fix: 完善聊天解析与导出体验

- 修复引用消息名称和图片布局
- 明确单会话图片测试日志范围
- 支持导出文件附件
- 完善图片批测、会话刷新和安全退出

tests/unit/image-decrypt.test.ts

@@ -16,6 +16,7 @@ import { ImageDecryptService } from '../../src/main/image-decrypt-service'
 
 const aesKey = '0123456789abcdef'
 const xorKey = 0x40
+const originalResourcesPath = process.resourcesPath
 
 function writeV2Dat(file: string): Buffer {
   const aesPlain = Buffer.from([0x89, 0x50, 0x4e, 0x47, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12])
@@ -35,22 +36,95 @@ function writeV2Dat(file: string): Buffer {
 }
 
 describe('DAT image decryption', () => {
-  beforeAll(() => mkdirSync(root, { recursive: true }))
-  afterAll(() => rmSync(root, { recursive: true, force: true }))
+  beforeAll(() => {
+    mkdirSync(root, { recursive: true })
+    Object.defineProperty(process, 'resourcesPath', { configurable: true, value: root })
+  })
+  afterAll(() => {
+    Object.defineProperty(process, 'resourcesPath', {
+      configurable: true,
+      value: originalResourcesPath
+    })
+    rmSync(root, { recursive: true, force: true })
+  })
 
   it('decrypts a synthetic V2 AES/raw/XOR fixture', () => {
     const file = join(root, 'fixture.dat')
     const expected = writeV2Dat(file)
-    expect(new ImageDecryptService('0x40', aesKey).decryptImage(file)).toEqual(expected)
+    const service = new ImageDecryptService('0x40', aesKey)
+    expect(service.decryptImage(file)).toEqual(expected)
+    expect(service.decryptImageToBase64(file)).toMatch(/^data:image\/png;base64,/)
+    expect(service.getLastDecodeDiagnostic()).toMatchObject({
+      code: 'SUCCESS',
+      datVersion: 2,
+      imageFormat: 'PNG'
+    })
   })
 
   it('rejects the wrong AES key and unsupported legacy signatures accurately', () => {
     const file = join(root, 'fixture.dat')
     writeV2Dat(file)
-    expect(new ImageDecryptService('0x40', 'fedcba9876543210').decryptImage(file)).toBeNull()
+    const wrongKeyService = new ImageDecryptService('0x40', 'fedcba9876543210')
+    expect(wrongKeyService.decryptImage(file)).toBeNull()
+    expect(wrongKeyService.getLastDecodeDiagnostic()).toMatchObject({
+      code: 'AES_DECRYPT_FAILED',
+      datVersion: 2
+    })
 
     const legacy = join(root, 'legacy.dat')
-    writeFileSync(legacy, Buffer.from([0xff, 0xd8, 0xff, 0x00]))
-    expect(new ImageDecryptService('0x40', aesKey).decryptImage(legacy)).toBeNull()
+    writeFileSync(legacy, Buffer.from([0x12, 0x34, 0x56, 0x78]))
+    const legacyService = new ImageDecryptService('0x40', aesKey)
+    expect(legacyService.decryptImage(legacy)).toBeNull()
+    expect(legacyService.getLastDecodeDiagnostic()).toMatchObject({
+      code: 'UNSUPPORTED_DAT_VERSION',
+      datVersion: 0
+    })
+  })
+
+  it('finds modern _M variants and reads plain images stored with a DAT extension', async () => {
+    const accountRoot = join(root, 'modern-account')
+    const sessionId = '77705c31c50e8a4242a9d527fe9433de'
+    const imageDirectory = join(accountRoot, 'msg', 'attach', sessionId, '2025-10', 'Img')
+    mkdirSync(imageDirectory, { recursive: true })
+
+    const imageBase = '9718e38ad90f57f9e833d17ff2373abd'
+    const mediumFile = join(imageDirectory, `${imageBase}_M.dat`)
+    writeFileSync(mediumFile, Buffer.from([0x89, 0x50, 0x4e, 0x47, 1, 2, 3, 4]))
+
+    const service = new ImageDecryptService('0x40', aesKey)
+    await expect(
+      service.findImageFileAsync(undefined, imageBase, {
+        allowThumbnail: false,
+        accountDir: accountRoot,
+        sessionId
+      })
+    ).resolves.toBe(mediumFile)
+    expect(service.decryptImageToBase64(mediumFile)).toMatch(/^data:image\/png;base64,/)
+    expect(service.getLastDecodeDiagnostic()).toMatchObject({
+      code: 'DIRECT_IMAGE',
+      imageFormat: 'PNG'
+    })
+    await expect(service.decryptImageToBase64WithFallbackAsync(mediumFile, true)).resolves.toEqual(
+      expect.objectContaining({ filePath: mediumFile })
+    )
+
+    const thumbnailBase = '37a9000000000000000000000000ceaa'
+    const thumbnailFile = join(imageDirectory, `${thumbnailBase}_t_M.dat`)
+    writeFileSync(thumbnailFile, Buffer.from([0xff, 0xd8, 0xff, 0x00]))
+    expect(service.isThumbnailFile(thumbnailFile)).toBe(true)
+    await expect(
+      service.findImageFileAsync(undefined, `${thumbnailBase}_t_M.dat`, {
+        allowThumbnail: false,
+        accountDir: accountRoot,
+        sessionId
+      })
+    ).resolves.toBeNull()
+    await expect(
+      service.findImageFileAsync(undefined, `${thumbnailBase}_t_M.dat`, {
+        allowThumbnail: true,
+        accountDir: accountRoot,
+        sessionId
+      })
+    ).resolves.toBe(thumbnailFile)
   })
 })