fix: 优化 Windows 启动性能与聊天图片缓存

- 增加聊天图片磁盘持久化缓存，重启后直接复用
- 将 DAT 图片解密移至 Worker，避免阻塞主进程
- 增加图片加载优先级和并发控制
- 优化会话目录与图片文件的异步查找
- 使用本地媒体协议加载缓存图片，减少 Base64 IPC 开销
- 优化启动缓存与数据库初始化流程，降低窗口未响应时间

(cherry picked from commit 82bcc8d32ca674de38c745cc9925ed2309887dc7)

src/main/image-decrypt-service.ts

@@ -1,7 +1,9 @@
-import { basename, dirname, extname, join } from 'path'
-import { existsSync, readFileSync, statSync, readdirSync } from 'fs'
+import { basename, dirname, extname, join, resolve } from 'path'
+import { existsSync, readFileSync, statSync, readdirSync, promises as fsPromises } from 'fs'
 import crypto from 'crypto'
 import os from 'os'
+import { app } from 'electron'
+import { Worker } from 'worker_threads'
 import { Wcdb4Client } from './wcdb4-client'
 
 const imageDecryptDebugEnabled = process.env['WECHATEXPLORER_DEBUG_IMAGE'] === '1'
@@ -9,13 +11,207 @@ const imageDecryptLog = (...args: unknown[]): void => {
   if (imageDecryptDebugEnabled) console.log(...args)
 }
 
-type DecodedImage = {
+export type DecodedImage = {
   data: string
   filePath: string
   isThumbnail: boolean
+  cacheFilePath?: string
+  mimeType?: string
+}
+
+type ImageFindOptions = {
+  allowThumbnail?: boolean
+  accountDir?: string
+  preferThumbnail?: boolean
+  sessionId?: string
 }
 
 const MAX_DECODED_IMAGE_CACHE_BYTES = 48 * 1024 * 1024
+const MAX_PERSISTENT_IMAGE_CACHE_BYTES = 512 * 1024 * 1024
+const MAX_PERSISTENT_IMAGE_CACHE_FILES = 512
+const PERSISTENT_IMAGE_CACHE_VERSION = 2
+
+interface PersistentImageMeta {
+  version: number
+  sourcePath: string
+  sourceSize: number
+  sourceMtimeMs: number
+  fileName: string
+  cacheSize: number
+  mimeType: string
+  isThumbnail: boolean
+}
+
+const IMAGE_DECRYPT_WORKER_SOURCE = String.raw`
+const crypto = require('node:crypto')
+const fs = require('node:fs')
+const path = require('node:path')
+const { parentPort, workerData } = require('node:worker_threads')
+
+function normalizeDatBase(value) {
+  const lower = String(value || '').trim().toLowerCase()
+  if (!lower) return ''
+  const file = lower.split('/').pop().split('\\').pop()
+  const withoutDat = file.endsWith('.dat') ? file.slice(0, -4) : file
+  return withoutDat.replace(/(_thumb|\.thumb|_hd|\.hd|_h|\.h|_t|\.t|_c|\.c)$/i, '')
+}
+
+function isThumbnailName(fileName) {
+  const lower = fileName.toLowerCase()
+  return lower.includes('_t.dat') || lower.includes('_thumb.dat') || lower.includes('.thumb.dat')
+}
+
+function buildPreferredDatNames(baseName) {
+  const base = normalizeDatBase(baseName)
+  if (!base) return []
+  return [
+    base + '.dat',
+    base + '_hd.dat',
+    base + '_h.dat',
+    base + '_b.dat',
+    base + '_w.dat',
+    base + '_c.dat',
+    base + '_t.dat',
+    base + '.thumb.dat',
+    base + '_thumb.dat'
+  ]
+}
+
+function detectImageExtension(buffer) {
+  if (buffer.length < 4) return null
+  if (buffer[0] === 0xff && buffer[1] === 0xd8 && buffer[2] === 0xff) return '.jpg'
+  if (buffer[0] === 0x89 && buffer[1] === 0x50 && buffer[2] === 0x4e && buffer[3] === 0x47) return '.png'
+  if (buffer[0] === 0x47 && buffer[1] === 0x49 && buffer[2] === 0x46 && buffer[3] === 0x38) return '.gif'
+  if (buffer[0] === 0x42 && buffer[1] === 0x4d) return '.bmp'
+  if (buffer[0] === 0x52 && buffer[1] === 0x49 && buffer[2] === 0x46 && buffer[3] === 0x46) return '.webp'
+  return null
+}
+
+function getMimeType(extension) {
+  if (extension === '.png') return 'image/png'
+  if (extension === '.gif') return 'image/gif'
+  if (extension === '.bmp') return 'image/bmp'
+  if (extension === '.webp') return 'image/webp'
+  return 'image/jpeg'
+}
+
+function strictRemovePadding(buffer) {
+  if (buffer.length === 0) return buffer
+  const paddingLength = buffer[buffer.length - 1]
+  if (paddingLength <= 0 || paddingLength > 16 || paddingLength > buffer.length) return buffer
+  for (let index = buffer.length - paddingLength; index < buffer.length; index += 1) {
+    if (buffer[index] !== paddingLength) return buffer
+  }
+  return buffer.subarray(0, buffer.length - paddingLength)
+}
+
+function unwrapWxgf(buffer) {
+  if (
+    buffer.length < 20 ||
+    buffer[0] !== 0x77 ||
+    buffer[1] !== 0x78 ||
+    buffer[2] !== 0x67 ||
+    buffer[3] !== 0x66
+  ) {
+    return buffer
+  }
+  for (let index = 4; index < Math.min(buffer.length - 12, 4096); index += 1) {
+    if (buffer[index] === 0xff && buffer[index + 1] === 0xd8 && buffer[index + 2] === 0xff) {
+      return buffer.subarray(index)
+    }
+    if (
+      buffer[index] === 0x89 &&
+      buffer[index + 1] === 0x50 &&
+      buffer[index + 2] === 0x4e &&
+      buffer[index + 3] === 0x47
+    ) {
+      return buffer.subarray(index)
+    }
+  }
+  return buffer
+}
+
+function decryptCandidate(filePath, aesKey, xorKey) {
+  const bytes = fs.readFileSync(filePath)
+  if (!path.extname(filePath).toLowerCase().includes('dat')) {
+    const extension = detectImageExtension(bytes) || path.extname(filePath).toLowerCase()
+    return { data: 'data:' + getMimeType(extension) + ';base64,' + bytes.toString('base64'), filePath }
+  }
+  if (
+    bytes.length < 15 ||
+    bytes[0] !== 0x07 ||
+    bytes[1] !== 0x08 ||
+    bytes[2] !== 0x56 ||
+    bytes[3] !== 0x32 ||
+    bytes[4] !== 0x08 ||
+    bytes[5] !== 0x07 ||
+    !aesKey
+  ) {
+    return null
+  }
+
+  const payload = bytes.subarray(15)
+  const aesSize = bytes.readInt32LE(6)
+  const xorSize = bytes.readInt32LE(10)
+  const remainder = ((aesSize % 16) + 16) % 16
+  const alignedAesSize = aesSize + (16 - remainder)
+  if (alignedAesSize > payload.length) return null
+
+  const aesData = payload.subarray(0, alignedAesSize)
+  let unpadded = Buffer.alloc(0)
+  if (aesData.length > 0) {
+    const key = Buffer.from(aesKey, 'ascii').subarray(0, 16)
+    const decipher = crypto.createDecipheriv('aes-128-ecb', key, null)
+    decipher.setAutoPadding(false)
+    unpadded = strictRemovePadding(Buffer.concat([decipher.update(aesData), decipher.final()]))
+  }
+
+  const remaining = payload.subarray(alignedAesSize)
+  if (xorSize < 0 || xorSize > remaining.length) return null
+  const rawLength = remaining.length - xorSize
+  const rawData = remaining.subarray(0, rawLength)
+  const xorData = remaining.subarray(rawLength)
+  const xorPlain = Buffer.allocUnsafe(xorData.length)
+  for (let index = 0; index < xorData.length; index += 1) {
+    xorPlain[index] = xorData[index] ^ xorKey
+  }
+
+  const image = unwrapWxgf(Buffer.concat([unpadded, rawData, xorPlain]))
+  const extension = detectImageExtension(image)
+  if (!extension) return null
+  return {
+    data: 'data:' + getMimeType(extension) + ';base64,' + image.toString('base64'),
+    filePath
+  }
+}
+
+function collectCandidates(datPath, allowThumbnail) {
+  const candidates = [datPath]
+  if (!path.extname(datPath).toLowerCase().includes('dat')) return candidates
+  const directory = path.dirname(datPath)
+  const base = normalizeDatBase(path.basename(datPath))
+  const siblings = buildPreferredDatNames(base)
+    .filter((name) => allowThumbnail || !isThumbnailName(name))
+    .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)))
+      return thumbnailOrder || fs.statSync(right).size - fs.statSync(left).size
+    })
+  return Array.from(new Set(candidates.concat(siblings)))
+}
+
+let result = null
+for (const candidate of collectCandidates(workerData.datPath, workerData.allowThumbnail)) {
+  try {
+    result = decryptCandidate(candidate, workerData.aesKey, workerData.xorKey)
+    if (result) break
+  } catch {
+    // Try the next local quality variant.
+  }
+}
+parentPort.postMessage(result)
+`
 
 export class ImageDecryptService {
   private xorKey: number = 0
@@ -26,8 +222,15 @@ export class ImageDecryptService {
   private imagePathCache = new Map<string, string>()
   private decodedImageCache = new Map<string, DecodedImage>()
   private decodedImageCacheBytes = 0
+  private persistentCachePrunePromise: Promise<void> | null = null
+  private persistentCachePrunePending = false
 
-  constructor(xorKey: string, aesKey: string, wcdb4Client?: Wcdb4Client | null) {
+  constructor(
+    xorKey: string,
+    aesKey: string,
+    wcdb4Client?: Wcdb4Client | null,
+    configuredAccountDir?: string
+  ) {
     // 解析 XOR Key (支持 0x40 或 64 格式)
     const xorHex = xorKey.trim().toLowerCase()
     if (xorHex.startsWith('0x')) {
@@ -39,6 +242,12 @@ export class ImageDecryptService {
     // AES Key 直接使用
     this.aesKey = aesKey.trim()
     this.wcdb4Client = wcdb4Client || null
+
+    const accountDir = this.wcdb4Client?.getAccountRoot() || configuredAccountDir
+    if (accountDir && existsSync(accountDir)) {
+      this.cachedAccountDir = accountDir
+      this.accountDirResolved = true
+    }
   }
 
   /**
@@ -96,17 +305,19 @@ export class ImageDecryptService {
   findImageFile(
     md5?: string,
     imageDatName?: string,
-    options?: { allowThumbnail?: boolean; accountDir?: string; preferThumbnail?: boolean }
+    options?: ImageFindOptions
   ): string | null {
     const allowThumbnail = options?.allowThumbnail !== false
     const normalizedMd5 = this.normalizeDatBase(md5 || '')
     const normalizedDatName = this.normalizeDatBase(imageDatName || '')
+    const sessionDirectory = this.getSessionDirectoryName(options?.sessionId)
     const pathCacheKey = [
       normalizedMd5,
       normalizedDatName,
       allowThumbnail ? 'thumb' : 'original',
       options?.preferThumbnail ? 'prefer-thumb' : 'prefer-original',
-      options?.accountDir || ''
+      options?.accountDir || '',
+      sessionDirectory
     ].join('|')
     const cachedPath = this.imagePathCache.get(pathCacheKey)
     if (cachedPath && existsSync(cachedPath)) return cachedPath
@@ -126,9 +337,30 @@ export class ImageDecryptService {
       md5: normalizedMd5,
       imageDatName: normalizedDatName,
       accountDir,
-      allowThumbnail
+      allowThumbnail,
+      sessionDirectory
     })
 
+    const attachDir = join(accountDir, 'msg', 'attach')
+    // The attach directory stores DAT filenames, while the message MD5 often
+    // identifies the original image rather than the local file.
+    const searchKeys = this.uniq([normalizedDatName, normalizedMd5])
+
+    // Message rows already identify their conversation. Prefer that small,
+    // deterministic directory before consulting the native hardlink database.
+    if (sessionDirectory && existsSync(attachDir)) {
+      for (const key of searchKeys) {
+        const scopedHit = this.fastProbabilisticSearch(
+          attachDir,
+          key,
+          allowThumbnail,
+          options?.preferThumbnail,
+          sessionDirectory
+        )
+        if (scopedHit) return rememberPath(scopedHit)
+      }
+    }
+
     for (const key of this.uniq([normalizedMd5, normalizedDatName])) {
       const hardlink = this.wcdb4Client?.resolveImageHardlink(key)
       const fullPath = typeof hardlink?.full_path === 'string' ? hardlink.full_path : ''
@@ -146,7 +378,6 @@ export class ImageDecryptService {
     }
 
     // 尝试 WechatExplorer 的目录结构: msg/attach/{hash}/{YYYY-MM}/Img/
-    const attachDir = join(accountDir, 'msg', 'attach')
     if (!existsSync(attachDir)) {
       imageDecryptLog('[ImageDecrypt] attach dir not found:', attachDir)
       return rememberPath(
@@ -159,17 +390,18 @@ export class ImageDecryptService {
       )
     }
 
-    const searchKeys = this.uniq([normalizedMd5, normalizedDatName])
     if (searchKeys.length === 0) return null
 
-    for (const key of searchKeys) {
-      const directHit = this.fastProbabilisticSearch(
-        attachDir,
-        key,
-        allowThumbnail,
-        options?.preferThumbnail
-      )
-      if (directHit) return rememberPath(directHit)
+    if (!sessionDirectory) {
+      for (const key of searchKeys) {
+        const directHit = this.fastProbabilisticSearch(
+          attachDir,
+          key,
+          allowThumbnail,
+          options?.preferThumbnail
+        )
+        if (directHit) return rememberPath(directHit)
+      }
     }
 
     const legacyHit = this.findImageFileInLegacyDirs(
@@ -184,15 +416,41 @@ export class ImageDecryptService {
     return null
   }
 
-  getCachedDecodedImage(key: string): DecodedImage | null {
+  async getCachedDecodedImage(
+    key: string,
+    options: { includeData?: boolean } = {}
+  ): Promise<DecodedImage | null> {
     const cached = this.decodedImageCache.get(key)
-    if (!cached) return null
-    this.decodedImageCache.delete(key)
-    this.decodedImageCache.set(key, cached)
-    return cached
+    if (cached) {
+      this.decodedImageCache.delete(key)
+      this.decodedImageCache.set(key, cached)
+      return cached
+    }
+
+    const persistent = await this.getPersistentDecodedImage(key, options.includeData !== false)
+    if (!persistent) return null
+    if (persistent.data) this.putDecodedImageInMemory(key, persistent)
+    return persistent
   }
 
-  cacheDecodedImage(key: string, image: DecodedImage): void {
+  async cacheDecodedImage(key: string, image: DecodedImage): Promise<void> {
+    this.putDecodedImageInMemory(key, image)
+
+    try {
+      const persisted = await this.writePersistentDecodedImage(key, image)
+      if (persisted) {
+        const current = this.decodedImageCache.get(key)
+        if (current) {
+          current.cacheFilePath = persisted.cacheFilePath
+          current.mimeType = persisted.mimeType
+        }
+      }
+    } catch (error) {
+      imageDecryptLog('[ImageDecrypt] persistent cache write failed:', error)
+    }
+  }
+
+  private putDecodedImageInMemory(key: string, image: DecodedImage): void {
     const size = image.data.length * 2
     const previous = this.decodedImageCache.get(key)
     if (previous) {
@@ -213,11 +471,436 @@ export class ImageDecryptService {
     }
   }
 
+  private getPersistentCacheDir(): string | null {
+    try {
+      return join(app.getPath('userData'), 'cache', 'images')
+    } catch (error) {
+      imageDecryptLog('[ImageDecrypt] persistent cache path unavailable:', error)
+      return null
+    }
+  }
+
+  private getPersistentCacheKey(key: string): string {
+    const accountDir = this.getAccountDir() || this.wcdb4Client?.getAccountRoot() || ''
+    const resolvedAccountDir = accountDir ? resolve(accountDir) : ''
+    const accountScope =
+      process.platform === 'win32'
+        ? resolvedAccountDir.replace(/\\/g, '/').toLowerCase()
+        : resolvedAccountDir
+    const scope = JSON.stringify({
+      version: PERSISTENT_IMAGE_CACHE_VERSION,
+      accountDir: accountScope,
+      key
+    })
+    return crypto.createHash('sha256').update(scope).digest('hex')
+  }
+
+  private async getPersistentDecodedImage(
+    key: string,
+    includeData: boolean
+  ): Promise<DecodedImage | null> {
+    const cacheDir = this.getPersistentCacheDir()
+    if (!cacheDir) return null
+
+    const cacheKey = this.getPersistentCacheKey(key)
+    const metadataPath = join(cacheDir, `${cacheKey}.json`)
+    let metadata: PersistentImageMeta | null = null
+
+    try {
+      metadata = JSON.parse(await fsPromises.readFile(metadataPath, 'utf8')) as PersistentImageMeta
+      if (!this.isValidPersistentImageMeta(metadata, cacheKey)) {
+        throw new Error('invalid persistent image metadata')
+      }
+
+      const sourceStat = await fsPromises.stat(metadata.sourcePath)
+      if (
+        !sourceStat.isFile() ||
+        sourceStat.size !== metadata.sourceSize ||
+        Math.trunc(sourceStat.mtimeMs) !== Math.trunc(metadata.sourceMtimeMs)
+      ) {
+        throw new Error('persistent image source changed')
+      }
+
+      const cacheFilePath = join(cacheDir, metadata.fileName)
+      const cacheStat = await fsPromises.stat(cacheFilePath)
+      if (!cacheStat.isFile() || cacheStat.size <= 0 || cacheStat.size !== metadata.cacheSize) {
+        throw new Error('persistent image payload changed')
+      }
+
+      const payload = includeData
+        ? await fsPromises.readFile(cacheFilePath)
+        : await this.readImageSignature(cacheFilePath)
+      const extension = this.detectImageExtension(payload)
+      if (!extension || this.getMimeType(extension) !== metadata.mimeType) {
+        throw new Error('persistent image payload is invalid')
+      }
+
+      const now = new Date()
+      void Promise.all([
+        fsPromises.utimes(cacheFilePath, now, now),
+        fsPromises.utimes(metadataPath, now, now)
+      ]).catch(() => undefined)
+
+      return {
+        data: includeData ? `data:${metadata.mimeType};base64,${payload.toString('base64')}` : '',
+        filePath: metadata.sourcePath,
+        isThumbnail: metadata.isThumbnail,
+        cacheFilePath,
+        mimeType: metadata.mimeType
+      }
+    } catch (error) {
+      if ((error as NodeJS.ErrnoException).code !== 'ENOENT') {
+        imageDecryptLog('[ImageDecrypt] persistent cache miss:', error)
+      }
+      await this.removePersistentCacheEntry(cacheDir, cacheKey, metadata?.fileName)
+      return null
+    }
+  }
+
+  private async writePersistentDecodedImage(
+    key: string,
+    image: DecodedImage
+  ): Promise<{ cacheFilePath: string; mimeType: string } | null> {
+    const cacheDir = this.getPersistentCacheDir()
+    if (!cacheDir || !image.filePath) return null
+
+    const payload = await this.getDecodedImagePayload(image)
+    if (!payload) return null
+
+    const extension = this.detectImageExtension(payload)
+    if (!extension) return null
+
+    const sourceStat = await fsPromises.stat(image.filePath)
+    if (!sourceStat.isFile()) return null
+
+    const cacheKey = this.getPersistentCacheKey(key)
+    const fileName = `${cacheKey}${extension}`
+    const cacheFilePath = join(cacheDir, fileName)
+    const metadataPath = join(cacheDir, `${cacheKey}.json`)
+    const mimeType = this.getMimeType(extension)
+    const nonce = `${process.pid}-${Date.now()}-${crypto.randomBytes(4).toString('hex')}`
+    const payloadTempPath = join(cacheDir, `${cacheKey}.${nonce}.tmp`)
+    const metadataTempPath = join(cacheDir, `${cacheKey}.${nonce}.json.tmp`)
+    const metadata: PersistentImageMeta = {
+      version: PERSISTENT_IMAGE_CACHE_VERSION,
+      sourcePath: image.filePath,
+      sourceSize: sourceStat.size,
+      sourceMtimeMs: sourceStat.mtimeMs,
+      fileName,
+      cacheSize: payload.length,
+      mimeType,
+      isThumbnail: image.isThumbnail
+    }
+
+    await fsPromises.mkdir(cacheDir, { recursive: true })
+    try {
+      await fsPromises.writeFile(payloadTempPath, payload)
+      await this.replaceFileAtomically(payloadTempPath, cacheFilePath)
+      await fsPromises.writeFile(metadataTempPath, JSON.stringify(metadata))
+      await this.replaceFileAtomically(metadataTempPath, metadataPath)
+      await this.removeOtherPersistentPayloads(cacheDir, cacheKey, fileName)
+    } finally {
+      await Promise.allSettled([
+        fsPromises.rm(payloadTempPath, { force: true }),
+        fsPromises.rm(metadataTempPath, { force: true })
+      ])
+    }
+
+    this.schedulePersistentCachePrune()
+    return { cacheFilePath, mimeType }
+  }
+
+  private async getDecodedImagePayload(image: DecodedImage): Promise<Buffer | null> {
+    const separatorIndex = image.data.indexOf(',')
+    if (separatorIndex > 0) {
+      const header = image.data.slice(0, separatorIndex)
+      if (/^data:image\/[a-z0-9.+-]+;base64$/i.test(header)) {
+        const payload = Buffer.from(image.data.slice(separatorIndex + 1), 'base64')
+        return payload.length > 0 ? payload : null
+      }
+    }
+
+    if (image.cacheFilePath) {
+      try {
+        return await fsPromises.readFile(image.cacheFilePath)
+      } catch {
+        return null
+      }
+    }
+    return null
+  }
+
+  async findImageFileAsync(
+    md5?: string,
+    imageDatName?: string,
+    options?: ImageFindOptions
+  ): Promise<string | null> {
+    const sessionDirectory = this.getSessionDirectoryName(options?.sessionId)
+    if (!sessionDirectory) return this.findImageFile(md5, imageDatName, options)
+
+    const allowThumbnail = options?.allowThumbnail !== false
+    const normalizedMd5 = this.normalizeDatBase(md5 || '')
+    const normalizedDatName = this.normalizeDatBase(imageDatName || '')
+    const pathCacheKey = [
+      normalizedMd5,
+      normalizedDatName,
+      allowThumbnail ? 'thumb' : 'original',
+      options?.preferThumbnail ? 'prefer-thumb' : 'prefer-original',
+      options?.accountDir || '',
+      sessionDirectory
+    ].join('|')
+    const cachedPath = this.imagePathCache.get(pathCacheKey)
+    if (cachedPath && existsSync(cachedPath)) return cachedPath
+
+    const rememberPath = (filePath: string | null): string | null => {
+      if (filePath) this.imagePathCache.set(pathCacheKey, filePath)
+      return filePath
+    }
+    const accountDir =
+      options?.accountDir && existsSync(options.accountDir)
+        ? options.accountDir
+        : this.getAccountDir()
+    if (!accountDir) return null
+
+    const attachDir = join(accountDir, 'msg', 'attach')
+    if (normalizedDatName && existsSync(attachDir)) {
+      const scopedHit = await this.findImageInSessionDirectoryAsync(
+        attachDir,
+        normalizedDatName,
+        allowThumbnail,
+        options?.preferThumbnail,
+        sessionDirectory
+      )
+      if (scopedHit) return rememberPath(scopedHit)
+    }
+
+    for (const key of this.uniq([normalizedMd5, normalizedDatName])) {
+      const hardlink = await this.wcdb4Client?.resolveImageHardlinkAsync(key)
+      const fullPath = typeof hardlink?.full_path === 'string' ? hardlink.full_path : ''
+      if (!fullPath || !existsSync(fullPath)) continue
+      const selected = this.getPreferredDatVariantPath(
+        fullPath,
+        allowThumbnail,
+        options?.preferThumbnail
+      )
+      if (allowThumbnail || !this.isThumbnailName(basename(selected))) {
+        return rememberPath(selected)
+      }
+    }
+
+    return null
+  }
+
+  private async findImageInSessionDirectoryAsync(
+    attachDir: string,
+    datName: string,
+    allowThumbnail: boolean,
+    preferThumbnail: boolean | undefined,
+    sessionDirectory: string
+  ): Promise<string | null> {
+    const normalized = this.normalizeDatBase(datName)
+    if (!normalized || !sessionDirectory) return null
+
+    const sessionRoot = join(attachDir, sessionDirectory)
+    let monthDirectories: string[]
+    try {
+      monthDirectories = (await fsPromises.readdir(sessionRoot, { withFileTypes: true }))
+        .filter((entry) => entry.isDirectory() && /^\d{4}-\d{2}$/.test(entry.name))
+        .map((entry) => entry.name)
+        .sort((left, right) => right.localeCompare(left))
+    } catch {
+      return null
+    }
+
+    const variants = this.buildPreferredDatNames(normalized)
+    for (const month of monthDirectories) {
+      const candidates = ['Img', 'Image', 'image'].flatMap((subDirectory) =>
+        variants.map((variant) => join(sessionRoot, month, subDirectory, variant))
+      )
+      const found = await this.getLargestExistingPathAsync(
+        candidates,
+        allowThumbnail,
+        preferThumbnail
+      )
+      if (found) return found
+    }
+    return null
+  }
+
+  private isValidPersistentImageMeta(
+    metadata: PersistentImageMeta,
+    cacheKey: string
+  ): boolean {
+    return (
+      metadata !== null &&
+      typeof metadata === 'object' &&
+      metadata.version === PERSISTENT_IMAGE_CACHE_VERSION &&
+      typeof metadata.sourcePath === 'string' &&
+      metadata.sourcePath.length > 0 &&
+      Number.isFinite(metadata.sourceSize) &&
+      metadata.sourceSize >= 0 &&
+      Number.isFinite(metadata.sourceMtimeMs) &&
+      typeof metadata.fileName === 'string' &&
+      basename(metadata.fileName) === metadata.fileName &&
+      metadata.fileName.startsWith(`${cacheKey}.`) &&
+      Number.isFinite(metadata.cacheSize) &&
+      metadata.cacheSize > 0 &&
+      typeof metadata.mimeType === 'string' &&
+      metadata.mimeType.startsWith('image/') &&
+      typeof metadata.isThumbnail === 'boolean'
+    )
+  }
+
+  private async readImageSignature(filePath: string): Promise<Buffer> {
+    const handle = await fsPromises.open(filePath, 'r')
+    try {
+      const signature = Buffer.alloc(16)
+      const { bytesRead } = await handle.read(signature, 0, signature.length, 0)
+      return signature.subarray(0, bytesRead)
+    } finally {
+      await handle.close()
+    }
+  }
+
+  private async replaceFileAtomically(tempPath: string, targetPath: string): Promise<void> {
+    try {
+      await fsPromises.rename(tempPath, targetPath)
+    } catch (error) {
+      const code = (error as NodeJS.ErrnoException).code
+      if (code !== 'EEXIST' && code !== 'EPERM') throw error
+      await fsPromises.rm(targetPath, { force: true })
+      await fsPromises.rename(tempPath, targetPath)
+    }
+  }
+
+  private async removeOtherPersistentPayloads(
+    cacheDir: string,
+    cacheKey: string,
+    keepFileName: string
+  ): Promise<void> {
+    const names = await fsPromises.readdir(cacheDir)
+    const obsolete = names.filter(
+      (name) =>
+        name !== keepFileName &&
+        name.startsWith(`${cacheKey}.`) &&
+        /^\.(?:jpe?g|png|gif|bmp|webp)$/i.test(name.slice(cacheKey.length))
+    )
+    await Promise.allSettled(
+      obsolete.map((name) => fsPromises.rm(join(cacheDir, name), { force: true }))
+    )
+  }
+
+  private async removePersistentCacheEntry(
+    cacheDir: string,
+    cacheKey: string,
+    fileName?: string
+  ): Promise<void> {
+    const candidates = new Set<string>([`${cacheKey}.json`])
+    if (fileName && basename(fileName) === fileName && fileName.startsWith(`${cacheKey}.`)) {
+      candidates.add(fileName)
+    } else {
+      try {
+        const names = await fsPromises.readdir(cacheDir)
+        for (const name of names) {
+          if (
+            name.startsWith(`${cacheKey}.`) &&
+            /^\.(?:jpe?g|png|gif|bmp|webp)$/i.test(name.slice(cacheKey.length))
+          ) {
+            candidates.add(name)
+          }
+        }
+      } catch {
+        return
+      }
+    }
+    await Promise.allSettled(
+      Array.from(candidates, (name) => fsPromises.rm(join(cacheDir, name), { force: true }))
+    )
+  }
+
+  private schedulePersistentCachePrune(): void {
+    if (this.persistentCachePrunePromise) {
+      this.persistentCachePrunePending = true
+      return
+    }
+    this.persistentCachePrunePromise = this.prunePersistentCache()
+      .catch((error) => imageDecryptLog('[ImageDecrypt] persistent cache prune failed:', error))
+      .finally(() => {
+        this.persistentCachePrunePromise = null
+        if (this.persistentCachePrunePending) {
+          this.persistentCachePrunePending = false
+          this.schedulePersistentCachePrune()
+        }
+      })
+  }
+
+  private async prunePersistentCache(): Promise<void> {
+    const cacheDir = this.getPersistentCacheDir()
+    if (!cacheDir) return
+
+    const entries = await fsPromises.readdir(cacheDir, { withFileTypes: true })
+    const payloadNames = entries
+      .filter(
+        (entry) =>
+          entry.isFile() &&
+          /^[a-f0-9]{64}\.(?:jpe?g|png|gif|bmp|webp)$/i.test(entry.name)
+      )
+      .map((entry) => entry.name)
+    const payloads = (
+      await Promise.all(
+        payloadNames.map(async (name) => {
+          try {
+            const stat = await fsPromises.stat(join(cacheDir, name))
+            return { name, size: stat.size, mtimeMs: stat.mtimeMs }
+          } catch {
+            return null
+          }
+        })
+      )
+    )
+      .filter((entry): entry is { name: string; size: number; mtimeMs: number } => entry !== null)
+      .sort((left, right) => left.mtimeMs - right.mtimeMs)
+
+    let totalBytes = payloads.reduce((total, entry) => total + entry.size, 0)
+    let totalFiles = payloads.length
+    for (const payload of payloads) {
+      if (
+        totalFiles <= MAX_PERSISTENT_IMAGE_CACHE_FILES &&
+        totalBytes <= MAX_PERSISTENT_IMAGE_CACHE_BYTES
+      ) {
+        break
+      }
+      const cacheKey = payload.name.slice(0, 64)
+      await Promise.allSettled([
+        fsPromises.rm(join(cacheDir, payload.name), { force: true }),
+        fsPromises.rm(join(cacheDir, `${cacheKey}.json`), { force: true })
+      ])
+      totalFiles -= 1
+      totalBytes -= payload.size
+    }
+
+    const remainingPayloadKeys = new Set(
+      payloads
+        .slice(payloads.length - totalFiles)
+        .map((payload) => payload.name.slice(0, 64))
+    )
+    const staleMetadata = entries.filter(
+      (entry) =>
+        entry.isFile() &&
+        /^[a-f0-9]{64}\.json$/i.test(entry.name) &&
+        !remainingPayloadKeys.has(entry.name.slice(0, 64))
+    )
+    await Promise.allSettled(
+      staleMetadata.map((entry) => fsPromises.rm(join(cacheDir, entry.name), { force: true }))
+    )
+  }
+
   private fastProbabilisticSearch(
     attachDir: string,
     datName: string,
     allowThumbnail = true,
-    preferThumbnail = false
+    preferThumbnail = false,
+    sessionDirectory = ''
   ): string | null {
     const normalized = this.normalizeDatBase(datName)
     if (!normalized) return null
@@ -243,9 +926,13 @@ export class ImageDecryptService {
     }
 
     try {
-      const sessionDirs = readdirSync(attachDir).filter(
-        (name) => name.length === 32 && /^[a-f0-9]+$/i.test(name)
-      )
+      const sessionDirs = sessionDirectory
+        ? existsSync(join(attachDir, sessionDirectory))
+          ? [sessionDirectory]
+          : []
+        : readdirSync(attachDir).filter(
+            (name) => name.length === 32 && /^[a-f0-9]+$/i.test(name)
+          )
 
       const now = new Date()
       const months: string[] = []
@@ -462,6 +1149,54 @@ export class ImageDecryptService {
     return null
   }
 
+  async decryptImageToBase64WithFallbackAsync(
+    datPath: string,
+    allowThumbnail = true
+  ): Promise<{ data: string; filePath: string } | null> {
+    if (!existsSync(datPath)) return null
+
+    return new Promise((resolve) => {
+      let settled = false
+      const worker = new Worker(IMAGE_DECRYPT_WORKER_SOURCE, {
+        eval: true,
+        workerData: {
+          datPath,
+          allowThumbnail,
+          xorKey: this.xorKey,
+          aesKey: this.aesKey
+        }
+      })
+      const timeout = setTimeout(() => {
+        imageDecryptLog('[ImageDecrypt] worker timed out:', datPath)
+        void worker.terminate()
+        finish(null)
+      }, 30_000)
+      const finish = (result: { data: string; filePath: string } | null): void => {
+        if (settled) return
+        settled = true
+        clearTimeout(timeout)
+        resolve(result)
+      }
+      worker.once('message', (value: unknown) => {
+        if (
+          value &&
+          typeof value === 'object' &&
+          typeof (value as { data?: unknown }).data === 'string' &&
+          typeof (value as { filePath?: unknown }).filePath === 'string'
+        ) {
+          finish(value as { data: string; filePath: string })
+          return
+        }
+        finish(null)
+      })
+      worker.once('error', (error) => {
+        imageDecryptLog('[ImageDecrypt] worker failed:', error)
+        finish(null)
+      })
+      worker.once('exit', () => finish(null))
+    })
+  }
+
   /**
    * 检测 DAT 文件版本（仅识别 WeChat 4.0 头 V2）。
    * 老 V1 头（V3 及以下）直接返回 0，由调用方走"不支持"分支。
@@ -584,6 +1319,13 @@ export class ImageDecryptService {
     return withoutDat.replace(/(_thumb|\.thumb|_hd|\.hd|_h|\.h|_t|\.t|_c|\.c)$/i, '').toLowerCase()
   }
 
+  private getSessionDirectoryName(sessionId?: string): string {
+    const value = String(sessionId || '').trim()
+    if (!value) return ''
+    if (/^[a-f0-9]{32}$/i.test(value)) return value.toLowerCase()
+    return crypto.createHash('md5').update(value).digest('hex')
+  }
+
   private buildPreferredDatNames(baseName: string): string[] {
     const base = this.normalizeDatBase(baseName)
     if (!base) return []
@@ -651,6 +1393,37 @@ export class ImageDecryptService {
     return existing[0]?.candidate || null
   }
 
+  private async getLargestExistingPathAsync(
+    paths: string[],
+    allowThumbnail: boolean,
+    preferThumbnail = false
+  ): Promise<string | null> {
+    const sized = (
+      await Promise.all(
+        paths.map(async (candidate) => {
+          try {
+            const stat = await fsPromises.stat(candidate)
+            return stat.isFile() ? { candidate, size: stat.size } : null
+          } catch {
+            return null
+          }
+        })
+      )
+    )
+      .filter((entry): entry is { candidate: string; size: number } => entry !== null)
+      .sort((left, right) => right.size - left.size)
+
+    if (preferThumbnail) {
+      const thumbnail = sized.find((entry) => this.isThumbnailName(basename(entry.candidate)))
+      if (thumbnail) return thumbnail.candidate
+    }
+    const nonThumbnail = sized.find(
+      (entry) => !this.isThumbnailName(basename(entry.candidate))
+    )
+    if (nonThumbnail) return nonThumbnail.candidate
+    return allowThumbnail ? sized[0]?.candidate || null : null
+  }
+
   private isThumbnailName(fileName: string): boolean {
     const lower = fileName.toLowerCase()
     return lower.includes('_t.dat') || lower.includes('_thumb.dat') || lower.includes('.thumb.dat')

src/main/index.ts

@@ -21,7 +21,7 @@ import { bootstrapWcdbNativeAsync, Wcdb4Client } from './wcdb4-client'
 import { VoiceService } from './voice-service'
 import { StickerService } from './sticker-service'
 import { parseMessageContent } from './message-parser'
-import { ImageDecryptService } from './image-decrypt-service'
+import { ImageDecryptService, type DecodedImage } from './image-decrypt-service'
 import { exportGroupReport } from './group-report-service'
 import {
   deleteGeneratedReport,
@@ -103,6 +103,71 @@ let recallArchiveMonitor: RecallArchiveMonitor | null = null
 let recallProtectionGeneration = 0
 let recallJournalTimer: NodeJS.Timeout | null = null
 let wcdbBootstrapPromise: Promise<unknown> | null = null
+type ColdImageLoadItem = {
+  priority: number
+  sequence: number
+  run: () => Promise<unknown>
+  resolve: (value: unknown) => void
+  reject: (reason: unknown) => void
+}
+const coldImageLoadQueue: ColdImageLoadItem[] = []
+let activeColdImageLoads = 0
+let coldImageLoadSequence = 0
+let coldImageLoadTimer: NodeJS.Timeout | null = null
+let nextColdImageLoadAt = 0
+
+const COLD_IMAGE_LOAD_GAP_MS = 100
+const MAX_CONCURRENT_COLD_IMAGE_LOADS = 2
+
+function pumpColdImageLoads(): void {
+  if (
+    activeColdImageLoads >= MAX_CONCURRENT_COLD_IMAGE_LOADS ||
+    coldImageLoadQueue.length === 0
+  ) {
+    return
+  }
+
+  const waitMs = Math.max(0, nextColdImageLoadAt - Date.now())
+  if (waitMs > 0) {
+    if (!coldImageLoadTimer) {
+      coldImageLoadTimer = setTimeout(() => {
+        coldImageLoadTimer = null
+        pumpColdImageLoads()
+      }, waitMs)
+    }
+    return
+  }
+
+  coldImageLoadQueue.sort(
+    (left, right) => left.priority - right.priority || left.sequence - right.sequence
+  )
+  const item = coldImageLoadQueue.shift()
+  if (!item) return
+
+  activeColdImageLoads += 1
+  nextColdImageLoadAt = Date.now() + COLD_IMAGE_LOAD_GAP_MS
+  void item
+    .run()
+    .then(item.resolve, item.reject)
+    .finally(() => {
+      activeColdImageLoads -= 1
+      pumpColdImageLoads()
+    })
+  pumpColdImageLoads()
+}
+
+function enqueueColdImageLoad<T>(task: () => Promise<T> | T, priority = 0): Promise<T> {
+  return new Promise<T>((resolve, reject) => {
+    coldImageLoadQueue.push({
+      priority,
+      sequence: coldImageLoadSequence++,
+      run: async () => task(),
+      resolve: (value) => resolve(value as T),
+      reject
+    })
+    pumpColdImageLoads()
+  })
+}
 
 function configureRecallProtection(
   wcdb4Client: Wcdb4Client,
@@ -199,9 +264,58 @@ function getConfiguredImageKeys(): { xorKey: string; aesKey: string } {
   }
 }
 
+function getImageMediaService(): VideoAssetService | null {
+  if (videoAssetService) return videoAssetService
+  const client = chat.getChatDb()?.getWcdb4Client()
+  if (!client) return null
+  videoAssetService = new VideoAssetService(client)
+  return videoAssetService
+}
+
+function getLocalMediaMimeType(filePath: string): string {
+  switch (extname(filePath).toLowerCase()) {
+    case '.mp4':
+      return 'video/mp4'
+    case '.jpg':
+    case '.jpeg':
+      return 'image/jpeg'
+    case '.png':
+      return 'image/png'
+    case '.gif':
+      return 'image/gif'
+    case '.webp':
+      return 'image/webp'
+    case '.bmp':
+      return 'image/bmp'
+    default:
+      return 'application/octet-stream'
+  }
+}
+
+function buildImageResponse(image: DecodedImage): {
+  success: true
+  data: string
+  isThumb: boolean
+  filePath: string
+  mimeType?: string
+} {
+  const mediaService = image.cacheFilePath ? getImageMediaService() : null
+  const data =
+    mediaService && image.cacheFilePath && existsSync(image.cacheFilePath)
+      ? mediaService.createLocalMediaUrl(image.cacheFilePath)
+      : image.data
+  return {
+    success: true,
+    data,
+    isThumb: image.isThumbnail,
+    filePath: image.filePath,
+    mimeType: image.mimeType
+  }
+}
+
 async function createLocalMediaResponse(request: Request, filePath: string): Promise<Response> {
   const { size } = await fsPromises.stat(filePath)
-  const mimeType = extname(filePath).toLowerCase() === '.mp4' ? 'video/mp4' : 'image/jpeg'
+  const mimeType = getLocalMediaMimeType(filePath)
   const commonHeaders = {
     'Accept-Ranges': 'bytes',
     'Content-Type': mimeType,
@@ -292,8 +406,7 @@ function createWindow(): void {
 // 某些 API 只能在此事件发生后使用
 app.whenReady().then(async () => {
   protocol.handle('wxe-media', async (request) => {
-    const token = new URL(request.url).pathname.replace(/^\/+/, '')
-    const filePath = videoAssetService?.pathForToken(token)
+    const filePath = videoAssetService?.pathForUrl(request.url)
     if (!filePath) return new Response('Not found', { status: 404 })
     try {
       return await createLocalMediaResponse(request, filePath)
@@ -393,24 +506,24 @@ app.whenReady().then(async () => {
         }
         chat.setChatDb(nextWechatDb)
         const wcdb4Client = nextWechatDb.getWcdb4Client()
+        const sessions = await wcdb4Client.getSessionsAsync()
         configureRecallProtection(wcdb4Client, resolvedRoot, settings.recallProtectionEnabled)
         voiceService = new VoiceService(wcdb4Client)
         stickerService = new StickerService(wcdb4Client)
         videoAssetService = new VideoAssetService(wcdb4Client)
-        const monitoring = wcdb4Client.startMonitor((type, json) => {
+        const monitoring = await wcdb4Client.startMonitor((type, json) => {
           wcdb4Client.invalidateSessionCache()
           recallArchiveMonitor?.handleDatabaseChange(json)
           for (const window of BrowserWindow.getAllWindows()) {
             if (!window.isDestroyed()) window.webContents.send('wcdb-change', { type, json })
           }
         })
-        setImmediate(() => {
-          const recentSession = wcdb4Client.getSessions()[0]
-          if (!recentSession?.username) return
+        const recentSession = sessions[0]
+        if (recentSession?.username) {
           void wcdb4Client
             .getMessagesAsync(recentSession.username, undefined, undefined, { limit: 1 })
             .catch((error) => console.warn('[WCDB4] message cursor warmup failed:', error))
-        })
+        }
         imageDecryptService = null
         return { success: true, monitoring }
       } catch (error) {
@@ -574,11 +687,11 @@ app.whenReady().then(async () => {
     }
   )
 
-  ipcMain.handle('db:getContacts', (_, filter?: string) => {
+  ipcMain.handle('db:getContacts', async (_, filter?: string) => {
     const accountRoot = chat.getCurrentAccountRoot()
     const contacts = accountRoot
-      ? mergeCachedContactAvatars(accountRoot, chat.listContacts(filter))
-      : chat.listContacts(filter)
+      ? mergeCachedContactAvatars(accountRoot, await chat.listContactsAsync(filter))
+      : await chat.listContactsAsync(filter)
     if (!filter && chat.isReady() && accountRoot) {
       saveBootstrapContacts(accountRoot, contacts)
     }
@@ -643,9 +756,15 @@ app.whenReady().then(async () => {
     aiProviderService.migrateLegacy(config)
   )
 
-  ipcMain.handle('copy-image', async (_, base64String) => {
+  ipcMain.handle('copy-image', async (_, imageSource: unknown) => {
     try {
-      const image = nativeImage.createFromDataURL(base64String)
+      if (typeof imageSource !== 'string' || !imageSource) {
+        return { success: false, error: 'Image source is empty' }
+      }
+      const image = imageSource.startsWith('wxe-media://')
+        ? nativeImage.createFromPath(getImageMediaService()?.pathForUrl(imageSource) || '')
+        : nativeImage.createFromDataURL(imageSource)
+      if (image.isEmpty()) return { success: false, error: 'Image source is invalid' }
       clipboard.writeImage(image)
       return { success: true }
     } catch (error: unknown) {
@@ -716,68 +835,100 @@ app.whenReady().then(async () => {
       imageMd5?: string,
       imageDatNameOrThumb?: string | boolean,
       _sessionId?: string,
-      options?: { force?: boolean; preferThumbnail?: boolean }
+      options?: { force?: boolean; preferThumbnail?: boolean; priority?: number }
     ) => {
-      void _sessionId
-      if (!imageDecryptService) {
+      let service = imageDecryptService
+      if (!service) {
         const { xorKey, aesKey } = getConfiguredImageKeys()
-        if (!aesKey) {
-          return { success: false, error: '未配置图片解密密钥' }
-        }
-        imageDecryptService = new ImageDecryptService(
+        // Reading an already-decoded cache entry does not require the AES key.
+        // Before db:init resolves the account identity, secure storage may not
+        // expose that key yet, so keep this cache-only service local.
+        service = new ImageDecryptService(
           xorKey,
           aesKey,
-          chat.getChatDb()?.getWcdb4Client()
+          chat.getChatDb()?.getWcdb4Client(),
+          loadSettings().dbRoot
         )
+        if (aesKey) imageDecryptService = service
       }
 
       const imageDatName = typeof imageDatNameOrThumb === 'string' ? imageDatNameOrThumb : undefined
       const force = options?.force === true
       const preferThumbnail = options?.preferThumbnail === true
+      const priority = Number.isFinite(options?.priority) ? Number(options?.priority) : 0
       const imageCacheKey = [
         imageMd5 || '',
         imageDatName || '',
         force ? 'original' : preferThumbnail ? 'thumbnail' : 'auto'
       ].join('|')
-      const cachedImage = imageDecryptService.getCachedDecodedImage(imageCacheKey)
-      if (cachedImage) {
-        return {
-          success: true,
-          data: cachedImage.data,
-          isThumb: cachedImage.isThumbnail,
-          filePath: cachedImage.filePath
-        }
-      }
-      let filePath = force
-        ? imageDecryptService.findImageFile(imageMd5, imageDatName, { allowThumbnail: false })
-        : null
-      if (!filePath) {
-        filePath = imageDecryptService.findImageFile(imageMd5, imageDatName, {
-          allowThumbnail: true,
-          preferThumbnail
-        })
-      }
-      if (!filePath) {
-        return { success: false, error: force ? '未找到原图或缩略图文件' : '未找到图片文件' }
-      }
-
-      const decrypted = imageDecryptService.decryptImageToBase64WithFallback(filePath, true)
-      if (!decrypted) {
-        return { success: false, error: '图片解密失败' }
-      }
-
-      const result = {
-        success: true,
-        data: decrypted.data,
-        isThumb: imageDecryptService.isThumbnailFile(decrypted.filePath),
-        filePath: decrypted.filePath
-      }
-      imageDecryptService.cacheDecodedImage(imageCacheKey, {
-        data: result.data,
-        filePath: result.filePath,
-        isThumbnail: result.isThumb
+      const mediaService = getImageMediaService()
+      const cachedImage = await service.getCachedDecodedImage(imageCacheKey, {
+        includeData: !mediaService
       })
-      return result
+      if (cachedImage) {
+        return buildImageResponse(cachedImage)
+      }
+
+      return enqueueColdImageLoad(async () => {
+        // Disk cache was already checked without waiting for database startup.
+        // Only a real miss needs the initialized WCDB client and hardlink index.
+        if (dbInitInFlight) {
+          await dbInitInFlight.catch(() => undefined)
+        }
+
+        let coldService = imageDecryptService
+        if (!coldService) {
+          const { xorKey, aesKey } = getConfiguredImageKeys()
+          if (!aesKey) return { success: false, error: '未配置图片解密密钥' }
+          coldService = new ImageDecryptService(
+            xorKey,
+            aesKey,
+            chat.getChatDb()?.getWcdb4Client(),
+            loadSettings().dbRoot
+          )
+          imageDecryptService = coldService
+        }
+
+        // A previous queued request may have populated the cache while this one waited.
+        const queuedMediaService = getImageMediaService()
+        const queuedCacheHit = await coldService.getCachedDecodedImage(imageCacheKey, {
+          includeData: !queuedMediaService
+        })
+        if (queuedCacheHit) return buildImageResponse(queuedCacheHit)
+
+        let filePath = force
+          ? await coldService.findImageFileAsync(imageMd5, imageDatName, {
+              allowThumbnail: false,
+              sessionId: _sessionId
+            })
+          : null
+        if (!filePath) {
+          filePath = await coldService.findImageFileAsync(imageMd5, imageDatName, {
+            allowThumbnail: true,
+            preferThumbnail,
+            sessionId: _sessionId
+          })
+        }
+        if (!filePath) {
+          return {
+            success: false,
+            error: force ? '未找到原图或缩略图文件' : '未找到图片文件'
+          }
+        }
+
+        const decrypted = await coldService.decryptImageToBase64WithFallbackAsync(filePath, true)
+        if (!decrypted) {
+          return { success: false, error: '图片解密失败' }
+        }
+
+        const decodedImage: DecodedImage = {
+          data: decrypted.data,
+          filePath: decrypted.filePath,
+          isThumbnail: coldService.isThumbnailFile(decrypted.filePath)
+        }
+        await coldService.cacheDecodedImage(imageCacheKey, decodedImage)
+        return buildImageResponse(decodedImage)
+      }, priority)
     }
   )
 

src/main/services/bootstrap-cache.ts

@@ -24,135 +24,364 @@ export interface CachedGroupSnapshot {
   }[]
 }
 
-interface CachedMessageBucket {
+interface StartupCacheFile {
+  version: 2
+  platform: NodeJS.Platform
+  accountRoot: string
+  updatedAt: number
+  self?: CachedSelfInfo
+  contacts: Contact[]
+}
+
+interface CachedMessageBucketFile {
+  version: 2
+  platform: NodeJS.Platform
+  accountRoot: string
+  cacheKey: string
   updatedAt: number
   startTime?: number
   endTime?: number
   items: Message[]
 }
 
-interface BootstrapCacheFile {
-  version: 1
+interface CachedGroupSnapshotFile {
+  version: 2
   platform: NodeJS.Platform
   accountRoot: string
+  userMd5: string
   updatedAt: number
-  self?: CachedSelfInfo
-  contacts?: Contact[]
-  messages?: Record<string, CachedMessageBucket>
-  groupSnapshots?: Record<string, { updatedAt: number; snapshot: CachedGroupSnapshot }>
+  snapshot: CachedGroupSnapshot
 }
 
-const CACHE_VERSION = 1
+interface ScheduledWrite {
+  value: unknown
+  revision: number
+  generation: number
+  cleanupFile?: string
+  prune?: { directory: string; maxFiles: number }
+}
+
+interface AccountCachePaths {
+  root: string
+  startup: string
+  messages: string
+  groups: string
+  legacy: string
+}
+
+const CACHE_VERSION = 2
 const MAX_MESSAGE_BUCKETS = 768
+const MAX_GROUP_SNAPSHOTS = 768
 const MAX_MESSAGES_PER_BUCKET = 120
+const MAX_MEMORY_MESSAGE_BUCKETS = 32
+const MAX_MEMORY_GROUP_SNAPSHOTS = 32
 const WRITE_DEBOUNCE_MS = 300
-const memoryCache = new Map<string, BootstrapCacheFile>()
+const PRUNE_INTERVAL_MS = 30_000
+
+const startupMemory = new Map<string, StartupCacheFile>()
+const messageMemory = new Map<string, CachedMessageBucketFile>()
+const groupMemory = new Map<string, CachedGroupSnapshotFile>()
 const writeTimers = new Map<string, NodeJS.Timeout>()
 const writeQueues = new Map<string, Promise<void>>()
+const scheduledWrites = new Map<string, ScheduledWrite>()
+const writeRevisions = new Map<string, number>()
+const lastPrunedAt = new Map<string, number>()
+let cacheGeneration = 0
 
 function normalizeRoot(accountRoot?: string): string {
   return String(accountRoot || '').trim()
 }
 
-function getCacheFile(accountRoot?: string): string {
-  const normalizedRoot = normalizeRoot(accountRoot) || 'default'
-  const hash = crypto
-    .createHash('sha1')
-    .update(`${process.platform}:${normalizedRoot}`)
-    .digest('hex')
-    .slice(0, 16)
-  return path.join(
-    app.getPath('userData'),
-    'cache',
-    'bootstrap',
-    `${process.platform}-${hash}.json`
-  )
+function digest(value: string): string {
+  return crypto.createHash('sha1').update(value).digest('hex').slice(0, 24)
 }
 
-function readCacheFile(accountRoot?: string): BootstrapCacheFile | null {
+function getAccountCachePaths(accountRoot: string): AccountCachePaths {
   const normalizedRoot = normalizeRoot(accountRoot)
-  if (!normalizedRoot) return null
-  const file = getCacheFile(normalizedRoot)
-  const cached = memoryCache.get(file)
-  if (cached) return cached
-  try {
-    if (!fs.existsSync(file)) return null
-    const raw = fs.readJsonSync(file) as Partial<BootstrapCacheFile>
-    if (raw.version !== CACHE_VERSION || raw.platform !== process.platform) return null
-    if (normalizeRoot(raw.accountRoot) !== normalizedRoot) return null
-    const result: BootstrapCacheFile = {
-      version: CACHE_VERSION,
-      platform: process.platform,
-      accountRoot: normalizedRoot,
-      updatedAt: Number(raw.updatedAt) || 0,
-      self: raw.self,
-      contacts: Array.isArray(raw.contacts) ? raw.contacts : [],
-      messages: raw.messages && typeof raw.messages === 'object' ? raw.messages : {},
-      groupSnapshots:
-        raw.groupSnapshots && typeof raw.groupSnapshots === 'object' ? raw.groupSnapshots : {}
-    }
-    memoryCache.set(file, result)
-    return result
-  } catch (error) {
-    console.warn('[BootstrapCache] read failed:', error)
-    return null
+  const accountKey = digest(`${process.platform}:${normalizedRoot}`)
+  const bootstrapRoot = path.join(app.getPath('userData'), 'cache', 'bootstrap')
+  const root = path.join(bootstrapRoot, `${process.platform}-${accountKey}`)
+  return {
+    root,
+    startup: path.join(root, 'startup.json'),
+    messages: path.join(root, 'messages'),
+    groups: path.join(root, 'groups'),
+    legacy: path.join(bootstrapRoot, `${process.platform}-${accountKey.slice(0, 16)}.json`)
   }
 }
 
-function writeCacheFile(cache: BootstrapCacheFile): void {
-  const file = getCacheFile(cache.accountRoot)
-  memoryCache.set(file, cache)
-  const existingTimer = writeTimers.get(file)
-  if (existingTimer) clearTimeout(existingTimer)
-  writeTimers.set(
-    file,
-    setTimeout(() => {
-      writeTimers.delete(file)
-      const serialized = JSON.stringify(memoryCache.get(file) || cache)
-      const previous = writeQueues.get(file) || Promise.resolve()
-      const next = previous
-        .catch(() => undefined)
-        .then(async () => {
-          await fs.ensureDir(path.dirname(file))
-          await fs.writeFile(file, serialized, 'utf8')
-        })
-        .catch((error) => {
-          console.warn('[BootstrapCache] write failed:', error)
-        })
-        .finally(() => {
-          if (writeQueues.get(file) === next) writeQueues.delete(file)
-        })
-      writeQueues.set(file, next)
-    }, WRITE_DEBOUNCE_MS)
-  )
-}
-
-function loadOrCreate(accountRoot?: string): BootstrapCacheFile | null {
-  const normalizedRoot = normalizeRoot(accountRoot)
-  if (!normalizedRoot) return null
-  const existing = readCacheFile(normalizedRoot)
-  if (existing) return existing
-  const created: BootstrapCacheFile = {
-    version: CACHE_VERSION,
-    platform: process.platform,
-    accountRoot: normalizedRoot,
-    updatedAt: Date.now(),
-    contacts: [],
-    messages: {},
-    groupSnapshots: {}
-  }
-  memoryCache.set(getCacheFile(normalizedRoot), created)
-  return created
-}
-
 function messageBucketKey(userMd5: string, startTime?: number, endTime?: number): string {
   return `${userMd5}:${startTime ?? ''}:${endTime ?? ''}`
 }
 
-function cachedMessageIdentity(message: Message): string {
-  if (message.localId) return `local:${message.localId}`
-  if (message.serverId) return `server:${message.serverId}`
-  return `id:${message.id}`
+function getMessageCacheFile(accountRoot: string, cacheKey: string): string {
+  return path.join(getAccountCachePaths(accountRoot).messages, `${digest(cacheKey)}.json`)
+}
+
+function getGroupCacheFile(accountRoot: string, userMd5: string): string {
+  return path.join(getAccountCachePaths(accountRoot).groups, `${digest(userMd5)}.json`)
+}
+
+function readScheduledValue<T>(file: string): T | null {
+  const scheduled = scheduledWrites.get(file)
+  return scheduled ? (scheduled.value as T) : null
+}
+
+function touchMemory<T>(memory: Map<string, T>, file: string, value: T, maxEntries: number): void {
+  memory.delete(file)
+  memory.set(file, value)
+  while (memory.size > maxEntries) {
+    const oldest = memory.keys().next().value
+    if (!oldest) break
+    memory.delete(oldest)
+  }
+}
+
+function isCurrentAccountFile(
+  value: {
+    version?: number
+    platform?: NodeJS.Platform
+    accountRoot?: string
+  },
+  accountRoot: string
+): boolean {
+  return (
+    value.version === CACHE_VERSION &&
+    value.platform === process.platform &&
+    normalizeRoot(value.accountRoot) === normalizeRoot(accountRoot)
+  )
+}
+
+function readStartupCacheFile(accountRoot: string): StartupCacheFile | null {
+  const normalizedRoot = normalizeRoot(accountRoot)
+  if (!normalizedRoot) return null
+  const file = getAccountCachePaths(normalizedRoot).startup
+  const scheduled = readScheduledValue<StartupCacheFile>(file)
+  if (scheduled) return scheduled
+  const memory = startupMemory.get(file)
+  if (memory) return memory
+
+  try {
+    if (!fs.existsSync(file)) return null
+    const raw = fs.readJsonSync(file) as Partial<StartupCacheFile>
+    if (!isCurrentAccountFile(raw, normalizedRoot)) return null
+    const result: StartupCacheFile = {
+      version: CACHE_VERSION,
+      platform: process.platform,
+      accountRoot: normalizedRoot,
+      updatedAt: Number(raw.updatedAt) || 0,
+      self: raw.self,
+      contacts: Array.isArray(raw.contacts) ? raw.contacts : []
+    }
+    startupMemory.set(file, result)
+    return result
+  } catch (error) {
+    console.warn('[BootstrapCache] startup read failed:', error)
+    return null
+  }
+}
+
+function readMessageBucketFile(
+  accountRoot: string,
+  cacheKey: string
+): CachedMessageBucketFile | null {
+  const normalizedRoot = normalizeRoot(accountRoot)
+  if (!normalizedRoot) return null
+  const file = getMessageCacheFile(normalizedRoot, cacheKey)
+  const scheduled = readScheduledValue<CachedMessageBucketFile>(file)
+  if (scheduled) return scheduled
+  const memory = messageMemory.get(file)
+  if (memory) {
+    touchMemory(messageMemory, file, memory, MAX_MEMORY_MESSAGE_BUCKETS)
+    return memory
+  }
+
+  try {
+    if (!fs.existsSync(file)) return null
+    const raw = fs.readJsonSync(file) as Partial<CachedMessageBucketFile>
+    if (!isCurrentAccountFile(raw, normalizedRoot) || raw.cacheKey !== cacheKey) return null
+    const result: CachedMessageBucketFile = {
+      version: CACHE_VERSION,
+      platform: process.platform,
+      accountRoot: normalizedRoot,
+      cacheKey,
+      updatedAt: Number(raw.updatedAt) || 0,
+      startTime: raw.startTime,
+      endTime: raw.endTime,
+      items: Array.isArray(raw.items) ? raw.items : []
+    }
+    touchMemory(messageMemory, file, result, MAX_MEMORY_MESSAGE_BUCKETS)
+    return result
+  } catch (error) {
+    console.warn('[BootstrapCache] message read failed:', error)
+    return null
+  }
+}
+
+function readGroupSnapshotFile(
+  accountRoot: string,
+  userMd5: string
+): CachedGroupSnapshotFile | null {
+  const normalizedRoot = normalizeRoot(accountRoot)
+  if (!normalizedRoot) return null
+  const file = getGroupCacheFile(normalizedRoot, userMd5)
+  const scheduled = readScheduledValue<CachedGroupSnapshotFile>(file)
+  if (scheduled) return scheduled
+  const memory = groupMemory.get(file)
+  if (memory) {
+    touchMemory(groupMemory, file, memory, MAX_MEMORY_GROUP_SNAPSHOTS)
+    return memory
+  }
+
+  try {
+    if (!fs.existsSync(file)) return null
+    const raw = fs.readJsonSync(file) as Partial<CachedGroupSnapshotFile>
+    if (!isCurrentAccountFile(raw, normalizedRoot) || raw.userMd5 !== userMd5 || !raw.snapshot) {
+      return null
+    }
+    const result: CachedGroupSnapshotFile = {
+      version: CACHE_VERSION,
+      platform: process.platform,
+      accountRoot: normalizedRoot,
+      userMd5,
+      updatedAt: Number(raw.updatedAt) || 0,
+      snapshot: raw.snapshot
+    }
+    touchMemory(groupMemory, file, result, MAX_MEMORY_GROUP_SNAPSHOTS)
+    return result
+  } catch (error) {
+    console.warn('[BootstrapCache] group snapshot read failed:', error)
+    return null
+  }
+}
+
+async function pruneCacheDirectory(directory: string, maxFiles: number): Promise<void> {
+  const now = Date.now()
+  if (now - (lastPrunedAt.get(directory) || 0) < PRUNE_INTERVAL_MS) return
+  lastPrunedAt.set(directory, now)
+
+  try {
+    const names = (await fs.readdir(directory)).filter((name) => name.endsWith('.json'))
+    if (names.length <= maxFiles) return
+    const entries = await Promise.all(
+      names.map(async (name) => {
+        const file = path.join(directory, name)
+        const stat = await fs.stat(file)
+        return { file, modifiedAt: stat.mtimeMs }
+      })
+    )
+    const expired = entries
+      .sort((left, right) => right.modifiedAt - left.modifiedAt)
+      .slice(maxFiles)
+    await Promise.all(
+      expired.map(async ({ file }) => {
+        messageMemory.delete(file)
+        groupMemory.delete(file)
+        await fs.remove(file)
+      })
+    )
+  } catch (error) {
+    if ((error as NodeJS.ErrnoException).code !== 'ENOENT') {
+      console.warn('[BootstrapCache] prune failed:', error)
+    }
+  }
+}
+
+function queueWrite(file: string): void {
+  const scheduled = scheduledWrites.get(file)
+  if (!scheduled) return
+  const previous = writeQueues.get(file) || Promise.resolve()
+  const next = previous
+    .catch(() => undefined)
+    .then(async () => {
+      const current = scheduledWrites.get(file)
+      if (
+        !current ||
+        current.revision !== scheduled.revision ||
+        current.generation !== cacheGeneration
+      ) {
+        return
+      }
+
+      const tempFile = `${file}.${process.pid}.${scheduled.revision}.tmp`
+      await fs.ensureDir(path.dirname(file))
+      await fs.writeFile(tempFile, JSON.stringify(current.value), 'utf8')
+      const latest = scheduledWrites.get(file)
+      if (
+        !latest ||
+        latest.revision !== scheduled.revision ||
+        latest.generation !== cacheGeneration
+      ) {
+        await fs.remove(tempFile)
+        return
+      }
+      await fs.move(tempFile, file, { overwrite: true })
+      const completed = scheduledWrites.get(file)
+      if (
+        completed?.revision === scheduled.revision &&
+        completed.generation === scheduled.generation
+      ) {
+        scheduledWrites.delete(file)
+      }
+      if (current.cleanupFile) await fs.remove(current.cleanupFile)
+      if (current.prune) {
+        void pruneCacheDirectory(current.prune.directory, current.prune.maxFiles)
+      }
+    })
+    .catch((error) => {
+      console.warn('[BootstrapCache] write failed:', error)
+    })
+    .finally(() => {
+      if (writeQueues.get(file) === next) writeQueues.delete(file)
+    })
+  writeQueues.set(file, next)
+}
+
+function scheduleWrite(
+  file: string,
+  value: unknown,
+  options?: { cleanupFile?: string; prune?: { directory: string; maxFiles: number } }
+): void {
+  const existingTimer = writeTimers.get(file)
+  if (existingTimer) clearTimeout(existingTimer)
+  const revision = (writeRevisions.get(file) || 0) + 1
+  writeRevisions.set(file, revision)
+  scheduledWrites.set(file, {
+    value,
+    revision,
+    generation: cacheGeneration,
+    cleanupFile: options?.cleanupFile,
+    prune: options?.prune
+  })
+  writeTimers.set(
+    file,
+    setTimeout(() => {
+      writeTimers.delete(file)
+      queueWrite(file)
+    }, WRITE_DEBOUNCE_MS)
+  )
+}
+
+function loadOrCreateStartupCache(accountRoot: string): StartupCacheFile | null {
+  const normalizedRoot = normalizeRoot(accountRoot)
+  if (!normalizedRoot) return null
+  const existing = readStartupCacheFile(normalizedRoot)
+  if (existing) return existing
+  const created: StartupCacheFile = {
+    version: CACHE_VERSION,
+    platform: process.platform,
+    accountRoot: normalizedRoot,
+    updatedAt: Date.now(),
+    contacts: []
+  }
+  startupMemory.set(getAccountCachePaths(normalizedRoot).startup, created)
+  return created
+}
+
+function writeStartupCache(cache: StartupCacheFile): void {
+  const paths = getAccountCachePaths(cache.accountRoot)
+  startupMemory.set(paths.startup, cache)
+  scheduleWrite(paths.startup, cache, { cleanupFile: paths.legacy })
 }
 
 function containsLegacyMisparsedAppMessage(items: Message[]): boolean {
@@ -160,8 +389,7 @@ function containsLegacyMisparsedAppMessage(items: Message[]): boolean {
     const content = message.contentData
     if (content?.type === 'system' && content.raw) {
       return (
-        /<weappinfo\b/i.test(content.raw) &&
-        /<type>\s*(?:33|36|2001)\s*<\/type>/i.test(content.raw)
+        /<weappinfo\b/i.test(content.raw) && /<type>\s*(?:33|36|2001)\s*<\/type>/i.test(content.raw)
       )
     }
     if (
@@ -176,27 +404,16 @@ function containsLegacyMisparsedAppMessage(items: Message[]): boolean {
   })
 }
 
-function pruneMessageBuckets(messages: Record<string, CachedMessageBucket>): void {
-  const entries = Object.entries(messages)
-  if (entries.length <= MAX_MESSAGE_BUCKETS) return
-  entries
-    .sort((left, right) => (right[1].updatedAt || 0) - (left[1].updatedAt || 0))
-    .slice(MAX_MESSAGE_BUCKETS)
-    .forEach(([key]) => {
-      delete messages[key]
-    })
-}
-
 export function getBootstrapCache(accountRoot?: string): {
   self?: CachedSelfInfo
   contacts: Contact[]
   updatedAt: number
 } | null {
-  const cache = readCacheFile(accountRoot)
+  const cache = readStartupCacheFile(normalizeRoot(accountRoot))
   if (!cache) return null
   return {
     self: cache.self,
-    contacts: cache.contacts || [],
+    contacts: cache.contacts,
     updatedAt: cache.updatedAt
   }
 }
@@ -212,8 +429,8 @@ function isRawContactName(contact: Contact): boolean {
 }
 
 export function mergeCachedContactAvatars(accountRoot: string, contacts: Contact[]): Contact[] {
-  const cache = readCacheFile(accountRoot)
-  if (!cache?.contacts?.length) return contacts
+  const cache = readStartupCacheFile(accountRoot)
+  if (!cache?.contacts.length) return contacts
   const avatarByUsername = new Map(
     cache.contacts
       .filter((contact) => contact.m_nsUsrName && contact.avatar)
@@ -241,23 +458,23 @@ export function mergeCachedContactAvatars(accountRoot: string, contacts: Contact
 }
 
 export function saveBootstrapSelf(accountRoot: string, self: CachedSelfInfo): void {
-  const cache = loadOrCreate(accountRoot)
+  const cache = loadOrCreateStartupCache(accountRoot)
   if (!cache) return
   cache.self = self
   cache.updatedAt = Date.now()
-  writeCacheFile(cache)
+  writeStartupCache(cache)
 }
 
 export function saveBootstrapContacts(accountRoot: string, contacts: Contact[]): void {
-  const cache = loadOrCreate(accountRoot)
+  const cache = loadOrCreateStartupCache(accountRoot)
   if (!cache) return
   const avatarByUsername = new Map(
-    (cache.contacts || [])
+    cache.contacts
       .filter((contact) => contact.m_nsUsrName && contact.avatar)
       .map((contact) => [contact.m_nsUsrName, contact.avatar as string])
   )
   const nameByUsername = new Map(
-    (cache.contacts || [])
+    cache.contacts
       .filter(
         (contact) => contact.m_nsUsrName && contact.m_nsNickName && !isRawContactName(contact)
       )
@@ -275,12 +492,12 @@ export function saveBootstrapContacts(accountRoot: string, contacts: Contact[]):
         : nameByUsername.get(contact.m_nsUsrName) || contact.m_nsNickName
   }))
   cache.updatedAt = Date.now()
-  writeCacheFile(cache)
+  writeStartupCache(cache)
 }
 
 export function mergeBootstrapAvatars(accountRoot: string, avatars: Record<string, string>): void {
-  const cache = loadOrCreate(accountRoot)
-  if (!cache || !cache.contacts?.length) return
+  const cache = loadOrCreateStartupCache(accountRoot)
+  if (!cache?.contacts.length) return
   let changed = false
   cache.contacts = cache.contacts.map((contact) => {
     const avatar = avatars[contact.m_nsUsrName]
@@ -290,7 +507,7 @@ export function mergeBootstrapAvatars(accountRoot: string, avatars: Record<strin
   })
   if (!changed) return
   cache.updatedAt = Date.now()
-  writeCacheFile(cache)
+  writeStartupCache(cache)
 }
 
 export function getCachedMessages(
@@ -299,9 +516,9 @@ export function getCachedMessages(
   startTime?: number,
   endTime?: number
 ): Message[] {
-  const cache = readCacheFile(accountRoot)
-  const bucket = cache?.messages?.[messageBucketKey(userMd5, startTime, endTime)]
-  return bucket?.items || []
+  return (
+    readMessageBucketFile(accountRoot, messageBucketKey(userMd5, startTime, endTime))?.items || []
+  )
 }
 
 export function getCachedMessagePage(
@@ -310,35 +527,12 @@ export function getCachedMessagePage(
   startTime?: number,
   endTime?: number
 ): { hit: boolean; messages: Message[]; groupSnapshot?: CachedGroupSnapshot } {
-  const cache = readCacheFile(accountRoot)
-  const key = messageBucketKey(userMd5, startTime, endTime)
-  let bucket = cache?.messages?.[key]
-  if (!bucket && cache?.messages && startTime === undefined && endTime === undefined) {
-    const merged = new Map<string, Message>()
-    for (const [cachedKey, candidate] of Object.entries(cache.messages)) {
-      if (!cachedKey.startsWith(`${userMd5}:`)) continue
-      for (const message of candidate.items || []) {
-        merged.set(cachedMessageIdentity(message), message)
-      }
-    }
-    const migratedMessages = Array.from(merged.values())
-      .sort((left, right) => (left.createTime || 0) - (right.createTime || 0))
-      .slice(-MAX_MESSAGES_PER_BUCKET)
-    if (migratedMessages.length > 0) {
-      bucket = {
-        updatedAt: Date.now(),
-        items: migratedMessages
-      }
-      cache.messages[key] = bucket
-      cache.updatedAt = Date.now()
-      pruneMessageBuckets(cache.messages)
-      writeCacheFile(cache)
-    }
-  }
+  const bucket = readMessageBucketFile(accountRoot, messageBucketKey(userMd5, startTime, endTime))
+  const messages = bucket?.items || []
   return {
-    hit: Boolean(bucket) && !containsLegacyMisparsedAppMessage(bucket?.items || []),
-    messages: bucket?.items || [],
-    groupSnapshot: cache?.groupSnapshots?.[userMd5]?.snapshot
+    hit: Boolean(bucket) && !containsLegacyMisparsedAppMessage(messages),
+    messages,
+    groupSnapshot: readGroupSnapshotFile(accountRoot, userMd5)?.snapshot
   }
 }
 
@@ -347,33 +541,22 @@ export function saveCachedGroupSnapshot(
   userMd5: string,
   snapshot: CachedGroupSnapshot
 ): void {
-  const cache = loadOrCreate(accountRoot)
-  if (!cache) return
-  cache.groupSnapshots ||= {}
-  cache.groupSnapshots[userMd5] = { updatedAt: Date.now(), snapshot }
-  cache.updatedAt = Date.now()
-  writeCacheFile(cache)
-}
-
-export function flushBootstrapCacheWritesSync(): void {
-  for (const [file, cache] of memoryCache) {
-    const timer = writeTimers.get(file)
-    if (timer) clearTimeout(timer)
-    writeTimers.delete(file)
-    try {
-      fs.ensureDirSync(path.dirname(file))
-      fs.writeFileSync(file, JSON.stringify(cache), 'utf8')
-    } catch (error) {
-      console.warn('[BootstrapCache] flush failed:', error)
-    }
+  const normalizedRoot = normalizeRoot(accountRoot)
+  if (!normalizedRoot || !userMd5) return
+  const paths = getAccountCachePaths(normalizedRoot)
+  const file = getGroupCacheFile(normalizedRoot, userMd5)
+  const value: CachedGroupSnapshotFile = {
+    version: CACHE_VERSION,
+    platform: process.platform,
+    accountRoot: normalizedRoot,
+    userMd5,
+    updatedAt: Date.now(),
+    snapshot
   }
-}
-
-export function clearBootstrapCache(): void {
-  for (const timer of writeTimers.values()) clearTimeout(timer)
-  writeTimers.clear()
-  writeQueues.clear()
-  memoryCache.clear()
+  touchMemory(groupMemory, file, value, MAX_MEMORY_GROUP_SNAPSHOTS)
+  scheduleWrite(file, value, {
+    prune: { directory: paths.groups, maxFiles: MAX_GROUP_SNAPSHOTS }
+  })
 }
 
 export function saveCachedMessages(
@@ -383,17 +566,52 @@ export function saveCachedMessages(
   endTime: number | undefined,
   messages: Message[]
 ): void {
-  const cache = loadOrCreate(accountRoot)
-  if (!cache) return
-  const nextMessages = cache.messages || {}
-  nextMessages[messageBucketKey(userMd5, startTime, endTime)] = {
+  const normalizedRoot = normalizeRoot(accountRoot)
+  if (!normalizedRoot || !userMd5) return
+  const cacheKey = messageBucketKey(userMd5, startTime, endTime)
+  const paths = getAccountCachePaths(normalizedRoot)
+  const file = getMessageCacheFile(normalizedRoot, cacheKey)
+  const value: CachedMessageBucketFile = {
+    version: CACHE_VERSION,
+    platform: process.platform,
+    accountRoot: normalizedRoot,
+    cacheKey,
     updatedAt: Date.now(),
     startTime,
     endTime,
     items: messages.slice(-MAX_MESSAGES_PER_BUCKET)
   }
-  pruneMessageBuckets(nextMessages)
-  cache.messages = nextMessages
-  cache.updatedAt = Date.now()
-  writeCacheFile(cache)
+  touchMemory(messageMemory, file, value, MAX_MEMORY_MESSAGE_BUCKETS)
+  scheduleWrite(file, value, {
+    prune: { directory: paths.messages, maxFiles: MAX_MESSAGE_BUCKETS }
+  })
+}
+
+export function flushBootstrapCacheWritesSync(): void {
+  for (const timer of writeTimers.values()) clearTimeout(timer)
+  writeTimers.clear()
+  const writes = Array.from(scheduledWrites.entries())
+  scheduledWrites.clear()
+  for (const [file, scheduled] of writes) {
+    try {
+      fs.ensureDirSync(path.dirname(file))
+      fs.writeFileSync(file, JSON.stringify(scheduled.value), 'utf8')
+      if (scheduled.cleanupFile) fs.removeSync(scheduled.cleanupFile)
+    } catch (error) {
+      console.warn('[BootstrapCache] flush failed:', error)
+    }
+  }
+}
+
+export function clearBootstrapCache(): void {
+  cacheGeneration += 1
+  for (const timer of writeTimers.values()) clearTimeout(timer)
+  writeTimers.clear()
+  scheduledWrites.clear()
+  writeQueues.clear()
+  writeRevisions.clear()
+  lastPrunedAt.clear()
+  startupMemory.clear()
+  messageMemory.clear()
+  groupMemory.clear()
 }

src/main/services/chat-service.ts

@@ -172,6 +172,12 @@ export function listContacts(filter?: string): FormattedContact[] {
   return contacts
 }
 
+export async function listContactsAsync(filter?: string): Promise<FormattedContact[]> {
+  if (!dbRef) return []
+  await dbRef.getWcdb4Client().getSessionsAsync()
+  return listContacts(filter)
+}
+
 export function getContactAvatars(usernames: string[]): Record<string, string> {
   if (!dbRef) return {}
   const normalized = Array.from(

src/main/video-asset-service.ts

@@ -10,6 +10,7 @@ type VideoAsset = {
 
 export class VideoAssetService {
   private readonly urlTokens = new Map<string, string>()
+  private readonly fileTokens = new Map<string, string>()
   private index: Map<string, VideoAsset> | null = null
 
   constructor(private readonly client: Wcdb4Client) {}
@@ -48,8 +49,8 @@ export class VideoAssetService {
       if (!asset) continue
       return {
         success: true,
-        url: this.createUrl(asset.filePath),
-        poster: asset.posterPath ? this.createUrl(asset.posterPath) : undefined
+        url: this.createLocalMediaUrl(asset.filePath),
+        poster: asset.posterPath ? this.createLocalMediaUrl(asset.posterPath) : undefined
       }
     }
     return { success: false, error: '本地未找到该视频文件' }
@@ -61,12 +62,33 @@ export class VideoAssetService {
     return filePath
   }
 
-  private createUrl(filePath: string): string {
+  pathForUrl(url: string): string | undefined {
+    try {
+      const parsed = new URL(url)
+      if (parsed.protocol !== 'wxe-media:' || parsed.hostname !== 'local') return undefined
+      return this.pathForToken(parsed.pathname.replace(/^\/+/, ''))
+    } catch {
+      return undefined
+    }
+  }
+
+  createLocalMediaUrl(filePath: string): string {
+    const normalizedPath = path.resolve(filePath)
+    const existingToken = this.fileTokens.get(normalizedPath)
+    if (existingToken && this.urlTokens.get(existingToken) === normalizedPath) {
+      return `wxe-media://local/${existingToken}`
+    }
+
     const token = crypto.randomBytes(18).toString('hex')
-    this.urlTokens.set(token, filePath)
-    if (this.urlTokens.size > 500) {
-      const first = this.urlTokens.keys().next().value
-      if (first) this.urlTokens.delete(first)
+    this.urlTokens.set(token, normalizedPath)
+    this.fileTokens.set(normalizedPath, token)
+    if (this.urlTokens.size > 2048) {
+      const oldestToken = this.urlTokens.keys().next().value
+      if (oldestToken) {
+        const oldestPath = this.urlTokens.get(oldestToken)
+        this.urlTokens.delete(oldestToken)
+        if (oldestPath) this.fileTokens.delete(oldestPath)
+      }
     }
     return `wxe-media://local/${token}`
   }

src/main/wcdb4-client.ts

@@ -241,6 +241,8 @@ export class Wcdb4Client {
   private groupNicknameCache = new Map<string, Map<string, string>>()
   private cachedSessions: Wcdb4Session[] | null = null
   private cachedChatTables: { name: string; db_number: string }[] | null = null
+  private sessionsInFlight: Promise<Wcdb4Session[]> | null = null
+  private sessionCacheGeneration = 0
 
   private wcdbShutdown: (() => number) | null = null
   private wcdbOpenAccount:
@@ -531,7 +533,11 @@ export class Wcdb4Client {
     this.handle = handleOut[0]
     if (this.wcdbSetMyWxid) {
       try {
-        this.wcdbSetMyWxid(this.handle, this.wxid)
+        await this.callAsyncCode(
+          this.wcdbSetMyWxid as unknown as KoffiAsyncFunction,
+          this.handle,
+          this.wxid
+        )
       } catch {
         // Optional helper. Failure does not block message reads.
       }
@@ -557,14 +563,16 @@ export class Wcdb4Client {
     this.groupNicknameCache.clear()
   }
 
-  startMonitor(callback: (type: string, json: string) => void): boolean {
+  async startMonitor(callback: (type: string, json: string) => void): Promise<boolean> {
     if (!this.wcdbStartMonitorPipe || !this.wcdbGetMonitorPipeName || !this.koffi) return false
 
     this.stopMonitor()
     this.monitorCallback = callback
 
     try {
-      const startResult = this.wcdbStartMonitorPipe()
+      const startResult = await this.callAsyncCode(
+        this.wcdbStartMonitorPipe as unknown as KoffiAsyncFunction
+      )
       if (startResult !== 0) {
         this.monitorCallback = null
         console.warn(`[WCDB4] wcdb_start_monitor_pipe 失败，错误码: ${startResult}`)
@@ -573,7 +581,10 @@ export class Wcdb4Client {
       this.monitorStarted = true
 
       const outName: WcdbVoidOut = [null]
-      const nameResult = this.wcdbGetMonitorPipeName(outName)
+      const nameResult = await this.callAsyncCode(
+        this.wcdbGetMonitorPipeName as unknown as KoffiAsyncFunction,
+        outName
+      )
       if (nameResult !== 0 || !outName[0]) {
         console.warn(`[WCDB4] wcdb_get_monitor_pipe_name 失败，错误码: ${nameResult}`)
         this.stopMonitor()
@@ -715,9 +726,45 @@ export class Wcdb4Client {
     return this.cachedSessions
   }
 
+  async getSessionsAsync(): Promise<Wcdb4Session[]> {
+    if (this.cachedSessions) return this.cachedSessions
+    if (this.sessionsInFlight) return this.sessionsInFlight
+    if (!this.wcdbGetSessions) return []
+
+    const generation = this.sessionCacheGeneration
+    const request = (async (): Promise<Wcdb4Session[]> => {
+      const rows = await this.callJsonAsync<Record<string, unknown>[]>(
+        this.wcdbGetSessions as unknown as KoffiAsyncFunction
+      )
+      const sessions = (Array.isArray(rows) ? rows : [])
+        .map((row) => this.normalizeSession(row))
+        .filter((session) => session.username)
+      await this.hydrateDisplayNamesAsync(
+        sessions
+          .filter((session) => this.shouldHydrateSessionDisplayName(session))
+          .map((session) => session.username)
+      )
+      const hydrated = sessions.map((session) => ({
+        ...session,
+        nickname:
+          this.displayNameCache.get(session.username) || session.nickname || session.username
+      }))
+      if (generation === this.sessionCacheGeneration) this.cachedSessions = hydrated
+      return hydrated
+    })()
+    this.sessionsInFlight = request
+    try {
+      return await request
+    } finally {
+      if (this.sessionsInFlight === request) this.sessionsInFlight = null
+    }
+  }
+
   invalidateSessionCache(): void {
+    this.sessionCacheGeneration += 1
     this.cachedSessions = null
     this.cachedChatTables = null
+    this.sessionsInFlight = null
   }
 
   getChatTables(): { name: string; db_number: string }[] {
@@ -1527,6 +1574,25 @@ export class Wcdb4Client {
     }
   }
 
+  async resolveImageHardlinkAsync(md5: string): Promise<Wcdb4ImageHardlink | null> {
+    if (!this.wcdbResolveImageHardlink) return null
+    const normalizedMd5 = String(md5 || '')
+      .trim()
+      .toLowerCase()
+    if (!normalizedMd5) return null
+
+    try {
+      return await this.callJsonAsync<Wcdb4ImageHardlink>(
+        this.wcdbResolveImageHardlink as unknown as KoffiAsyncFunction,
+        normalizedMd5,
+        this.accountRoot
+      )
+    } catch (error) {
+      console.warn('[WCDB4] async image hardlink resolve failed:', error)
+      return null
+    }
+  }
+
   resolveVideoHardlink(md5: string, dbPath: string): Wcdb4VideoHardlink | null {
     if (!this.wcdbResolveVideoHardlink) return null
     const normalizedMd5 = String(md5 || '')

src/preload/index.d.ts

@@ -205,7 +205,7 @@ declare global {
         imageMd5?: string,
         imageDatNameOrThumb?: string | boolean,
         sessionId?: string,
-        options?: { force?: boolean; preferThumbnail?: boolean }
+        options?: { force?: boolean; preferThumbnail?: boolean; priority?: number }
       ) => Promise<{
         success: boolean
         data?: string

src/preload/index.ts

@@ -76,7 +76,7 @@ const api = {
     imageMd5?: string,
     imageDatNameOrThumb?: string | boolean,
     sessionId?: string,
-    options?: { force?: boolean; preferThumbnail?: boolean }
+    options?: { force?: boolean; preferThumbnail?: boolean; priority?: number }
   ) => ipcRenderer.invoke('db:getImage', imageMd5, imageDatNameOrThumb, sessionId, options),
   getVideo: (hashes: string[]) => ipcRenderer.invoke('db:getVideo', hashes),
   getSticker: (cdnUrl?: string, md5?: string) => ipcRenderer.invoke('db:getSticker', cdnUrl, md5),

src/renderer/src/components/ImageBubble.tsx

@@ -29,93 +29,92 @@ export function ImageBubble({
   const [usingFallback, setUsingFallback] = useState(false)
   const containerRef = useRef<HTMLDivElement>(null)
   const mountedRef = useRef(true)
-  const backgroundUpgradeRef = useRef(false)
 
   useEffect(() => {
+    mountedRef.current = true
     return () => {
       mountedRef.current = false
     }
   }, [])
 
-  const upgradeOriginalInBackground = useCallback(() => {
-    if (!isThumbnail || backgroundUpgradeRef.current || (!imageMd5 && !imageDatName)) return
-    backgroundUpgradeRef.current = true
-    void requestImage(imageMd5, imageDatName, sessionId, { force: true }, 1)
-      .then((original) => {
-        if (!mountedRef.current) return
-        setImageUrl(original.data)
-        setIsThumbnail(false)
-      })
-      .catch(() => undefined)
-  }, [imageDatName, imageMd5, isThumbnail, sessionId])
-
-  const loadImage = useCallback(async () => {
-    if (imageUrl || loading) return
-    if (!imageMd5 && !imageDatName) {
-      if (fallbackUrl) {
-        setImageUrl(fallbackUrl)
-        setUsingFallback(true)
-        setError(null)
+  const loadImage = useCallback(
+    async (priority = 0) => {
+      if (imageUrl) return
+      if (!imageMd5 && !imageDatName) {
+        if (fallbackUrl) {
+          setImageUrl(fallbackUrl)
+          setUsingFallback(true)
+          setError(null)
+          return
+        }
+        setError('缺少图片标识')
         return
       }
-      setError('缺少图片标识')
-      return
-    }
-
-    setLoading(true)
-    try {
-      const result = await requestImage(
-        imageMd5,
-        imageDatName,
-        sessionId,
-        { preferThumbnail: true },
-        0
-      )
-      setImageUrl(result.data)
-      setUsingFallback(false)
-      setIsThumbnail(result.isThumbnail)
-      setError(null)
-      if (result.isThumbnail) upgradeOriginalInBackground()
-    } catch (error) {
-      if (fallbackUrl) {
-        setImageUrl(fallbackUrl)
-        setUsingFallback(true)
-        setError(null)
-      } else {
-        setError(error instanceof Error ? error.message : '加载图片失败')
+      if (loading) {
+        if (priority === 0) {
+          void requestImage(
+            imageMd5,
+            imageDatName,
+            sessionId,
+            { preferThumbnail: true },
+            priority
+          ).catch(() => undefined)
+        }
+        return
       }
-    } finally {
-      setLoading(false)
-    }
-  }, [
-    fallbackUrl,
-    imageDatName,
-    imageMd5,
-    imageUrl,
-    loading,
-    sessionId,
-    upgradeOriginalInBackground
-  ])
+
+      setLoading(true)
+      try {
+        const result = await requestImage(
+          imageMd5,
+          imageDatName,
+          sessionId,
+          { preferThumbnail: true },
+          priority
+        )
+        if (!mountedRef.current) return
+        setImageUrl(result.data)
+        setUsingFallback(false)
+        setIsThumbnail(result.isThumbnail)
+        setError(null)
+      } catch (error) {
+        if (!mountedRef.current) return
+        if (fallbackUrl) {
+          setImageUrl(fallbackUrl)
+          setUsingFallback(true)
+          setError(null)
+        } else {
+          setError(error instanceof Error ? error.message : '加载图片失败')
+        }
+      } finally {
+        if (mountedRef.current) setLoading(false)
+      }
+    },
+    [fallbackUrl, imageDatName, imageMd5, imageUrl, loading, sessionId]
+  )
 
   useEffect(() => {
-    if (initialCachedImage?.isThumbnail) upgradeOriginalInBackground()
-  }, [initialCachedImage?.isThumbnail, upgradeOriginalInBackground])
-
-  useEffect(() => {
-    if (imageUrl || loading || error) return
+    if (imageUrl || error) return
     const element = containerRef.current
     if (!element || typeof IntersectionObserver === 'undefined') {
-      const timer = window.setTimeout(() => void loadImage(), 0)
+      const timer = window.setTimeout(() => void loadImage(0), 0)
       return () => window.clearTimeout(timer)
     }
 
     const observer = new IntersectionObserver(
       (entries) => {
-        if (!entries.some((entry) => entry.isIntersecting)) return
+        const entry = entries.find((candidate) => candidate.isIntersecting)
+        if (!entry) return
+        const rect = entry.boundingClientRect
+        const isInViewport =
+          rect.bottom >= 0 &&
+          rect.top <= window.innerHeight &&
+          rect.right >= 0 &&
+          rect.left <= window.innerWidth
         observer.disconnect()
-        void loadImage()
+        void loadImage(isInViewport ? 0 : 1)
       },
-      { rootMargin: '400px 0px' }
+      { rootMargin: loading ? '0px' : '400px 0px' }
     )
     observer.observe(element)
     return () => observer.disconnect()
@@ -143,7 +142,7 @@ export function ImageBubble({
     setUpgrading(true)
     try {
       const result = await requestImage(imageMd5, imageDatName, sessionId, { force: true }, 0)
-      if (result.data.startsWith('data:image/')) {
+      if (result.data.startsWith('data:image/') || result.data.startsWith('wxe-media://')) {
         setImageUrl(result.data)
         setUsingFallback(false)
         setIsThumbnail(result.isThumbnail)
@@ -162,7 +161,7 @@ export function ImageBubble({
 
   if (loading) {
     return (
-      <div className="image-bubble image-loading" onClick={handleClick}>
+      <div ref={containerRef} className="image-bubble image-loading" onClick={handleClick}>
         <div className="image-loading-skeleton" aria-hidden />
         <div className="image-quality-badge">加载中</div>
       </div>
@@ -171,7 +170,7 @@ export function ImageBubble({
 
   if (error) {
     return (
-      <div className="image-bubble image-error" onClick={loadImage}>
+      <div className="image-bubble image-error" onClick={() => void loadImage(0)}>
         <div className="image-error-text">{error || '图片未缓存'}</div>
         <div className="image-quality-badge">加载失败</div>
       </div>

src/renderer/src/components/image-loader.ts

@@ -9,13 +9,17 @@ export type ImageLoadOptions = {
 }
 
 type QueueItem = {
+  requestKey: string
   priority: number
   run: () => Promise<LoadedImage>
   resolve: (value: LoadedImage) => void
   reject: (error: Error) => void
 }
 
-const MAX_CONCURRENT_IMAGE_LOADS = 3
+// Cache probes are cheap asynchronous IPC calls. Cold decrypts are serialized
+// in the main process, so renderer concurrency only controls how quickly disk
+// cache hits can become visible after a restart.
+const MAX_CONCURRENT_IMAGE_LOADS = 32
 const MAX_IMAGE_CACHE_BYTES = 48 * 1024 * 1024
 const imageCache = new Map<string, LoadedImage>()
 const imageCacheSizes = new Map<string, number>()
@@ -99,6 +103,8 @@ function cacheImage(
 }
 
 function pumpImageQueue(): void {
+  if (activeImageLoads >= MAX_CONCURRENT_IMAGE_LOADS || imageQueue.length === 0) return
+
   while (activeImageLoads < MAX_CONCURRENT_IMAGE_LOADS && imageQueue.length > 0) {
     imageQueue.sort((left, right) => left.priority - right.priority)
     const item = imageQueue.shift()
@@ -114,6 +120,10 @@ function pumpImageQueue(): void {
   }
 }
 
+function isSupportedImageUrl(value: string | undefined): value is string {
+  return Boolean(value?.startsWith('data:image/') || value?.startsWith('wxe-media://'))
+}
+
 export function getCachedLoadedImage(
   imageMd5?: string,
   imageDatName?: string,
@@ -136,16 +146,24 @@ export function requestImage(
   if (!identity) return Promise.reject(new Error('缺少图片标识'))
   const requestKey = `${identity}:${cacheMode(options)}`
   const existingRequest = imageRequests.get(requestKey)
-  if (existingRequest) return existingRequest
+  if (existingRequest) {
+    const queuedItem = imageQueue.find((item) => item.requestKey === requestKey)
+    if (queuedItem && priority < queuedItem.priority) queuedItem.priority = priority
+    return existingRequest
+  }
 
   const request = new Promise<LoadedImage>((resolve, reject) => {
     imageQueue.push({
+      requestKey,
       priority,
       resolve,
       reject,
       run: async () => {
-        const result = await window.api.getImage(imageMd5, imageDatName, sessionId, options)
-        if (!result.success || !result.data?.startsWith('data:image/')) {
+        const result = await window.api.getImage(imageMd5, imageDatName, sessionId, {
+          ...options,
+          priority
+        })
+        if (!result.success || !isSupportedImageUrl(result.data)) {
           throw new Error(result.error || '加载图片失败')
         }
         const loadedImage = {