：blocks 是顶层的块，tree 是它的状态和动作（见 BlockTreeHandle）。 */
+export function BlockTree({ blocks, tree }: { blocks: BlockView[], tree: BlockTreeHandle }): ReactElement {
+  return (
+    <BlockTreeContext value={tree}>
+      <BlockLevel blocks={blocks} />
+    </BlockTreeContext>
+  )
+}
+
+/** 块树的状态：folds 由 collapsed 按卡片分好（见 foldsByCard），和 previous 里一样的那几份沿用。 */
+export function treeState(state: Omit<BlockTreeState, 'folds'>, previous?: BlockTreeState): BlockTreeState {
+  return { ...state, folds: foldsByCard(state.collapsed, previous?.folds) }
+}
+
+const NO_FOLDS: ReadonlySet<string> = new Set()
+const NO_REMOVED: readonly PlacedRemoved[] = []
+/** 没有问 AI、重写注释的块树（定义卡片浮窗）：一直不能用 */
+const NO_CHAT: ReadableStore<ChatState> = staticStore(EMPTY_CHAT)
+
 /**
  * 块下面有没有画出来的子块（删掉的子块也算）：子块都被筛掉、被盖住时不留空的一层、不给折叠箭头。
  * 挂在卡片子行上的子块（BlockSlot）画在卡片属性表里，不算。
  */
-function hasShownChildren(block: BlockView, tree: BlockTreeState): boolean {
-  return block.children.some(child => !child.slot && shown(child, tree)) || (!tree.covered.has(block.id) && tree.diff?.removed.has(block.id) === true)
+function hasShownChildren(block: BlockView, state: BlockTreeState): boolean {
+  return block.children.some(child => !child.slot && shown(child, state)) || (!state.covered.has(block.id) && state.diff?.removed.has(block.id) === true)
 }
 
 const CHANGE_NAMES = { add: '新增', mod: '修改', del: '删除' } as const
 
 /** 标差异时卡片左边外侧的改动色条（没变的留一条透明的，同一层照样对齐）；不标差异时原样。 */
-function ChangeRow({ tree, change, children }: { tree: BlockTreeState, change: keyof typeof CHANGE_NAMES | undefined, children: ReactNode }): ReactElement {
-  if (!tree.diff)
+function ChangeRow({ diff, change, children }: { diff: boolean, change: keyof typeof CHANGE_NAMES | undefined, children: ReactNode }): ReactElement {
+  if (!diff)
     return <>{children}</>
   return (
     <div className="cr-change-row flex gap-[5px]">
@@ -118,9 +159,9 @@ function ChangeRow({ tree, change, children }: { tree: BlockTreeState, change: k
 }
 
 /** 「只看改动」时连着没变的几块折成的一条「… N 块没变」，点开恢复这几块。 */
-function UnchangedStrip({ count, tree, onOpen }: { count: number, tree: BlockTreeState, onOpen: () => void }): ReactElement {
+function UnchangedStrip({ count, onOpen }: { count: number, onOpen: () => void }): ReactElement {
   return (
-    <ChangeRow tree={tree} change={undefined}>
+    <ChangeRow diff change={undefined}>
       <button type="button" className="cr-unchanged flex h-[22px] w-full items-center gap-1.5 rounded px-2.5 text-xs" onClick={onOpen}>
         <ChevronsUpDown size={12} strokeWidth={1.8} className="shrink-0" aria-hidden />
         {`… ${count} 块没变`}
@@ -131,8 +172,8 @@ function UnchangedStrip({ count, tree, onOpen }: { count: number, tree: BlockTre
 }
 
 /** 块画不画：被筛掉的、被正在编辑的祖先盖住的都不画。 */
-function shown(block: BlockView, tree: BlockTreeState): boolean {
-  return !tree.hidden.has(block.id) && !tree.covered.has(block.id)
+function shown(block: BlockView, state: BlockTreeState): boolean {
+  return !state.hidden.has(block.id) && !state.covered.has(block.id)
 }
 
 /**
@@ -148,24 +189,184 @@ export function kindProps(block: Pick<BlockView, 'kind' | 'badge'> | undefined):
   return { 'data-kind': block.kind, 'data-badge': '', 'style': { '--kind-dark': dark, '--kind-light': light } as CSSProperties }
 }
 
+/** 一块画成什么样要的块树状态：只选这一块自己的，别的块变了它不重画。 */
+interface BlockShape {
+  /** 画不画：被筛掉的、被正在编辑的祖先盖住的、「只看改动」折起来的不画 */
+  shown: boolean
+  /** 「只看改动」时从这块起折起来的一段有几块 */
+  run?: number
+  /** 子块那一层画不画 */
+  open: boolean
+  /** 标差异 */
+  diff: boolean
+  change?: ChangedBlock
+  /** 页面上正是差异算的那一版：卡片里的标记这时才画 */
+  current: boolean
+  editing: boolean
+  /** 这张卡片里折叠着的（见 foldsByCard） */
+  folds: ReadonlySet<string>
+  hasChildren: boolean
+  temporary: boolean
+  focus: boolean
+  /** 编辑框每来一份新文档都要对一次内容；不在编辑的卡片不跟着版本重画 */
+  version?: number
+  /** 调用树：扩展端标了能看调用树（BlockView.callTree）的块才有棵数 */
+  calls?: number
+  callOpen: boolean
+}
+
+function shapeOf(block: BlockView, state: BlockTreeState): BlockShape {
+  const editing = state.edit?.editing.has(block.id) ?? false
+  return {
+    shown: shown(block, state) && !state.folded?.folded.has(block.id),
+    run: state.folded?.runs.get(block.id),
+    open: hasShownChildren(block, state) && !state.collapsed.has(block.id),
+    diff: state.diff !== undefined,
+    change: state.diff?.changes.get(block.id),
+    current: state.diff?.current ?? false,
+    editing,
+    folds: state.folds.get(block.id) ?? NO_FOLDS,
+    // 点父卡片子行才展开的子块：画出来就是展开着的，箭头收起整张
+    hasChildren: block.slot !== undefined || hasShownChildren(block, state),
+    temporary: state.temporary.has(block.id),
+    focus: state.edit?.focusId === block.id,
+    version: editing ? state.edit?.version : undefined,
+    calls: state.callTree && block.callTree ? state.callTree.counts.get(block.anchor) ?? 0 : undefined,
+    callOpen: state.callTree?.openAnchor === block.anchor,
+  }
+}
+
+/** 一块的问 AI：能问（文件在工作区文件夹里）时按钮展开没有；对话区展开着或说过时才有，没展开又没说过的块不画。 */
+interface AskShape {
+  asking?: boolean
+  chat?: ChatView
+}
+
+const NO_ASK: AskShape = {}
+
+function askOf(anchor: string, state: ChatState): AskShape {
+  if (!state.available)
+    return NO_ASK
+  const chat = chatOf(state, anchor)
+  return { asking: chat.open, ...((chat.open || chat.history.length > 0) && { chat }) }
+}
+
+/**
+ * 一块的重写注释：能写注释的块才有按钮。重写过、记录收着时点了先展开记录（好接着说）；展开着、或还没重写过时点了按技能命令重写。
+ * 展开着又正在写、排着队时不能再点。重写记录同问 AI 的对话区。
+ */
+interface RewriteShape {
+  tool?: Omit<RewriteTool, 'onRewrite'>
+  chat?: ChatView
+}
+
+const NO_REWRITE: RewriteShape = {}
+
+function rewriteOf(block: BlockView, state: ChatState): RewriteShape {
+  if (!state.available)
+    return NO_REWRITE
+  const chat = chatOf(state, block.anchor)
+  return {
+    ...(block.commentTarget && {
+      tool: {
+        fresh: block.commentTarget.kind === 'insert',
+        rewriting: chat.open && chat.asks.some(unfinished),
+        reopen: !chat.open && (chat.asks.length > 0 || chat.history.length > 0),
+      },
+    }),
+    ...((chat.open || chat.history.length > 0) && { chat }),
+  }
+}
+
+function sameChatIn(a: ChatView | undefined, b: ChatView | undefined): boolean {
+  return a === b || (a !== undefined && b !== undefined && sameChat(a, b))
+}
+
+function sameAsk(a: AskShape, b: AskShape): boolean {
+  return a.asking === b.asking && sameChatIn(a.chat, b.chat)
+}
+
+function sameRewrite(a: RewriteShape, b: RewriteShape): boolean {
+  return shallowEqual(a.tool, b.tool) && sameChatIn(a.chat, b.chat)
+}
+
+/**
+ * 一块：「只看改动」折起来的一段、卡片、下面的问答区和重写记录、子块那一层。块树、问 AI、重写注释三份状态里只订阅这一块自己的，
+ * 都没变就不重画；子块那一层的各块、卡片的内容各自 memo，这一块重画了它们也不跟着重画。
+ */
+const BlockItem = memo(({ block }: { block: BlockView }): ReactElement => {
+  const tree = useBlockTree()
+  const { qa, rewrite } = tree
+  const shape = useStore(tree.state, state => shapeOf(block, state), shallowEqual)
+  const ask = useStore(qa?.store ?? NO_CHAT, state => askOf(block.anchor, state), sameAsk)
+  const rewriting = useStore(rewrite?.store ?? NO_CHAT, state => rewriteOf(block, state), sameRewrite)
+  const { anchor } = block
+  return (
+    <>
+      {shape.run !== undefined && <UnchangedStrip count={shape.run} onOpen={() => tree.onOpenRun(block.id)} />}
+      {shape.shown && (
+        <>
+          <ChangeRow diff={shape.diff} change={shape.change?.change}>
+            <BlockCard block={block} shape={shape} ask={ask} rewrite={rewriting} />
+          </ChangeRow>
+          {/* 输入框、展开状态跟着块的记号走，文档刷新块 id 变了也不丢 */}
+          {qa && ask.chat && (
+            <AskThread
+              key={anchor}
+              history={ask.chat.history}
+              asks={ask.chat.asks}
+              open={ask.chat.open}
+              profiles={ask.chat.profiles}
+              onSelectProfile={qa.onSelectProfile}
+              onAsk={(question, images) => qa.onAsk(anchor, question, images)}
+              onStop={qa.onStop}
+              onDelete={entryId => qa.onDelete(anchor, entryId)}
+              onClose={() => qa.onClose(anchor)}
+            />
+          )}
+          {/* 重写记录紧跟在问答区后面；样子和问答区一样，输入框里说的是对这段注释的修改意见 */}
+          {rewrite && rewriting.chat && (
+            <AskThread
+              key={`rewrite ${anchor}`}
+              wording={REWRITE_THREAD}
+              history={rewriting.chat.history}
+              asks={rewriting.chat.asks}
+              open={rewriting.chat.open}
+              profiles={rewriting.chat.profiles}
+              onSelectProfile={rewrite.onSelectProfile}
+              onAsk={(request, images) => rewrite.onAsk(anchor, request, images)}
+              onStop={rewrite.onStop}
+              onDelete={entryId => rewrite.onDelete(anchor, entryId)}
+              onClose={() => rewrite.onClose(anchor)}
+            />
+          )}
+          {shape.open && <BlockLevel blocks={block.children} owner={block} />}
+        </>
+      )}
+    </>
+  )
+})
+BlockItem.displayName = 'BlockItem'
+
 /**
  * 一层代码块：左边一条竖线标出这一层，每块的子块紧跟在它下面、再往右缩进一层。被筛掉、被盖住的块不画，不留空位，竖线跟着变短。
  * owner 是这一层所属的块（顶层没有，记在 data-owner 上，钉住卡片时按它算卡片连同子块管到哪、套着几层），悬停它时竖线换成它的种类色。
  * 标差异时每张卡片左边外侧一条改动色条，删掉的块收成一行放回原来的位置（见 RemovedCard）；「只看改动」时连着没变的块折成一条（UnchangedStrip）。
  * slotted：这一层是画在卡片属性表某一行下面的子块（BlockSlot），blocks 只有那几块。
  */
-export function BlockLevel({ blocks, owner, tree, slotted = false }: { blocks: BlockView[], owner?: BlockView, tree: BlockTreeState, slotted?: boolean }): ReactElement {
+export function BlockLevel({ blocks, owner, slotted = false }: { blocks: BlockView[], owner?: BlockView, slotted?: boolean }): ReactElement {
+  const tree = useBlockTree()
   // 挂在卡片子行上的子块画在卡片属性表里（slotted 的那一层），这一层不画；删掉的块都放回卡片后面这一层
-  const listed = slotted ? blocks : blocks.filter(block => !block.slot)
-  const removed = slotted ? [] : tree.diff?.removed.get(owner?.id ?? '') ?? []
+  const listed = useMemo(() => slotted ? blocks : blocks.filter(block => !block.slot), [blocks, slotted])
+  const removed = useStore(tree.state, state => slotted ? NO_REMOVED : state.diff?.removed.get(owner?.id ?? '') ?? NO_REMOVED)
   const listedIds = new Set(listed.map(block => block.id))
   // 删掉的块排在它原来前面那块后面；那块被筛掉了也照排，不跟着消失；那块画在卡片里时排到这一层最后
   const removedAfter = (id: string | undefined): ReactElement[] => removed
     .filter(item => item.after === id)
-    .map(item => <RemovedCard key={item.id} placed={item} tree={tree} />)
+    .map(item => <RemovedCard key={item.id} placed={item} />)
   const removedElsewhere = removed
     .filter(item => item.after !== undefined && !listedIds.has(item.after))
-    .map(item => <RemovedCard key={item.id} placed={item} tree={tree} />)
+    .map(item => <RemovedCard key={item.id} placed={item} />)
   return (
     <div className="cr-level flex gap-2" {...kindProps(owner)} data-owner={owner?.id}>
       <div className="flex w-3 shrink-0 justify-center">
@@ -175,19 +376,7 @@ export function BlockLevel({ blocks, owner, tree, slotted = false }: { blocks: B
         {removedAfter(undefined)}
         {listed.map(block => (
           <Fragment key={block.id}>
-            {tree.folded?.runs.has(block.id) && <UnchangedStrip count={tree.folded.runs.get(block.id) ?? 0} tree={tree} onOpen={() => tree.onOpenRun(block.id)} />}
-            {shown(block, tree) && !tree.folded?.folded.has(block.id) && (
-              <>
-                <ChangeRow tree={tree} change={tree.diff?.changes.get(block.id)?.change}>
-                  <BlockCard block={block} tree={tree} />
-                </ChangeRow>
-                {tree.qa && <BlockQa key={block.anchor} anchor={block.anchor} qa={tree.qa} />}
-                {tree.rewrite && <BlockRewrite key={`rewrite ${block.anchor}`} anchor={block.anchor} rewrite={tree.rewrite} />}
-                {hasShownChildren(block, tree) && !tree.collapsed.has(block.id) && (
-                  <BlockLevel blocks={block.children} owner={block} tree={tree} />
-                )}
-              </>
-            )}
+            <BlockItem block={block} />
             {removedAfter(block.id)}
           </Fragment>
         ))}
@@ -197,50 +386,17 @@ export function BlockLevel({ blocks, owner, tree, slotted = false }: { blocks: B
   )
 }
 
-/** 块下面的问答区，紧跟在块后面、子块前面；输入框、展开状态跟着块的记号走，文档刷新块 id 变了也不丢 */
-function BlockQa({ anchor, qa }: { anchor: string, qa: QaTree }): ReactElement {
-  return (
-    <AskThread
-      history={historyOf(qa.state, anchor)}
-      asks={asksOf(qa.state, anchor)}
-      open={qa.state.open.includes(anchor)}
-      profiles={qa.state.profiles}
-      onSelectProfile={qa.onSelectProfile}
-      onAsk={(question, images) => qa.onAsk(anchor, question, images)}
-      onStop={qa.onStop}
-      onDelete={entryId => qa.onDelete(anchor, entryId)}
-      onClose={() => qa.onClose(anchor)}
-    />
-  )
-}
-
-/** 块下面的重写记录，紧跟在问答区后面；样子和问答区一样，输入框里说的是对这段注释的修改意见 */
-function BlockRewrite({ anchor, rewrite }: { anchor: string, rewrite: RewriteTree }): ReactElement | null {
-  return (
-    <AskThread
-      wording={REWRITE_THREAD}
-      history={historyOf(rewrite.state, anchor)}
-      asks={asksOf(rewrite.state, anchor)}
-      open={rewrite.state.open.includes(anchor)}
-      profiles={rewrite.state.profiles}
-      onSelectProfile={rewrite.onSelectProfile}
-      onAsk={(request, images) => rewrite.onAsk(anchor, request, images)}
-      onStop={rewrite.onStop}
-      onDelete={entryId => rewrite.onDelete(anchor, entryId)}
-      onClose={() => rewrite.onClose(anchor)}
-    />
-  )
-}
-
 /**
  * 预览状态的内容：函数、类、枚举、导入、常量、变量块和库规则的卡片是属性表，其余是一行译文；
  * 译文下面依次接着拆开的各项（跨几行写的字面量，排法同变量初始值下面的）、摊开实参的表（跨几行写的调用）、说明、几行属性（「注释」一行）。
- * 标差异时 marks 是这块自己的内容改了哪些（页面上正是差异算的那一版才给）。
+ * folds 是这张卡片里折叠着的（见 foldsByCard）；标差异时 marks 是这块自己的内容改了哪些（页面上正是差异算的那一版才给）。
  */
-function BlockPreview({ block, tree, marks }: { block: BlockView, tree: BlockTreeState, marks?: BlockMarks }): ReactElement {
+const BlockPreview = memo(({ block, folds, marks }: { block: BlockView, folds: ReadonlySet<string>, marks?: BlockMarks }): ReactElement => {
+  const tree = useBlockTree()
+  const slots = useMemo(() => cardSlots(block, folds, tree), [block, folds, tree])
   if ('properties' in block)
-    return <PropertyGrid blockId={block.id} rows={block.properties} collapsed={tree.collapsed} onToggleFold={tree.onToggleFold} marks={marks?.rows} slots={cardSlots(block, tree)} />
-  const folding = { collapsed: tree.collapsed, onToggleFold: tree.onToggleFold }
+    return <PropertyGrid blockId={block.id} rows={block.properties} collapsed={folds} onToggleFold={tree.onToggleFold} marks={marks?.rows} slots={slots} />
+  const folding = { collapsed: folds, onToggleFold: tree.onToggleFold }
   return (
     <>
       {marks?.translation ? <DiffText diff={marks.translation} /> : <TextPreview text={block.translation} />}
@@ -257,59 +413,27 @@ function BlockPreview({ block, tree, marks }: { block: BlockView, tree: BlockTre
       {marks?.doc ? <DiffText diff={marks.doc} className="mt-0.5" /> : block.doc && <TextPreview text={block.doc} className="mt-0.5" />}
       {block.rows && (
         <div className="mt-[3px]">
-          <PropertyGrid blockId={block.id} rows={block.rows} collapsed={tree.collapsed} onToggleFold={tree.onToggleFold} marks={marks?.rows} />
+          <PropertyGrid blockId={block.id} rows={block.rows} collapsed={folds} onToggleFold={tree.onToggleFold} marks={marks?.rows} />
         </div>
       )}
     </>
   )
-}
-
-/** 这块的调用树按钮：扩展端标了能看调用树（BlockView.callTree）的块才有。 */
-function callTreeTool(block: BlockView, tree: BlockTreeState) {
-  const callTree = tree.callTree
-  if (!callTree || !block.callTree)
-    return undefined
-  return {
-    anchor: block.anchor,
-    count: callTree.counts.get(block.anchor) ?? 0,
-    open: callTree.openAnchor === block.anchor,
-    onOpen: () => callTree.onOpen(block.anchor),
-  }
-}
-
-/**
- * 这块的「重写注释」按钮：能写注释的块才有。重写过、记录收着时点了先展开记录（好接着说）；展开着、或还没重写过时点了按技能命令重写。
- * 展开着又正在写、排着队时不能再点。
- */
-function rewriteTool(block: BlockView, tree: BlockTreeState): RewriteTool | undefined {
-  const { edit, rewrite } = tree
-  if (!edit || !rewrite || !block.commentTarget)
-    return undefined
-  const { anchor } = block
-  const open = rewrite.state.open.includes(anchor)
-  const asks = asksOf(rewrite.state, anchor)
-  const reopen = !open && (asks.length > 0 || historyOf(rewrite.state, anchor).length > 0)
-  return {
-    fresh: block.commentTarget.kind === 'insert',
-    rewriting: open && asks.some(unfinished),
-    reopen,
-    onRewrite: () => reopen ? rewrite.onOpen(anchor) : rewrite.onRewrite(anchor),
-  }
-}
+})
+BlockPreview.displayName = 'BlockPreview'
 
 /**
  * 挂在卡片子行上的子块（BlockSlot）怎么画：一行下面展开着的几块画成一层块（同块树）；点那个子行的第一格展开它、
  * 同一行里别的收起，展开着的再点收起。卡片没有挂在子行上的子块时没有。
  */
-function cardSlots(block: BlockView, tree: BlockTreeState): GridSlots | undefined {
+function cardSlots(block: BlockView, folds: ReadonlySet<string>, tree: BlockTreeHandle): GridSlots | undefined {
   const blocks = block.children.filter(child => child.slot)
   if (blocks.length === 0)
     return undefined
   return {
     blocks,
-    render: list => <BlockLevel blocks={list} owner={block} tree={tree} slotted />,
+    render: list => <BlockLevel blocks={list} owner={block} slotted />,
     onToggle: (child) => {
-      if (!tree.collapsed.has(child.id)) {
+      if (!folds.has(child.id)) {
         tree.onSetFolds({ [child.id]: true })
         return
       }
@@ -320,30 +444,30 @@ function cardSlots(block: BlockView, tree: BlockTreeState): GridSlots | undefine
 }
 
 /**
- * 一块：折叠箭头、种类图标、预览内容或源码、右上角的一排图标按钮（BlockTools，只读的块树没有）。
+ * 一块的卡片：折叠箭头、种类图标、预览内容或源码、右上角的一排图标按钮（BlockTools，只读的块树没有）。
  * 卡片上记着块记号（data-anchor），说明里不带路径的引用靠它认自己写在哪块（见 commentLinkOf）。
  */
-function BlockCard({ block, tree }: { block: BlockView, tree: BlockTreeState }): ReactElement {
-  const { edit } = tree
-  const editing = edit?.editing.has(block.id) ?? false
-  const collapsed = tree.collapsed.has(block.id)
-  // 点父卡片子行才展开的子块：画出来就是展开着的，箭头收起整张
+function BlockCard({ block, shape, ask, rewrite }: { block: BlockView, shape: BlockShape, ask: AskShape, rewrite: RewriteShape }): ReactElement {
+  const tree = useBlockTree()
+  const { edit, onOpenCall } = tree
+  const { anchor } = block
+  const collapsed = shape.folds.has(block.id)
   const toggled = block.slot !== undefined
-  const hasChildren = toggled || hasShownChildren(block, tree)
   const Chevron = collapsed && !toggled ? ChevronRight : ChevronDown
-  const change = tree.diff?.changes.get(block.id)
+  const { change } = shape
+  const { tool } = rewrite
   return (
     <div
       className="cr-block relative flex items-start gap-2.5 rounded-lg py-2 pr-2.5 pl-2"
       {...kindProps(block)}
       data-id={block.id}
-      data-anchor={block.anchor}
+      data-anchor={anchor}
       data-line={block.startLine}
-      data-editing={editing ? '' : undefined}
+      data-editing={shape.editing ? '' : undefined}
       data-change={change?.change}
     >
       {change?.outermost && <span className="cr-added-badge">新增</span>}
-      {hasChildren
+      {shape.hasChildren
         ? (
             <button
               type="button"
@@ -358,19 +482,19 @@ function BlockCard({ block, tree }: { block: BlockView, tree: BlockTreeState }):
         : <span className="w-3.5 shrink-0" />}
       <KindIcon concepts={block.concepts} />
       <div className="min-w-0 flex-1">
-        {edit && editing
+        {edit && shape.version !== undefined
           ? (
               <CodeEditor
                 block={block}
-                version={edit.version}
-                autoFocus={edit.focusId === block.id}
+                version={shape.version}
+                autoFocus={shape.focus}
                 onAutoFocused={edit.onFocused}
                 onExit={() => edit.onToggleEdit(block.id)}
               />
             )
-          : <BlockPreview block={block} tree={tree} marks={tree.diff?.current ? change?.marks : undefined} />}
+          : <BlockPreview block={block} folds={shape.folds} marks={shape.current ? change?.marks : undefined} />}
       </div>
-      {tree.temporary.has(block.id) && (
+      {shape.temporary && (
         <span className="cr-temporary flex h-5 shrink-0 items-center gap-1 rounded px-1.5 text-[11px] whitespace-nowrap">
           <EyeOff size={12} strokeWidth={1.8} aria-hidden />
           已被筛选隐藏，临时显示
@@ -378,12 +502,12 @@ function BlockCard({ block, tree }: { block: BlockView, tree: BlockTreeState }):
       )}
       {edit && (
         <BlockTools
-          editing={editing}
+          editing={shape.editing}
           onToggleEdit={() => edit.onToggleEdit(block.id)}
-          asking={tree.qa?.state.open.includes(block.anchor)}
-          onToggleAsk={tree.qa && (() => tree.qa?.onToggle(block.anchor))}
-          rewrite={rewriteTool(block, tree)}
-          callTree={callTreeTool(block, tree)}
+          asking={ask.asking}
+          onToggleAsk={tree.qa && ask.asking !== undefined ? () => tree.qa?.onToggle(anchor) : undefined}
+          rewrite={tree.rewrite && tool && { ...tool, onRewrite: () => tool.reopen ? tree.rewrite?.onOpen(anchor) : tree.rewrite?.onRewrite(anchor) }}
+          callTree={onOpenCall && shape.calls !== undefined ? { anchor, count: shape.calls, open: shape.callOpen, onOpen: () => onOpenCall(anchor) } : undefined}
         />
       )}
     </div>
@@ -394,14 +518,18 @@ function BlockCard({ block, tree }: { block: BlockView, tree: BlockTreeState }):
  * 删掉的一块，放在原来的位置：红色虚线边、半透明，没有编辑、问 AI 按钮。默认收成一行「已删除 · 种类 名字」，
  * 点箭头或这一行展开，下面是旧内容（整张划掉，名字不能跳定义）；子块不画。
  */
-function RemovedCard({ placed, tree }: { placed: PlacedRemoved, tree: BlockTreeState }): ReactElement {
+function RemovedCard({ placed }: { placed: PlacedRemoved }): ReactElement {
+  const tree = useBlockTree()
   const [open, setOpen] = useState(false)
+  const folds = useStore(tree.state, state => state.folds.get(placed.id) ?? NO_FOLDS)
   const { block, kindName } = placed.removed
   const title = removedTitle(block)
   const Chevron = open ? ChevronDown : ChevronRight
   const toggle = (): void => setOpen(value => !value)
+  // 旧块的 id 是旧版本里的位置，换成页面上认删掉的块用的 id，属性行的 id 才不和现在的块撞上
+  const old = useMemo(() => ({ ...block, id: placed.id }), [block, placed.id])
   return (
-    <ChangeRow tree={tree} change="del">
+    <ChangeRow diff change="del">
       <div className="cr-block cr-removed flex items-start gap-2.5 rounded-lg py-2 pr-2.5 pl-2" {...kindProps(block)} data-id={placed.id}>
         <button
           type="button"
@@ -421,8 +549,7 @@ function RemovedCard({ placed, tree }: { placed: PlacedRemoved, tree: BlockTreeS
           </div>
           {open && (
             <div className="cr-removed-old mt-1">
-              {/* 旧块的 id 是旧版本里的位置，换成页面上认删掉的块用的 id，属性行的 id 才不和现在的块撞上 */}
-              <BlockPreview block={{ ...block, id: placed.id }} tree={tree} />
+              <BlockPreview block={old} folds={folds} />
             </div>
           )}
         </div>
diff --git a/vscode/webview-ui/src/codeReader/CallTreeDialog.test.tsx b/vscode/webview-ui/src/codeReader/CallTreeDialog.test.tsx
index ef8616c..bd84207 100644
--- a/vscode/webview-ui/src/codeReader/CallTreeDialog.test.tsx
+++ b/vscode/webview-ui/src/codeReader/CallTreeDialog.test.tsx
@@ -2,18 +2,15 @@
 
 import type { ReactElement } from 'react'
 import type { Root } from 'react-dom/client'
-import type { BlockTreeState } from './BlockTree'
+import type { BlockTreeHandle, CallTreeState } from './BlockTree'
 import type { BlockView, CallTree } from './types'
 import { act, useState } from 'react'
 import { createRoot } from 'react-dom/client'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import { BlockLevel } from './BlockTree'
+import { BlockTree, treeState } from './BlockTree'
 import { CallTreeDialog, splitWhere } from './CallTreeDialog'
+import { staticStore } from './store'
 
-vi.mock('./useOccurrences', async () => {
-  const { createContext } = await import('react')
-  return { HighlightContext: createContext(undefined) }
-})
 vi.mock('./vscode', () => ({ postMessage: () => {}, onMessage: () => () => {}, viewState: { get: () => ({ editing: [], folds: {} }), update: () => {} } }))
 
 let container: HTMLDivElement
@@ -53,26 +50,22 @@ function block(kind: string, id = kind, callTree?: BlockView['callTree']): Block
   }
 }
 
-function tree(callTree?: BlockTreeState['callTree'], edit = true): BlockTreeState {
+/** 块树：callTree 是各块的棵数、开着哪一块的弹框和点按钮时做什么；edit 是 false 时是只读的树 */
+function tree(callTree?: CallTreeState & { onOpen: (anchor: string) => void }, edit = true): BlockTreeHandle {
   return {
-    ...(edit && {
-      edit: {
-        version: 1,
-        editing: new Set<string>(),
-        focusId: null,
-        onFocused: () => {},
-        onToggleEdit: () => {},
-      },
-    }),
-    collapsed: new Set(),
-    hidden: new Set(),
-    temporary: new Set(),
-    covered: new Map(),
-    kindName: kind => kind,
+    state: staticStore(treeState({
+      ...(edit && { edit: { version: 1, editing: new Set<string>(), focusId: null } }),
+      collapsed: new Set(),
+      hidden: new Set(),
+      temporary: new Set(),
+      covered: new Map(),
+      ...(callTree && { callTree: { counts: callTree.counts, ...(callTree.openAnchor !== undefined && { openAnchor: callTree.openAnchor }) } }),
+    })),
     onToggleFold: () => {},
     onSetFolds: () => {},
     onOpenRun: () => {},
-    ...(callTree && { callTree }),
+    ...(edit && { edit: { onToggleEdit: () => {}, onFocused: () => {} } }),
+    ...(callTree && { onOpenCall: callTree.onOpen }),
   }
 }
 
@@ -106,7 +99,7 @@ describe('调用树弹框', () => {
     const counts = new Map([['function', 0], ['class', 2], ['statement', 4], ['route', 1], ['bare', 5]])
     const endpoint = { method: 'GET', path: '/agents' }
     await render(
-      <BlockLevel
+      <BlockTree
         blocks={[block('function', 'function', {}), block('class', 'class', {}), block('statement'), block('fastapi.route', 'route', { endpoint }), block('function', 'bare')]}
         tree={tree({ counts, onOpen: () => {} })}
       />,
@@ -118,7 +111,7 @@ describe('调用树弹框', () => {
     expect(container.querySelector('[data-call-tree="route"]')!.textContent).toBe('1')
     expect(container.querySelector('[data-call-tree="bare"]')).toBeNull()
 
-    await render(<BlockLevel blocks={[block('function', 'function', {})]} tree={tree({ counts: new Map([['function', 3]]), onOpen: () => {} }, false)} />)
+    await render(<BlockTree blocks={[block('function', 'function', {})]} tree={tree({ counts: new Map([['function', 3]]), onOpen: () => {} }, false)} />)
     expect(container.querySelector('[aria-label="块操作"]')).toBeNull()
     expect(container.querySelector('[data-call-tree="function"]')).toBeNull()
   })
@@ -129,7 +122,7 @@ describe('调用树弹框', () => {
       const [open, setOpen] = useState(false)
       return (
         <>
-          <BlockLevel
+          <BlockTree
             blocks={[card]}
             tree={tree({ counts: new Map([['mask', 3]]), openAnchor: open ? 'mask' : undefined, onOpen: () => setOpen(true) })}
           />
diff --git a/vscode/webview-ui/src/codeReader/DefinitionPeekPopup.tsx b/vscode/webview-ui/src/codeReader/DefinitionPeekPopup.tsx
index e3b1472..9858d94 100644
--- a/vscode/webview-ui/src/codeReader/DefinitionPeekPopup.tsx
+++ b/vscode/webview-ui/src/codeReader/DefinitionPeekPopup.tsx
@@ -1,14 +1,15 @@
 import type { ReactElement } from 'react'
-import type { BlockTreeState } from './BlockTree'
+import type { BlockTreeHandle, BlockTreeState } from './BlockTree'
 import type { ShownPeek } from './definitionPeek'
 import type { DefinitionPeek } from './types'
 import { useLayoutEffect, useMemo, useRef, useState } from 'react'
 import { createPortal } from 'react-dom'
-import { BlockLevel } from './BlockTree'
+import { BlockTree, treeState } from './BlockTree'
 import { PEEK_ATTRIBUTE, placePeek } from './definitionPeek'
-import { DisplayNameContext, nameMap } from './displayNames'
+import { nameMap } from './displayNames'
+import { TextMarksContext } from './SegmentText'
+import { createStore, staticStore } from './store'
 import { MarkdownKindContext } from './TextPreview'
-import { HighlightContext } from './useOccurrences'
 import { collapsedIds } from './viewState'
 
 const NONE: ReadonlySet<string> = new Set()
@@ -19,28 +20,30 @@ const NOT_COVERED: ReadonlyMap<string, string> = new Map()
  * 名字的下标是那个文件的：中文名换成卡片带来的，不画页面上的高亮；Markdown 不认不带路径的引用。
  */
 export function PeekTree({ peek }: { peek: DefinitionPeek }): ReactElement {
-  const [folds, setFolds] = useState<Record<string, boolean>>({})
-  const collapsed = useMemo(() => collapsedIds([peek.block], folds), [peek, folds])
-  const names = useMemo(() => nameMap(peek.names), [peek])
-  const tree: BlockTreeState = {
-    collapsed,
-    hidden: NONE,
-    temporary: NONE,
-    covered: NOT_COVERED,
-    kindName: kind => kind,
-    onToggleFold: id => setFolds(prev => ({ ...prev, [id]: !collapsed.has(id) })),
-    onSetFolds: next => setFolds(prev => ({ ...prev, ...next })),
-    // 不标差异就没有「只看改动」折起来的块
-    onOpenRun: () => {},
-  }
+  const [tree] = useState((): BlockTreeHandle => {
+    const viewOf = (folds: Record<string, boolean>, previous?: BlockTreeState): BlockTreeState =>
+      treeState({ collapsed: collapsedIds([peek.block], folds), hidden: NONE, temporary: NONE, covered: NOT_COVERED }, previous)
+    let folds: Record<string, boolean> = {}
+    const state = createStore(viewOf(folds))
+    const setFolds = (next: Record<string, boolean>): void => {
+      folds = { ...folds, ...next }
+      state.set(previous => viewOf(folds, previous))
+    }
+    return {
+      state,
+      onToggleFold: id => setFolds({ [id]: !state.get().collapsed.has(id) }),
+      onSetFolds: setFolds,
+      // 不标差异就没有「只看改动」折起来的块
+      onOpenRun: () => {},
+    }
+  })
+  const marks = useMemo(() => staticStore({ names: nameMap(peek.names) }), [peek])
   return (
-    <HighlightContext value={undefined}>
-      <DisplayNameContext value={names}>
-        <MarkdownKindContext value="peek">
-          <BlockLevel blocks={[peek.block]} tree={tree} />
-        </MarkdownKindContext>
-      </DisplayNameContext>
-    </HighlightContext>
+    <TextMarksContext value={marks}>
+      <MarkdownKindContext value="peek">
+        <BlockTree blocks={[peek.block]} tree={tree} />
+      </MarkdownKindContext>
+    </TextMarksContext>
   )
 }
 
diff --git a/vscode/webview-ui/src/codeReader/SegmentText.test.tsx b/vscode/webview-ui/src/codeReader/SegmentText.test.tsx
index 66b2226..4dd1293 100644
--- a/vscode/webview-ui/src/codeReader/SegmentText.test.tsx
+++ b/vscode/webview-ui/src/codeReader/SegmentText.test.tsx
@@ -1,13 +1,7 @@
 import { renderToStaticMarkup } from 'react-dom/server'
-import { describe, expect, it, vi } from 'vitest'
+import { describe, expect, it } from 'vitest'
 import { SegmentText } from './SegmentText'
 
-// 高亮的上下文所在的模块连着和 VS Code 收发消息的那一套，渲染成 HTML 用不着
-vi.mock('./useOccurrences', async () => {
-  const { createContext } = await import('react')
-  return { HighlightContext: createContext(undefined) }
-})
-
 describe('着色的词', () => {
   it('按词性上色；带自己颜色的词（库规则给的）把暗色、亮色写在 style 上，CSS 按主题挑', () => {
     const html = renderToStaticMarkup(
diff --git a/vscode/webview-ui/src/codeReader/SegmentText.tsx b/vscode/webview-ui/src/codeReader/SegmentText.tsx
index dfa10fb..1f8d962 100644
--- a/vscode/webview-ui/src/codeReader/SegmentText.tsx
+++ b/vscode/webview-ui/src/codeReader/SegmentText.tsx
@@ -1,11 +1,26 @@
 import type { LucideIcon } from 'lucide-react'
 import type { CSSProperties, ReactElement } from 'react'
-import type { GroupStyle, Inline, SegmentGroup } from './types'
-import { useContext, useState } from 'react'
-import { DisplayNameContext, shownName } from './displayNames'
+import type { NameMap } from './displayNames'
+import type { Highlight, OccurrenceStyle } from './occurrences'
+import type { ReadableStore } from './store'
+import type { GroupStyle, Inline, Segment, SegmentGroup, ShownName } from './types'
+import { createContext, memo, useContext, useState } from 'react'
+import { sameShownName, shownName } from './displayNames'
 import { KIND_ICON_COMPONENTS } from './kindIcons'
 import { isCurrent, segmentOccurrence, sourceOf } from './occurrences'
-import { HighlightContext } from './useOccurrences'
+import { staticStore, useStore } from './store'
+
+/** 页面上文字的两样标记：中文名（下标 → 显示成什么），眼下高亮着的名字（没有高亮时没有）。 */
+export interface TextMarks {
+  names: NameMap
+  highlight?: Highlight
+}
+
+/**
+ * 文字的标记从哪份 store 读：页面上是 App 的那份（中文名、单击高亮都记在里面）；定义卡片浮窗是那个文件的中文名，钉住的行不画高亮。
+ * 每段文字只订阅自己那几段的标记。
+ */
+export const TextMarksContext = createContext<ReadableStore<TextMarks>>(staticStore({ names: new Map() }))
 
 /**
  * 按词性给每一段上色，颜色在 codeReader.css 的 .cr-role-* 里按主题切换，带自己颜色（color）的段用它（.cr-colored）；带源码下标的名字记在 data-offset 上
@@ -13,24 +28,25 @@ import { HighlightContext } from './useOccurrences'
  * 再标 data-current。起了中文名的名字显示中文名（data-name），悬停看原名，定义处本身在后面淡淡写原名；下标照旧，跳到定义、高亮照常。
  * 带悬停提示（tooltip）的段悬停看它。
  * 框起来的一组词画成小框，框里的词同样处理。
+ * 中文名和高亮只订阅自己这几段的（TextMarksContext）：中文名到了、换了高亮的名字，只有字或底色变了的那几串文字重画。
  */
-export function SegmentText({ segments }: { segments: Inline[] }): ReactElement {
-  const highlight = useContext(HighlightContext)
-  const names = useContext(DisplayNameContext)
+export const SegmentText = memo(({ segments }: { segments: Inline[] }): ReactElement => {
+  const marks = useStore(useContext(TextMarksContext), current => segments.map(piece => 'role' in piece ? markOf(piece, current) : undefined), sameMarks)
   return (
     <>
       {segments.map((piece, index) => {
         if (!('role' in piece))
           return <GroupBox key={index} group={piece} />
-        const shown = shownName(piece, names)
+        const mark = marks[index]
+        const shown = mark?.shown
         return (
           <span
             key={index}
             className={piece.color ? `cr-role-${piece.role} cr-colored` : `cr-role-${piece.role}`}
             style={piece.color && { '--color-dark': piece.color.dark, '--color-light': piece.color.light } as CSSProperties}
             data-offset={sourceOf(piece)?.start}
-            data-occurrence={highlight && segmentOccurrence(piece, highlight.occurrences)}
-            data-current={highlight && isCurrent(piece, highlight) ? '' : undefined}
+            data-occurrence={mark?.occurrence}
+            data-current={mark?.current ? '' : undefined}
             data-name={shown?.name}
             data-tooltip={shown ? `原名 ${piece.text}` : piece.tooltip}
           >
@@ -41,6 +57,28 @@ export function SegmentText({ segments }: { segments: Inline[] }): ReactElement
       })}
     </>
   )
+})
+SegmentText.displayName = 'SegmentText'
+
+/** 一段的标记：显示成的中文名，高亮里画哪种底色、是不是当前那一处；都没有时没有。 */
+interface SegmentMark {
+  shown?: ShownName
+  occurrence?: OccurrenceStyle
+  current: boolean
+}
+
+function markOf(piece: Segment, { names, highlight }: TextMarks): SegmentMark | undefined {
+  const shown = shownName(piece, names)
+  const occurrence = highlight && segmentOccurrence(piece, highlight.occurrences)
+  const current = highlight !== undefined && isCurrent(piece, highlight)
+  return shown || occurrence || current ? { shown, occurrence, current } : undefined
+}
+
+function sameMarks(a: (SegmentMark | undefined)[], b: (SegmentMark | undefined)[]): boolean {
+  return a.length === b.length && a.every((mark, index) => {
+    const other = b[index]
+    return mark === other || (mark !== undefined && other !== undefined && sameShownName(mark.shown, other.shown) && mark.occurrence === other.occurrence && mark.current === other.current)
+  })
 }
 
 /**
diff --git a/vscode/webview-ui/src/codeReader/StickyLines.test.tsx b/vscode/webview-ui/src/codeReader/StickyLines.test.tsx
index a1322c2..a36c8c4 100644
--- a/vscode/webview-ui/src/codeReader/StickyLines.test.tsx
+++ b/vscode/webview-ui/src/codeReader/StickyLines.test.tsx
@@ -1,8 +1,10 @@
 import type { BlockView } from './types'
 import { renderToStaticMarkup } from 'react-dom/server'
 import { describe, expect, it, vi } from 'vitest'
-import { DisplayNameContext, nameMap } from './displayNames'
+import { nameMap } from './displayNames'
+import { TextMarksContext } from './SegmentText'
 import { PinnedHead } from './StickyLines'
+import { staticStore } from './store'
 
 vi.mock('./vscode', () => ({ postMessage: () => {}, onMessage: () => () => {}, viewState: { get: () => ({ editing: [], folds: {} }), update: () => {} } }))
 
@@ -25,9 +27,9 @@ function block(kind: string, extra: Partial<BlockView>): BlockView {
 
 function render(view: BlockView): string {
   return renderToStaticMarkup(
-    <DisplayNameContext value={nameMap([{ offset: 40, length: 10, name: '加载配置', definition: true }])}>
+    <TextMarksContext value={staticStore({ names: nameMap([{ offset: 40, length: 10, name: '加载配置', definition: true }]) })}>
       <PinnedHead block={view} />
-    </DisplayNameContext>,
+    </TextMarksContext>,
   )
 }
 
diff --git a/vscode/webview-ui/src/codeReader/StickyLines.tsx b/vscode/webview-ui/src/codeReader/StickyLines.tsx
index fa95fe8..ce9bde2 100644
--- a/vscode/webview-ui/src/codeReader/StickyLines.tsx
+++ b/vscode/webview-ui/src/codeReader/StickyLines.tsx
@@ -1,9 +1,9 @@
 import type { ReactElement, RefObject } from 'react'
 import type { BlockView, StickyScrollSettings } from './types'
-import { useLayoutEffect, useMemo } from 'react'
+import { useContext, useLayoutEffect, useMemo } from 'react'
 import { KindIcon } from './kindIcons'
-import { SegmentText } from './SegmentText'
-import { HighlightContext } from './useOccurrences'
+import { SegmentText, TextMarksContext } from './SegmentText'
+import { selectStore } from './store'
 import { flash } from './useReveal'
 import { pinnedHeight, usePinnedHeight } from './useScrollPosition'
 import { STICKY_LINE_HEIGHT, stickyInset, useStickyLines } from './useStickyScroll'
@@ -52,6 +52,9 @@ export function StickyLines({ content, blocks, settings }: { content: RefObject<
   const top = usePinnedHeight()
   const lines = useStickyLines(content, settings.maxLineCount)
   const byId = useMemo(() => blocksById(blocks), [blocks])
+  // 钉着的名字照换中文名，不画页面上的高亮
+  const marks = useContext(TextMarksContext)
+  const unhighlighted = useMemo(() => selectStore(marks, ({ names }) => ({ names })), [marks])
   const count = lines.scopes.length
   const height = count * STICKY_LINE_HEIGHT + lines.offset
 
@@ -76,7 +79,7 @@ export function StickyLines({ content, blocks, settings }: { content: RefObject<
   }
 
   return (
-    <HighlightContext value={undefined}>
+    <TextMarksContext value={unhighlighted}>
       <div className="cr-sticky" style={{ top, height }}>
         {lines.scopes.map((scope, index) => {
           const block = byId.get(scope.id)
@@ -96,6 +99,6 @@ export function StickyLines({ content, blocks, settings }: { content: RefObject<
           )
         })}
       </div>
-    </HighlightContext>
+    </TextMarksContext>
   )
 }
diff --git a/vscode/webview-ui/src/codeReader/TextPreview.tsx b/vscode/webview-ui/src/codeReader/TextPreview.tsx
index 1aa624e..9233c3c 100644
--- a/vscode/webview-ui/src/codeReader/TextPreview.tsx
+++ b/vscode/webview-ui/src/codeReader/TextPreview.tsx
@@ -1,7 +1,7 @@
 import type { ReactElement } from 'react'
 import type { MarkdownKind } from './markdown'
 import type { PreviewText } from './types'
-import { createContext, useContext, useMemo } from 'react'
+import { createContext, memo, useContext, useMemo } from 'react'
 import { cn } from '@/lib/utils'
 import { renderMarkdown } from './markdown'
 import { SegmentText } from './SegmentText'
@@ -10,7 +10,7 @@ import { SegmentText } from './SegmentText'
 export const MarkdownKindContext = createContext<Exclude<MarkdownKind, 'answer'>>('comment')
 
 /** 预览里的一段文字：着色的词按源码排版；Markdown 说明渲染成段落、列表、代码块。 */
-export function TextPreview({ text, className }: { text: PreviewText, className?: string }): ReactElement {
+export const TextPreview = memo(({ text, className }: { text: PreviewText, className?: string }): ReactElement => {
   const kind = useContext(MarkdownKindContext)
   if ('markdown' in text)
     return <MarkdownPreview html={renderMarkdown(text.markdown, kind)} className={className} />
@@ -19,7 +19,8 @@ export function TextPreview({ text, className }: { text: PreviewText, className?
       <SegmentText segments={text} />
     </p>
   )
-}
+})
+TextPreview.displayName = 'TextPreview'
 
 export function MarkdownPreview({ html, className }: { html: string, className?: string }): ReactElement {
   const content = useMemo(() => ({ __html: html }), [html])
diff --git a/vscode/webview-ui/src/codeReader/displayNames.test.tsx b/vscode/webview-ui/src/codeReader/displayNames.test.tsx
index 1d12a24..22ffff9 100644
--- a/vscode/webview-ui/src/codeReader/displayNames.test.tsx
+++ b/vscode/webview-ui/src/codeReader/displayNames.test.tsx
@@ -1,15 +1,10 @@
 import type { Inline, ShownName, WebviewToExtension } from './types'
 import { renderToStaticMarkup } from 'react-dom/server'
-import { describe, expect, it, vi } from 'vitest'
-import { acceptNames, DisplayNameContext, documentNames, nameMap, shownName } from './displayNames'
+import { describe, expect, it } from 'vitest'
+import { nameMap, sameShownName, shownName } from './displayNames'
 import { OccurrenceHighlight } from './occurrences'
-import { SegmentText } from './SegmentText'
-
-// 高亮的上下文所在的模块连着和 VS Code 收发消息的那一套，渲染成 HTML 用不着
-vi.mock('./useOccurrences', async () => {
-  const { createContext } = await import('react')
-  return { HighlightContext: createContext(undefined) }
-})
+import { SegmentText, TextMarksContext } from './SegmentText'
+import { staticStore } from './store'
 
 const CURRENT_USER: ShownName = { offset: 40, length: 12, name: '当前用户', definition: true }
 const USE: ShownName = { offset: 90, length: 12, name: '当前用户' }
@@ -17,19 +12,19 @@ const ADMIN: ShownName = { offset: 130, length: 5, name: '管理员' }
 
 function render(segments: Inline[], names: ShownName[]): string {
   return renderToStaticMarkup(
-    <DisplayNameContext value={nameMap(names)}>
+    <TextMarksContext value={staticStore({ names: nameMap(names) })}>
       <SegmentText segments={segments} />
-    </DisplayNameContext>,
+    </TextMarksContext>,
   )
 }
 
 describe('页面上的中文名', () => {
-  it('收到新文档换成它带来的；查到的是页面上这个版本的才换上，迟到的旧版本不理', () => {
-    const current = documentNames(3, [USE])
-    expect([...current.names.values()]).toEqual([USE])
-    expect(acceptNames(current, 2, [ADMIN])).toBe(current)
-    expect([...acceptNames(current, 3, [USE, ADMIN])!.names.values()]).toEqual([USE, ADMIN])
-    expect(acceptNames(undefined, 3, [ADMIN])).toBeUndefined()
+  it('两段显示成的中文名按内容比：中文名重新发来是新对象，字没变就算一样（那段文字不重画）', () => {
+    expect(sameShownName(USE, { ...USE })).toBe(true)
+    expect(sameShownName(USE, undefined)).toBe(false)
+    expect(sameShownName(undefined, undefined)).toBe(true)
+    expect(sameShownName(USE, { ...USE, name: '用户' })).toBe(false)
+    expect(sameShownName(CURRENT_USER, { ...CURRENT_USER, definition: undefined })).toBe(false)
   })
 
   it('只认下标和长度都对得上的名字：没下标的译词、长度不一样的（名字改长了）不换', () => {
diff --git a/vscode/webview-ui/src/codeReader/displayNames.ts b/vscode/webview-ui/src/codeReader/displayNames.ts
index f68a2f6..6c79a8c 100644
--- a/vscode/webview-ui/src/codeReader/displayNames.ts
+++ b/vscode/webview-ui/src/codeReader/displayNames.ts
@@ -1,34 +1,19 @@
 import type { Segment, ShownName } from './types'
-import { createContext } from 'react'
 
 /** 页面上这个版本的中文名：下标 → 显示成什么。 */
 export type NameMap = ReadonlyMap<number, ShownName>
 
-/** 眼下页面上显示成中文名的名字，SegmentText 按它换字。 */
-export const DisplayNameContext = createContext<NameMap>(new Map())
-
-/** 某个文档版本的中文名。 */
-export interface VersionNames {
-  version: number
-  names: NameMap
-}
-
 export function nameMap(names: readonly ShownName[]): NameMap {
   return new Map(names.map(name => [name.offset, name]))
 }
 
-/** 收到新文档：换成它带来的中文名（上一版查到的跟着改动挪过位置的，或这一版查过的）。 */
-export function documentNames(version: number, names: readonly ShownName[]): VersionNames {
-  return { version, names: nameMap(names) }
-}
-
-/** 收到查到的中文名：是页面上这个版本的才换上，迟到的旧版本的不理。 */
-export function acceptNames(current: VersionNames | undefined, version: number, names: readonly ShownName[]): VersionNames | undefined {
-  return current?.version === version ? { version, names: nameMap(names) } : current
-}
-
 /** 这段名字显示成什么中文名：照抄自源码、下标和长度都对得上才算。 */
 export function shownName(segment: Segment, names: NameMap): ShownName | undefined {
   const shown = segment.offset === undefined ? undefined : names.get(segment.offset)
   return shown?.length === segment.text.length ? shown : undefined
 }
+
+/** 两段显示成的中文名一样（中文名到了是新对象，按内容比）。 */
+export function sameShownName(a: ShownName | undefined, b: ShownName | undefined): boolean {
+  return a === b || (a !== undefined && b !== undefined && a.name === b.name && a.definition === b.definition)
+}
diff --git a/vscode/webview-ui/src/codeReader/kindIcons.tsx b/vscode/webview-ui/src/codeReader/kindIcons.tsx
index 2e2e293..efc7fb1 100644
--- a/vscode/webview-ui/src/codeReader/kindIcons.tsx
+++ b/vscode/webview-ui/src/codeReader/kindIcons.tsx
@@ -43,6 +43,7 @@ import {
   Variable,
   Zap,
 } from 'lucide-react'
+import { memo } from 'react'
 
 /** 插件定义的这组种类图标，每个名字一个 lucide 图标（逐个 import，打包只带这些）。 */
 export const KIND_ICON_COMPONENTS: Record<KindIconName, LucideIcon> = {
@@ -93,7 +94,7 @@ export const KIND_ICON_COMPONENTS: Record<KindIconName, LucideIcon> = {
  * 没有颜色的是语言的种类，按 id 用 CSS 的种类色；有颜色的只给这个图标上色。
  * 每个图标悬停自己的名字（data-tooltip，见 components/ui/tooltip.tsx）；读屏把名字连起来念。
  */
-export function KindIcon({ concepts }: { concepts: readonly BlockConcept[] }): ReactElement {
+export const KindIcon = memo(({ concepts }: { concepts: readonly BlockConcept[] }): ReactElement => {
   return (
     <span className="flex shrink-0 items-center gap-0.5" role="img" aria-label={concepts.map(concept => concept.label).join('，')}>
       {concepts.map((concept) => {
@@ -109,4 +110,5 @@ export function KindIcon({ concepts }: { concepts: readonly BlockConcept[] }): R
       })}
     </span>
   )
-}
+})
+KindIcon.displayName = 'KindIcon'
diff --git a/vscode/webview-ui/src/codeReader/occurrences.test.ts b/vscode/webview-ui/src/codeReader/occurrences.test.ts
index 45848ba..0b2db0f 100644
--- a/vscode/webview-ui/src/codeReader/occurrences.test.ts
+++ b/vscode/webview-ui/src/codeReader/occurrences.test.ts
@@ -46,6 +46,27 @@ describe('occurrences：哪些段画高亮', () => {
     expect(segmentOccurrence({ text: '\'./util\'', role: 'string', offset: 9 }, occurrences)).toBe('normal')
   })
 
+  it('出现很多、乱序、有长有短还互相重叠时，结果和逐处比一样', () => {
+    const brute = (segment: Segment, occurrences: readonly Occurrence[]): string | undefined => {
+      const hits = occurrences.filter(occurrence => occurrence.start < segment.offset! + segment.text.length && segment.offset! < occurrence.end)
+      return hits.length === 0 ? undefined : hits.some(hit => hit.kind === 'write') ? 'strong' : 'normal'
+    }
+    let seed = 7
+    const random = (n: number): number => {
+      seed = (seed * 1103515245 + 12345) % 2147483648
+      return seed % n
+    }
+    const kinds: Occurrence['kind'][] = ['read', 'write', 'text']
+    const occurrences = Array.from({ length: 300 }, () => {
+      const start = random(2000)
+      return at(start, start + 1 + random(12), kinds[random(3)])
+    })
+    for (let offset = 0; offset < 2020; offset += 3) {
+      const segment = name('x'.repeat(1 + (offset % 7)), offset)
+      expect(segmentOccurrence(segment, occurrences), `offset ${offset}`).toBe(brute(segment, occurrences))
+    }
+  })
+
   it('写入用强高亮色，读取和按文字认出的用普通高亮色；同一段碰上两种按写入画', () => {
     expect(occurrenceStyle('write')).toBe('strong')
     expect(occurrenceStyle('read')).toBe('normal')
diff --git a/vscode/webview-ui/src/codeReader/occurrences.ts b/vscode/webview-ui/src/codeReader/occurrences.ts
index 68aaa28..d2b57e4 100644
--- a/vscode/webview-ui/src/codeReader/occurrences.ts
+++ b/vscode/webview-ui/src/codeReader/occurrences.ts
@@ -12,9 +12,16 @@ export function occurrenceStyle(kind: Occurrence['kind']): OccurrenceStyle {
  * 同时碰上写入和读取的按写入画。没有下标的（译词、提示词、编辑状态的源码）不画。
  */
 export function segmentOccurrence(segment: Segment, occurrences: readonly Occurrence[]): OccurrenceStyle | undefined {
+  const source = sourceOf(segment)
+  if (!source)
+    return undefined
+  const { sorted, longest } = occurrenceIndex(occurrences)
+  // 起点不早于段尾的都不重叠；往前看到起点早于段头一整个最长出现的为止，再往前的都在段头之前结束
+  let index = firstStartAtOrAfter(sorted, source.end)
   let style: OccurrenceStyle | undefined
-  for (const occurrence of occurrences) {
-    if (overlaps(segment, occurrence)) {
+  while (--index >= 0 && sorted[index].start > source.start - longest) {
+    const occurrence = sorted[index]
+    if (occurrence.end > source.start) {
       style = occurrenceStyle(occurrence.kind)
       if (style === 'strong')
         return style
@@ -23,6 +30,40 @@ export function segmentOccurrence(segment: Segment, occurrences: readonly Occurr
   return style
 }
 
+/** 一份出现按起点排好，带最长的一处有多长：整份文档几千段文字各找一次和自己重叠的那几处，按二分找，不逐处比 */
+interface OccurrenceIndex {
+  sorted: readonly Occurrence[]
+  longest: number
+}
+
+const indexes = new WeakMap<readonly Occurrence[], OccurrenceIndex>()
+
+function occurrenceIndex(occurrences: readonly Occurrence[]): OccurrenceIndex {
+  let index = indexes.get(occurrences)
+  if (!index) {
+    index = {
+      sorted: [...occurrences].sort((a, b) => a.start - b.start),
+      longest: occurrences.reduce((max, occurrence) => Math.max(max, occurrence.end - occurrence.start), 0),
+    }
+    indexes.set(occurrences, index)
+  }
+  return index
+}
+
+/** 第一处起点不早于 at 的出现的序号，没有时是总数 */
+function firstStartAtOrAfter(sorted: readonly Occurrence[], at: number): number {
+  let low = 0
+  let high = sorted.length
+  while (low < high) {
+    const middle = (low + high) >> 1
+    if (sorted[middle].start < at)
+      low = middle + 1
+    else
+      high = middle
+  }
+  return low
+}
+
 /**
  * 段讲的是源码里哪个名字，[start, end)：讲别处名字的段（refers，写在字符串里的参数名）是那个名字，照抄自源码的段是它自己占的
  * [offset, offset + 字数)；没有下标的段（译词、提示词）没有。跳到定义、单击高亮、各处出现画在哪都按它。
diff --git a/vscode/webview-ui/src/codeReader/pageState.ts b/vscode/webview-ui/src/codeReader/pageState.ts
new file mode 100644
index 0000000..c7ada57
--- /dev/null
+++ b/vscode/webview-ui/src/codeReader/pageState.ts
@@ -0,0 +1,178 @@
+import type { BlockTreeState } from './BlockTree'
+import type { ChangeStop, DiffTree, FoldedRuns } from './diffView'
+import type { FilterView } from './filter'
+import type { ReadableStore } from './store'
+import type { BlockView, CallTree, ContractMiss, DocumentDiff, DocumentMessage, Excluded, KindBadge, Reveal } from './types'
+import { changeStops, diffTree, foldUnchanged, openedByDiff } from './diffView'
+import { coveredByEditing } from './editing'
+import { applyFilter, excludedBy } from './filter'
+import { createStore } from './store'
+import { collapsedIds, foldsByCard } from './viewState'
+
+/** 开着的调用树弹框：哪一版文档的哪一块、选中第几个入口，扩展端发来的树 */
+export interface OpenCall {
+  anchor: string
+  version: number
+  entry: number
+  status: 'loading' | 'ready'
+  name: string
+  where: string
+  kind: string
+  badge?: KindBadge
+  trees: CallTree[]
+  contractMiss?: ContractMiss
+}
+
+/** 页面状态里由扩展端发来、由用户点出来的那些；别的都由它们算出来（见 Page）。 */
+export interface PageInputs {
+  doc: DocumentMessage | null
+  /** 停在「编辑」的块 */
+  editing: string[]
+  /** 用户自己点过折叠箭头的块、属性行和子行：id → 折叠着没有 */
+  folds: Record<string, boolean>
+  /** 刚点了「编辑」、要把光标放进去的块 */
+  focusId: string | null
+  /** 等着滚过去的位置：新预览第一份文档带的，或已开着的预览收到的 reveal */
+  reveal: Reveal | null
+  /** 扩展端发来的块筛选（整个工作区共用）；本地不改，改了发给扩展端、等它发回来 */
+  excluded: Excluded
+  /** 跳到定义时临时露出来的块（目标和它的各层祖先），筛选一变、文档一刷新就回到筛选状态 */
+  keep: ReadonlySet<string>
+  /** 这份文件相比对比基准改了什么：审查工作副本里的、从「未提交的更改」点开的有改动的文件扩展端算好了补来，不比时是 null */
+  diff: DocumentDiff | null
+  /** 「只看改动」开着（整个工作区共用，扩展端记着）；本地不改，改了发给扩展端、等它发回来 */
+  onlyChanges: boolean
+  /** 「只看改动」时点开过的几段没变的块（按第一块的 id），筛选一变就重新折 */
+  openedRuns: ReadonlySet<string>
+  /** 后台数出的各块落在几棵调用树里，是哪一版文档的 */
+  callCounts: { version: number, counts: Record<string, number> } | undefined
+  openCall: OpenCall | null
+}
+
+/** 整页的状态：输入的那些，和由它们算出来的；块树要的那部分在 tree 上，卡片按自己那部分订阅。 */
+export interface Page extends PageInputs {
+  /** 标差异时各块改了什么；解析失败、不比时没有 */
+  changes: DiffTree | undefined
+  collapsed: ReadonlySet<string>
+  filter: FilterView
+  covered: ReadonlyMap<string, string>
+  /** 「只看改动」折起来的块 */
+  folded: FoldedRuns | undefined
+  /** 页面上没画出来的块：被筛掉的，和「只看改动」折起来的 */
+  unshown: ReadonlySet<string>
+  stops: ChangeStop[]
+  tree: BlockTreeState
+}
+
+/** 整页状态的 store：update 改输入，算出来的部分只在它依赖的输入换了时重算，没换的还是原来那个对象。 */
+export interface PageStore extends ReadableStore<Page> {
+  update: (patch: Partial<PageInputs> | ((page: Page) => Partial<PageInputs>)) => void
+}
+
+const NONE: ReadonlySet<string> = new Set()
+const NO_BLOCKS: BlockView[] = []
+const NO_COUNTS: ReadonlyMap<string, number> = new Map()
+
+/** 只记上一次：参数（逐个同一个对象）和上次一样就交回上次的结果，同 memoize-one */
+function memoizeOne<A extends unknown[], R>(compute: (...args: A) => R): (...args: A) => R {
+  let last: { args: A, result: R } | undefined
+  return (...args: A): R => {
+    if (last && last.args.length === args.length && last.args.every((arg, index) => Object.is(arg, args[index])))
+      return last.result
+    const result = compute(...args)
+    last = { args, result }
+    return result
+  }
+}
+
+export function createPageStore(initial: Pick<PageInputs, 'editing' | 'folds'>): PageStore {
+  // 按 doc.blocks 而不是 doc 认：同一版重发、只改了版本号时块是原来那份（见 shareUnchanged），算出来的也还是原来的
+  const changesOf = memoizeOne((blocks: BlockView[], version: number, error: boolean, diff: DocumentDiff | null, excluded: Excluded) => error
+    ? undefined
+    // 删掉的块按块筛选同样藏
+    : diffTree(blocks, diff, version, removed => !excludedBy(removed.block, excluded)))
+  const collapsedOf = memoizeOne((blocks: BlockView[], folds: Record<string, boolean>, changes: DiffTree | undefined) => collapsedIds(blocks, folds, openedByDiff(changes)))
+  const filterOf = memoizeOne(applyFilter)
+  const editingOf = memoizeOne((editing: string[]) => new Set(editing))
+  const coveredOf = memoizeOne(coveredByEditing)
+  const foldedOf = memoizeOne((blocks: BlockView[], changes: DiffTree | undefined, onlyChanges: boolean, filter: FilterView, covered: ReadonlyMap<string, string>, openedRuns: ReadonlySet<string>, keep: ReadonlySet<string>) => changes && onlyChanges
+    ? foldUnchanged(blocks, changes, block => !filter.hidden.has(block.id) && !covered.has(block.id), openedRuns, keep)
+    : undefined)
+  const unshownOf = memoizeOne((filter: FilterView, folded: FoldedRuns | undefined) => folded ? new Set([...filter.hidden, ...folded.folded]) : filter.hidden)
+  const stopsOf = memoizeOne((blocks: BlockView[], changes: DiffTree | undefined, filter: FilterView) => changes ? changeStops(blocks, changes, filter.hidden) : [])
+  let folds: ReadonlyMap<string, ReadonlySet<string>> | undefined
+  const foldsOf = memoizeOne((collapsed: ReadonlySet<string>) => {
+    folds = foldsByCard(collapsed, folds)
+    return folds
+  })
+  const countsOf = memoizeOne((version: number | undefined, callCounts: PageInputs['callCounts']) => callCounts && callCounts.version === version
+    ? new Map(Object.entries(callCounts.counts))
+    : NO_COUNTS)
+  const treeOf = memoizeOne((
+    version: number,
+    editing: ReadonlySet<string>,
+    focusId: string | null,
+    counts: ReadonlyMap<string, number>,
+    openAnchor: string | undefined,
+    collapsed: ReadonlySet<string>,
+    folds: ReadonlyMap<string, ReadonlySet<string>>,
+    filter: FilterView,
+    covered: ReadonlyMap<string, string>,
+    changes: DiffTree | undefined,
+    folded: FoldedRuns | undefined,
+  ): BlockTreeState => ({
+    edit: { version, editing, focusId },
+    callTree: { counts, ...(openAnchor !== undefined && { openAnchor }) },
+    collapsed,
+    folds,
+    hidden: filter.hidden,
+    temporary: filter.temporary,
+    covered,
+    ...(changes && { diff: changes }),
+    ...(folded && { folded }),
+  }))
+
+  const derive = (inputs: PageInputs): Page => {
+    const { doc } = inputs
+    const blocks = doc?.blocks ?? NO_BLOCKS
+    const version = doc?.version ?? 0
+    const changes = doc ? changesOf(blocks, version, doc.error !== undefined, inputs.diff, inputs.excluded) : undefined
+    const collapsed = collapsedOf(blocks, inputs.folds, changes)
+    const filter = filterOf(blocks, inputs.excluded, inputs.keep)
+    const editing = editingOf(inputs.editing)
+    const covered = coveredOf(blocks, editing)
+    const folded = foldedOf(blocks, changes, inputs.onlyChanges, filter, covered, inputs.openedRuns, inputs.keep)
+    const openAnchor = inputs.openCall?.version === version ? inputs.openCall.anchor : undefined
+    return {
+      ...inputs,
+      changes,
+      collapsed,
+      filter,
+      covered,
+      folded,
+      unshown: unshownOf(filter, folded),
+      stops: stopsOf(blocks, changes, filter),
+      tree: treeOf(version, editing, inputs.focusId, countsOf(doc?.version, inputs.callCounts), openAnchor, collapsed, foldsOf(collapsed), filter, covered, changes, folded),
+    }
+  }
+
+  const store = createStore(derive({
+    doc: null,
+    editing: initial.editing,
+    folds: initial.folds,
+    focusId: null,
+    reveal: null,
+    excluded: {},
+    keep: NONE,
+    diff: null,
+    onlyChanges: false,
+    openedRuns: NONE,
+    callCounts: undefined,
+    openCall: null,
+  }))
+  return {
+    get: store.get,
+    subscribe: store.subscribe,
+    update: patch => store.set(page => derive({ ...page, ...(typeof patch === 'function' ? patch(page) : patch) })),
+  }
+}
diff --git a/vscode/webview-ui/src/codeReader/qa.ts b/vscode/webview-ui/src/codeReader/qa.ts
index d48381b..fe0bfdf 100644
--- a/vscode/webview-ui/src/codeReader/qa.ts
+++ b/vscode/webview-ui/src/codeReader/qa.ts
@@ -5,6 +5,8 @@
  */
 
 import type { AskRound, ProfileChoice, QaEntryView, QaMessage, QaThreadView, RoundEnd } from './types'
+import { shareUnchanged } from './sharing'
+import { shallowEqual } from './store'
 
 /** 这次打开以来的一轮 */
 export interface Ask {
@@ -92,7 +94,8 @@ export function chatReducer<S extends ChatState>(state: S, action: ChatAction):
       return {
         ...state,
         available: action.available,
-        threads: action.threads,
+        // 没变的记录还是原来的对象：块下面的对话区按自己那几条订阅，别的块的记录变了它不重画
+        threads: shareUnchanged(state.threads, action.threads),
         asks: [...state.asks, ...adopted],
         open: adopted.reduce((open, round) => withOpen(open, round.anchor), state.open),
       }
@@ -137,7 +140,7 @@ export function qaReducer(state: QaState, action: QaAction): QaState {
   switch (action.type) {
     case 'qa': {
       const { available, threads, current, path, subject } = action.message
-      return { ...chatReducer(state, { type: 'sync', available, threads, current }), path, subject }
+      return { ...chatReducer(state, { type: 'sync', available, threads, current }), path: shareUnchanged(state.path, path), subject }
     }
     default:
       return chatReducer(state, action)
@@ -163,6 +166,24 @@ export function historyOf(state: ChatState & { path?: QaEntryView[] }, anchor: s
   return entries.filter(entry => !current.has(entry.id))
 }
 
+/** 一块下面的对话区要画的：灰字历史、当前这一轮、展开着没有、输入框旁边的 profile 下拉。 */
+export interface ChatView {
+  history: QaEntryView[]
+  asks: Ask[]
+  open: boolean
+  profiles: ProfileChoice
+}
+
+/** anchor 那块的对话区（顶部问答是 PATH_ASK_ANCHOR）。块按自己的记号订阅它，比较用 sameChat。 */
+export function chatOf(state: ChatState & { path?: QaEntryView[] }, anchor: string): ChatView {
+  return { history: historyOf(state, anchor), asks: asksOf(state, anchor), open: state.open.includes(anchor), profiles: state.profiles }
+}
+
+/** 两次选出来的对话区一样：同样的几条历史、几轮（同一个对象），展开状态和下拉一样。别的块问答变了，这块不重画。 */
+export function sameChat(a: ChatView, b: ChatView): boolean {
+  return a.open === b.open && a.profiles === b.profiles && shallowEqual(a.history, b.history) && shallowEqual(a.asks, b.asks)
+}
+
 const MINUTE = 60_000
 const DAY = 24 * 60 * MINUTE
 
diff --git a/vscode/webview-ui/src/codeReader/sharing.test.ts b/vscode/webview-ui/src/codeReader/sharing.test.ts
new file mode 100644
index 0000000..460ef07
--- /dev/null
+++ b/vscode/webview-ui/src/codeReader/sharing.test.ts
@@ -0,0 +1,41 @@
+import { describe, expect, it } from 'vitest'
+import { shareUnchanged } from './sharing'
+
+describe('新消息里没变的部分沿用上一份的对象', () => {
+  const prev = {
+    version: 1,
+    blocks: [
+      { id: '0', translation: [{ text: 'a', offset: 1 }], children: [] },
+      { id: '1', translation: [{ text: 'b', offset: 5 }], children: [{ id: '1.0', children: [] }] },
+    ],
+  }
+
+  it('整份一样：交回上一份本身', () => {
+    expect(shareUnchanged(prev, structuredClone(prev))).toBe(prev)
+  })
+
+  it('只改了一块：那一块（连同它的各层父对象）是新的，别的块还是原来的对象', () => {
+    const next = structuredClone(prev)
+    next.version = 2
+    next.blocks[1].translation[0].offset = 6
+    const shared = shareUnchanged(prev, next)
+    expect(shared).not.toBe(prev)
+    expect(shared).toEqual(next)
+    expect(shared.blocks).not.toBe(prev.blocks)
+    expect(shared.blocks[0]).toBe(prev.blocks[0])
+    expect(shared.blocks[1]).not.toBe(prev.blocks[1])
+    expect(shared.blocks[1].children).toBe(prev.blocks[1].children)
+  })
+
+  it('多了、少了项或键都算变了；没有上一份时原样交回', () => {
+    const longer = { ...structuredClone(prev), blocks: [...structuredClone(prev.blocks), { id: '2', translation: [], children: [] }] }
+    const shared = shareUnchanged(prev, longer)
+    expect(shared.blocks).not.toBe(prev.blocks)
+    expect(shared.blocks[0]).toBe(prev.blocks[0])
+    const withKey = { ...structuredClone(prev), error: 'x' }
+    expect(shareUnchanged(prev, withKey)).not.toBe(prev)
+    const { version: _, ...withoutKey } = structuredClone(prev)
+    expect(shareUnchanged(prev, withoutKey)).not.toBe(prev)
+    expect(shareUnchanged(undefined, withKey)).toBe(withKey)
+  })
+})
diff --git a/vscode/webview-ui/src/codeReader/sharing.ts b/vscode/webview-ui/src/codeReader/sharing.ts
new file mode 100644
index 0000000..15ab93a
--- /dev/null
+++ b/vscode/webview-ui/src/codeReader/sharing.ts
@@ -0,0 +1,37 @@
+/**
+ * 新收到的一份数据里，和上一份内容一样的部分换回上一份里的那个对象（整份一样就交回上一份本身），
+ * 同 TanStack Query 的 replaceEqualDeep：扩展端每次发来的都是新对象，换回去之后没变的块、行还是原来那个，按卡片订阅的组件看得出没变、不重画。
+ * 只认消息里那样的数据：普通对象、数组、原始值。
+ */
+export function shareUnchanged<T>(prev: unknown, next: T): T {
+  if (Object.is(prev, next))
+    return next
+  if (Array.isArray(prev) && Array.isArray(next)) {
+    let same = prev.length === next.length
+    const shared = next.map((item: unknown, index) => {
+      const value = shareUnchanged(prev[index], item)
+      same &&= Object.is(value, prev[index])
+      return value
+    })
+    return (same ? prev : shared) as T
+  }
+  if (isPlainObject(prev) && isPlainObject(next)) {
+    const keys = Object.keys(next)
+    let same = keys.length === Object.keys(prev).length
+    const shared: Record<string, unknown> = {}
+    for (const key of keys) {
+      const value = shareUnchanged(prev[key], next[key])
+      same &&= Object.hasOwn(prev, key) && Object.is(value, prev[key])
+      shared[key] = value
+    }
+    return (same ? prev : shared) as T
+  }
+  return next
+}
+
+function isPlainObject(value: unknown): value is Record<string, unknown> {
+  if (typeof value !== 'object' || value === null)
+    return false
+  const proto = Object.getPrototypeOf(value)
+  return proto === Object.prototype || proto === null
+}
diff --git a/vscode/webview-ui/src/codeReader/store.test.tsx b/vscode/webview-ui/src/codeReader/store.test.tsx
new file mode 100644
index 0000000..073b0a1
--- /dev/null
+++ b/vscode/webview-ui/src/codeReader/store.test.tsx
@@ -0,0 +1,61 @@
+// @vitest-environment happy-dom
+
+import type { Root } from 'react-dom/client'
+import { act } from 'react'
+import { createRoot } from 'react-dom/client'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { createStore, selectStore, shallowEqual, useStore } from './store'
+
+let container: HTMLDivElement
+let root: Root
+
+beforeEach(() => {
+  vi.stubGlobal('IS_REACT_ACT_ENVIRONMENT', true)
+  container = document.createElement('div')
+  document.body.append(container)
+  root = createRoot(container)
+})
+
+afterEach(async () => {
+  await act(async () => root.unmount())
+  container.remove()
+  vi.unstubAllGlobals()
+})
+
+describe('按自己用到的那部分订阅', () => {
+  it('选出来的值变了才重画；按 isEqual 相等时还是上次那个对象', async () => {
+    const store = createStore({ counts: { a: 1, b: 1 }, other: 0 })
+    const seen: unknown[] = []
+    function Count({ name }: { name: 'a' | 'b' }): null {
+      seen.push(useStore(store, state => ({ count: state.counts[name] }), shallowEqual))
+      return null
+    }
+    await act(async () => root.render(<Count name="a" />))
+    expect(seen).toHaveLength(1)
+    await act(async () => store.set(state => ({ ...state, other: 1 })))
+    await act(async () => store.set(state => ({ ...state, counts: { ...state.counts, b: 2 } })))
+    expect(seen).toHaveLength(1)
+    await act(async () => store.set(state => ({ ...state, counts: { ...state.counts, a: 3 } })))
+    expect(seen).toEqual([{ count: 1 }, { count: 3 }])
+    // props 变了重新选：选出来的一样就还是上次那个对象
+    await act(async () => root.render(<Count name="b" />))
+    await act(async () => root.render(<Count name="b" />))
+    expect(seen[2]).toEqual({ count: 2 })
+    expect(seen[3]).toBe(seen[2])
+  })
+
+  it('换成同一个对象不通知；一部分当成 store 时，整份没换就选出同一个对象', () => {
+    const store = createStore({ names: ['x'], other: 0 })
+    const listener = vi.fn()
+    store.subscribe(listener)
+    store.set(state => state)
+    expect(listener).not.toHaveBeenCalled()
+    const names = selectStore(store, state => ({ names: state.names }))
+    const first = names.get()
+    expect(names.get()).toBe(first)
+    store.set(state => ({ ...state, other: 1 }))
+    expect(listener).toHaveBeenCalledTimes(1)
+    expect(names.get()).not.toBe(first)
+    expect(names.get()).toEqual(first)
+  })
+})
diff --git a/vscode/webview-ui/src/codeReader/store.ts b/vscode/webview-ui/src/codeReader/store.ts
new file mode 100644
index 0000000..0b025c8
--- /dev/null
+++ b/vscode/webview-ui/src/codeReader/store.ts
@@ -0,0 +1,84 @@
+import { useRef, useSyncExternalStore } from 'react'
+
+/** 放在 React 外面的一份状态：能读、能订阅变化。组件按自己用到的那部分订阅（useStore）。 */
+export interface ReadableStore<T> {
+  get: () => T
+  subscribe: (listener: () => void) => () => void
+}
+
+/** 能改的一份状态：换成新的一份（不可变），和原来不是同一个对象时通知订阅的组件。 */
+export interface Store<T> extends ReadableStore<T> {
+  set: (next: T | ((prev: T) => T)) => void
+}
+
+export function createStore<T>(initial: T): Store<T> {
+  let state = initial
+  const listeners = new Set<() => void>()
+  return {
+    get: () => state,
+    set: (next) => {
+      const value = typeof next === 'function' ? (next as (prev: T) => T)(state) : next
+      if (Object.is(value, state))
+        return
+      state = value
+      for (const listener of listeners)
+        listener()
+    },
+    subscribe: (listener) => {
+      listeners.add(listener)
+      return () => listeners.delete(listener)
+    },
+  }
+}
+
+/** 一份不会变的状态：没有订阅方的地方（定义卡片浮窗、钉住的行、测试）给个固定值。 */
+export function staticStore<T>(state: T): ReadableStore<T> {
+  return { get: () => state, subscribe: () => () => {} }
+}
+
+/** 两个值浅比较相等：同一个值，或同样的键（数组是同样的项）各自是同一个值。 */
+export function shallowEqual<T>(a: T, b: T): boolean {
+  if (Object.is(a, b))
+    return true
+  if (typeof a !== 'object' || typeof b !== 'object' || a === null || b === null)
+    return false
+  if (Array.isArray(a) || Array.isArray(b))
+    return Array.isArray(a) && Array.isArray(b) && a.length === b.length && a.every((item, index) => Object.is(item, b[index]))
+  const keys = Object.keys(a)
+  return keys.length === Object.keys(b).length
+    && keys.every(key => Object.hasOwn(b, key) && Object.is((a as Record<string, unknown>)[key], (b as Record<string, unknown>)[key]))
+}
+
+/**
+ * 订阅 store 里的一部分：select 从整份状态里选出这个组件要的值，状态变了、选出来的值按 isEqual 也变了才重画，
+ * 一样时交回上次那个值。同 React 官方 use-sync-external-store 的 useSyncExternalStoreWithSelector。
+ */
+export function useStore<T, S>(store: ReadableStore<T>, select: (state: T) => S, isEqual: (a: S, b: S) => boolean = Object.is): S {
+  /** 上次选的：整份状态、用的 select、选出来的值。状态和 select 都没换就交回它；新选出来的和它相等也交回它，props 变了重新选也不换对象 */
+  const last = useRef<{ state: T, select: (state: T) => S, selection: S } | null>(null)
+  const getSelection = (): S => {
+    const state = store.get()
+    const memo = last.current
+    if (memo && Object.is(memo.state, state) && memo.select === select)
+      return memo.selection
+    const next = select(state)
+    const selection = memo && isEqual(memo.selection, next) ? memo.selection : next
+    last.current = { state, select, selection }
+    return selection
+  }
+  return useSyncExternalStore(store.subscribe, getSelection, getSelection)
+}
+
+/** store 里的一部分当成一份只读的 store：select 只在整份状态换了时重选（交回的对象要能当快照用，同一份状态选出同一个对象）。 */
+export function selectStore<T, S>(store: ReadableStore<T>, select: (state: T) => S): ReadableStore<S> {
+  let memo: { state: T, selection: S } | undefined
+  return {
+    get: () => {
+      const state = store.get()
+      if (!memo || !Object.is(memo.state, state))
+        memo = { state, selection: select(state) }
+      return memo.selection
+    },
+    subscribe: store.subscribe,
+  }
+}
diff --git a/vscode/webview-ui/src/codeReader/useOccurrences.ts b/vscode/webview-ui/src/codeReader/useOccurrences.ts
index 2ca1a52..cd48b1e 100644
--- a/vscode/webview-ui/src/codeReader/useOccurrences.ts
+++ b/vscode/webview-ui/src/codeReader/useOccurrences.ts
@@ -1,15 +1,15 @@
 import type { Click, Highlight, ScrollPosition } from './occurrences'
+import type { TextMarks } from './SegmentText'
+import type { Store } from './store'
 import type { BlockView, Occurrence } from './types'
-import { createContext, useCallback, useEffect, useLayoutEffect, useRef, useState } from 'react'
+import { useCallback, useEffect, useLayoutEffect, useRef, useState } from 'react'
 import { documentNameAt, PEEK_ATTRIBUTE } from './definitionPeek'
 import { clickAction, KeyScroll, OccurrenceHighlight, occurrenceJumpKey, OccurrenceNavigation } from './occurrences'
 import { occurrencePlan } from './reveal'
+import { useStore } from './store'
 import { showInViewport } from './useReveal'
 import { onMessage, postMessage } from './vscode'
 
-/** 眼下高亮着的名字，SegmentText 按它给各处出现上底色、给当前那一处描边。 */
-export const HighlightContext = createContext<Highlight | undefined>(undefined)
-
 /** 自己管点击的东西：点在上面（名字以外的地方）高亮不动。定义卡片浮窗里的名字是别的文件的，点了也不动 */
 const CONTROLS = `a, button, input, select, textarea, [role="listbox"], [role="dialog"], .cr-filter-bar, .cr-prop-label, [${PEEK_ATTRIBUTE}]`
 
@@ -72,15 +72,16 @@ function scrollBack({ x, y }: ScrollPosition, own: (position: ScrollPosition) =>
 }
 
 /**
- * 单击名字高亮它在文档里的各处出现，点空白处、Esc、换文档版本或翻译清掉；返回眼下高亮着的名字，和筛选栏上「上一处 / 下一处」用的跳转。
+ * 单击名字高亮它在文档里的各处出现，点空白处、Esc、换文档版本或翻译清掉；高亮着的名字记进 marks（页面文字的标记），返回它和筛选栏上「上一处 / 下一处」用的跳转。
  * 高亮着时扩展端的「跳到下一处 / 上一处高亮」命令发来 moveOccurrence，筛选栏上的按钮走同一条跳转：当前那一处换成下一处页面上找得到的出现，
  * 展开把它折叠住的块、属性行和子行，再把它滚进视口。按钮不是按键，不按 ⌘↓ 那样拉回按键时的位置。
  * 默认的 ⌘↓ / ⌘↑（Windows 是 ctrl）在能跳的时候取消浏览器滚到底 / 滚到顶，但不停事件继续传（VS Code 在后面才把按键收成命令）。
  * 别的键浏览器仍可能自己滚，跳的时候盖掉它，见 KeyScroll。
  */
-export function useOccurrences(version: number | undefined, translatorId: string | undefined, page: OccurrencePage | undefined): { highlight: Highlight | undefined, moveOccurrence: (step: 1 | -1) => void } {
-  const [highlight, setHighlight] = useState<Highlight | undefined>()
-  const [occurrences] = useState(() => new OccurrenceHighlight(postMessage, setHighlight))
+export function useOccurrences(version: number | undefined, translatorId: string | undefined, page: OccurrencePage | undefined, marks: Store<TextMarks>): { highlight: Highlight | undefined, moveOccurrence: (step: 1 | -1) => void } {
+  // 高亮记在页面文字的标记里（TextMarksContext），各段文字按自己那几段订阅，换个名字高亮只重画画法变了的那几段
+  const highlight = useStore(marks, current => current.highlight)
+  const [occurrences] = useState(() => new OccurrenceHighlight(postMessage, next => marks.set(current => ({ ...current, highlight: next }))))
   const [navigation] = useState(() => new OccurrenceNavigation(postMessage, { focused: document.hasFocus(), typing: isTyping(document.activeElement) }))
   const [keyScroll] = useState(() => new KeyScroll())
   /** 用键盘或筛选栏按钮跳过几次：每跳一次，画完后把当前那一处滚进视口 */
diff --git a/vscode/webview-ui/src/codeReader/useQa.ts b/vscode/webview-ui/src/codeReader/useQa.ts
index 0e1faa6..ab8d9ad 100644
--- a/vscode/webview-ui/src/codeReader/useQa.ts
+++ b/vscode/webview-ui/src/codeReader/useQa.ts
@@ -1,19 +1,39 @@
 import type { QaTree } from './BlockTree'
-import type { QaState } from './qa'
-import { useEffect, useMemo, useReducer, useRef } from 'react'
+import type { QaAction, QaState } from './qa'
+import { useEffect, useState } from 'react'
 import { EMPTY_QA, newAskId, qaReducer } from './qa'
 import { toAskImage } from './qaImages'
+import { createStore } from './store'
 import { onMessage, postMessage } from './vscode'
 
-/** 逐字长出来的回答最多隔多久画一次：一个字一画整棵块树跟着重画，大文件会卡 */
+/** 逐字长出来的回答最多隔多久画一次：一个字一画，正在答的那块的对话区跟着重画太勤 */
 export const ANSWER_FRAME_MS = 80
 
-/** 问 AI：收扩展端的问答、正在答的进展，给块树用的状态和动作（问、停、删、展开 / 收起）。 */
+/** 问 AI：收扩展端的问答、正在答的进展，给块树用的状态（块按自己的记号订阅）和动作（问、停、删、展开 / 收起）。整页一份，不跟着状态变。 */
 export function useQa(): QaTree {
-  const [state, dispatch] = useReducer(qaReducer, EMPTY_QA)
-  /** 动作里读眼下的状态（这块展开着没有） */
-  const current = useRef<QaState>(state)
-  current.current = state
+  const [{ tree, dispatch }] = useState(() => {
+    const store = createStore<QaState>(EMPTY_QA)
+    const dispatch = (action: QaAction): void => store.set(state => qaReducer(state, action))
+    /** 收起就结束这一轮，扩展端留着的那一轮（出错、被叫停的）也去掉 */
+    const close = (anchor: string): void => {
+      dispatch({ type: 'close', anchor })
+      postMessage({ type: 'forgetRound', kind: 'ask', anchor })
+    }
+    const tree: QaTree = {
+      store,
+      onToggle: anchor => store.get().open.includes(anchor) ? close(anchor) : dispatch({ type: 'open', anchor }),
+      onClose: close,
+      onAsk: (anchor, question, images) => {
+        const askId = newAskId()
+        dispatch({ type: 'ask', askId, anchor, question, images: images.map(image => image.url) })
+        postMessage({ type: 'ask', askId, anchor, question, images: images.map(toAskImage) })
+      },
+      onStop: askId => postMessage({ type: 'stopAsk', askId }),
+      onDelete: (anchor, entryId) => postMessage({ type: 'deleteQa', anchor, entryId }),
+      onSelectProfile: id => postMessage({ type: 'selectProfile', kind: 'ask', id }),
+    }
+    return { tree, dispatch }
+  })
 
   useEffect(() => {
     /** 攒着没画的回答：askId → 最新的一份 */
@@ -48,26 +68,7 @@ export function useQa(): QaTree {
       clearTimeout(timer)
       off()
     }
-  }, [])
+  }, [dispatch])
 
-  return useMemo((): QaTree => {
-    /** 收起就结束这一轮，扩展端留着的那一轮（出错、被叫停的）也去掉 */
-    const close = (anchor: string): void => {
-      dispatch({ type: 'close', anchor })
-      postMessage({ type: 'forgetRound', kind: 'ask', anchor })
-    }
-    return {
-      state,
-      onToggle: anchor => current.current.open.includes(anchor) ? close(anchor) : dispatch({ type: 'open', anchor }),
-      onClose: close,
-      onAsk: (anchor, question, images) => {
-        const askId = newAskId()
-        dispatch({ type: 'ask', askId, anchor, question, images: images.map(image => image.url) })
-        postMessage({ type: 'ask', askId, anchor, question, images: images.map(toAskImage) })
-      },
-      onStop: askId => postMessage({ type: 'stopAsk', askId }),
-      onDelete: (anchor, entryId) => postMessage({ type: 'deleteQa', anchor, entryId }),
-      onSelectProfile: id => postMessage({ type: 'selectProfile', kind: 'ask', id }),
-    }
-  }, [state])
+  return tree
 }
diff --git a/vscode/webview-ui/src/codeReader/useRewrite.ts b/vscode/webview-ui/src/codeReader/useRewrite.ts
index bdb77c4..4ca2b18 100644
--- a/vscode/webview-ui/src/codeReader/useRewrite.ts
+++ b/vscode/webview-ui/src/codeReader/useRewrite.ts
@@ -1,17 +1,46 @@
 import type { RewriteTree } from './BlockTree'
-import type { ChatState } from './qa'
-import { useEffect, useMemo, useReducer, useRef } from 'react'
+import type { ChatAction, ChatState } from './qa'
+import { useEffect, useState } from 'react'
 import { chatReducer, EMPTY_CHAT, newAskId, unfinished } from './qa'
 import { toAskImage } from './qaImages'
+import { createStore } from './store'
 import { ANSWER_FRAME_MS } from './useQa'
 import { onMessage, postMessage } from './vscode'
 
 /**
- * 按注释规范重写：收扩展端的重写记录、当前一轮的进展，给块树用的状态和动作。和问 AI 同一套：
+ * 按注释规范重写：收扩展端的重写记录、当前一轮的进展，给块树用的状态（块按自己的记号订阅）和动作。和问 AI 同一套：
  * 排着队的、进行中的、出错被叫停留着的那一轮记在扩展端，页面重新加载后随 qa 消息的 rewriteCurrent 接上。profile 下拉是自己的，和问 AI 的互不影响。
  */
 export function useRewrite(): RewriteTree {
-  const [state, dispatch] = useReducer(chatReducer<ChatState>, EMPTY_CHAT)
+  const [{ tree, dispatch }] = useState(() => {
+    const store = createStore<ChatState>(EMPTY_CHAT)
+    const dispatch = (action: ChatAction): void => store.set(state => chatReducer(state, action))
+    const tree: RewriteTree = {
+      store,
+      onSelectProfile: id => postMessage({ type: 'selectProfile', kind: 'rewrite', id }),
+      onRewrite: (anchor) => {
+        if (store.get().asks.some(ask => ask.anchor === anchor && unfinished(ask)))
+          return
+        const askId = newAskId()
+        // 那句技能命令由扩展端拼好，开始后随 rewriteProgress 报上来
+        dispatch({ type: 'ask', askId, anchor, question: '', images: [] })
+        postMessage({ type: 'rewriteComment', askId, anchor, images: [] })
+      },
+      onAsk: (anchor, request, images) => {
+        const askId = newAskId()
+        dispatch({ type: 'ask', askId, anchor, question: request, images: images.map(image => image.url) })
+        postMessage({ type: 'rewriteComment', askId, anchor, request, images: images.map(toAskImage) })
+      },
+      onStop: askId => postMessage({ type: 'stopRewrite', askId }),
+      onDelete: (anchor, entryId) => postMessage({ type: 'deleteRewrite', anchor, entryId }),
+      onOpen: anchor => dispatch({ type: 'open', anchor }),
+      onClose: (anchor) => {
+        dispatch({ type: 'close', anchor })
+        postMessage({ type: 'forgetRound', kind: 'rewrite', anchor })
+      },
+    }
+    return { tree, dispatch }
+  })
 
   useEffect(() => {
     /** 攒着没画的进展：askId → 最新的一份 */
@@ -46,34 +75,7 @@ export function useRewrite(): RewriteTree {
       clearTimeout(timer)
       off()
     }
-  }, [])
+  }, [dispatch])
 
-  /** 动作里读眼下的状态（这块是不是已经在写或排着队） */
-  const current = useRef(state)
-  current.current = state
-
-  return useMemo((): RewriteTree => ({
-    state,
-    onSelectProfile: id => postMessage({ type: 'selectProfile', kind: 'rewrite', id }),
-    onRewrite: (anchor) => {
-      if (current.current.asks.some(ask => ask.anchor === anchor && unfinished(ask)))
-        return
-      const askId = newAskId()
-      // 那句技能命令由扩展端拼好，开始后随 rewriteProgress 报上来
-      dispatch({ type: 'ask', askId, anchor, question: '', images: [] })
-      postMessage({ type: 'rewriteComment', askId, anchor, images: [] })
-    },
-    onAsk: (anchor, request, images) => {
-      const askId = newAskId()
-      dispatch({ type: 'ask', askId, anchor, question: request, images: images.map(image => image.url) })
-      postMessage({ type: 'rewriteComment', askId, anchor, request, images: images.map(toAskImage) })
-    },
-    onStop: askId => postMessage({ type: 'stopRewrite', askId }),
-    onDelete: (anchor, entryId) => postMessage({ type: 'deleteRewrite', anchor, entryId }),
-    onOpen: anchor => dispatch({ type: 'open', anchor }),
-    onClose: (anchor) => {
-      dispatch({ type: 'close', anchor })
-      postMessage({ type: 'forgetRound', kind: 'rewrite', anchor })
-    },
-  }), [state])
+  return tree
 }
diff --git a/vscode/webview-ui/src/codeReader/viewState.test.ts b/vscode/webview-ui/src/codeReader/viewState.test.ts
index 4762bc5..7d3b442 100644
--- a/vscode/webview-ui/src/codeReader/viewState.test.ts
+++ b/vscode/webview-ui/src/codeReader/viewState.test.ts
@@ -1,7 +1,7 @@
 import type { BlockKind, BlockView } from './types'
 import type { ViewStateStorage } from './viewState'
 import { describe, expect, it } from 'vitest'
-import { collapsedIds, createViewStateStore, propertyItemId, propertyRowId, unfoldToShow } from './viewState'
+import { collapsedIds, createViewStateStore, foldsByCard, propertyItemId, propertyRowId, unfoldToShow } from './viewState'
 
 /** 模拟 VS Code 的 webview 状态：存进去的要能序列化，页面重新加载后原样取回；也能塞进旧版本存的东西 */
 function memoryStorage(initial?: unknown): ViewStateStorage {
@@ -166,3 +166,24 @@ describe('眼下折叠着哪些', () => {
     expect([...collapsedIds(BLOCKS, { [outer]: false, [inner]: true })].sort()).toEqual(['0/p2/0/3', '1', '1.0.0', '2', '2.0'])
   })
 })
+
+describe('折叠着的 id 按卡片分', () => {
+  it('属性行、子行归它那张卡片；块归它自己和它的父卡片（父卡片画挂在子行上的子块）', () => {
+    const folds = foldsByCard(new Set(['0/p2', '0/p2/1', '1', '1.0', '1.0.3', 'removed-2/p0']))
+    expect([...folds.get('0')!]).toEqual(['0/p2', '0/p2/1'])
+    expect([...folds.get('1')!]).toEqual(['1', '1.0'])
+    expect([...folds.get('1.0')!]).toEqual(['1.0', '1.0.3'])
+    expect([...folds.get('1.0.3')!]).toEqual(['1.0.3'])
+    expect([...folds.get('removed-2')!]).toEqual(['removed-2/p0'])
+    expect(folds.has('2')).toBe(false)
+  })
+
+  it('和上一次一样的那几张卡片沿用上一次的那份：别的卡片折叠、展开时它订阅的还是同一个对象', () => {
+    const before = foldsByCard(new Set(['0/p2', '1', '2/p0']))
+    const after = foldsByCard(new Set(['0/p2', '1', '2/p0', '2/p1']), before)
+    expect(after.get('0')).toBe(before.get('0'))
+    expect(after.get('1')).toBe(before.get('1'))
+    expect(after.get('2')).not.toBe(before.get('2'))
+    expect([...after.get('2')!]).toEqual(['2/p0', '2/p1'])
+  })
+})
diff --git a/vscode/webview-ui/src/codeReader/viewState.ts b/vscode/webview-ui/src/codeReader/viewState.ts
index 159c1ff..96c2f3b 100644
--- a/vscode/webview-ui/src/codeReader/viewState.ts
+++ b/vscode/webview-ui/src/codeReader/viewState.ts
@@ -98,6 +98,39 @@ export function collapsedIds(blocks: readonly BlockView[], folds: Readonly<Recor
   return collapsed
 }
 
+/**
+ * 折叠着的 id 按卡片分好，卡片只订阅自己那份：属性行、子行的 id（`<块 id>/…`）归它那张卡片；块 id 归它自己，
+ * 也归它的父卡片（挂在父卡片子行上的子块由父卡片的属性表画、点子行开关）。
+ * 和 previous 里同一张卡片的那份一样时沿用那一份：别的卡片折叠、展开时，这张卡片订阅的还是原来那个对象，不重画。
+ */
+export function foldsByCard(collapsed: ReadonlySet<string>, previous?: ReadonlyMap<string, ReadonlySet<string>>): ReadonlyMap<string, ReadonlySet<string>> {
+  const groups = new Map<string, Set<string>>()
+  const add = (card: string, id: string): void => {
+    const group = groups.get(card)
+    if (group)
+      group.add(id)
+    else
+      groups.set(card, new Set([id]))
+  }
+  for (const id of collapsed) {
+    const slash = id.indexOf('/')
+    if (slash >= 0) {
+      add(id.slice(0, slash), id)
+      continue
+    }
+    add(id, id)
+    const dot = id.lastIndexOf('.')
+    if (dot >= 0)
+      add(id.slice(0, dot), id)
+  }
+  if (!previous)
+    return groups
+  return new Map([...groups].map(([card, ids]) => {
+    const before = previous.get(card)
+    return [card, before && before.size === ids.size && [...ids].every(id => before.has(id)) ? before : ids]
+  }))
+}
+
 /**
  * 属性表里带子行的那一行（输入参数、导入项、字典 / 对象的值）的折叠 id，和块 id 放在同一份 folds 里：
  * `<块 id>/p<行序号>`，例如 '6.1.0/p3'。块 id 只由数字和点组成，带 '/' 的不会和任何块 id 撞上。