修复部分自定义表情导出后图裂的问题

校验应用缓存、微信 Emoticon 缓存及 CDN 响应的真实图片格式，无效缓存自动回退下载。

增量导出会识别并替换旧归档中的无效表情资源；刷新失败时移除破图引用并保留明确错误。

补充 StickerService 单元测试和 HTML 媒体增量导出回归测试。

tests/integration/export-media-flow.test.ts

@@ -44,6 +44,9 @@ const state = vi.hoisted(() => ({
   >,
   voiceLookups: [] as number[],
   voiceBatches: [] as number[][],
+  stickerLookups: [] as Array<{ cdnUrl?: string; md5?: string }>,
+  stickerData: 'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==',
+  stickerError: undefined as string | undefined,
   videoLookups: [] as {
     createTime?: number
     byteLength?: number
@@ -214,7 +217,16 @@ vi.mock('../../src/main/video-asset-service', () => ({
   }
 }))
 vi.mock('../../src/main/sticker-service', () => ({
-  StickerService: class {}
+  StickerService: class {
+    async resolveSticker(
+      cdnUrl?: string,
+      md5?: string
+    ): Promise<{ success: boolean; data?: string; error?: string }> {
+      state.stickerLookups.push({ cdnUrl, md5 })
+      if (state.stickerError) return { success: false, error: state.stickerError }
+      return { success: true, data: state.stickerData }
+    }
+  }
 }))
 
 const message = (overrides: Partial<Message>): Message => ({
@@ -273,6 +285,8 @@ describe('media export flow', () => {
     state.groupSnapshots = {}
     state.voiceLookups = []
     state.voiceBatches = []
+    state.stickerLookups = []
+    state.stickerError = undefined
     const fileMonth = join(state.accountRoot, 'msg', 'file', '2026-08')
     mkdirSync(fileMonth, { recursive: true })
     writeFileSync(join(fileMonth, '测试附件.txt'), '附件内容')
@@ -720,6 +734,70 @@ describe('media export flow', () => {
     expect(existsSync(imagePath)).toBe(true)
   })
 
+  it('replaces an invalid sticker file during an incremental export', async () => {
+    const { runExport } = await import('../../src/main/export-service')
+    const win = { isDestroyed: () => true, webContents: { send: vi.fn() } }
+    const request = {
+      targets: [target('fixture-user', '表情修复会话')],
+      format: 'html' as const,
+      outputName: 'sticker-repair-fixture',
+      kinds: ['sticker'] as const,
+      includeMedia: true,
+      keepMissing: true
+    }
+    state.messages = [
+      message({
+        id: 'sticker-invalid-cache',
+        type: '表情包',
+        contentData: {
+          type: 'sticker',
+          md5: '4671f60b074db0a2cc8ace8281c8c0f0',
+          url: 'https://fixture.invalid/sticker.gif'
+        }
+      })
+    ]
+
+    const first = await runExport(
+      { ...request, jobId: 'sticker-repair-first', kinds: [...request.kinds] },
+      win as never
+    )
+    expect(first.success, first.error).toBe(true)
+    const firstSticker = readArchive(first.outputPath!).messages[0]
+    const stickerPath = join(dirname(first.outputPath!), firstSticker.exportMediaUrl!)
+    expect(readFileSync(stickerPath).subarray(0, 3).toString('ascii')).toBe('GIF')
+
+    writeFileSync(stickerPath, Buffer.from('encrypted-wechat-emoticon-cache'))
+    state.stickerLookups = []
+    const second = await runExport(
+      { ...request, jobId: 'sticker-repair-second', kinds: [...request.kinds] },
+      win as never
+    )
+
+    expect(second.success, second.error).toBe(true)
+    expect(state.stickerLookups).toEqual([
+      {
+        cdnUrl: 'https://fixture.invalid/sticker.gif',
+        md5: '4671f60b074db0a2cc8ace8281c8c0f0'
+      }
+    ])
+    const repairedSticker = readArchive(second.outputPath!).messages[0]
+    expect(repairedSticker.exportMediaUrl).toBe(firstSticker.exportMediaUrl)
+    expect(readFileSync(stickerPath).subarray(0, 3).toString('ascii')).toBe('GIF')
+
+    writeFileSync(stickerPath, Buffer.from('encrypted-wechat-emoticon-cache'))
+    state.stickerError = '表情链接已过期'
+    const third = await runExport(
+      { ...request, jobId: 'sticker-repair-third', kinds: [...request.kinds] },
+      win as never
+    )
+
+    expect(third.success, third.error).toBe(true)
+    const unavailableSticker = readArchive(third.outputPath!).messages[0]
+    expect(unavailableSticker.exportMediaUrl).toBeUndefined()
+    expect(unavailableSticker.exportMediaError).toBe('表情链接已过期')
+    expect(existsSync(stickerPath)).toBe(false)
+  })
+
   it('rechecks a previous low-quality image and upgrades it when an original appears', async () => {
     const { runExport } = await import('../../src/main/export-service')
     const win = { isDestroyed: () => true, webContents: { send: vi.fn() } }

tests/unit/sticker-service.test.ts

@@ -0,0 +1,93 @@
+import crypto from 'crypto'
+import fs from 'fs-extra'
+import http from 'http'
+import os from 'os'
+import path from 'path'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { StickerService } from '../../src/main/sticker-service'
+import type { Wcdb4Client } from '../../src/main/wcdb4-client'
+
+const validGif = Buffer.from(
+  '47494638396101000100800000000000ffffff21f90401000000002c00000000010001000002024401003b',
+  'hex'
+)
+
+describe('StickerService', () => {
+  let homeDir = ''
+  const servers: http.Server[] = []
+
+  beforeEach(() => {
+    homeDir = fs.mkdtempSync(path.join(os.tmpdir(), 'sticker-service-'))
+    vi.stubEnv('HOME', homeDir)
+  })
+
+  afterEach(async () => {
+    vi.unstubAllEnvs()
+    await Promise.all(
+      servers
+        .splice(0)
+        .map(
+          (server) =>
+            new Promise<void>((resolve, reject) =>
+              server.close((error) => (error ? reject(error) : resolve()))
+            )
+        )
+    )
+    fs.removeSync(homeDir)
+  })
+
+  const serve = async (body: Buffer): Promise<{ url: string; requests: () => number }> => {
+    let requestCount = 0
+    const server = http.createServer((_request, response) => {
+      requestCount += 1
+      response.writeHead(200)
+      response.end(body)
+    })
+    servers.push(server)
+    await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve))
+    const address = server.address()
+    if (!address || typeof address === 'string') throw new Error('HTTP fixture did not bind a port')
+    return {
+      url: `http://127.0.0.1:${address.port}/sticker.gif`,
+      requests: () => requestCount
+    }
+  }
+
+  it('ignores invalid app and WeChat caches and falls back to the CDN', async () => {
+    const md5 = crypto.createHash('md5').update(validGif).digest('hex')
+    const invalidCache = Buffer.from('encrypted-wechat-emoticon-cache')
+    const appCache = path.join(homeDir, 'Documents', 'TraceMemo', 'Emojis', `${md5}.gif`)
+    fs.ensureDirSync(path.dirname(appCache))
+    fs.writeFileSync(appCache, invalidCache)
+
+    const accountRoot = path.join(homeDir, 'account')
+    const wechatCache = path.join(accountRoot, 'cache', '2026-08', 'Emoticon', md5.slice(0, 2), md5)
+    fs.ensureDirSync(path.dirname(wechatCache))
+    fs.writeFileSync(wechatCache, invalidCache)
+
+    const fixture = await serve(validGif)
+    const client = { getAccountRoot: () => accountRoot } as unknown as Wcdb4Client
+    const result = await new StickerService(client).resolveSticker(fixture.url, md5)
+
+    expect(result.success, result.error).toBe(true)
+    expect(result.data).toBe(`data:image/gif;base64,${validGif.toString('base64')}`)
+    expect(fixture.requests()).toBe(1)
+    expect(fs.readFileSync(appCache)).toEqual(validGif)
+    expect(fs.readFileSync(wechatCache)).toEqual(invalidCache)
+  })
+
+  it('rejects an HTTP 200 response whose body is not an image', async () => {
+    const md5 = 'a'.repeat(32)
+    const fixture = await serve(Buffer.from('expired sticker response'))
+    const result = await new StickerService().resolveSticker(fixture.url, md5)
+
+    expect(result).toMatchObject({
+      success: false,
+      error: '表情包响应不是支持的图片格式'
+    })
+    expect(fixture.requests()).toBe(1)
+    expect(
+      fs.existsSync(path.join(homeDir, 'Documents', 'TraceMemo', 'Emojis', `${md5}.gif`))
+    ).toBe(false)
+  })
+})