⚡ perf(vscode): 代码阅读预览按卡片订阅状态：中文名、调用树棵数、单击高亮、问答一条消息只重画受影响的卡片和文字，新文档里内容没变的块沿用原来的对象不重画，没展开又没说过的块不画问答区

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)
+  })
+})