feat(账号): 新建的号不再加 ks + 班号前缀，班级单独选；学生改不了真名了

- 批量建号先选班再贴名单，用户名就是名字；被别的班或注册的号占了自动加数字（xuyue2）。
  查重改成查「这个班里有没有同名的」，老号按剥掉 ks 前缀的名字比
- 后台编辑、新建用户能直接选班级；以前班级只能从用户名的 ks 前缀推，改不了
- 登录点名字时名单接口一并给出用户名，新号老号都登得上；本机记的班级兼容旧的 ks257 写法
- 筛选、抽人、「看看他们的写法」都按班级认人，不再拼 ks 前缀（新号拼出来永远圈不进去）
- 接口 PUT /me/profile 不再收真名：界面早没入口，但早几届有 44 人把真名改成了外号
- 0042：两个被推成非班号班级的老号（xrm、王仁杰）改成没填班级
- 老账号不改名，只认 ks 前缀的地方收在契约 username.ts 一处

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/admin/api.ts

@@ -103,6 +103,7 @@ export function getBaseInfo() {
   return api.get<DashboardInfo>('admin/dashboard')
 }
 
+/** 后台首页「抽一个人」：从这个班（班号）随机拿 10 个显示用的名字 */
 export function randomUser10(classroom: string) {
   return api.get<string[]>('admin/random-usernames', {
     params: { classroom },
@@ -245,9 +246,11 @@ export function getUserList(
 }
 
 /** 批量建号之前查重：这些用户名哪些已经有了 */
-export function checkUsernames(usernames: string[]) {
+/** 批量建号查重：这个班里已经有的同名账号，和每个名字会建成的用户名 */
+export function checkUsernames(className: string, names: string[]) {
   return api.post<CheckUsernamesResponse>('admin/users/check', {
-    usernames,
+    className,
+    names,
   } satisfies CheckUsernamesRequest)
 }
 
@@ -260,6 +263,7 @@ export function editUser(user: AdminUserForm) {
     adminType: toAdminType(user.adminType),
     problemPermission: toProblemPermission(user.problemPermission),
     realName: user.realName ?? null,
+    className: user.className ?? null,
     isDisabled: user.isDisabled,
     password: user.password ?? '',
   } satisfies UpdateUserRequest)

apps/web/src/admin/home/index.vue

@@ -118,8 +118,8 @@ function stopRolling() {
 /** 名字滚两秒停下：接口一次给 10 个随机的，最后一个就是抽中的 */
 async function draw() {
   if (!luckyClass.value) return
-  const prefix = `ks${luckyClass.value}`
-  const names = (await randomUser10(prefix)).map((name) => name.slice(prefix.length) || name)
+  // 后端按班级随机拿 10 个，回的就是显示的名字（老号已经剥掉 ks 前缀）
+  const names = await randomUser10(luckyClass.value)
   if (!names.length) {
     luckyGuy.value = '这个班没有人'
     return

apps/web/src/admin/user/generate.vue

@@ -34,7 +34,8 @@ const classError = computed(() => {
   }
   return ''
 })
-const prefix = computed(() => (classNo.value.trim() ? `ks${classNo.value.trim()}` : ''))
+/** 填好了、格式也对的班号；没填或填错是空串 */
+const klass = computed(() => (classNo.value.trim() && !classError.value ? classNo.value.trim() : ''))
 
 /** 名单：一行一个，前后和中间的空格都去掉（从表格里复制常带空格），空行不算 */
 const names = computed(() =>
@@ -56,11 +57,16 @@ function passwordOf(name: string) {
   return value
 }
 
+/**
+ * 用户名就是名字（2026-11 起不再加 ks + 班号）。名字被别的班、注册的号占了，后端给的是加了数字的（杨涵宇2）；
+ * 查重还没回来之前先按名字摆着
+ */
+const suggested = ref<Map<string, string>>(new Map())
 const rows = computed(() =>
   names.value.map((name) => ({
     name,
-    username: prefix.value + name,
-    password: passwordOf(prefix.value + name),
+    username: suggested.value.get(name) ?? name,
+    password: passwordOf(name),
   })),
 )
 
@@ -69,7 +75,7 @@ const duplicates = computed(() => {
   const first = new Map<string, number>()
   const result: { line: number; firstLine: number; name: string }[] = []
   rows.value.forEach((row, i) => {
-    const key = row.username.toLowerCase()
+    const key = row.name.toLowerCase()
     const seen = first.get(key)
     if (seen === undefined) first.set(key, i + 1)
     else result.push({ line: i + 1, firstLine: seen, name: row.name })
@@ -77,22 +83,26 @@ const duplicates = computed(() => {
   return result
 })
 
-// 已经有的账号：停手半秒再去查
-const existing = ref<{ username: string; createTime: string | null }[]>([])
+// 这个班已经有的同名账号（老号按剥掉 ks 前缀的名字比），顺带拿回每个名字会建成的用户名：停手半秒再去查
+const existing = ref<{ name: string; username: string; createTime: string | null }[]>([])
 const checking = ref(false)
 watchDebounced(
-  () => rows.value.map((row) => row.username).join('\n'),
+  () => `${klass.value}\n${names.value.join('\n')}`,
   async () => {
-    const usernames = [...new Set(rows.value.map((row) => row.username))]
-    if (!usernames.length || classError.value || usernames.length > 500) {
+    const list = [...new Set(names.value)]
+    if (!list.length || !klass.value || list.length > 500) {
       existing.value = []
+      suggested.value = new Map()
       return
     }
     checking.value = true
     try {
-      existing.value = (await checkUsernames(usernames)).existing
+      const res = await checkUsernames(klass.value, list)
+      existing.value = res.existing
+      suggested.value = new Map(list.map((name, i) => [name, res.usernames[i] ?? name]))
     } catch {
       existing.value = []
+      suggested.value = new Map()
     } finally {
       checking.value = false
     }
@@ -102,7 +112,7 @@ watchDebounced(
 
 const tooMany = computed(() => rows.value.length > 500)
 const issueCount = computed(() => (classError.value ? 1 : 0) + duplicates.value.length + existing.value.length + (tooMany.value ? 1 : 0))
-const canSubmit = computed(() => rows.value.length > 0 && !issueCount.value && !checking.value && !!prefix.value)
+const canSubmit = computed(() => rows.value.length > 0 && !issueCount.value && !checking.value && !!klass.value)
 
 // ---------------------------------------------------------------- 建号
 
@@ -118,8 +128,9 @@ async function submit() {
   const payload: ImportUsersRequest['users'] = rows.value.map((row, i) => [
     row.username,
     row.password,
-    `${prefix.value || 'user'}.${batch}.${i + 1}@example.com`,
+    `c${klass.value}.${batch}.${i + 1}@example.com`,
     row.name,
+    klass.value,
   ])
   saving.value = true
   try {
@@ -142,7 +153,7 @@ function again() {
 
 function download() {
   if (!done.value) return
-  downloadAccountsCsv(done.value, prefix.value || '账号')
+  downloadAccountsCsv(done.value, klass.value ? classLabel(klass.value) : '账号')
 }
 
 /** 打印账号条：一人一张，一页四列，打出来剪开发下去 */
@@ -196,7 +207,6 @@ body{margin:12mm;font-family:"Microsoft YaHei","PingFang SC",sans-serif}
     <div class="left">
       <label class="label" for="class-no">班级号</label>
       <div class="class-row">
-        <span class="ks">ks</span>
         <n-input v-model:value="classNo" :input-props="{ id: 'class-no', inputmode: 'numeric' }" placeholder="如 2612" style="width: 120px" />
         <span v-if="classNo.trim() && !classError" class="class-name">
           {{ classLabel(classNo.trim()) }}
@@ -210,7 +220,7 @@ body{margin:12mm;font-family:"Microsoft YaHei","PingFang SC",sans-serif}
       <template v-if="rows.length">
         <div class="head">
           <b>会建这 {{ rows.length }} 个账号</b>
-          <n-tag v-if="!issueCount && !checking && prefix" type="success" :bordered="false" round> 没有重名 </n-tag>
+          <n-tag v-if="!issueCount && !checking && klass" type="success" :bordered="false" round> 没有重名 </n-tag>
           <n-tag v-if="issueCount" type="warning" :bordered="false" round> 有 {{ issueCount }} 处要先改 </n-tag>
         </div>
 
@@ -221,7 +231,7 @@ body{margin:12mm;font-family:"Microsoft YaHei","PingFang SC",sans-serif}
             第 {{ dup.line }} 行「{{ dup.name }}」和第 {{ dup.firstLine }} 行重名 —— 同班同名的，名字后面加个 1、2 区分
           </div>
           <div v-for="it in existing" :key="it.username">
-            {{ it.username }} 已经有这个账号了<template v-if="it.createTime">（{{ parseTime(it.createTime, 'YYYY-MM-DD') }} 建的）</template>
+            {{ classLabel(klass) }}已经有「{{ it.name }}」了<template v-if="it.createTime">（{{ parseTime(it.createTime, 'YYYY-MM-DD') }} 建的）</template>
             —— 删掉这一行，或者换个名字
           </div>
         </div>
@@ -249,7 +259,7 @@ body{margin:12mm;font-family:"Microsoft YaHei","PingFang SC",sans-serif}
           <n-button type="primary" size="large" :disabled="!canSubmit" :loading="saving || checking" @click="submit">
             建好这 {{ rows.length }} 个账号
           </n-button>
-          <n-text v-if="!prefix" depth="3" class="hint" style="margin-left: 12px"> 先填班级号 </n-text>
+          <n-text v-if="!klass" depth="3" class="hint" style="margin-left: 12px"> 先填班级号 </n-text>
         </div>
       </template>
       <n-empty v-else :description="`${isMobile ? '上面' : '左边'}粘进名单，这里就列出会建成的账号`" :style="{ marginTop: isMobile ? '24px' : '80px' }" />
@@ -288,11 +298,6 @@ body{margin:12mm;font-family:"Microsoft YaHei","PingFang SC",sans-serif}
   gap: 8px;
 }
 
-.ks {
-  font-size: 18px;
-  opacity: 0.6;
-}
-
 .class-name {
   font-size: 15px;
 }

apps/web/src/admin/user/list.vue

@@ -50,6 +50,10 @@ const classOptions = computed(() => [
   ...groupClassOptions(configStore.config?.classList ?? []),
   { label: classLabel(NO_CLASS), value: NO_CLASS },
 ])
+/** 编辑框的班级：配置里的班，外加这个人现在的班（老班不在配置里也要显示得出来） */
+const editClassOptions = computed(() =>
+  groupClassOptions([...(configStore.config?.classList ?? []), ...(userEditing.value?.className ? [userEditing.value.className] : [])]),
+)
 const neverLoggedIn = ref(0)
 
 const total = ref(0)
@@ -314,7 +318,7 @@ async function handleEditUser() {
   try {
     if (create.value) {
       const newUser: ImportUsersRequest['users'] = [
-        [userEditing.value.username, password.value, userEditing.value.email ?? '', userEditing.value.realName ?? ''],
+        [userEditing.value.username, password.value, userEditing.value.email ?? '', userEditing.value.realName ?? '', userEditing.value.className],
       ]
       await importUsers(newUser)
       listUsers()
@@ -388,10 +392,9 @@ watch(() => [query.page, query.limit, query.type, query.orderBy, query.className
         <n-form-item-gi :span="1" label="真名">
           <n-input v-model:value="userEditing.realName" />
         </n-form-item-gi>
-        <!-- 班级是后端从用户名的 ks 数字前缀推出来的（classNameOf），
-             editUser 也不发这个字段，所以这里只读 —— 以前是个能改、改了没用的输入框 -->
-        <n-form-item-gi v-if="!create" :span="1" label="班级">
-          <n-input :value="userEditing.className" disabled placeholder="由用户名自动推导" />
+        <!-- 班级单独存一列，2026-11 起不再从用户名的 ks 前缀推（新号不带前缀）。老师、管理员不填 -->
+        <n-form-item-gi :span="1" label="班级">
+          <n-select v-model:value="userEditing.className" :options="editClassOptions" filterable clearable placeholder="没填班级" />
         </n-form-item-gi>
         <n-form-item-gi :span="1" label="邮箱">
           <n-input v-model:value="userEditing.email" />

apps/web/src/oj/api.ts

@@ -179,7 +179,7 @@ export function getSubmissionStatistics(
   duration: { start?: string; end: string },
   problemDisplayId?: string,
   username?: string,
-  /** 班级（user.class_name）精确匹配。别再拼 `ks231` 塞进 username —— 会连带 2311、2312 班 */
+  /** 班级（user.class_name）精确匹配。别拿用户名前缀当班级 —— 新号不带 ks 前缀，老号 `ks231` 还会连带 2311、2312 班 */
   className?: string,
 ) {
   return api.get<SubmissionStatistics>('submissions/statistics', {
@@ -346,7 +346,7 @@ export function uploadAvatar(file: File) {
   return api.post('me/avatar', form)
 }
 
-export function updateProfile(data: { realName?: string; mood?: string }) {
+export function updateProfile(data: { mood?: string }) {
   return api.put<Profile>('me/profile', data satisfies UpdateProfileRequest)
 }
 

apps/web/src/oj/problem/components/ProblemSubmission.vue

@@ -62,7 +62,7 @@ const rankLine = computed(() => {
   return null
 })
 
-/** 「看看他们的写法」：同班的走 'ks' + 班级名的用户名前缀约定（设计文档第 13 节） */
+/** 「看看他们的写法」：同班的按班级（class_name）筛，全站的不筛 */
 function goAccepted() {
   const r = rank.value
   if (!r) return
@@ -73,7 +73,7 @@ function goAccepted() {
       result: '0',
       page: 1,
       limit: 10,
-      ...(r.className ? { username: 'ks' + r.className } : {}),
+      ...(r.className ? { className: r.className } : {}),
     },
   }
   // 协作中跳走这一页协作就断了

apps/web/src/oj/rank/list.vue

@@ -8,7 +8,8 @@ import { useBreakpoints } from 'shared/composables/breakpoints'
 import { useConfigStore } from 'shared/store/config'
 import { useUserStore } from 'shared/store/user'
 import { errorCode } from 'utils/api'
-import { STORAGE_KEY, USERNAME_CLASS_RE } from 'utils/constants'
+import { displayName } from '@oj2/contract'
+import { STORAGE_KEY } from 'utils/constants'
 import storage from 'utils/storage'
 import ChampionList from './components/ChampionList.vue'
 import ClassBattle from './components/ClassBattle.vue'
@@ -236,7 +237,7 @@ const daysLeft = computed(() => {
 const trendLines = computed(() => {
   const b = board.value
   if (!b?.me) return []
-  const short = (row: RankRow) => row.user.username.replace(USERNAME_CLASS_RE, '') || row.user.username
+  const short = (row: RankRow) => displayName(row.user.username)
   return [
     ...(b.behind ? [{ userId: b.behind.user.id, label: short(b.behind), color: palette.value.threat }] : []),
     ...(b.ahead ? [{ userId: b.ahead.user.id, label: short(b.ahead), color: palette.value.chase }] : []),

apps/web/src/shared/api.ts

@@ -1,5 +1,5 @@
 import type { AuthTokens, LoginRequest, RefreshTokenRequest, RegisterRequest } from '@oj2/contract'
-import type { ClassActivity, MarkAchievementsRead, ProblemAuthor, ProblemList, Quote, WebsiteConfig } from '@oj2/contract'
+import type { ClassActivity, ClassMember, MarkAchievementsRead, ProblemAuthor, ProblemList, Quote, WebsiteConfig } from '@oj2/contract'
 import api from 'utils/api'
 import { getRefreshToken, saveTokens } from 'utils/auth'
 import { contractDeferred } from 'utils/contract'
@@ -42,8 +42,9 @@ export function getHitokoto() {
   return api.get<Quote>('quotes/random')
 }
 
-export function getClassUsernames(classroom: string) {
-  return api.get<string[]>(`classes/${encodeURIComponent(classroom)}/usernames`)
+/** 登录框点名字的名单：名字给人点，用户名拿去登录（老号 ks232张三，新号就是名字） */
+export function getClassUsernames(className: string) {
+  return api.get<ClassMember[]>(`classes/${encodeURIComponent(className)}/usernames`)
 }
 
 // 下面这个是启动就要调的（config store），所以放在 shared 而不是

apps/web/src/shared/components/Login.vue

@@ -2,7 +2,8 @@
 import { Icon } from '@iconify/vue'
 import { useThemeVars } from 'naive-ui'
 import RankAvatar from 'shared/components/RankAvatar.vue'
-import { classLabel, groupClassOptions } from 'utils/classes'
+import type { ClassMember } from '@oj2/contract'
+import { groupClassOptions } from 'utils/classes'
 import { errorCode } from 'utils/api'
 import { STORAGE_KEY } from 'utils/constants'
 import storage from 'utils/storage'
@@ -46,12 +47,13 @@ const themeVars = computed(() => ({
 }))
 
 const mode = ref<Mode>('pick')
-/** 选中的班，带 ks 前缀（`ks257`），和用户名的前缀同一个写法 */
+/** 选中的班（班号，`257`） */
 const klass = ref<string | null>(null)
-const names = ref<string[]>([])
+const names = ref<ClassMember[]>([])
 const namesLoading = ref(false)
 const query = ref('')
-const picked = ref<string | null>(null)
+/** 点中的人：名字给人看，用户名拿去登录（老号 ks257张三，新号就是名字） */
+const picked = ref<ClassMember | null>(null)
 const username = ref('')
 const password = ref('')
 const loading = ref(false)
@@ -63,13 +65,8 @@ const searchRef = useTemplateRef('searchRef')
 const passwordRef = useTemplateRef('passwordRef')
 const usernameRef = useTemplateRef('usernameRef')
 
-const knownClasses = computed(() => (configStore.config?.classList ?? []).map((c) => `ks${c}`))
-const classOptions = computed(() =>
-  groupClassOptions(configStore.config?.classList ?? [], (item) => ({
-    label: classLabel(item),
-    value: `ks${item}`,
-  })),
-)
+const knownClasses = computed(() => configStore.config?.classList ?? [])
+const classOptions = computed(() => groupClassOptions(knownClasses.value))
 /** 还没选过班的电脑：名单的位置先摆一排排班级 */
 const classGroups = computed(() => classOptions.value.flatMap((option) => ('children' in option ? [{ label: option.label, items: option.children }] : [])))
 
@@ -96,16 +93,16 @@ function matches(name: string, keyword: string) {
 const collator = new Intl.Collator('zh-CN')
 const shown = computed(() => {
   const keyword = query.value.trim()
-  return keyword ? names.value.filter((name) => matches(name, keyword)) : names.value
+  return keyword ? names.value.filter((member) => matches(member.name, keyword)) : names.value
 })
 
 async function loadNames(value: string) {
   namesLoading.value = true
   names.value = []
   try {
-    const list = await getClassUsernames(value.slice(2))
+    const list = await getClassUsernames(value)
     // 切班的请求比上一个先回来时，别让旧班的名单盖上来
-    if (klass.value === value) names.value = [...list].sort(collator.compare)
+    if (klass.value === value) names.value = [...list].sort((a, b) => collator.compare(a.name, b.name))
   } catch {
     if (klass.value === value) names.value = []
   } finally {
@@ -142,8 +139,8 @@ function focusSearch() {
   if (!touchScreen.value) focusLater(() => searchRef.value)
 }
 
-function pick(name: string) {
-  picked.value = name
+function pick(member: ClassMember) {
+  picked.value = member
   password.value = ''
   clearError()
   focusLater(() => passwordRef.value)
@@ -178,7 +175,7 @@ function goSignup() {
 
 async function submit() {
   if (loading.value || locked.value) return
-  const name = mode.value === 'pick' ? `${klass.value ?? ''}${picked.value ?? ''}` : username.value.trim()
+  const name = mode.value === 'pick' ? (picked.value?.username ?? '') : username.value.trim()
   if (mode.value === 'user' && !name) {
     error.value = '写上用户名'
     focusLater(() => usernameRef.value)
@@ -227,8 +224,10 @@ async function submit() {
 function restoreLast() {
   const lastMode = storage.get(STORAGE_KEY.LOGIN_MODE)
   mode.value = lastMode === 'user' ? 'user' : 'pick'
-  const last = storage.get(STORAGE_KEY.LOGIN_CLASS)
-  if (typeof last === 'string' && knownClasses.value.includes(last)) {
+  // 2026-11 之前存的是带 ks 前缀的（ks257），读的时候剥掉
+  const stored = storage.get(STORAGE_KEY.LOGIN_CLASS)
+  const last = typeof stored === 'string' ? stored.replace(/^ks/i, '') : null
+  if (last && knownClasses.value.includes(last)) {
     if (klass.value === last) {
       // 同一个班：名单留着，只把上一个人的痕迹清掉
       picked.value = null
@@ -284,8 +283,8 @@ watch(
       <template v-if="mode === 'pick'">
         <!-- 点了名字：名单换成这个人，光标直接在密码框 -->
         <div v-if="picked" class="me">
-          <RankAvatar :username="`${klass}${picked}`" :avatar="null" :size="64" />
-          <div class="me-name"><UserName :username="`${klass}${picked}`" /></div>
+          <RankAvatar :username="picked.username" :avatar="null" :size="64" />
+          <div class="me-name"><UserName :username="picked.username" /></div>
           <div class="field narrow">
             <n-input
               ref="passwordRef"
@@ -322,8 +321,8 @@ watch(
             <div v-else-if="!names.length" class="empty">这个班还没有名单</div>
             <div v-else-if="!shown.length" class="empty">没有叫这个的</div>
             <div v-else class="grid">
-              <button v-for="name in shown" :key="name" class="cell" type="button" @click="pick(name)">
-                {{ name }}
+              <button v-for="member in shown" :key="member.username" class="cell" type="button" @click="pick(member)">
+                {{ member.name }}
               </button>
             </div>
           </div>

apps/web/src/shared/components/RankAvatar.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { useDark } from '@vueuse/core'
 import { rgba } from 'shared/composables/tone'
-import { USERNAME_CLASS_RE } from 'utils/constants'
+import { displayName } from '@oj2/contract'
 
 /**
  * 排名页的头像。九成以上的学生没换过头像（1797 个号是 default.png），一排一模一样的
@@ -26,7 +26,7 @@ watch(
 const PALETTE = ['#2f6fd0', '#c76a12', '#6a4bd8', '#0f7a6c', '#b4315f', '#4d5967', '#8a6a00']
 
 const letter = computed(() => {
-  const name = props.username.replace(USERNAME_CLASS_RE, '') || props.username
+  const name = displayName(props.username)
   return Array.from(name).at(-1) ?? '?'
 })
 

apps/web/src/shared/components/UserName.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
 import { useThemeVars } from 'naive-ui'
-import { USERNAME_CLASS_RE } from 'utils/constants'
+import { LEGACY_CLASS_PREFIX_RE } from '@oj2/contract'
 
 /**
  * 用户名：班级前缀（`ks253`）淡一档，名字加粗 —— 一个班的人前缀都一样，
@@ -11,7 +11,7 @@ const props = defineProps<{ username: string; muted?: boolean }>()
 const theme = useThemeVars()
 
 const parts = computed(() => {
-  const match = props.username.match(USERNAME_CLASS_RE)
+  const match = props.username.match(LEGACY_CLASS_PREFIX_RE)
   if (!match) return { prefix: '', name: props.username }
   return { prefix: match[0], name: props.username.slice(match[0].length) || match[0] }
 })

apps/web/src/utils/constants.ts

@@ -1,4 +1,4 @@
-import type { JudgeStatusValue } from '@oj2/contract'
+import { CLASS_NAME_MAX_DIGITS, CLASS_NAME_MIN_DIGITS, type JudgeStatusValue } from '@oj2/contract'
 import type { AchievementRarity, SUBMISSION_RESULT, ReactionKey } from './types'
 
 // 与后端 judge/status.ts 的 JudgeStatus 逐条对齐（submitting 除外，见下）。
@@ -308,18 +308,8 @@ export function sortFlowchartCriteria<T>(details: Record<string, T>): [string, T
   return Object.entries(details).sort(([a], [b]) => rank(a) - rank(b))
 }
 
-// 班级号的位数范围。学生用户名形如 ks<班级号><姓名>，班级号还要跟
-// 网站配置里的班级列表对得上。
-// 后端 OnlineJudge/utils/shortcuts.py 的 CLASS_NAME_MIN/MAX_DIGITS
-// 是同一条规则的另一份，改这里必须同时改那边。
-export const CLASS_NAME_MIN_DIGITS = 3
-export const CLASS_NAME_MAX_DIGITS = 4
-
-/** 合法班级号：3~4 位纯数字 */
-export const CLASS_NAME_RE = new RegExp(`^\\d{${CLASS_NAME_MIN_DIGITS},${CLASS_NAME_MAX_DIGITS}}$`)
-
-/** 用户名开头的 ks<班级号>，用于从用户名里认出班级 */
-export const USERNAME_CLASS_RE = new RegExp(`^ks\\d{${CLASS_NAME_MIN_DIGITS},${CLASS_NAME_MAX_DIGITS}}`)
+// 班级号的位数和格式只有契约里一份（packages/contract/src/username.ts），这里转出去给旧的引用处用
+export { CLASS_NAME_MAX_DIGITS, CLASS_NAME_MIN_DIGITS, CLASS_NAME_RE } from '@oj2/contract'
 
 /** 班级号作为数字时的上下界，给 n-input-number 用 */
 export const CLASS_NAME_MIN_VALUE = 10 ** (CLASS_NAME_MIN_DIGITS - 1)