修复bug，第一次导出缩略图，后面有了高清图后再次导出应该覆盖

按原图、中图和缩略图对本地图片资源分级，始终优先选择高清变体。

增量导出仅复用满足清晰度要求的图片，重新探测旧缩略图并在高清图出现后替换；仅缩略图降级时显示提示。

src/main/export-service.ts

@@ -23,6 +23,7 @@ import { getImageExportAttempts } from '../shared/export-media'
 import { FileAssetService } from './file-asset-service'
 import { mergeCachedSelfInfo } from './services/bootstrap-cache'
 import type { VoiceRecognitionUseCase } from './voice-pipeline/voice-recognition-use-case'
+import { imageFileQuality } from '../shared/image-quality'
 
 const jobs = new Set<string>()
 const activeArchives = new Map<string, Archiver>()
@@ -250,6 +251,7 @@ const mergeArchiveMessage = (previous: Message, current: Message): Message => {
     'exportMediaUrl',
     'exportMediaType',
     'exportMediaName',
+    'exportMediaQuality',
     'exportAvatarUrl'
   ]
   for (const key of preserveWhenMissing) {
@@ -706,6 +708,7 @@ export async function runExport(
       message.exportMediaUrl = undefined
       message.exportMediaType = undefined
       message.exportMediaName = undefined
+      message.exportMediaQuality = undefined
       message.exportMediaError = undefined
       message.voiceDataUrl = undefined
       message.voiceTranscript = undefined
@@ -1063,15 +1066,20 @@ export async function runExport(
             : message.contentData.type === 'share' && message.contentData.typeVal === '6'
               ? 'file'
               : null
+        const reusableImageQuality =
+          previous?.exportMediaQuality === 'original' ||
+          (request.preferOriginal === false && previous?.exportMediaQuality === 'thumbnail')
         if (
           reusableMediaType &&
           previous?.exportMediaUrl &&
           (!previous.exportMediaType || previous.exportMediaType === reusableMediaType) &&
+          (reusableMediaType !== 'image' || reusableImageQuality) &&
           (await resourceExists(previous.exportMediaUrl))
         ) {
           message.exportMediaUrl = previous.exportMediaUrl
           message.exportMediaType = reusableMediaType
           message.exportMediaName = previous.exportMediaName
+          message.exportMediaQuality = previous.exportMediaQuality
           send({
             jobId: request.jobId,
             phase: 'media',
@@ -1087,7 +1095,6 @@ export async function runExport(
           } else {
             let fileFound = false
             let decryptedImage: { data: string; filePath: string } | null = null
-            let usedFallback = false
             for (const attempt of getImageExportAttempts(request)) {
               const file = await imageService.findImageFileAsync(
                 message.contentData.md5,
@@ -1116,7 +1123,6 @@ export async function runExport(
               }
               if (!decrypted) continue
               decryptedImage = decrypted
-              usedFallback = attempt.fallback || imageService.isThumbnailFile(decrypted.filePath)
               break
             }
             const decoded = decryptedImage ? decodeDataUrl(decryptedImage.data) : null
@@ -1129,7 +1135,8 @@ export async function runExport(
               }
               message.exportMediaUrl = mediaUrl
               message.exportMediaType = 'image'
-              if (usedFallback) {
+              message.exportMediaQuality = imageFileQuality(decryptedImage!.filePath)
+              if (request.preferOriginal !== false && message.exportMediaQuality === 'thumbnail') {
                 keepMediaError(request, message, '原图不可用，已降级使用缩略图')
               }
             } else if (!fileFound) {

src/main/image-decrypt-service.ts

@@ -7,6 +7,7 @@ import { execFile } from 'child_process'
 import { Worker } from 'worker_threads'
 import ffmpegStaticPath from 'ffmpeg-static'
 import type { ImageDecoderSource, ImageDecoderStatus } from '../shared/image-decryption'
+import { imageFileQuality, imageQualityRank } from '../shared/image-quality'
 import { loadSettings } from './services/settings-store'
 import { Wcdb4Client } from './wcdb4-client'
 
@@ -208,6 +209,13 @@ function isThumbnailName(fileName) {
   return /(?:_t(?:_m)?|_thumb|\.thumb|_b|_w|_c)\.dat$/i.test(lower)
 }
 
+function imageQualityRank(fileName) {
+  const lower = fileName.toLowerCase()
+  if (/(?:_t(?:_m)?|_thumb|\.thumb|_b|_w|_c)\.dat$/i.test(lower)) return 1
+  if (/(?:_hd|\.hd|_h_m|_h|\.h)\.dat$/i.test(lower)) return 3
+  return 2
+}
+
 function buildPreferredDatNames(baseName) {
   const base = normalizeDatBase(baseName)
   if (!base) return []
@@ -436,8 +444,8 @@ function collectCandidates(datPath, allowThumbnail) {
     .map((name) => path.join(directory, name))
     .filter((candidate) => fs.existsSync(candidate))
     .sort((left, right) => {
-      const thumbnailOrder = Number(isThumbnailName(path.basename(left))) - Number(isThumbnailName(path.basename(right)))
+      const qualityOrder = imageQualityRank(path.basename(right)) - imageQualityRank(path.basename(left))
-      return thumbnailOrder || fs.statSync(right).size - fs.statSync(left).size
+      return qualityOrder || fs.statSync(right).size - fs.statSync(left).size
     })
   return Array.from(new Set(candidates.concat(siblings)))
 }
@@ -1824,17 +1832,17 @@ export class ImageDecryptService {
         .sort((left, right) => right.size - left.size)
 
     const thumbnail = toSized(
-      paths.filter((candidate) => this.isThumbnailName(basename(candidate)))
+      paths.filter((candidate) => imageFileQuality(candidate) === 'thumbnail')
     )
     if (preferThumbnail && thumbnail[0]) return thumbnail[0].candidate
-    const nonThumb = toSized(
+    const allowed = toSized(paths)
-      paths.filter((candidate) => !this.isThumbnailName(basename(candidate)))
+      .filter((entry) => allowThumbnail || imageFileQuality(entry.candidate) !== 'thumbnail')
+      .sort(
+        (left, right) =>
+          imageQualityRank(imageFileQuality(right.candidate)) -
+            imageQualityRank(imageFileQuality(left.candidate)) || right.size - left.size
       )
-    if (nonThumb[0]) return nonThumb[0].candidate
+    return allowed[0]?.candidate || null
-    if (!allowThumbnail) return null
-
-    const existing = toSized(paths)
-    return existing[0]?.candidate || null
   }
 
   private async getLargestExistingPathAsync(
@@ -1858,17 +1866,21 @@ export class ImageDecryptService {
       .sort((left, right) => right.size - left.size)
 
     if (preferThumbnail) {
-      const thumbnail = sized.find((entry) => this.isThumbnailName(basename(entry.candidate)))
+      const thumbnail = sized.find((entry) => imageFileQuality(entry.candidate) === 'thumbnail')
       if (thumbnail) return thumbnail.candidate
     }
-    const nonThumbnail = sized.find((entry) => !this.isThumbnailName(basename(entry.candidate)))
+    const allowed = sized
-    if (nonThumbnail) return nonThumbnail.candidate
+      .filter((entry) => allowThumbnail || imageFileQuality(entry.candidate) !== 'thumbnail')
-    return allowThumbnail ? sized[0]?.candidate || null : null
+      .sort(
+        (left, right) =>
+          imageQualityRank(imageFileQuality(right.candidate)) -
+            imageQualityRank(imageFileQuality(left.candidate)) || right.size - left.size
+      )
+    return allowed[0]?.candidate || null
   }
 
   private isThumbnailName(fileName: string): boolean {
-    const lower = fileName.toLowerCase()
+    return imageFileQuality(fileName) === 'thumbnail'
-    return /(?:_t(?:_m)?|_thumb|\.thumb|_b|_w|_c)\.dat$/i.test(lower)
   }
 
   isThumbnailFile(filePath: string): boolean {

src/main/services/chat-service.ts

@@ -10,6 +10,7 @@ import type {
   DatabaseKeyValidationResult
 } from '../../shared/database-key'
 import { mergeRecallArchiveMessages, recordRecallArchiveMessages } from './recall-archive-service'
+import type { ExportImageQuality } from '../../shared/image-quality'
 
 export function getCurrentKey(): string {
   if (!dbRef) return ''
@@ -60,6 +61,7 @@ export interface FormattedMessage {
   exportMediaUrl?: string
   exportMediaType?: 'image' | 'video' | 'sticker' | 'file'
   exportMediaName?: string
+  exportMediaQuality?: ExportImageQuality
   exportShowAvatar?: boolean
   exportMediaError?: string
   exportAvatarUrl?: string

src/shared/export-media.ts

@@ -3,20 +3,17 @@ import type { ExportRequest } from './export'
 export type ImageExportAttempt = {
   allowThumbnail: boolean
   preferThumbnail: boolean
-  fallback: boolean
 }
 
 export function getImageExportAttempts(
   request: Pick<ExportRequest, 'preferOriginal' | 'fallbackThumbnail'>
 ): ImageExportAttempt[] {
   if (request.preferOriginal === false) {
-    return [{ allowThumbnail: true, preferThumbnail: true, fallback: false }]
+    return [{ allowThumbnail: true, preferThumbnail: true }]
   }
-  const attempts: ImageExportAttempt[] = [
+  const attempts: ImageExportAttempt[] = [{ allowThumbnail: false, preferThumbnail: false }]
-    { allowThumbnail: false, preferThumbnail: false, fallback: false }
-  ]
   if (request.fallbackThumbnail !== false) {
-    attempts.push({ allowThumbnail: true, preferThumbnail: true, fallback: true })
+    attempts.push({ allowThumbnail: true, preferThumbnail: true })
   }
   return attempts
 }

src/shared/image-quality.ts

@@ -0,0 +1,24 @@
+export type ExportImageQuality = 'original' | 'medium' | 'thumbnail'
+
+const fileNameOf = (filePath: string): string =>
+  String(filePath || '')
+    .trim()
+    .toLowerCase()
+    .split(/[\\/]/)
+    .pop() || ''
+
+export const imageFileQuality = (filePath: string): ExportImageQuality => {
+  const fileName = fileNameOf(filePath)
+  if (!fileName.endsWith('.dat')) return 'original'
+  if (/(?:_t(?:_m)?|_thumb|\.thumb|_b|_w|_c)\.dat$/i.test(fileName)) {
+    return 'thumbnail'
+  }
+  if (/(?:_hd|\.hd|_h_m|_h|\.h)\.dat$/i.test(fileName)) return 'original'
+  return 'medium'
+}
+
+export const imageQualityRank = (quality: ExportImageQuality): number => {
+  if (quality === 'original') return 3
+  if (quality === 'medium') return 2
+  return 1
+}

src/shared/types.ts

@@ -1,3 +1,5 @@
+import type { ExportImageQuality } from './image-quality'
+
 export interface Contact {
   m_nsUsrName: string
   m_nsNickName: string
@@ -36,6 +38,7 @@ export interface Message {
   exportMediaUrl?: string
   exportMediaType?: 'image' | 'video' | 'sticker' | 'file'
   exportMediaName?: string
+  exportMediaQuality?: ExportImageQuality
   exportShowAvatar?: boolean
   exportMediaError?: string
   exportAvatarUrl?: string

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

@@ -41,7 +41,10 @@ const state = vi.hoisted(() => ({
     sessionId?: string
     sessionMd5?: string
     createTime?: number
-  }[]
+  }[],
+  imageFilePath: 'fixture_h.dat',
+  imageData:
+    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAusB9Y9ZQmcAAAAASUVORK5CYII='
 }))
 
 vi.mock('electron', () => ({
@@ -128,7 +131,7 @@ vi.mock('../../src/main/image-decrypt-service', () => ({
       }
     ): string {
       state.imageLookups.push(options)
-      return 'fixture-original.dat'
+      return state.imageFilePath
     }
     async findImageFileAsync(
       md5: string,
@@ -145,8 +148,8 @@ vi.mock('../../src/main/image-decrypt-service', () => ({
     }
     decryptImageToBase64WithFallback(): { data: string; filePath: string } {
       return {
-        data: 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAusB9Y9ZQmcAAAAASUVORK5CYII=',
+        data: state.imageData,
-        filePath: 'fixture-original.dat'
+        filePath: state.imageFilePath
       }
     }
     async decryptImageToBase64WithFallbackAsync(): Promise<{
@@ -229,6 +232,9 @@ describe('media export flow', () => {
       Buffer.from('000000186674797069736f6d0000020069736f6d69736f32', 'hex')
     )
     state.imageLookups = []
+    state.imageFilePath = 'fixture_h.dat'
+    state.imageData =
+      'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAusB9Y9ZQmcAAAAASUVORK5CYII='
     state.videoLookups = []
     state.messagesByUser = {}
     state.exportReads = []
@@ -595,6 +601,88 @@ describe('media export flow', () => {
     expect(existsSync(imagePath)).toBe(true)
   })
 
+  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() } }
+    const request = {
+      targets: [target('fixture-user', '图片升级会话')],
+      format: 'html' as const,
+      outputName: 'image-quality-upgrade-fixture',
+      kinds: ['image'] as const,
+      includeMedia: true,
+      preferOriginal: true,
+      fallbackThumbnail: true,
+      keepMissing: true
+    }
+    state.messages = [
+      message({
+        id: 'upgrade-image',
+        type: '图片',
+        sessionId: 'fixture-session',
+        contentData: { type: 'image', md5: 'c'.repeat(32), datName: 'upgrade.dat' }
+      })
+    ]
+    state.imageFilePath = 'upgrade_t.dat'
+    state.imageData = `data:image/png;base64,${Buffer.from('thumbnail-image').toString('base64')}`
+
+    const first = await runExport(
+      { ...request, jobId: 'image-quality-upgrade-first', kinds: [...request.kinds] },
+      win as never
+    )
+    expect(first.success, first.error).toBe(true)
+    const firstImage = readArchive(first.outputPath!).messages[0]
+    const firstImagePath = join(dirname(first.outputPath!), firstImage.exportMediaUrl!)
+    expect(firstImage.exportMediaQuality).toBe('thumbnail')
+    expect(firstImage.exportMediaError).toBe('原图不可用，已降级使用缩略图')
+
+    state.imageFilePath = 'upgrade_h.dat'
+    state.imageData = `data:image/png;base64,${Buffer.from('high-resolution-image').toString('base64')}`
+    const second = await runExport(
+      { ...request, jobId: 'image-quality-upgrade-second', kinds: [...request.kinds] },
+      win as never
+    )
+    expect(second.success, second.error).toBe(true)
+    const upgradedImage = readArchive(second.outputPath!).messages[0]
+    expect(state.imageLookups).toHaveLength(2)
+    expect(upgradedImage.exportMediaQuality).toBe('original')
+    expect(upgradedImage.exportMediaError).toBeUndefined()
+    expect(upgradedImage.exportMediaUrl).not.toBe(firstImage.exportMediaUrl)
+    expect(existsSync(join(dirname(second.outputPath!), upgradedImage.exportMediaUrl!))).toBe(true)
+    expect(existsSync(firstImagePath)).toBe(false)
+  })
+
+  it('does not show a warning for a medium-quality image', async () => {
+    const { runExport } = await import('../../src/main/export-service')
+    state.messages = [
+      message({
+        id: 'medium-image',
+        type: '图片',
+        contentData: { type: 'image', md5: 'd'.repeat(32), datName: 'medium.dat' }
+      })
+    ]
+    state.imageFilePath = 'medium.dat'
+
+    const result = await runExport(
+      {
+        jobId: 'medium-image-export',
+        targets: [target()],
+        format: 'html',
+        outputName: 'medium-image-fixture',
+        kinds: ['image'],
+        includeMedia: true,
+        preferOriginal: true,
+        fallbackThumbnail: true,
+        keepMissing: true
+      },
+      { isDestroyed: () => true, webContents: { send: vi.fn() } } as never
+    )
+
+    expect(result.success, result.error).toBe(true)
+    const exported = readArchive(result.outputPath!).messages[0]
+    expect(exported.exportMediaQuality).toBe('medium')
+    expect(exported.exportMediaError).toBeUndefined()
+  })
+
   it('keeps historical avatars and creates a new version only after a real visual change', async () => {
     const { runExport } = await import('../../src/main/export-service')
     const win = { isDestroyed: () => true, webContents: { send: vi.fn() } }

tests/unit/export-media.test.ts

@@ -15,8 +15,8 @@ describe('export media', () => {
     const repeated = getImageExportAttempts({ preferOriginal: true, fallbackThumbnail: true })
 
     expect(first).toEqual([
-      { allowThumbnail: false, preferThumbnail: false, fallback: false },
+      { allowThumbnail: false, preferThumbnail: false },
-      { allowThumbnail: true, preferThumbnail: true, fallback: true }
+      { allowThumbnail: true, preferThumbnail: true }
     ])
     expect(repeated).toEqual(first)
   })

tests/unit/image-decrypt.test.ts

@@ -13,6 +13,7 @@ vi.mock('../../src/main/services/settings-store', () => ({
 vi.mock('../../src/main/wcdb4-client', () => ({ Wcdb4Client: class {} }))
 
 import { ImageDecryptService } from '../../src/main/image-decrypt-service'
+import { imageFileQuality } from '../../src/shared/image-quality'
 
 const aesKey = '0123456789abcdef'
 const xorKey = 0x40
@@ -109,6 +110,7 @@ describe('DAT image decryption', () => {
       mediumFile
     )
     expect(service.decryptImageToBase64(mediumFile)).toMatch(/^data:image\/png;base64,/)
+    expect(imageFileQuality(mediumFile)).toBe('medium')
     expect(service.getLastDecodeDiagnostic()).toMatchObject({
       code: 'DIRECT_IMAGE',
       imageFormat: 'PNG'
@@ -121,6 +123,7 @@ describe('DAT image decryption', () => {
     const thumbnailFile = join(imageDirectory, `${thumbnailBase}_t_M.dat`)
     writeFileSync(thumbnailFile, Buffer.from([0xff, 0xd8, 0xff, 0x00]))
     expect(service.isThumbnailFile(thumbnailFile)).toBe(true)
+    expect(imageFileQuality(thumbnailFile)).toBe('thumbnail')
     await expect(
       service.findImageFileAsync(undefined, `${thumbnailBase}_t_M.dat`, {
         allowThumbnail: false,
@@ -164,5 +167,22 @@ describe('DAT image decryption', () => {
     await expect(service.findImageFileAsync(undefined, bubbleBase, bubbleOptions)).resolves.toBe(
       bubblePreview
     )
+
+    const qualityBase = '6a62000000000000000000000000cafe'
+    const standardFile = join(imageDirectory, `${qualityBase}.dat`)
+    const highFile = join(imageDirectory, `${qualityBase}_h.dat`)
+    const largeThumbnailFile = join(imageDirectory, `${qualityBase}_t.dat`)
+    writeFileSync(standardFile, Buffer.alloc(200, 1))
+    writeFileSync(highFile, Buffer.alloc(20, 2))
+    writeFileSync(largeThumbnailFile, Buffer.alloc(400, 3))
+    expect(imageFileQuality(highFile)).toBe('original')
+    await expect(
+      service.findImageFileAsync(undefined, qualityBase, {
+        allowThumbnail: false,
+        accountDir: accountRoot,
+        sessionMd5,
+        createTime: Math.floor(new Date(2025, 9, 15).getTime() / 1000)
+      })
+    ).resolves.toBe(highFile)
   })
 })