diff --git a/web/src/core/api/client.test.ts b/web/src/core/api/client.test.ts
index fbdcdc1..b5942d9 100644
--- a/web/src/core/api/client.test.ts
+++ b/web/src/core/api/client.test.ts
@@ -269,6 +269,94 @@ describe('token 失效时更换身份', () => {
     expect(events).toEqual([])
     expect(local.getItem(memberTokenKey)).toBe('good')
   })
+
+  it('修改密码时当前密码错误返回 INVALID_CREDENTIALS，不更换身份', async () => {
+    local.setItem(memberTokenKey, 'good')
+    routes.set('PUT /api/account/password', () => errorResponse(401, 'INVALID_CREDENTIALS', '当前密码错误'))
+    const { api, events, IdentityRenewedError } = await load()
+    const error: unknown = await api.changePassword({ currentPassword: 'wrong horse', newPassword: 'correct horse' }).catch((reason: unknown) => reason)
+    expect(error).not.toBeInstanceOf(IdentityRenewedError)
+    expect(error).toMatchObject({ code: 'INVALID_CREDENTIALS', status: 401 })
+    expect(events).toEqual([])
+    expect(local.getItem(memberTokenKey)).toBe('good')
+  })
+
+  it('账号密码错误不更换身份', async () => {
+    local.setItem(memberTokenKey, 'good')
+    routes.set('POST /api/sessions', () => errorResponse(401, 'INVALID_CREDENTIALS', '用户名或密码错误'))
+    const { api, events } = await load()
+    await expect(api.login({ username: 'alice', password: 'wrong horse' })).rejects.toMatchObject({ code: 'INVALID_CREDENTIALS', status: 401 })
+    expect(events).toEqual([])
+    expect(local.getItem(memberTokenKey)).toBe('good')
+  })
+})
+
+describe('其他标签页更换身份', () => {
+  let listeners: ((event: { key: string | null }) => void)[]
+  let changed: ReturnType<typeof vi.fn<() => void>>
+
+  function storageEvent(key: string | null = memberTokenKey) {
+    for (const listener of listeners)
+      listener({ key })
+  }
+
+  beforeEach(() => {
+    listeners = []
+    changed = vi.fn<() => void>()
+    vi.stubGlobal('window', {
+      addEventListener: (type: string, listener: (event: { key: string | null }) => void) => {
+        if (type === 'storage')
+          listeners.push(listener)
+      },
+    })
+  })
+
+  it('本标签页正在使用的 token 被换成另一个时通知切换', async () => {
+    local.setItem(memberTokenKey, 'good')
+    const { api, followMemberTokenChanges } = await load()
+    followMemberTokenChanges(changed)
+    await api.getMe()
+
+    local.setItem(memberTokenKey, 'other')
+    storageEvent()
+    expect(changed).toHaveBeenCalledOnce()
+  })
+
+  it('token 没有变化、无关的 key 或被删除时不切换', async () => {
+    local.setItem(memberTokenKey, 'good')
+    const { api, followMemberTokenChanges } = await load()
+    followMemberTokenChanges(changed)
+    await api.getMe()
+
+    storageEvent()
+    local.setItem('alisten.volume', '80')
+    storageEvent('alisten.volume')
+    local.removeItem(memberTokenKey)
+    storageEvent()
+    expect(changed).not.toHaveBeenCalled()
+  })
+
+  it('两个标签页都没有 token 各自创建游客时，先创建的另一个标签页不触发切换', async () => {
+    const { api, followMemberTokenChanges } = await load()
+    followMemberTokenChanges(changed)
+    const pending = api.getMe()
+
+    local.setItem(memberTokenKey, 'other-tab')
+    storageEvent()
+    expect(changed).not.toHaveBeenCalled()
+    await pending
+  })
+
+  it('本标签页后写入的 token 覆盖了另一个标签页，迟到的事件不触发切换', async () => {
+    const { api, followMemberTokenChanges } = await load()
+    followMemberTokenChanges(changed)
+    const pending = api.getMe()
+    local.setItem(memberTokenKey, 'other-tab')
+    await pending
+    expect(local.getItem(memberTokenKey)).toBe('issued')
+    storageEvent()
+    expect(changed).not.toHaveBeenCalled()
+  })
 })
 
 describe('换取票据', () => {
diff --git a/web/src/core/api/client.ts b/web/src/core/api/client.ts
index 47e621a..35ad237 100644
--- a/web/src/core/api/client.ts
+++ b/web/src/core/api/client.ts
@@ -1,7 +1,7 @@
 import type { Auth, CreateTicketRequest, CreateTicketResponse, ErrorResponse, HttpRequest } from './http.gen'
 import type { ErrorCode, Member } from '@/core/realtime'
 import { Emitter } from '@/shared/lib/emitter'
-import { deleteMemberToken, loadAdminToken, loadMemberToken, saveMemberToken } from './credentials'
+import { deleteMemberToken, loadAdminToken, loadMemberToken, memberTokenKey, saveMemberToken } from './credentials'
 import { httpClient } from './http.gen'
 
 export class ApiError extends Error {
@@ -134,13 +134,17 @@ export const api = {
 }
 
 let creatingMember: Promise<string> | null = null
+let usedMemberToken: string | null = null
 
 function memberToken(): Promise<string> {
   const stored = loadMemberToken()
-  if (stored)
+  if (stored) {
+    usedMemberToken = stored
     return Promise.resolve(stored)
+  }
   creatingMember ??= api.createMember().then(({ memberToken }) => {
     saveMemberToken(memberToken)
+    usedMemberToken = memberToken
     return memberToken
   }).finally(() => {
     creatingMember = null
@@ -173,3 +177,15 @@ async function replaceIdentity(rejected: string): Promise<void> {
   }
   identityEvents.emit({ kind: 'renewed', member })
 }
+
+// 只有本标签页已经用过 token、并且保存的 token 换成了另一个时才算身份变了。
+// 两个标签页同时创建游客时，对方先写入的 token 会被后写入的覆盖，此时本标签页还没有用过 token，或用的就是最终保存的 token，都不触发，避免互相刷新。
+export function followMemberTokenChanges(onChange: () => void): void {
+  window.addEventListener('storage', (event) => {
+    if (event.key !== memberTokenKey)
+      return
+    const stored = loadMemberToken()
+    if (usedMemberToken !== null && stored !== null && stored !== usedMemberToken)
+      onChange()
+  })
+}
diff --git a/web/src/core/api/credentials.test.ts b/web/src/core/api/credentials.test.ts
new file mode 100644
index 0000000..11fe4f6
--- /dev/null
+++ b/web/src/core/api/credentials.test.ts
@@ -0,0 +1,44 @@
+import { afterEach, expect, it, vi } from 'vitest'
+
+class FakeStorage {
+  readonly #items = new Map<string, string>()
+
+  get length(): number {
+    return this.#items.size
+  }
+
+  key(index: number): string | null {
+    return [...this.#items.keys()][index] ?? null
+  }
+
+  getItem(key: string): string | null {
+    return this.#items.get(key) ?? null
+  }
+
+  setItem(key: string, value: string): void {
+    this.#items.set(key, value)
+  }
+
+  removeItem(key: string): void {
+    this.#items.delete(key)
+  }
+}
+
+afterEach(() => {
+  vi.unstubAllGlobals()
+})
+
+it('换身份时删除所有房间的票据，其他数据不动', async () => {
+  const local = new FakeStorage()
+  vi.stubGlobal('localStorage', local)
+  local.setItem('alisten.ticket.room-1', 't1')
+  local.setItem('alisten.member-token', 'm')
+  local.setItem('alisten.ticket.room-2', 't2')
+  local.setItem('alisten.volume', '80')
+  const { deleteAllTickets } = await import('./credentials')
+  deleteAllTickets()
+  expect(local.getItem('alisten.ticket.room-1')).toBeNull()
+  expect(local.getItem('alisten.ticket.room-2')).toBeNull()
+  expect(local.getItem('alisten.member-token')).toBe('m')
+  expect(local.getItem('alisten.volume')).toBe('80')
+})
diff --git a/web/src/core/api/credentials.ts b/web/src/core/api/credentials.ts
index f32b36e..a75de71 100644
--- a/web/src/core/api/credentials.ts
+++ b/web/src/core/api/credentials.ts
@@ -1,4 +1,4 @@
-const memberTokenKey = 'alisten.member-token'
+export const memberTokenKey = 'alisten.member-token'
 const adminTokenKey = 'alisten.admin-token'
 const ticketKeyPrefix = 'alisten.ticket.'
 
@@ -26,6 +26,15 @@ export function deleteTicket(roomId: string): void {
   localStorage.removeItem(ticketKeyPrefix + roomId)
 }
 
+// 票据属于签发时的成员，换了身份之后都不能再用。倒序遍历：删除会让后面的键前移。
+export function deleteAllTickets(): void {
+  for (let i = localStorage.length - 1; i >= 0; i--) {
+    const key = localStorage.key(i)
+    if (key?.startsWith(ticketKeyPrefix))
+      localStorage.removeItem(key)
+  }
+}
+
 export function loadAdminToken(): string | null {
   return sessionStorage.getItem(adminTokenKey)
 }
diff --git a/web/src/core/api/index.ts b/web/src/core/api/index.ts
index 5e82f02..af8e7a1 100644
--- a/web/src/core/api/index.ts
+++ b/web/src/core/api/index.ts
@@ -1,4 +1,4 @@
-export { api, ApiError, identityEvents, IdentityRenewedError } from './client'
+export { api, ApiError, followMemberTokenChanges, identityEvents, IdentityRenewedError } from './client'
 export type { IdentityEvent } from './client'
-export { deleteAdminToken, deleteTicket, loadAdminToken, loadTicket, saveAdminToken, saveTicket } from './credentials'
+export { deleteAdminToken, deleteAllTickets, deleteMemberToken, deleteTicket, loadAdminToken, loadTicket, saveAdminToken, saveMemberToken, saveTicket } from './credentials'
 export type * from './http.gen'
diff --git a/web/src/features/settings/account-section.tsx b/web/src/features/settings/account-section.tsx
new file mode 100644
index 0000000..21843a5
--- /dev/null
+++ b/web/src/features/settings/account-section.tsx
@@ -0,0 +1,170 @@
+import type { FormEvent } from 'react'
+import { useEffect, useId, useState } from 'react'
+import { api, IdentityRenewedError } from '@/core/api'
+import { errorMessage } from '@/core/errors'
+import { useStore } from '@/shared/lib/use-store'
+import { Modal, notificationStore } from '@/shared/ui'
+import { loginWithPassword } from './password-login'
+import { profileStore, switchIdentity } from './profile-store'
+
+type Dialog = 'register' | 'login' | 'password' | null
+
+const credentialTexts = { INVALID_ARGUMENT: '用户名要 3–32 位小写字母、数字、_ 或 -，密码要 8–128 位。' }
+
+// 对话框渲染在 portal 中，React 的事件仍会冒泡到设置页外层的表单，提交时要拦住，否则会顺带保存整页设置。
+function submitted(event: FormEvent, run: () => Promise<void>): void {
+  event.preventDefault()
+  event.stopPropagation()
+  void run()
+}
+
+export function AccountRow() {
+  const member = useStore(profileStore, s => s.member)
+  const account = useStore(profileStore, s => s.account)
+  const failed = useStore(profileStore, s => s.failed)
+  const [registrationOpen, setRegistrationOpen] = useState(false)
+  const [dialog, setDialog] = useState<Dialog>(null)
+  const [busy, setBusy] = useState(false)
+  useEffect(() => {
+    let active = true
+    api.getSite().then((site) => {
+      if (active)
+        setRegistrationOpen(site.registrationOpen)
+    }, () => {})
+    return () => {
+      active = false
+    }
+  }, [])
+  const logout = async () => {
+    setBusy(true)
+    if (!await profileStore.logout())
+      setBusy(false)
+  }
+  const description = member ? null : failed ? '暂时无法获取你的资料。' : '正在获取你的资料…'
+  return (
+    <div className="settings-row">
+      <div className="settings-row-copy">
+        <p className="settings-row-title text-ui-base">{account ? account.username : '游客'}</p>
+        {description && <p className="text-ui-caption muted">{description}</p>}
+      </div>
+      {member && (
+        <div className="settings-row-control settings-account-actions">
+          {account
+            ? (
+                <>
+                  <button type="button" className="button-secondary" onClick={() => setDialog('password')}>修改密码</button>
+                  <button type="button" className="button-secondary" disabled={busy} onClick={() => void logout()}>退出登录</button>
+                </>
+              )
+            : (
+                <>
+                  {registrationOpen && <button type="button" className="button-secondary" onClick={() => setDialog('register')}>注册</button>}
+                  <button type="button" className="button-secondary" onClick={() => setDialog('login')}>登录</button>
+                </>
+              )}
+        </div>
+      )}
+      {(dialog === 'register' || dialog === 'login') && <CredentialsDialog mode={dialog} onClose={() => setDialog(null)} />}
+      {dialog === 'password' && <PasswordDialog onClose={() => setDialog(null)} />}
+    </div>
+  )
+}
+
+function CredentialsDialog({ mode, onClose }: { mode: 'register' | 'login', onClose: () => void }) {
+  const [username, setUsername] = useState('')
+  const [password, setPassword] = useState('')
+  const [repeated, setRepeated] = useState('')
+  const [busy, setBusy] = useState(false)
+  const register = mode === 'register'
+  const submit = async () => {
+    setBusy(true)
+    try {
+      if (register) {
+        const { account } = await api.register({ username, password })
+        notificationStore.success('已注册')
+        onClose()
+        void profileStore.registered(account)
+      }
+      else {
+        switchIdentity(await loginWithPassword(username, password))
+      }
+    }
+    catch (error) {
+      notificationStore.error(error instanceof IdentityRenewedError ? (register ? '没有注册成功，再试一次。' : '没有登录，再试一次。') : errorMessage(error, credentialTexts))
+      setBusy(false)
+    }
+  }
+  return (
+    <Modal title={register ? '注册账号' : '登录'} onClose={onClose}>
+      <form className="form-stack" onSubmit={event => submitted(event, submit)}>
+        <label>
+          用户名
+          <input data-autofocus required autoComplete="username" pattern="[a-z0-9_\-]{3,32}" minLength={3} maxLength={32} value={username} onChange={event => setUsername(event.target.value.toLowerCase())} />
+        </label>
+        <label>
+          密码
+          <input type="password" required autoComplete={register ? 'new-password' : 'current-password'} minLength={8} maxLength={128} value={password} onChange={event => setPassword(event.target.value)} />
+        </label>
+        {register && <RepeatPassword label="再次输入密码" password={password} value={repeated} onChange={setRepeated} />}
+        <p className="text-ui-caption muted">
+          {register
+            ? '用户名 3–32 位，可用小写字母、数字、_ 和 -；密码至少 8 位。忘记密码需联系管理员。'
+            : '登录后页面会重新加载。'}
+        </p>
+        <button type="submit" className="button-primary" disabled={busy || (register && repeated !== password)}>
+          {busy ? (register ? '正在注册…' : '正在登录…') : (register ? '注册' : '登录')}
+        </button>
+      </form>
+    </Modal>
+  )
+}
+
+function PasswordDialog({ onClose }: { onClose: () => void }) {
+  const [currentPassword, setCurrentPassword] = useState('')
+  const [newPassword, setNewPassword] = useState('')
+  const [repeated, setRepeated] = useState('')
+  const [busy, setBusy] = useState(false)
+  const submit = async () => {
+    setBusy(true)
+    try {
+      await api.changePassword({ currentPassword, newPassword })
+      notificationStore.success('已修改密码，其他设备已退出登录')
+      onClose()
+    }
+    catch (error) {
+      notificationStore.error(error instanceof IdentityRenewedError ? '密码没有修改，再试一次。' : errorMessage(error, { INVALID_ARGUMENT: '密码要 8 到 128 位。' }))
+      setBusy(false)
+    }
+  }
+  return (
+    <Modal title="修改密码" onClose={onClose}>
+      <form className="form-stack" onSubmit={event => submitted(event, submit)}>
+        <label>
+          当前密码
+          <input type="password" data-autofocus required autoComplete="current-password" minLength={8} maxLength={128} value={currentPassword} onChange={event => setCurrentPassword(event.target.value)} />
+        </label>
+        <label>
+          新密码
+          <input type="password" required autoComplete="new-password" minLength={8} maxLength={128} value={newPassword} onChange={event => setNewPassword(event.target.value)} />
+        </label>
+        <RepeatPassword label="再次输入新密码" password={newPassword} value={repeated} onChange={setRepeated} />
+        <p className="text-ui-caption muted">修改后，其他设备需要重新登录。</p>
+        <button type="submit" className="button-primary" disabled={busy || repeated !== newPassword}>{busy ? '正在修改…' : '修改密码'}</button>
+      </form>
+    </Modal>
+  )
+}
+
+function RepeatPassword({ label, password, value, onChange }: { label: string, password: string, value: string, onChange: (value: string) => void }) {
+  const hintId = useId()
+  const mismatched = value !== '' && value !== password
+  return (
+    <>
+      <label>
+        {label}
+        <input type="password" required autoComplete="new-password" minLength={8} maxLength={128} value={value} onChange={event => onChange(event.target.value)} aria-invalid={mismatched} aria-describedby={mismatched ? hintId : undefined} />
+      </label>
+      {mismatched && <p id={hintId} className="text-ui-caption error-text">两次输入的密码不一样。</p>}
+    </>
+  )
+}
diff --git a/web/src/features/settings/password-login.test.ts b/web/src/features/settings/password-login.test.ts
new file mode 100644
index 0000000..587c318
--- /dev/null
+++ b/web/src/features/settings/password-login.test.ts
@@ -0,0 +1,107 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+class FakeStorage {
+  readonly #items = new Map<string, string>()
+
+  getItem(key: string): string | null {
+    return this.#items.get(key) ?? null
+  }
+
+  setItem(key: string, value: string): void {
+    this.#items.set(key, value)
+  }
+
+  removeItem(key: string): void {
+    this.#items.delete(key)
+  }
+}
+
+const devicesKey = 'alisten.login-devices'
+
+// 服务端发给这个账号的凭证，格式与协议中的 LoginDevice 一致。
+function deviceOf(username: string): string {
+  return username.padEnd(43, '0')
+}
+
+let local: FakeStorage
+let bodies: unknown[]
+let rejected: boolean
+
+beforeEach(() => {
+  vi.resetModules()
+  local = new FakeStorage()
+  bodies = []
+  rejected = false
+  vi.stubGlobal('localStorage', local)
+  vi.stubGlobal('sessionStorage', new FakeStorage())
+  vi.stubGlobal('window', new EventTarget())
+  local.setItem('alisten.member-token', 'guest')
+  vi.stubGlobal('fetch', async (path: string, init: RequestInit) => {
+    if (`${init.method} ${path}` !== 'POST /api/sessions')
+      return new Response(null, { status: 404 })
+    const body = JSON.parse(String(init.body)) as { username: string }
+    bodies.push(body)
+    if (rejected)
+      return new Response(JSON.stringify({ error: { code: 'INVALID_CREDENTIALS', message: '用户名或密码错误' } }), { status: 401 })
+    const { username } = body
+    return new Response(JSON.stringify({
+      memberToken: `${username}-token`,
+      member: { id: username, name: username, avatarHash: '' },
+      account: { username, github: false },
+      device: deviceOf(username),
+    }), { status: 201 })
+  })
+})
+
+async function login(username: string): Promise<string> {
+  const { loginWithPassword } = await import('./password-login')
+  return loginWithPassword(username, 'correct horse')
+}
+
+function saved(): unknown {
+  return JSON.parse(local.getItem(devicesKey)!)
+}
+
+describe('登录设备凭证', () => {
+  it('第一次登录不带凭证，保存响应里的凭证；再登录同一个账号时带上它', async () => {
+    expect(await login('alice')).toBe('alice-token')
+    expect(bodies).toEqual([{ username: 'alice', password: 'correct horse' }])
+    expect(saved()).toEqual({ alice: deviceOf('alice') })
+
+    await login('alice')
+    expect(bodies[1]).toEqual({ username: 'alice', password: 'correct horse', device: deviceOf('alice') })
+  })
+
+  it('按用户名分别保存：登录别的账号不带这个账号的凭证，也不覆盖它', async () => {
+    await login('alice')
+    await login('bob')
+    expect(bodies[1]).toEqual({ username: 'bob', password: 'correct horse' })
+    expect(saved()).toEqual({ alice: deviceOf('alice'), bob: deviceOf('bob') })
+  })
+
+  it('服务端不认带去的凭证、换发了新的时，保存新的', async () => {
+    const stale = 'x'.repeat(43)
+    local.setItem(devicesKey, JSON.stringify({ alice: stale }))
+    await login('alice')
+    expect(bodies).toEqual([{ username: 'alice', password: 'correct horse', device: stale }])
+    expect(saved()).toEqual({ alice: deviceOf('alice') })
+  })
+
+  it('登录失败时不改动保存的凭证', async () => {
+    local.setItem(devicesKey, JSON.stringify({ alice: deviceOf('alice') }))
+    rejected = true
+    await expect(login('alice')).rejects.toMatchObject({ code: 'INVALID_CREDENTIALS' })
+    await expect(login('bob')).rejects.toMatchObject({ code: 'INVALID_CREDENTIALS' })
+    expect(saved()).toEqual({ alice: deviceOf('alice') })
+  })
+
+  it('保存的内容不是凭证时不带上，登录成功后重新保存', async () => {
+    for (const [stored, username] of [['not json', 'alice'], [JSON.stringify({ alice: 'too short' }), 'alice'], ['{}', 'constructor']]) {
+      bodies = []
+      local.setItem(devicesKey, stored)
+      await login(username)
+      expect(bodies).toEqual([{ username, password: 'correct horse' }])
+      expect(saved()).toEqual({ [username]: deviceOf(username) })
+    }
+  })
+})
diff --git a/web/src/features/settings/password-login.ts b/web/src/features/settings/password-login.ts
new file mode 100644
index 0000000..a242553
--- /dev/null
+++ b/web/src/features/settings/password-login.ts
@@ -0,0 +1,26 @@
+import { api } from '@/core/api'
+
+// 按用户名保存服务端发给本机的登录设备凭证：一台设备可能登录过多个账号。退出登录时保留，下次登录这个账号时带上，
+// 别人反复猜这个账号的密码时本机仍然能登录。
+const devicesKey = 'alisten.login-devices'
+// 与协议中的 LoginDevice 一致：本机保存的内容被改坏时不能带上，否则服务端会拒绝整个登录请求。
+const devicePattern = /^[\w-]{43}$/
+
+function loadDevices(): Record<string, unknown> {
+  try {
+    const devices: unknown = JSON.parse(localStorage.getItem(devicesKey) ?? '{}')
+    if (typeof devices === 'object' && devices !== null)
+      return devices as Record<string, unknown>
+  }
+  catch {}
+  return {}
+}
+
+// 返回账号的新成员 token。
+export async function loginWithPassword(username: string, password: string): Promise<string> {
+  const device = loadDevices()[username]
+  const response = await api.login(typeof device === 'string' && devicePattern.test(device) ? { username, password, device } : { username, password })
+  // 等待响应期间别的标签页可能保存了别的账号的凭证，重新读取之后再写回。
+  localStorage.setItem(devicesKey, JSON.stringify({ ...loadDevices(), [username]: response.device }))
+  return response.memberToken
+}
diff --git a/web/src/features/settings/profile-store.test.ts b/web/src/features/settings/profile-store.test.ts
new file mode 100644
index 0000000..8de1d53
--- /dev/null
+++ b/web/src/features/settings/profile-store.test.ts
@@ -0,0 +1,339 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+class FakeStorage {
+  readonly #items = new Map<string, string>()
+
+  get length(): number {
+    return this.#items.size
+  }
+
+  key(index: number): string | null {
+    return [...this.#items.keys()][index] ?? null
+  }
+
+  getItem(key: string): string | null {
+    return this.#items.get(key) ?? null
+  }
+
+  setItem(key: string, value: string): void {
+    this.#items.set(key, value)
+  }
+
+  removeItem(key: string): void {
+    this.#items.delete(key)
+  }
+}
+
+const memberTokenKey = 'alisten.member-token'
+const emailKey = 'alisten.email'
+const member = { id: 'm1', name: 'alice', avatarHash: '' }
+const renewed = { id: 'm2', name: '游客-1a2b', avatarHash: '' }
+
+let local: FakeStorage
+let storageListeners: ((event: { key: string }) => void)[]
+let reload: ReturnType<typeof vi.fn>
+let me: unknown
+let updates: unknown[]
+let patchFails: boolean
+let patchError: { status: number, code: string } | null
+let extraRoutes: Map<string, () => Response>
+
+async function load() {
+  const [{ profileStore, switchIdentity }, { identityEvents }] = await Promise.all([import('./profile-store'), import('@/core/api')])
+  return { profileStore, switchIdentity, identityEvents }
+}
+
+beforeEach(() => {
+  vi.resetModules()
+  // 通知按计时器消失。
+  vi.useFakeTimers()
+  local = new FakeStorage()
+  reload = vi.fn()
+  me = { member }
+  updates = []
+  patchFails = false
+  patchError = null
+  extraRoutes = new Map()
+  vi.stubGlobal('localStorage', local)
+  vi.stubGlobal('sessionStorage', new FakeStorage())
+  storageListeners = []
+  vi.stubGlobal('window', { location: { reload }, addEventListener: (_type: string, listener: (event: { key: string }) => void) => storageListeners.push(listener) })
+  vi.stubGlobal('fetch', (path: string, init: RequestInit) => {
+    const request = `${init.method} ${path}`
+    if (request === 'PATCH /api/me') {
+      if (patchFails)
+        return Promise.reject(new TypeError('offline'))
+      updates.push(JSON.parse(String(init.body)))
+      if (patchError)
+        return Promise.resolve(new Response(JSON.stringify({ error: { code: patchError.code, message: '邮箱格式不对' } }), { status: patchError.status }))
+      return Promise.resolve(new Response(JSON.stringify({ member }), { status: 200 }))
+    }
+    const extra = extraRoutes.get(request)
+    if (extra)
+      return Promise.resolve(extra())
+    if (request !== 'GET /api/me')
+      throw new Error(`没有预期的请求 ${request}`)
+    return Promise.resolve(new Response(JSON.stringify(me), { status: 200 }))
+  })
+})
+
+afterEach(() => {
+  vi.useRealTimers()
+  vi.unstubAllGlobals()
+})
+
+describe('switchIdentity', () => {
+  it('换成新的 token，删除所有票据和本机的邮箱，重新加载页面', async () => {
+    local.setItem(memberTokenKey, 'guest')
+    local.setItem('alisten.ticket.r1', 't1')
+    local.setItem('alisten.ticket.r2', 't2')
+    local.setItem(emailKey, 'alice@example.com')
+    local.setItem('alisten.volume', '80')
+    const { switchIdentity } = await load()
+    switchIdentity('account')
+
+    expect(local.getItem(memberTokenKey)).toBe('account')
+    expect(local.getItem('alisten.ticket.r1')).toBeNull()
+    expect(local.getItem('alisten.ticket.r2')).toBeNull()
+    expect(local.getItem(emailKey)).toBeNull()
+    expect(local.getItem('alisten.volume')).toBe('80')
+    expect(reload).toHaveBeenCalledOnce()
+  })
+
+  it('退出登录时删除 token，重新加载之后换成新的游客；登录设备凭证保留', async () => {
+    const devices = JSON.stringify({ alice: 'a'.repeat(43) })
+    local.setItem(memberTokenKey, 'account')
+    local.setItem('alisten.ticket.r1', 't1')
+    local.setItem(emailKey, 'alice@example.com')
+    local.setItem('alisten.login-devices', devices)
+    const { switchIdentity } = await load()
+    switchIdentity(null)
+
+    expect(local.getItem(memberTokenKey)).toBeNull()
+    expect(local.getItem('alisten.ticket.r1')).toBeNull()
+    expect(local.getItem(emailKey)).toBeNull()
+    expect(local.getItem('alisten.login-devices')).toBe(devices)
+    expect(reload).toHaveBeenCalledOnce()
+  })
+})
+
+describe('其他标签页更换身份', () => {
+  it('其他标签页换了 token 之后重新加载页面', async () => {
+    local.setItem(memberTokenKey, 'good')
+    const { profileStore } = await load()
+    profileStore.start()
+    await profileStore.load()
+    local.setItem(memberTokenKey, 'other')
+    for (const listener of storageListeners) listener({ key: memberTokenKey })
+    expect(reload).toHaveBeenCalledOnce()
+  })
+})
+
+describe('退出登录', () => {
+  beforeEach(() => {
+    local.setItem(memberTokenKey, 'account')
+  })
+
+  it('成功后删除 token 并重新加载页面', async () => {
+    extraRoutes.set('DELETE /api/sessions/current', () => new Response(null, { status: 204 }))
+    const { profileStore } = await load()
+    await profileStore.logout()
+    expect(local.getItem(memberTokenKey)).toBeNull()
+    expect(reload).toHaveBeenCalledOnce()
+  })
+
+  it('会话已经失效、客户端换成了新的游客时，重新加载页面', async () => {
+    extraRoutes.set('DELETE /api/sessions/current', () => new Response(JSON.stringify({ error: { code: 'UNAUTHORIZED', message: '身份已失效' } }), { status: 401 }))
+    extraRoutes.set('POST /api/members', () => new Response(JSON.stringify({ member: renewed, memberToken: 'guest' }), { status: 200 }))
+    me = { member: renewed }
+    const { profileStore } = await load()
+    await profileStore.logout()
+    expect(local.getItem(memberTokenKey)).toBe('guest')
+    expect(reload).toHaveBeenCalledOnce()
+  })
+
+  it('其他错误不重新加载页面，token 保留', async () => {
+    extraRoutes.set('DELETE /api/sessions/current', () => new Response(JSON.stringify({ error: { code: 'INTERNAL', message: '出错了' } }), { status: 500 }))
+    const { profileStore } = await load()
+    expect(await profileStore.logout()).toBe(false)
+    expect(local.getItem(memberTokenKey)).toBe('account')
+    expect(reload).not.toHaveBeenCalled()
+  })
+})
+
+describe('账号状态', () => {
+  beforeEach(() => {
+    local.setItem(memberTokenKey, 'good')
+  })
+
+  it('取回资料时一并取回账号', async () => {
+    me = { member, account: { username: 'alice' } }
+    const { profileStore } = await load()
+    await profileStore.load()
+    expect(profileStore.state).toMatchObject({ member, account: { username: 'alice' } })
+  })
+
+  it('游客没有账号', async () => {
+    const { profileStore } = await load()
+    await profileStore.registered({ username: 'alice' })
+    await profileStore.load()
+    expect(profileStore.state).toMatchObject({ member, account: null })
+  })
+
+  it('注册之后设置账号', async () => {
+    const { profileStore } = await load()
+    await profileStore.load()
+    await profileStore.registered({ username: 'alice' })
+    expect(profileStore.state).toMatchObject({ member, account: { username: 'alice' } })
+  })
+
+  it('身份被拒绝或更换之后没有账号', async () => {
+    const { profileStore, identityEvents } = await load()
+    profileStore.start()
+    await profileStore.registered({ username: 'alice' })
+    identityEvents.emit({ kind: 'rejected' })
+    expect(profileStore.state).toMatchObject({ member: null, account: null })
+
+    await profileStore.registered({ username: 'alice' })
+    identityEvents.emit({ kind: 'renewed', member: renewed })
+    expect(profileStore.state).toMatchObject({ member: renewed, account: null })
+  })
+})
+
+describe('邮箱', () => {
+  beforeEach(() => {
+    local.setItem(memberTokenKey, 'good')
+  })
+
+  it('已注册时取自账号，不读本机', async () => {
+    local.setItem(emailKey, 'local@example.com')
+    me = { member, account: { username: 'alice', email: 'Alice@Example.COM' } }
+    const { profileStore } = await load()
+    profileStore.start()
+    await profileStore.load()
+    expect(profileStore.state.email).toBe('Alice@Example.COM')
+
+    local.removeItem(emailKey)
+    me = { member, account: { username: 'alice' } }
+    await profileStore.load()
+    expect(profileStore.state.email).toBe('')
+  })
+
+  it('游客取自本机', async () => {
+    local.setItem(emailKey, 'guest@example.com')
+    const { profileStore } = await load()
+    profileStore.start()
+    await profileStore.load()
+    expect(profileStore.state.email).toBe('guest@example.com')
+  })
+
+  it('已注册时保存到账号，不写本机', async () => {
+    me = { member, account: { username: 'alice' } }
+    const { profileStore } = await load()
+    await profileStore.load()
+
+    expect(await profileStore.save({ email: ' Alice@Example.COM ' })).toBe(true)
+    expect(updates).toEqual([{ email: ' Alice@Example.COM ' }])
+    expect(profileStore.state).toMatchObject({ email: 'Alice@Example.COM', account: { username: 'alice', email: 'Alice@Example.COM' } })
+    expect(local.getItem(emailKey)).toBeNull()
+
+    expect(await profileStore.save({ email: '' })).toBe(true)
+    expect(profileStore.state.email).toBe('')
+    expect(profileStore.state.account).toEqual({ username: 'alice' })
+  })
+
+  it('游客保存到本机', async () => {
+    const { profileStore } = await load()
+    await profileStore.load()
+    expect(await profileStore.save({ email: 'guest@example.com' })).toBe(true)
+    expect(local.getItem(emailKey)).toBe('guest@example.com')
+    expect(profileStore.state.email).toBe('guest@example.com')
+  })
+
+  it('注册之后把本机的邮箱存进账号，并删除本机的副本', async () => {
+    local.setItem(emailKey, 'guest@example.com')
+    const { profileStore } = await load()
+    profileStore.start()
+    await profileStore.load()
+    await profileStore.registered({ username: 'alice' })
+
+    expect(updates).toEqual([{ email: 'guest@example.com' }])
+    expect(local.getItem(emailKey)).toBeNull()
+    expect(profileStore.state).toMatchObject({ email: 'guest@example.com', account: { username: 'alice', email: 'guest@example.com' } })
+  })
+
+  it('注册时本机没有邮箱就不发请求', async () => {
+    const { profileStore } = await load()
+    await profileStore.load()
+    await profileStore.registered({ username: 'alice' })
+    expect(updates).toEqual([])
+  })
+
+  it('注册时转存失败，本机的副本保留，下次加载时重试并删除副本', async () => {
+    local.setItem(emailKey, 'guest@example.com')
+    patchFails = true
+    const { profileStore } = await load()
+    profileStore.start()
+    await profileStore.registered({ username: 'alice' })
+    expect(local.getItem(emailKey)).toBe('guest@example.com')
+
+    patchFails = false
+    me = { member, account: { username: 'alice' } }
+    await profileStore.load()
+    expect(updates).toEqual([{ email: 'guest@example.com' }])
+    expect(local.getItem(emailKey)).toBeNull()
+    expect(profileStore.state).toMatchObject({ email: 'guest@example.com', account: { username: 'alice', email: 'guest@example.com' } })
+  })
+
+  it('服务端判定本机的邮箱不合格时删除副本，之后加载不再转存', async () => {
+    local.setItem(emailKey, 'legacy')
+    patchError = { status: 400, code: 'INVALID_ARGUMENT' }
+    me = { member, account: { username: 'alice' } }
+    const { profileStore } = await load()
+    await profileStore.load()
+    expect(local.getItem(emailKey)).toBeNull()
+    expect(updates).toEqual([{ email: 'legacy' }])
+
+    await profileStore.load()
+    expect(updates).toEqual([{ email: 'legacy' }])
+  })
+
+  it('重试仍失败时保留本机的副本，下次加载再试', async () => {
+    local.setItem(emailKey, 'guest@example.com')
+    patchFails = true
+    me = { member, account: { username: 'alice' } }
+    const { profileStore } = await load()
+    await profileStore.load()
+    expect(local.getItem(emailKey)).toBe('guest@example.com')
+
+    patchFails = false
+    await profileStore.load()
+    expect(local.getItem(emailKey)).toBeNull()
+    expect(updates).toEqual([{ email: 'guest@example.com' }])
+  })
+
+  it('已注册且本机没有副本，或账号已有邮箱时，加载不发更新请求', async () => {
+    me = { member, account: { username: 'alice' } }
+    const { profileStore } = await load()
+    await profileStore.load()
+
+    local.setItem(emailKey, 'guest@example.com')
+    me = { member, account: { username: 'alice', email: 'alice@example.com' } }
+    await profileStore.load()
+    expect(updates).toEqual([])
+  })
+
+  it('用户清空账号的邮箱时一并删除本机残留的副本，之后加载不再转存', async () => {
+    local.setItem(emailKey, 'guest@example.com')
+    me = { member, account: { username: 'alice', email: 'alice@example.com' } }
+    const { profileStore } = await load()
+    await profileStore.load()
+    expect(await profileStore.save({ email: '' })).toBe(true)
+    expect(local.getItem(emailKey)).toBeNull()
+
+    updates.length = 0
+    me = { member, account: { username: 'alice' } }
+    await profileStore.load()
+    expect(updates).toEqual([])
+  })
+})
diff --git a/web/src/features/settings/profile-store.ts b/web/src/features/settings/profile-store.ts
index 324773d..abfe525 100644
--- a/web/src/features/settings/profile-store.ts
+++ b/web/src/features/settings/profile-store.ts
@@ -1,23 +1,25 @@
 import type { IdentityEvent } from '@/core/api'
-import type { Member } from '@/core/realtime'
-import { api, identityEvents, IdentityRenewedError } from '@/core/api'
+import type { Account, Member } from '@/core/realtime'
+import { api, ApiError, deleteAllTickets, deleteMemberToken, followMemberTokenChanges, identityEvents, IdentityRenewedError, saveMemberToken } from '@/core/api'
 import { errorMessage } from '@/core/errors'
 import { Store } from '@/shared/lib/store'
 import { notificationStore } from '@/shared/ui'
 
-// 邮箱只保存在本机，用来在设置页回显；服务端只保存它的哈希。
+// 游客的邮箱只保存在本机，服务端只保存它的哈希；已注册账号的邮箱保存在账号里。
 const emailKey = 'alisten.email'
 
-class ProfileStore extends Store<{ member: Member | null, email: string, failed: boolean }> {
+class ProfileStore extends Store<{ member: Member | null, account: Account | null, email: string, failed: boolean }> {
   #loading: Promise<void> | null = null
 
   constructor() {
-    super({ member: null, email: '', failed: false })
+    super({ member: null, account: null, email: '', failed: false })
   }
 
   start(): void {
     this.setState({ email: localStorage.getItem(emailKey) ?? '' })
     identityEvents.on(this.#onIdentity)
+    // 其他标签页登录或退出之后，本标签页的资料、房间连接都属于旧身份，重新加载页面换成新身份。
+    followMemberTokenChanges(() => window.location.reload())
   }
 
   load(): Promise<void> {
@@ -27,26 +29,68 @@ class ProfileStore extends Store<{ member: Member | null, email: string, failed:
     return this.#loading
   }
 
+  // 本机已有的邮箱存进新账号，存失败只提示，不影响注册；本机的副本保留，下次加载时重试。
+  async registered(account: Account): Promise<void> {
+    this.setState({ account })
+    await this.#moveLocalEmail()
+  }
+
   // 返回 false 时，失败原因已经通过通知显示。
-  async save(changes: { name?: string, email?: string }): Promise<boolean> {
+  async logout(): Promise<boolean> {
     try {
-      const { member } = await api.updateMe(changes)
-      const email = changes.email ?? this.state.email
-      localStorage.setItem(emailKey, email)
-      this.setState({ member, email, failed: false })
-      return true
+      await api.logout()
+      switchIdentity(null)
     }
     catch (error) {
-      // 输入框限制了昵称和邮箱的长度，INVALID_ARGUMENT 只剩去掉首尾空白之后为空的昵称。
-      notificationStore.error(error instanceof IdentityRenewedError ? '个人资料没有保存，再保存一次。' : errorMessage(error, { INVALID_ARGUMENT: '昵称不能为空，也不能只有空格。' }))
+      // 账号在这台设备上的会话已经失效，客户端也已经换成新的游客，退出登录的目的已经达到。
+      if (error instanceof IdentityRenewedError) {
+        window.location.reload()
+        return true
+      }
+      notificationStore.error(errorMessage(error))
       return false
     }
+    return true
+  }
+
+  // 返回 false 时，失败原因已经通过通知显示。
+  async save(changes: { name?: string, email?: string }): Promise<boolean> {
+    return await this.#update(changes) === null
+  }
+
+  // 失败时返回错误，失败原因已经通过通知显示。
+  async #update(changes: { name?: string, email?: string }): Promise<unknown> {
+    try {
+      const { member } = await api.updateMe(changes)
+      const { account } = this.state
+      if (account) {
+        const email = changes.email?.trim() ?? this.state.email
+        // 用户对账号邮箱的修改是最终决定，本机残留的副本不能再覆盖它。
+        if (changes.email !== undefined)
+          localStorage.removeItem(emailKey)
+        this.setState({ member, email, account: { username: account.username, ...(email && { email }) }, failed: false })
+      }
+      else {
+        const email = changes.email ?? this.state.email
+        localStorage.setItem(emailKey, email)
+        this.setState({ member, email, failed: false })
+      }
+      return null
+    }
+    catch (error) {
+      // 客户端不能按服务端的 message 区分是哪个字段不合格。
+      notificationStore.error(error instanceof IdentityRenewedError ? '个人资料没有保存，再保存一次。' : errorMessage(error, { INVALID_ARGUMENT: '昵称不能为空；邮箱要写成 name@example.com 这样的格式。' }))
+      return error
+    }
   }
 
   async #load(): Promise<void> {
     this.setState({ failed: false })
     try {
-      this.setState({ member: (await api.getMe()).member, failed: false })
+      const { member, account } = await api.getMe()
+      this.setState({ member, account: account ?? null, email: account ? account.email ?? '' : localStorage.getItem(emailKey) ?? '', failed: false })
+      if (account && !account.email)
+        await this.#moveLocalEmail()
     }
     catch (error) {
       // 成员 token 被拒绝时身份已经更换，新的成员由身份事件设置。
@@ -57,15 +101,25 @@ class ProfileStore extends Store<{ member: Member | null, email: string, failed:
     }
   }
 
+  async #moveLocalEmail(): Promise<void> {
+    const email = localStorage.getItem(emailKey)
+    if (!email)
+      return
+    const error = await this.#update({ email })
+    // 服务端不接受的副本重试也不会成功，删掉免得每次加载都报错；其他错误（网络、服务端故障）留到下次再试。
+    if (error instanceof ApiError && error.code === 'INVALID_ARGUMENT')
+      localStorage.removeItem(emailKey)
+  }
+
   #onIdentity = (event: IdentityEvent): void => {
     switch (event.kind) {
       case 'rejected':
         // 本机保存的邮箱属于原来的身份。
         localStorage.removeItem(emailKey)
-        this.setState({ member: null, email: '', failed: false })
+        this.setState({ member: null, account: null, email: '', failed: false })
         return
       case 'renewed':
-        this.setState({ member: event.member, failed: false })
+        this.setState({ member: event.member, account: null, failed: false })
         notificationStore.info('原来的身份已经失效，已为你换了一个新的身份。', 8000)
         return
       case 'renewalFailed':
@@ -76,3 +130,14 @@ class ProfileStore extends Store<{ member: Member | null, email: string, failed:
 }
 
 export const profileStore = new ProfileStore()
+
+// 换了身份之后，进房票据和本机保存的邮箱都属于原来的身份，一并清除；重新加载页面，让房间连接和各处的状态都从新身份开始。
+export function switchIdentity(token: string | null): void {
+  if (token === null)
+    deleteMemberToken()
+  else
+    saveMemberToken(token)
+  deleteAllTickets()
+  localStorage.removeItem(emailKey)
+  window.location.reload()
+}
diff --git a/web/src/features/settings/settings-page.tsx b/web/src/features/settings/settings-page.tsx
index ac84d20..178d506 100644
--- a/web/src/features/settings/settings-page.tsx
+++ b/web/src/features/settings/settings-page.tsx
@@ -7,6 +7,7 @@ import { historyStore, searchLimits } from '@/features/history'
 import { reminderStore, requestNotificationPermission, systemNotificationsSupported, volumeStore } from '@/features/playback'
 import { useStore } from '@/shared/lib/use-store'
 import { notificationStore, Select } from '@/shared/ui'
+import { AccountRow } from './account-section'
 import { appearanceStore, fontSizes, themes } from './appearance-store'
 import { performanceLevels, performanceStore } from './performance-store'
 import { profileStore } from './profile-store'
@@ -68,6 +69,7 @@ export function SettingsPage() {
   const headingRef = useRef<HTMLHeadingElement>(null)
   const member = useStore(profileStore, s => s.member)
   const email = useStore(profileStore, s => s.email)
+  const account = useStore(profileStore, s => s.account)
   const profileFailed = useStore(profileStore, s => s.failed)
   const theme = useStore(appearanceStore, s => s.theme)
   const fontSize = useStore(appearanceStore, s => s.fontSize)
@@ -177,15 +179,16 @@ export function SettingsPage() {
         <div className="settings-page-body">
           <fieldset className="settings-fields" disabled={saving}>
             <div className="settings-content">
-              <section className="settings-section" aria-labelledby="settings-profile-title">
-                <h2 id="settings-profile-title" className="text-ui-lg">个人资料</h2>
+              <section className="settings-section" aria-labelledby="settings-account-title">
+                <h2 id="settings-account-title" className="text-ui-lg">账号</h2>
                 <div className="settings-group">
+                  <AccountRow />
                   <SettingRow id="settings-name" title="昵称" description={member ? '房间里的其他人看到的名字。' : profileFailed ? '暂时无法获取你的资料。' : '正在获取你的资料…'} field>
                     {!member && profileFailed
                       ? <button type="button" className="button-secondary" aria-describedby="settings-name-description" onClick={loadProfile}>重试</button>
                       : <input id="settings-name" aria-describedby="settings-name-description" value={draft.name} onChange={event => update('name', event.target.value)} disabled={!member} required maxLength={80} autoComplete="nickname" />}
                   </SettingRow>
-                  <SettingRow id="settings-email" title="邮箱" description="只用来显示 Gravatar 头像，访问不到 Gravatar 时改用镜像 WeAvatar 或 Cravatar；服务器不会保存邮箱地址，留空就不显示头像。" field>
+                  <SettingRow id="settings-email" title="邮箱" description={account ? '保存在账号里，用来显示头像。留空就不显示。' : '只保存在这台设备上，用来显示头像。留空就不显示。'} field>
                     <input id="settings-email" aria-describedby="settings-email-description" type="email" value={draft.email} onChange={event => update('email', event.target.value)} disabled={!member} maxLength={320} autoComplete="email" placeholder="name@example.com" />
                   </SettingRow>
                 </div>
diff --git a/web/src/features/settings/settings.css b/web/src/features/settings/settings.css
index d12db87..e811fb6 100644
--- a/web/src/features/settings/settings.css
+++ b/web/src/features/settings/settings.css
@@ -33,6 +33,7 @@
 .settings-page-footer { display: flex; align-items: center; justify-content: flex-end; gap: 20px; flex-shrink: 0; width: 100%; max-width: 1120px; margin: 0 auto; padding: 16px 40px 24px; }
 .settings-save-status { flex: 1; min-width: 0; overflow-wrap: anywhere; }
 .settings-page-footer .button-primary { min-width: 96px; }
+.settings-account-actions { flex-wrap: wrap; gap: 8px; }
 @container settings (max-width: 640px) {
   .settings-page-header { padding: 20px 20px 16px; }
   .settings-page-body { padding: 12px 16px 32px; }