diff --git a/docs/README.md b/docs/README.md
index 9ae512e..5eed667 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -56,6 +56,7 @@ TraceMemo 有两种不同的接入方式。微信机器人是普通用户可以
 - [macOS 数据访问说明](./platform/macos.md)
 - [开发、测试与构建](./development/overview.md)
 - [本地启动排障](./development/local-startup-troubleshooting.md)
+- [v2.2.0 品牌升级与本地数据兼容](./agent/release-notes-v2.2.0.md)
 - [v2.1.9 API 鉴权迁移说明](./agent/release-notes-v2.1.9.md)
 
 当前工作区版本：**2.2.0**。文档只描述当前代码已经实现的能力；版本兼容性、AI Provider 行为和媒体读取结果可能随系统、微信客户端和服务商变化。
diff --git a/docs/agent/release-notes-v2.2.0.md b/docs/agent/release-notes-v2.2.0.md
new file mode 100644
index 0000000..0b49177
--- /dev/null
+++ b/docs/agent/release-notes-v2.2.0.md
@@ -0,0 +1,45 @@
+# TraceMemo 2.2.0：品牌升级与本地数据兼容
+
+2.2.0 将用户可见品牌从 WechatExplorer 升级为 TraceMemo（迹忆）。这次升级不搬迁或复制用户的 Application Support 数据；macOS 和 Windows 上的旧用户会继续使用原有数据根，以避免设置、密钥和本地索引失联。
+
+## 升级后继续保留的内容
+
+- 微信数据库连接设置和其他用户设置；
+- AI Provider、模型配置和已加密 API Key；
+- Local HTTP API Token；
+- 微信数据库 Key 和图片解密 Key；
+- Knowledge 本地索引，包括现有 SQLite、WAL 和 SHM 文件；
+- 报告历史、防撤回归档和图片理解结果；
+- Renderer Local Storage 和其他 Chromium session 数据；
+- `~/.wechatexplorer/wechat-connector/accounts` 中的 Agent Hub 登录凭据。
+
+应用启动时会在任何业务模块读取 Electron 路径或使用 `safeStorage` 之前选择数据根，并将 `userData` 与 `sessionData` 设置为同一目录：
+
+- `WechatExplorer` 或 v2.1.9 使用的小写 `wechatexplorer` 目录包含有效用户资产时，继续使用对应旧目录；
+- 只有 TraceMemo 新目录包含有效用户资产时，使用新目录；
+- 多个旧目录或新旧目录同时包含有效用户资产时，不复制、不合并、不覆盖；两个大小写 legacy 目录均有效时确定性优先 `WechatExplorer` 并写入诊断日志；
+- 两边都没有有效用户资产时，全新安装使用 TraceMemo 新目录。
+
+仅有 `Local State`、Cache、Code Cache 或 GPUCache 等运行时文件，不会被判断为有效用户资产。
+
+## 有意保留的兼容标识
+
+内部 Electron runtime identity 在 macOS 上继续使用 `WechatExplorer`。前者用于兼容旧 `safeStorage` 密文，后者同时承担旧 `safeStorage` 与 WCDB 运行时兼容；它们都不是未完成的品牌替换。
+
+以下历史标识也继续保留：
+
+- bundle/app identifier：`com.wechatexplorer.app`；
+- Reader Skill 目录和标识：`wechatexplorer-reader`；
+- Agent 环境变量：`WECHATEXPLORER_API_TOKEN`；
+- Agent Hub 凭据目录：`~/.wechatexplorer`；
+- GitHub 仓库地址中的 `WechatExplorer`。
+
+Local HTTP API 的 endpoint、默认端口 `6131`、Bearer Token 格式、加密方式和 rotation 行为没有因为品牌升级而改变。旧 Token 文件会从旧数据根继续读取，不会仅因升级而重新生成。
+
+## Knowledge 与日志
+
+Knowledge 不会被复制、移动或自动重建。旧用户继续直接使用原有 Knowledge 目录，因此不需要为了 v2.2.0 重新建立索引。
+
+TraceMemo 的新诊断日志写入 TraceMemo 日志目录；WechatExplorer 历史日志保持原位置，不移动、不重命名、不删除。“打开诊断日志目录”会打开当前版本使用的 TraceMemo 日志。
+
+更多安全边界见[数据、隐私与安全](../user-guide/privacy.md)和[API 安全](./api-security.md)。
diff --git a/src/main/app-data-bootstrap.ts b/src/main/app-data-bootstrap.ts
index 6296711..a056b64 100644
--- a/src/main/app-data-bootstrap.ts
+++ b/src/main/app-data-bootstrap.ts
@@ -1,10 +1,6 @@
 import { app } from 'electron'
 import path from 'path'
-import {
-  chooseUserDataRoot,
-  getUserDataRoots,
-  LEGACY_USER_DATA_NAME
-} from './app-data-paths'
+import { getUserDataRoots, LEGACY_USER_DATA_NAME, selectUserDataRoot } from './app-data-paths'
 
 // This module must remain the first main-process import. Static imports in
 // settings/cache services can otherwise resolve Electron paths before the
@@ -13,10 +9,11 @@ app.setName(process.platform === 'win32' ? 'WeFlow' : LEGACY_USER_DATA_NAME)
 
 const isolatedUserData = process.env['WXE_USER_DATA']
 const roots = getUserDataRoots(app.getPath('appData'))
-const selectedUserData = chooseUserDataRoot({
+const userDataSelection = selectUserDataRoot({
   ...roots,
   isolated: isolatedUserData
 })
+const selectedUserData = userDataSelection.selected
 
 app.setPath('userData', selectedUserData)
 app.setPath('sessionData', selectedUserData)
@@ -28,4 +25,4 @@ if (process.platform === 'darwin') {
   app.setPath('logs', path.join(app.getPath('home'), 'Library', 'Logs', 'TraceMemo'))
 }
 
-export { roots, selectedUserData }
+export { roots, selectedUserData, userDataSelection }
diff --git a/src/main/app-data-paths.ts b/src/main/app-data-paths.ts
index 6d6c820..c3ae953 100644
--- a/src/main/app-data-paths.ts
+++ b/src/main/app-data-paths.ts
@@ -2,10 +2,12 @@ import fs from 'fs'
 import path from 'path'
 
 export const LEGACY_USER_DATA_NAME = 'WechatExplorer'
+export const LEGACY_PACKAGE_USER_DATA_NAME = 'wechatexplorer'
 export const CURRENT_USER_DATA_NAME = 'tracememo'
 
 export interface UserDataRoots {
   legacy: string
+  legacyPackage: string
   current: string
 }
 
@@ -13,6 +15,41 @@ export interface UserDataSelectionInput extends UserDataRoots {
   isolated?: string
 }
 
+export type UserDataRootKind = 'isolated' | 'legacy-display' | 'legacy-package' | 'current'
+
+export type UserDataSelectionReason =
+  | 'isolated-override'
+  | 'legacy-display-assets'
+  | 'legacy-package-assets'
+  | 'legacy-shared-assets'
+  | 'legacy-conflict-display-preferred'
+  | 'current-assets'
+  | 'clean-install'
+
+export interface UserDataSelection {
+  selected: string
+  selectedKind: UserDataRootKind
+  reason: UserDataSelectionReason
+  directories: {
+    legacy: boolean
+    legacyPackage: boolean
+    current: boolean
+  }
+  assets: {
+    legacy: boolean
+    legacyPackage: boolean
+    current: boolean
+  }
+  legacyRootsEquivalent: boolean
+  legacyConflict: boolean
+}
+
+export interface UserDataSelectionDependencies {
+  directoryExists: (root: string) => boolean
+  hasAssets: (root: string) => boolean
+  areSameDirectory: (first: string, second: string) => boolean
+}
+
 function isNonEmptyFile(filePath: string): boolean {
   try {
     const stat = fs.statSync(filePath)
@@ -37,7 +74,11 @@ function hasPersistentEntries(directoryPath: string): boolean {
 function hasDatabaseKey(directoryPath: string): boolean {
   try {
     return fs.readdirSync(directoryPath, { withFileTypes: true }).some((entry) => {
-      return entry.isFile() && entry.name.endsWith('.bin') && isNonEmptyFile(path.join(directoryPath, entry.name))
+      return (
+        entry.isFile() &&
+        entry.name.endsWith('.bin') &&
+        isNonEmptyFile(path.join(directoryPath, entry.name))
+      )
     })
   } catch {
     return false
@@ -56,6 +97,26 @@ function hasKnowledgeDatabase(root: string): boolean {
   }
 }
 
+function isExistingDirectory(directoryPath: string): boolean {
+  try {
+    return fs.statSync(directoryPath).isDirectory()
+  } catch {
+    return false
+  }
+}
+
+function areSameExistingDirectory(firstPath: string, secondPath: string): boolean {
+  try {
+    const first = fs.statSync(firstPath)
+    const second = fs.statSync(secondPath)
+    if (!first.isDirectory() || !second.isDirectory()) return false
+    if (first.ino && first.dev === second.dev && first.ino === second.ino) return true
+    return fs.realpathSync.native(firstPath) === fs.realpathSync.native(secondPath)
+  } catch {
+    return false
+  }
+}
+
 /**
  * Runtime-only Chromium files are deliberately excluded. A directory is a
  * valid data root only when it contains at least one user-owned marker.
@@ -85,20 +146,106 @@ export function hasValidUserAssets(root: string): boolean {
 export function getUserDataRoots(appDataPath: string): UserDataRoots {
   return {
     legacy: path.join(appDataPath, LEGACY_USER_DATA_NAME),
+    legacyPackage: path.join(appDataPath, LEGACY_PACKAGE_USER_DATA_NAME),
     current: path.join(appDataPath, CURRENT_USER_DATA_NAME)
   }
 }
 
 /**
  * Select exactly one root. This intentionally does not copy, merge, delete or
- * modify either directory. Legacy wins when both roots contain user assets so
- * a v2.1.9 upgrade remains deterministic and lossless.
+ * modify any directory. The visible-name legacy root remains first priority;
+ * the lowercase v2.1.9 package-name root is the fallback on case-sensitive
+ * filesystems. If both distinct legacy roots contain assets, the visible-name
+ * root wins deterministically and the caller receives conflict diagnostics.
  */
-export function chooseUserDataRoot(input: UserDataSelectionInput): string {
+export function selectUserDataRoot(
+  input: UserDataSelectionInput,
+  dependencies: UserDataSelectionDependencies = {
+    directoryExists: isExistingDirectory,
+    hasAssets: hasValidUserAssets,
+    areSameDirectory: areSameExistingDirectory
+  }
+): UserDataSelection {
   const isolated = input.isolated?.trim()
-  if (isolated) return path.resolve(isolated)
+  if (isolated) {
+    return {
+      selected: path.resolve(isolated),
+      selectedKind: 'isolated',
+      reason: 'isolated-override',
+      directories: { legacy: false, legacyPackage: false, current: false },
+      assets: { legacy: false, legacyPackage: false, current: false },
+      legacyRootsEquivalent: false,
+      legacyConflict: false
+    }
+  }
 
-  if (hasValidUserAssets(input.legacy)) return input.legacy
-  if (hasValidUserAssets(input.current)) return input.current
-  return input.current
+  const directories = {
+    legacy: dependencies.directoryExists(input.legacy),
+    legacyPackage: dependencies.directoryExists(input.legacyPackage),
+    current: dependencies.directoryExists(input.current)
+  }
+  const assets = {
+    legacy: dependencies.hasAssets(input.legacy),
+    legacyPackage: dependencies.hasAssets(input.legacyPackage),
+    current: dependencies.hasAssets(input.current)
+  }
+  const legacyRootsEquivalent =
+    directories.legacy &&
+    directories.legacyPackage &&
+    dependencies.areSameDirectory(input.legacy, input.legacyPackage)
+
+  if (assets.legacy) {
+    const legacyConflict = assets.legacyPackage && !legacyRootsEquivalent
+    return {
+      selected: input.legacy,
+      selectedKind: 'legacy-display',
+      reason: legacyConflict
+        ? 'legacy-conflict-display-preferred'
+        : legacyRootsEquivalent
+          ? 'legacy-shared-assets'
+          : 'legacy-display-assets',
+      directories,
+      assets,
+      legacyRootsEquivalent,
+      legacyConflict
+    }
+  }
+
+  if (assets.legacyPackage) {
+    return {
+      selected: input.legacyPackage,
+      selectedKind: 'legacy-package',
+      reason: 'legacy-package-assets',
+      directories,
+      assets,
+      legacyRootsEquivalent: false,
+      legacyConflict: false
+    }
+  }
+
+  if (assets.current) {
+    return {
+      selected: input.current,
+      selectedKind: 'current',
+      reason: 'current-assets',
+      directories,
+      assets,
+      legacyRootsEquivalent: false,
+      legacyConflict: false
+    }
+  }
+
+  return {
+    selected: input.current,
+    selectedKind: 'current',
+    reason: 'clean-install',
+    directories,
+    assets,
+    legacyRootsEquivalent: false,
+    legacyConflict: false
+  }
+}
+
+export function chooseUserDataRoot(input: UserDataSelectionInput): string {
+  return selectUserDataRoot(input).selected
 }
diff --git a/src/main/index.ts b/src/main/index.ts
index 1940060..a8e8368 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -1,4 +1,4 @@
-import './app-data-bootstrap'
+import { userDataSelection } from './app-data-bootstrap'
 import './preload-env'
 import {
   app,
@@ -513,6 +513,26 @@ app.whenReady().then(async () => {
     message: 'TraceMemo 启动',
     details: { build: BUILD_MARK, platform: process.platform, version: app.getVersion() }
   })
+  appLogger.write({
+    level: userDataSelection.legacyConflict ? 'warn' : 'info',
+    scope: 'app-data-bootstrap',
+    message: userDataSelection.legacyConflict
+      ? '检测到两个独立的 legacy userData，已按兼容优先级选择 WechatExplorer'
+      : 'userData 路径选择完成',
+    details: {
+      selectedPath: userDataSelection.selected,
+      selectedKind: userDataSelection.selectedKind,
+      reason: userDataSelection.reason,
+      legacyExists: userDataSelection.directories.legacy,
+      legacyPackageExists: userDataSelection.directories.legacyPackage,
+      currentExists: userDataSelection.directories.current,
+      legacyAssets: userDataSelection.assets.legacy,
+      legacyPackageAssets: userDataSelection.assets.legacyPackage,
+      currentAssets: userDataSelection.assets.current,
+      legacyRootsEquivalent: userDataSelection.legacyRootsEquivalent,
+      legacyConflict: userDataSelection.legacyConflict
+    }
+  })
   process.on('uncaughtException', (error) => {
     appLogger.write({
       level: 'error',
diff --git a/tests/unit/app-data-paths.test.ts b/tests/unit/app-data-paths.test.ts
index 1c4aa32..47450b5 100644
--- a/tests/unit/app-data-paths.test.ts
+++ b/tests/unit/app-data-paths.test.ts
@@ -2,7 +2,13 @@ import { mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'fs'
 import os from 'os'
 import path from 'path'
 import { afterEach, beforeEach, describe, expect, it } from 'vitest'
-import { chooseUserDataRoot, getUserDataRoots, hasValidUserAssets } from '../../src/main/app-data-paths'
+import {
+  chooseUserDataRoot,
+  getUserDataRoots,
+  hasValidUserAssets,
+  selectUserDataRoot,
+  type UserDataRoots
+} from '../../src/main/app-data-paths'
 
 let root = ''
 
@@ -23,6 +29,18 @@ function writeMarker(filePath: string): void {
   writeFileSync(filePath, 'fixture')
 }
 
+function selectWithAssets(
+  roots: UserDataRoots,
+  validRoots: string[],
+  legacyRootsEquivalent = false
+): ReturnType<typeof selectUserDataRoot> {
+  return selectUserDataRoot(roots, {
+    directoryExists: (candidate) => validRoots.includes(candidate),
+    hasAssets: (candidate) => validRoots.includes(candidate),
+    areSameDirectory: () => legacyRootsEquivalent
+  })
+}
+
 describe('app data compatibility root selection', () => {
   it('chooses the new root for a clean install', () => {
     const roots = fixtureRoots()
@@ -31,6 +49,66 @@ describe('app data compatibility root selection', () => {
     expect(chooseUserDataRoot(roots)).toBe(roots.current)
   })
 
+  it('chooses WechatExplorer when only the display-name legacy root exists', () => {
+    const roots = fixtureRoots()
+    const selection = selectWithAssets(roots, [roots.legacy])
+    expect(selection).toMatchObject({
+      selected: roots.legacy,
+      selectedKind: 'legacy-display',
+      reason: 'legacy-display-assets',
+      directories: { legacy: true, legacyPackage: false, current: false },
+      legacyConflict: false
+    })
+  })
+
+  it('chooses wechatexplorer when only the v2.1.9 package-name legacy root exists', () => {
+    const roots = fixtureRoots()
+    const selection = selectWithAssets(roots, [roots.legacyPackage])
+    expect(selection).toMatchObject({
+      selected: roots.legacyPackage,
+      selectedKind: 'legacy-package',
+      reason: 'legacy-package-assets',
+      directories: { legacy: false, legacyPackage: true, current: false },
+      legacyConflict: false
+    })
+  })
+
+  it('chooses WechatExplorer deterministically and reports a conflict when both exist', () => {
+    const roots = fixtureRoots()
+    const selection = selectWithAssets(roots, [roots.legacy, roots.legacyPackage])
+    expect(selection).toMatchObject({
+      selected: roots.legacy,
+      selectedKind: 'legacy-display',
+      reason: 'legacy-conflict-display-preferred',
+      directories: { legacy: true, legacyPackage: true, current: false },
+      legacyRootsEquivalent: false,
+      legacyConflict: true
+    })
+  })
+
+  it('chooses tracememo when neither legacy root exists', () => {
+    const roots = fixtureRoots()
+    const selection = selectWithAssets(roots, [])
+    expect(selection).toMatchObject({
+      selected: roots.current,
+      selectedKind: 'current',
+      reason: 'clean-install',
+      directories: { legacy: false, legacyPackage: false, current: false },
+      legacyConflict: false
+    })
+  })
+
+  it('does not report a conflict when both legacy spellings resolve to one directory', () => {
+    const roots = fixtureRoots()
+    const selection = selectWithAssets(roots, [roots.legacy, roots.legacyPackage], true)
+    expect(selection).toMatchObject({
+      selected: roots.legacy,
+      reason: 'legacy-shared-assets',
+      legacyRootsEquivalent: true,
+      legacyConflict: false
+    })
+  })
+
   it('ignores runtime-only Chromium files', () => {
     const roots = fixtureRoots()
     mkdirSync(roots.current, { recursive: true })