diff --git a/apps/web/CLAUDE.md b/apps/web/CLAUDE.md
index 48bb69e..8db7a27 100644
--- a/apps/web/CLAUDE.md
+++ b/apps/web/CLAUDE.md
@@ -58,7 +58,7 @@ API 调用不按模块分：学生端全在 `oj/api.ts`、后台全在 `admin/ap
 跨端的（登录、资料、标签、验证码）在 `shared/api.ts`。
 
 Shared logic lives in `shared/`:
-- `store/` — Pinia stores: `user` (auth/roles), `config` (site-wide settings), `authModal` (login/signup form state), `collab` (help-request queue + collab room), `achievement` (解锁弹窗队列), `myFlowchart` (题面「你画的流程图」那张 A/S 图的 mermaid 源码)
+- `store/` — Pinia stores: `user` (auth/roles), `config` (site-wide settings), `authModal` (登录框、注册框开没开), `collab` (help-request queue + collab room), `achievement` (解锁弹窗队列), `myFlowchart` (题面「你画的流程图」那张 A/S 图的 mermaid 源码)
 - `composables/` — `aiStream`, `pagination` (URL-synced), `websocket` (reconnect + heartbeat), `collabDoc` (Yjs binding for the collab channel), `configUpdate` (WS-pushed config sync), `useMermaid` (lazy Mermaid render), `darkTransition` (View Transitions，111 以下走降级分支), `leaveStudents` (课堂看板的「请假」), `problemJump` (按题号直达), `teacherHelp` (老师接单 / 打开学生编辑器), `chartTheme`, `breakpoints`, `rarity`
 - `layout/` — `default.vue` and `admin.vue` layout wrappers
 - `api.ts` — shared API calls (auth, profile, tags, captcha)
diff --git a/apps/web/src/shared/components/Login.vue b/apps/web/src/shared/components/Login.vue
index 97549df..03f5df5 100644
--- a/apps/web/src/shared/components/Login.vue
+++ b/apps/web/src/shared/components/Login.vue
@@ -1,34 +1,83 @@
 <script setup lang="ts">
+import { Icon } from "@iconify/vue"
+import { useThemeVars } from "naive-ui"
+import RankAvatar from "oj/rank/components/RankAvatar.vue"
 import { classLabel, groupClassOptions } from "oj/submission/utils"
 import { errorCode } from "utils/api"
 import { STORAGE_KEY } from "utils/constants"
 import storage from "utils/storage"
 import { getClassUsernames, login } from "../api"
-import { storeToRefs } from "pinia"
 import { useAuthModalStore } from "../store/authModal"
+import UserName from "./UserName.vue"
 import { useConfigStore } from "../store/config"
 import { useUserStore } from "../store/user"
 
+/**
+ * 登录框两种样子：
+ *
+ * - **点名字**（默认）：班级记在这台电脑上，一打开就是这个班的名单，点自己的名字再输密码。
+ *   机房一台电脑对一个班，学生一个字都不用打。
+ * - **写用户名**：老师、往届（班级已经从后台配置里删掉的）、自己注册的。9 月以来约一成的
+ *   登录走这条，所以入口「名单里没有我」「老师登录」一直摆在名单底下。
+ *
+ * 这台电脑上次用哪种登上的，下次就先开哪种 —— 老师的电脑不用每次都切。
+ */
+type Mode = "pick" | "user"
+
 const userStore = useUserStore()
 const configStore = useConfigStore()
 const authStore = useAuthModalStore()
+const { loginModalOpen } = storeToRefs(authStore)
+const theme = useThemeVars()
 
-const {
-  loginModalOpen,
-  loginForm: form,
-  loginLoading: isLoading,
-  loginError: msg,
-} = storeToRefs(authStore)
+// n-modal 把内容传送到 body 底下，CSS 的 v-bind() 挂不上去（变量挂在组件根上，
+// 这个组件的根是 n-modal 自己）—— 颜色直接写到弹框根节点的 style 里
+const themeVars = computed(() => ({
+  "--t-border-color": theme.value.borderColor,
+  "--t-box-shadow-3": theme.value.boxShadow3,
+  "--t-error-color": theme.value.errorColor,
+  "--t-hover-color": theme.value.hoverColor,
+  "--t-modal-color": theme.value.modalColor,
+  "--t-primary-color": theme.value.primaryColor,
+  "--t-primary-color-hover": theme.value.primaryColorHover,
+  "--t-text-color-1": theme.value.textColor1,
+  "--t-text-color-2": theme.value.textColor2,
+  "--t-text-color-3": theme.value.textColor3,
+}))
 
-// 学生页签走「班级 + 姓名」两个下拉，一个字都不用打；
-// 管理员页签只有用户名 + 密码，不拼班级前缀。
-const activeTab = ref<"student" | "admin">("student")
-const studentRef = useTemplateRef("studentRef")
-const adminRef = useTemplateRef("adminRef")
-const studentPasswordRef = useTemplateRef("studentPasswordRef")
-const classUserOptions = ref<SelectOption[]>([])
-const classUserLoading = ref(false)
-// 姓名支持拼音和拼音缩写搜索（张三 ← zhangsan / zs）。pinyin-pro 带着一份几百 K 的
+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 */
+const klass = ref<string | null>(null)
+const names = ref<string[]>([])
+const namesLoading = ref(false)
+const query = ref("")
+const picked = ref<string | null>(null)
+const username = ref("")
+const password = ref("")
+const loading = ref(false)
+const error = ref("")
+/** 错太多次被锁了：按钮灰掉，换个名字 / 换种登法才放开 */
+const locked = ref(false)
+
+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}`,
+  })),
+)
+/** 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 }] : [],
+  ),
+)
+
+// 名字支持拼音和拼音缩写搜索（张三 ← zhangsan / zs）。pinyin-pro 带着一份几百 K 的
 // 词典，静态引入会压进首屏 —— 改成打开登录框才拉，已登录的人一次都不会下载。
 // 用 match 而不是自己拼拼音串：多音字它两个读音都认（单田芳 ← stf 和 dtf 都能搜到）。
 type MatchFn = typeof import("pinyin-pro").match
@@ -41,301 +90,555 @@ async function ensurePinyin() {
     // 拉不下来就只剩中文匹配，不至于让人登不上
   }
 }
-function filterClassUser(pattern: string, option: SelectOption) {
-  const keyword = pattern.trim()
-  if (!keyword) return true
-  const label = String(option.label ?? "")
-  if (label.includes(keyword)) return true
-  return pinyinMatch.value
-    ? pinyinMatch.value(label, keyword, { continuous: true }) !== null
-    : false
-}
-// 空串是「没有我所在的班级」，null 才是没选 —— 往届的班级毕业后会从后台配置里删掉，
-// 这一项是他们唯一的入口，写完整用户名登录。放在最前：班级一多它沉在底下，要翻到底才找得到
-const OTHER_CLASS = ""
-const classList = computed<SelectOption[]>(() => [
-  { label: "没有我所在的班级", value: OTHER_CLASS },
-  ...groupClassOptions(configStore.config?.classList ?? [], (item) => ({
-    label: classLabel(item),
-    value: `ks${item}`,
-  })),
-])
-// 选了具体班级就是「选姓名」，选了「没有我所在的班级」就是「写用户名」
-const isClassLogin = computed(() => Boolean(form.value.class))
-const passwordRule: FormItemRule[] = [
-  { required: true, message: "密码必填", trigger: "blur" },
-  { min: 6, max: 20, message: "长度在 6 到 20 位之间", trigger: "input" },
-]
-const studentRules = computed<FormRules>(() => ({
-  class: [
-    {
-      validator: () => form.value.class !== null,
-      message: "班级必选",
-      trigger: ["blur", "change"],
-    },
-  ],
-  username: [
-    {
-      required: true,
-      message: isClassLogin.value ? "姓名必选" : "用户名必填",
-      trigger: ["blur", "change"],
-    },
-  ],
-  password: passwordRule,
-}))
-const adminRules: FormRules = {
-  username: [{ required: true, message: "用户名必填", trigger: ["blur", "change"] }],
-  password: passwordRule,
+
+function matches(name: string, keyword: string) {
+  if (name.includes(keyword)) return true
+  return pinyinMatch.value ? pinyinMatch.value(name, keyword, { continuous: true }) !== null : false
 }
 
-function resetForm() {
-  form.value.class = null
-  form.value.username = null
-  form.value.password = ""
-  classUserOptions.value = []
-  classUserLoading.value = false
-  authStore.clearLoginError()
+// 按拼音排：zh 的排序规则在 Chrome 里就是拼音序，不用等 pinyin-pro
+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
+})
+
+async function loadNames(value: string) {
+  namesLoading.value = true
+  names.value = []
+  try {
+    const list = await getClassUsernames(value.slice(2))
+    // 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)
+  } catch {
+    if (klass.value === value) names.value = []
+  } finally {
+    if (klass.value === value) namesLoading.value = false
+  }
 }
 
-function onTabChange(tab: "student" | "admin") {
-  resetForm()
-  studentRef.value?.restoreValidation()
-  adminRef.value?.restoreValidation()
-  // 切回学生页签把记住的班级填回去，别因为误点了一下管理员就得重选
-  if (tab === "student") restoreLastClass()
+watch(klass, (value) => {
+  picked.value = null
+  query.value = ""
+  clearError()
+  if (value) {
+    loadNames(value)
+    focusLater(() => searchRef.value)
+  } else names.value = []
+})
+
+function clearError() {
+  error.value = ""
+  locked.value = false
 }
 
-function submit() {
-  const formRef = activeTab.value === "student" ? studentRef : adminRef
-  formRef.value!.validate(async (errors?: unknown) => {
-    if (errors) return
-    try {
-      authStore.clearLoginError()
-      authStore.setLoginLoading(true)
-      const merged = {
-        username: form.value.username ?? "",
-        password: form.value.password,
-      }
-      // 选了班级的只填了姓名，ks + 班级号的前缀这里补
-      if (activeTab.value === "student" && form.value.class) {
-        merged.username = form.value.class + merged.username
-      }
-      await login(merged)
-    } catch (err) {
-      // 判错误码而不是错误文案：文案在后端，改一个字这里就静默掉进「无法登录」
-      if (errorCode(err) === "account-disabled") {
-        authStore.setLoginError("此账号已被封禁")
-      } else if (errorCode(err) === "invalid-credentials") {
-        authStore.setLoginError("用户名或密码不正确")
-      } else if (errorCode(err) === "too-many-login-attempts") {
-        authStore.setLoginError("密码错误次数太多，请 15 分钟后再试")
-      } else {
-        authStore.setLoginError("无法登录")
-      }
-    } finally {
-      authStore.setLoginLoading(false)
-    }
-    if (!msg.value) {
-      if (activeTab.value === "student") {
-        storage.set(STORAGE_KEY.LOGIN_CLASS, form.value.class)
-      }
-      authStore.closeLoginModal()
-      // 「上次登录以来」不再弹框，拆进了首页的「上次来」卡（/me/last-visit）
-      await userStore.getMyProfile()
-    }
-  })
+/** 要聚焦的框往往下一帧才渲染出来，所以传取值函数，到时候再取 */
+function focusLater(target: () => { focus: () => void } | null | undefined) {
+  nextTick(() => target()?.focus())
+}
+
+function pick(name: string) {
+  picked.value = name
+  password.value = ""
+  clearError()
+  focusLater(() => passwordRef.value)
+}
+
+function unpick() {
+  picked.value = null
+  password.value = ""
+  clearError()
+  focusLater(() => searchRef.value)
+}
+
+/** 搜到只剩一个人，回车就是点他 */
+function onSearchEnter() {
+  if (shown.value.length === 1) pick(shown.value[0]!)
+}
+
+function switchMode(next: Mode) {
+  mode.value = next
+  picked.value = null
+  username.value = ""
+  password.value = ""
+  query.value = ""
+  clearError()
+  focusLater(() => (next === "user" ? usernameRef.value : searchRef.value))
 }
 
 function goSignup() {
   authStore.switchToSignup()
 }
 
-async function loadClassUsernames(selectedClass: string) {
-  classUserLoading.value = true
-  try {
-    const res = await getClassUsernames(selectedClass)
-    classUserOptions.value = res.map((name: string) => ({
-      label: name,
-      value: name,
-    }))
-  } catch {
-    classUserOptions.value = []
-  } finally {
-    classUserLoading.value = false
+async function submit() {
+  if (loading.value || locked.value) return
+  const name =
+    mode.value === "pick" ? `${klass.value ?? ""}${picked.value ?? ""}` : username.value.trim()
+  if (mode.value === "user" && !name) {
+    error.value = "写上用户名"
+    focusLater(() => usernameRef.value)
+    return
   }
-}
-
-watch(
-  () => form.value.class,
-  (selectedClass) => {
-    classUserOptions.value = []
-    form.value.username = null
-    if (!selectedClass) {
-      classUserLoading.value = false
-      return
+  if (!password.value) {
+    error.value = "写上密码"
+    focusLater(() => passwordRef.value)
+    return
+  }
+  loading.value = true
+  clearError()
+  try {
+    await login({ username: name, password: password.value })
+  } catch (err) {
+    // 判错误码而不是错误文案：文案在后端，改一个字这里就静默掉进「登录不上」
+    const code = errorCode(err)
+    if (code === "invalid-credentials") {
+      // 名字是点出来的，错只会错在密码
+      error.value = mode.value === "pick" ? "密码不对，再试一次" : "用户名或密码不对"
+    } else if (code === "too-many-login-attempts") {
+      error.value = "密码错太多次了，15 分钟后再试"
+      locked.value = true
+    } else if (code === "account-disabled") {
+      error.value = "这个账号停用了，去找老师"
+    } else {
+      error.value = "登录不上，等一会儿再试"
     }
-    loadClassUsernames(selectedClass.slice(2))
-  },
-)
-
-// 选完姓名直接跳到密码框，学生的手不用离开这一列
-function onUsernamePicked() {
-  nextTick(() => studentPasswordRef.value?.focus())
+    password.value = ""
+    focusLater(() => passwordRef.value)
+    return
+  } finally {
+    loading.value = false
+  }
+  storage.set(STORAGE_KEY.LOGIN_MODE, mode.value)
+  if (mode.value === "pick") storage.set(STORAGE_KEY.LOGIN_CLASS, klass.value)
+  authStore.closeLoginModal()
+  // 「上次登录以来」不再弹框，拆进了首页的「上次来」卡（/me/last-visit）
+  await userStore.getMyProfile()
 }
 
 /**
  * 机房电脑一台对一个班，班级记在本地下次自动填上；
- * 姓名不记 —— 同一台机器换个人坐就是别人的名字了。
+ * 名字不记 —— 同一台机器换个人坐就是别人的名字了。
  */
-function restoreLastClass() {
-  if (form.value.class !== null) return
+function restoreLast() {
+  const lastMode = storage.get(STORAGE_KEY.LOGIN_MODE)
+  mode.value = lastMode === "user" ? "user" : "pick"
   const last = storage.get(STORAGE_KEY.LOGIN_CLASS)
-  const known = (configStore.config?.classList ?? []).map((item) => `ks${item}`)
-  if (typeof last === "string" && known.includes(last)) {
-    form.value.class = last
+  if (typeof last === "string" && 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
+      query.value = ""
+    } else klass.value = last
   }
 }
 
-watch(classList, restoreLastClass)
-
-// 每次打开都从干净的表单开始，别把上一个人的姓名和密码留在框里
-watch(loginModalOpen, (open) => {
-  if (!open) return
-  ensurePinyin()
-  resetForm()
-  studentRef.value?.restoreValidation()
-  adminRef.value?.restoreValidation()
-  restoreLastClass()
+// 配置是异步到的，登录框可能先开了
+watch(knownClasses, () => {
+  if (klass.value === null) restoreLast()
 })
 
-onMounted(() => {
-  authStore.clearLoginError()
-  restoreLastClass()
-  if (loginModalOpen.value) ensurePinyin()
-})
+// 每次打开都从干净的表单开始，别把上一个人的名字和密码留在框里
+watch(
+  loginModalOpen,
+  (open) => {
+    if (!open) return
+    ensurePinyin()
+    picked.value = null
+    username.value = ""
+    password.value = ""
+    query.value = ""
+    clearError()
+    restoreLast()
+    focusLater(() => (mode.value === "user" ? usernameRef.value : searchRef.value))
+  },
+  { immediate: true },
+)
 </script>
 
 <template>
-  <n-modal
-    :mask-closable="false"
-    v-model:show="loginModalOpen"
-    preset="card"
-    title="登录"
-    style="width: 420px"
-    :auto-focus="false"
-  >
-    <n-tabs v-model:value="activeTab" @update:value="onTabChange">
-      <n-tab-pane name="student" tab="学生登录">
-        <n-form ref="studentRef" :model="form" :rules="studentRules" show-require-mark>
-          <n-form-item label="班级" path="class">
-            <n-select
-              v-model:value="form.class"
-              :options="classList"
-              filterable
-              name="class"
-              id="login-class"
-              placeholder="选择班级"
-            />
-          </n-form-item>
-          <n-form-item :label="isClassLogin ? '姓名' : '用户名'" path="username">
-            <n-select
-              v-if="isClassLogin"
-              v-model:value="form.username"
-              :options="classUserOptions"
-              :loading="classUserLoading"
-              filterable
-              :filter="filterClassUser"
-              name="class-username"
-              id="login-class-username"
-              placeholder="选择姓名，可打拼音或缩写搜索"
-              @update:value="onUsernamePicked"
-            />
-            <n-input
-              v-else
-              v-model:value="form.username"
-              clearable
-              :disabled="form.class === null"
-              name="username"
-              id="login-username"
-              autocomplete="username"
-              placeholder="完整用户名，如 ks231张三"
-            />
-          </n-form-item>
-          <n-form-item label="密码" path="password">
-            <n-input
-              ref="studentPasswordRef"
-              v-model:value="form.password"
-              clearable
-              type="password"
-              :name="isClassLogin ? 'class-password' : 'password'"
-              :id="isClassLogin ? 'login-class-password' : 'login-password'"
-              :autocomplete="isClassLogin ? 'new-password' : 'current-password'"
-              @keyup.enter="submit"
-            />
-          </n-form-item>
-          <n-alert v-if="msg" type="error" :show-icon="false">{{ msg }}</n-alert>
-          <n-form-item>
-            <n-flex style="width: 100%">
-              <n-button
-                type="primary"
-                :loading="isLoading"
-                @click="submit"
-                :style="{
-                  flex: configStore.config?.allowRegister ? '0 0 auto' : '1',
-                }"
-              >
-                登录
-              </n-button>
-              <n-button v-if="configStore.config?.allowRegister" @click="goSignup">
-                没有账号？立即注册
-              </n-button>
-            </n-flex>
-          </n-form-item>
-          <n-alert :show-icon="false" class="tip">
-            往届的班级、列表里找不到的班级、以及自己注册的账号，选【没有我所在的班级】，用户名要写完整，比如
-            23 计算机 1 班张三写 ks231张三（姓名可以用拼音或拼音缩写快速查找）。
-          </n-alert>
-        </n-form>
-      </n-tab-pane>
+  <n-modal v-model:show="loginModalOpen" :mask-closable="false" :auto-focus="false">
+    <div class="box" :style="themeVars" :class="mode" role="dialog" aria-label="登录">
+      <div class="head">
+        <h2>登录</h2>
+        <n-select
+          v-if="mode === 'pick'"
+          v-model:value="klass"
+          class="klass"
+          :options="classOptions"
+          filterable
+          placeholder="选班级"
+          :consistent-menu-width="false"
+        />
+        <span class="grow"></span>
+        <button class="close" type="button" aria-label="关闭" @click="authStore.closeLoginModal()">
+          <Icon icon="ph:x" :width="18" />
+        </button>
+      </div>
 
-      <n-tab-pane name="admin" tab="管理员登录">
-        <n-form ref="adminRef" :model="form" :rules="adminRules" show-require-mark>
-          <n-form-item label="用户名" path="username">
+      <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>
+          <div class="field narrow">
             <n-input
-              v-model:value="form.username"
-              clearable
-              name="username"
-              id="login-admin-username"
-              autocomplete="username"
-              placeholder="请输入用户名"
-            />
-          </n-form-item>
-          <n-form-item label="密码" path="password">
-            <n-input
-              v-model:value="form.password"
-              clearable
+              ref="passwordRef"
+              v-model:value="password"
               type="password"
-              name="password"
-              id="login-admin-password"
-              autocomplete="current-password"
+              show-password-on="click"
+              size="large"
+              placeholder="密码"
+              :input-props="{ name: 'class-password', autocomplete: 'new-password' }"
+              :status="error ? 'error' : undefined"
+              @update:value="locked = false"
               @keyup.enter="submit"
             />
-          </n-form-item>
-          <n-alert v-if="msg" type="error" :show-icon="false">{{ msg }}</n-alert>
-          <n-form-item>
-            <n-button block type="primary" :loading="isLoading" @click="submit"> 登录 </n-button>
-          </n-form-item>
-          <n-alert :show-icon="false" class="tip">
-            管理员和老师从这里登录，学生请走【学生登录】页签。
-          </n-alert>
-        </n-form>
-      </n-tab-pane>
-    </n-tabs>
+            <div v-if="error" class="err">{{ error }}</div>
+          </div>
+          <n-button
+            class="narrow"
+            type="primary"
+            size="large"
+            :loading="loading"
+            :disabled="locked"
+            @click="submit"
+          >
+            登录
+          </n-button>
+          <button class="link back" type="button" @click="unpick">
+            <Icon icon="ph:caret-left-bold" :width="14" />不是我，换一个名字
+          </button>
+        </div>
+
+        <template v-else-if="klass">
+          <n-input
+            ref="searchRef"
+            v-model:value="query"
+            class="search"
+            clearable
+            placeholder="打名字或拼音缩写"
+            :input-props="{ autocomplete: 'off' }"
+            @keyup.enter="onSearchEnter"
+          >
+            <template #prefix><Icon icon="ph:magnifying-glass" :width="16" /></template>
+          </n-input>
+          <div class="scroll">
+            <div v-if="namesLoading" class="empty"><n-spin size="small" /></div>
+            <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>
+            </div>
+          </div>
+        </template>
+
+        <!-- 这台电脑还没登过：先选班 -->
+        <div v-else class="scroll classes">
+          <div v-for="group in classGroups" :key="group.label" class="grade">
+            <span class="grade-label">{{ group.label }}</span>
+            <div class="grid">
+              <button
+                v-for="item in group.items"
+                :key="item.value"
+                class="cell"
+                type="button"
+                @click="klass = item.value"
+              >
+                {{ item.label }}
+              </button>
+            </div>
+          </div>
+        </div>
+
+        <div class="links">
+          <button class="link" type="button" @click="switchMode('user')">名单里没有我</button>
+          <i></i>
+          <button class="link" type="button" @click="switchMode('user')">老师登录</button>
+          <template v-if="configStore.config?.allowRegister">
+            <i></i>
+            <button class="link" type="button" @click="goSignup">注册</button>
+          </template>
+        </div>
+      </template>
+
+      <!-- 写用户名：老师、往届、自己注册的 -->
+      <div v-else class="form">
+        <label class="field">
+          <span class="lab">用户名</span>
+          <n-input
+            ref="usernameRef"
+            v-model:value="username"
+            size="large"
+            clearable
+            placeholder="完整用户名，如 ks231张三"
+            :input-props="{ name: 'username', autocomplete: 'username' }"
+            @keyup.enter="passwordRef?.focus()"
+          />
+        </label>
+        <label class="field">
+          <span class="lab">密码</span>
+          <n-input
+            ref="passwordRef"
+            v-model:value="password"
+            type="password"
+            show-password-on="click"
+            size="large"
+            placeholder="密码"
+            :input-props="{ name: 'password', autocomplete: 'current-password' }"
+            :status="error ? 'error' : undefined"
+            @update:value="locked = false"
+            @keyup.enter="submit"
+          />
+          <span v-if="error" class="err">{{ error }}</span>
+        </label>
+        <n-button type="primary" size="large" :loading="loading" :disabled="locked" @click="submit">
+          登录
+        </n-button>
+        <div class="links">
+          <button class="link back" type="button" @click="switchMode('pick')">
+            <Icon icon="ph:caret-left-bold" :width="14" />按班级选名字
+          </button>
+          <template v-if="configStore.config?.allowRegister">
+            <i></i>
+            <button class="link" type="button" @click="goSignup">注册</button>
+          </template>
+        </div>
+      </div>
+    </div>
   </n-modal>
 </template>
 
 <style scoped>
-.tip {
-  margin-top: 4px;
+.box {
+  display: flex;
+  flex-direction: column;
+  box-sizing: border-box;
+  max-height: calc(100vh - 32px);
+  padding: 24px 28px;
+  border-radius: var(--oj-radius);
+  background: var(--t-modal-color);
+  color: var(--t-text-color-1);
+  box-shadow: var(--t-box-shadow-3);
+}
+
+.box.pick {
+  width: min(800px, calc(100vw - 32px));
+}
+
+.box.user {
+  width: min(420px, calc(100vw - 32px));
+}
+
+.head {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  flex-shrink: 0;
+}
+
+.head h2 {
+  margin: 0;
+  font-size: 20px;
+  line-height: 28px;
+}
+
+.klass {
+  width: 170px;
+}
+
+.grow {
+  flex: 1;
+}
+
+.close {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 32px;
+  height: 32px;
+  padding: 0;
+  border: 0;
+  border-radius: 6px;
+  background: transparent;
+  color: var(--t-text-color-2);
+  cursor: pointer;
+}
+
+.close:hover {
+  background: var(--t-hover-color);
+}
+
+.search {
+  margin-top: 18px;
+  flex-shrink: 0;
+}
+
+.scroll {
+  margin-top: 14px;
+  min-height: 0;
+  overflow-y: auto;
+}
+
+.grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(96px, 1fr));
+  gap: 8px;
+}
+
+.cell {
+  height: 40px;
+  padding: 0 6px;
+  border: 1px solid var(--t-border-color);
+  border-radius: 6px;
+  background: transparent;
+  font: inherit;
+  font-size: var(--oj-fs-body);
+  color: var(--t-text-color-1);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  cursor: pointer;
+}
+
+.cell:hover,
+.cell:focus-visible {
+  border-color: var(--t-primary-color);
+  color: var(--t-primary-color);
+  outline: none;
+}
+
+.classes {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+  margin-top: 20px;
+}
+
+.classes .grid {
+  grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
+}
+
+.grade {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.grade-label {
+  font-size: var(--oj-fs-sec);
+  color: var(--t-text-color-3);
+}
+
+.empty {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  height: 160px;
+  color: var(--t-text-color-3);
+}
+
+.me {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 18px;
+  padding: 36px 0 30px;
+}
+
+.me-name {
+  font-size: 22px;
+}
+
+.narrow {
+  width: min(300px, 100%);
+}
+
+.field {
+  display: flex;
+  flex-direction: column;
+}
+
+.lab {
+  margin-bottom: 6px;
+  font-size: var(--oj-fs-sec);
+  color: var(--t-text-color-2);
+}
+
+.err {
+  margin-top: 6px;
+  font-size: var(--oj-fs-sec);
+  line-height: 20px;
+  color: var(--t-error-color);
+}
+
+.form {
+  display: flex;
+  flex-direction: column;
+  gap: 18px;
+  margin-top: 20px;
+}
+
+.links {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 10px;
+  margin-top: 18px;
+  flex-shrink: 0;
+}
+
+.form .links {
+  margin-top: 0;
+}
+
+.links i {
+  width: 1px;
+  height: 12px;
+  background: var(--t-border-color);
+}
+
+.link {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  padding: 0;
+  border: 0;
+  background: none;
+  font: inherit;
+  font-size: var(--oj-fs-sec);
+  color: var(--t-primary-color);
+  cursor: pointer;
+}
+
+.link:hover {
+  color: var(--t-primary-color-hover);
+}
+
+/* 手机：铺满一屏，名单往下滑，底下两条入口一直在 */
+@media (max-width: 640px) {
+  .box.pick,
+  .box.user {
+    width: 100vw;
+    height: 100vh;
+    max-height: none;
+    border-radius: 0;
+    padding: 12px 16px 16px;
+  }
+
+  .klass {
+    width: 150px;
+  }
+
+  .scroll {
+    flex: 1;
+  }
 }
 </style>
diff --git a/apps/web/src/shared/components/Signup.vue b/apps/web/src/shared/components/Signup.vue
index 750a30d..2a9e225 100644
--- a/apps/web/src/shared/components/Signup.vue
+++ b/apps/web/src/shared/components/Signup.vue
@@ -1,130 +1,287 @@
 <script setup lang="ts">
+import { registerRequestSchema } from "@oj2/contract"
+import { Icon } from "@iconify/vue"
+import { useThemeVars } from "naive-ui"
 import { errorCode } from "utils/api"
-import { signup } from "../api"
-import { storeToRefs } from "pinia"
+import { login, signup } from "../api"
 import { useAuthModalStore } from "../store/authModal"
+import { useUserStore } from "../store/user"
+
+/**
+ * 注册框。错在哪个框就标在哪个框下面，不攒成最底下一条；注册完直接登上，
+ * 不用回登录框再输一遍。开关在后台设置里（allow_register），关着时顶栏没有入口。
+ */
+type Field = "username" | "email" | "password" | "again"
 
 const authStore = useAuthModalStore()
+const userStore = useUserStore()
+const { signupModalOpen } = storeToRefs(authStore)
+const theme = useThemeVars()
 
-const {
-  signupModalOpen,
-  signupForm: form,
-  signupLoading: isLoading,
-  signupError: msg,
-} = storeToRefs(authStore)
-const signupRef = useTemplateRef("signupRef")
+// n-modal 把内容传送到 body 底下，CSS 的 v-bind() 挂不上去（变量挂在组件根上，
+// 这个组件的根是 n-modal 自己）—— 颜色直接写到弹框根节点的 style 里
+const themeVars = computed(() => ({
+  "--t-box-shadow-3": theme.value.boxShadow3,
+  "--t-error-color": theme.value.errorColor,
+  "--t-hover-color": theme.value.hoverColor,
+  "--t-modal-color": theme.value.modalColor,
+  "--t-primary-color": theme.value.primaryColor,
+  "--t-primary-color-hover": theme.value.primaryColorHover,
+  "--t-text-color-1": theme.value.textColor1,
+  "--t-text-color-2": theme.value.textColor2,
+}))
 
-const rules: FormRules = {
-  username: [{ required: true, message: "用户名必填", trigger: "blur" }],
-  email: [{ required: true, message: "邮箱必填", trigger: "blur" }],
-  password: [
-    { required: true, message: "密码必填", trigger: "blur" },
-    { min: 6, max: 20, message: "长度在 6 到 20 位之间", trigger: "input" },
-  ],
-  passwordAgain: [
-    { required: true, message: "密码必填", trigger: "blur" },
-    { min: 6, max: 20, message: "长度在 6 到 20 位之间", trigger: "input" },
-    {
-      validator: (_: FormItemRule, value: string) => value === form.value.password,
-      message: "两次密码输入不一致",
-      trigger: "blur",
-    },
-  ],
+const form = reactive({ username: "", email: "", password: "", again: "" })
+const errors = reactive<Partial<Record<Field, string>>>({})
+/** 不归哪个框的错（注册太频繁、网络） */
+const general = ref("")
+const loading = ref(false)
+
+const usernameRef = useTemplateRef("usernameRef")
+
+function check() {
+  for (const key of Object.keys(errors) as Field[]) delete errors[key]
+  if (!form.username.trim()) errors.username = "写上用户名"
+  if (!form.email.trim()) errors.email = "写上邮箱"
+  else if (!registerRequestSchema.shape.email.safeParse(form.email.trim()).success) {
+    errors.email = "邮箱的样子不对，比如 zhangsan@qq.com"
+  }
+  if (form.password.length < 6 || form.password.length > 20) errors.password = "密码要 6 到 20 位"
+  if (!errors.password && form.again !== form.password) errors.again = "和上面的不一样"
+  return Object.keys(errors).length === 0
 }
 
-function goLogin() {
-  authStore.switchToLogin()
+function clearOne(field: Field) {
+  delete errors[field]
+  general.value = ""
 }
 
-function submit() {
-  signupRef.value!.validate(async (errors?: unknown) => {
-    if (!errors) {
-      try {
-        authStore.clearSignupError()
-        authStore.setSignupLoading(true)
-        await signup({
-          username: form.value.username,
-          email: form.value.email,
-          password: form.value.password,
-        })
-      } catch (err) {
-        if (errorCode(err) === "username-exists") {
-          authStore.setSignupError("用户名已存在")
-        } else if (errorCode(err) === "email-exists") {
-          authStore.setSignupError("邮箱已存在")
-        } else if (errorCode(err) === "too-many-registrations") {
-          authStore.setSignupError("注册太频繁，请稍后再试")
-        } else {
-          authStore.setSignupError("无法注册")
-        }
-      } finally {
-        authStore.setSignupLoading(false)
-      }
-      if (!msg.value) {
-        authStore.closeSignupModal()
-      }
-    }
-  })
+async function submit() {
+  if (loading.value || !check()) return
+  loading.value = true
+  general.value = ""
+  const username = form.username.trim()
+  try {
+    await signup({ username, email: form.email.trim(), password: form.password })
+  } catch (err) {
+    const code = errorCode(err)
+    if (code === "username-exists") errors.username = "这个名字已经有人用了，换一个"
+    else if (code === "email-exists") errors.email = "这个邮箱已经注册过了"
+    else if (code === "too-many-registrations") general.value = "注册太频繁了，等一会儿再试"
+    else if (code === "registration-disabled") general.value = "现在不开放注册"
+    else general.value = "注册不了，等一会儿再试"
+    loading.value = false
+    return
+  }
+  try {
+    await login({ username, password: form.password })
+    authStore.closeSignupModal()
+    await userStore.getMyProfile()
+  } catch {
+    // 号已经建好了，只是这一下没登上：回登录框自己登
+    authStore.switchToLogin()
+  } finally {
+    loading.value = false
+  }
 }
+
+watch(signupModalOpen, (open) => {
+  if (!open) return
+  Object.assign(form, { username: "", email: "", password: "", again: "" })
+  for (const key of Object.keys(errors) as Field[]) delete errors[key]
+  general.value = ""
+  nextTick(() => usernameRef.value?.focus())
+})
 </script>
 
 <template>
-  <n-modal
-    :mask-closable="false"
-    v-model:show="signupModalOpen"
-    preset="card"
-    title="注册"
-    style="width: 400px"
-    :auto-focus="false"
-  >
-    <n-form ref="signupRef" :model="form" :rules="rules" show-require-mark>
-      <n-form-item label="用户名" path="username">
-        <n-input
-          v-model:value="form.username"
-          autofocus
-          clearable
-          name="username"
-          id="signup-username"
-          autocomplete="username"
-        />
-      </n-form-item>
-      <n-form-item label="邮箱" path="email">
-        <n-input
-          v-model:value="form.email"
-          clearable
-          name="email"
-          id="signup-email"
-          autocomplete="email"
-          @change="submit"
-        />
-      </n-form-item>
-      <n-form-item label="密码" path="password">
-        <n-input
-          v-model:value="form.password"
-          clearable
-          type="password"
-          name="password"
-          id="signup-password"
-          autocomplete="new-password"
-        />
-      </n-form-item>
-      <n-form-item label="确认密码" path="passwordAgain">
-        <n-input
-          v-model:value="form.passwordAgain"
-          clearable
-          type="password"
-          name="passwordAgain"
-          id="signup-password-again"
-          autocomplete="new-password"
-        />
-      </n-form-item>
-      <n-alert v-if="msg" type="error" :show-icon="false"> {{ msg }}</n-alert>
-      <n-form-item>
-        <n-space>
-          <n-button type="primary" :loading="isLoading" @click="submit"> 注册 </n-button>
-          <n-button @click="goLogin">已经注册？现在登录</n-button>
-        </n-space>
-      </n-form-item>
-    </n-form>
+  <n-modal v-model:show="signupModalOpen" :mask-closable="false" :auto-focus="false">
+    <div class="box" :style="themeVars" role="dialog" aria-label="注册">
+      <div class="head">
+        <h2>注册</h2>
+        <span class="grow"></span>
+        <button class="close" type="button" aria-label="关闭" @click="authStore.closeSignupModal()">
+          <Icon icon="ph:x" :width="18" />
+        </button>
+      </div>
+      <div class="form">
+        <label class="field">
+          <span class="lab">用户名</span>
+          <n-input
+            ref="usernameRef"
+            v-model:value="form.username"
+            size="large"
+            clearable
+            :maxlength="32"
+            placeholder="以后登录就写它"
+            :input-props="{ name: 'username', autocomplete: 'username' }"
+            :status="errors.username ? 'error' : undefined"
+            @update:value="clearOne('username')"
+          />
+          <span v-if="errors.username" class="err">{{ errors.username }}</span>
+        </label>
+        <label class="field">
+          <span class="lab">邮箱</span>
+          <n-input
+            v-model:value="form.email"
+            size="large"
+            clearable
+            :maxlength="64"
+            placeholder="常用的邮箱"
+            :input-props="{ name: 'email', autocomplete: 'email' }"
+            :status="errors.email ? 'error' : undefined"
+            @update:value="clearOne('email')"
+          />
+          <span v-if="errors.email" class="err">{{ errors.email }}</span>
+        </label>
+        <label class="field">
+          <span class="lab">密码</span>
+          <n-input
+            v-model:value="form.password"
+            type="password"
+            show-password-on="click"
+            size="large"
+            :maxlength="20"
+            placeholder="6 到 20 位"
+            :input-props="{ name: 'password', autocomplete: 'new-password' }"
+            :status="errors.password ? 'error' : undefined"
+            @update:value="clearOne('password')"
+          />
+          <span v-if="errors.password" class="err">{{ errors.password }}</span>
+        </label>
+        <label class="field">
+          <span class="lab">再输一遍密码</span>
+          <n-input
+            v-model:value="form.again"
+            type="password"
+            show-password-on="click"
+            size="large"
+            :maxlength="20"
+            :input-props="{ name: 'password-again', autocomplete: 'new-password' }"
+            :status="errors.again ? 'error' : undefined"
+            @update:value="clearOne('again')"
+            @keyup.enter="submit"
+          />
+          <span v-if="errors.again" class="err">{{ errors.again }}</span>
+        </label>
+        <span v-if="general" class="err">{{ general }}</span>
+        <n-button type="primary" size="large" :loading="loading" @click="submit">
+          注册并登录
+        </n-button>
+        <div class="links">
+          <button class="link" type="button" @click="authStore.switchToLogin()">
+            已经有账号了，去登录
+          </button>
+        </div>
+      </div>
+    </div>
   </n-modal>
 </template>
+
+<style scoped>
+.box {
+  display: flex;
+  flex-direction: column;
+  box-sizing: border-box;
+  width: min(420px, calc(100vw - 32px));
+  max-height: calc(100vh - 32px);
+  overflow-y: auto;
+  padding: 24px 28px;
+  border-radius: var(--oj-radius);
+  background: var(--t-modal-color);
+  color: var(--t-text-color-1);
+  box-shadow: var(--t-box-shadow-3);
+}
+
+.head {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+}
+
+.head h2 {
+  margin: 0;
+  font-size: 20px;
+  line-height: 28px;
+}
+
+.grow {
+  flex: 1;
+}
+
+.close {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 32px;
+  height: 32px;
+  padding: 0;
+  border: 0;
+  border-radius: 6px;
+  background: transparent;
+  color: var(--t-text-color-2);
+  cursor: pointer;
+}
+
+.close:hover {
+  background: var(--t-hover-color);
+}
+
+.form {
+  display: flex;
+  flex-direction: column;
+  gap: 18px;
+  margin-top: 20px;
+}
+
+.field {
+  display: flex;
+  flex-direction: column;
+}
+
+.lab {
+  margin-bottom: 6px;
+  font-size: var(--oj-fs-sec);
+  color: var(--t-text-color-2);
+}
+
+.err {
+  margin-top: 6px;
+  font-size: var(--oj-fs-sec);
+  line-height: 20px;
+  color: var(--t-error-color);
+}
+
+.form > .err {
+  margin-top: -8px;
+}
+
+.links {
+  display: flex;
+  justify-content: center;
+}
+
+.link {
+  padding: 0;
+  border: 0;
+  background: none;
+  font: inherit;
+  font-size: var(--oj-fs-sec);
+  color: var(--t-primary-color);
+  cursor: pointer;
+}
+
+.link:hover {
+  color: var(--t-primary-color-hover);
+}
+
+@media (max-width: 640px) {
+  .box {
+    width: 100vw;
+    height: 100vh;
+    max-height: none;
+    border-radius: 0;
+    padding: 12px 16px 16px;
+  }
+}
+</style>
diff --git a/apps/web/src/shared/store/authModal.ts b/apps/web/src/shared/store/authModal.ts
index 6016e2d..1332057 100644
--- a/apps/web/src/shared/store/authModal.ts
+++ b/apps/web/src/shared/store/authModal.ts
@@ -1,157 +1,47 @@
 import { defineStore } from "pinia"
 
 /**
- * 认证状态管理 Store
- * 统一管理登录、注册相关的模态框状态和表单状态
+ * 登录框、注册框开没开。表单本身在两个组件里：每次打开都从干净的表单开始
+ * （机房一台电脑轮流坐人，别把上一个人的名字和密码留在框里），不需要跨组件共享。
  */
 export const useAuthModalStore = defineStore("authModal", () => {
-  // ==================== 模态框状态 ====================
   const loginModalOpen = ref(false)
   const signupModalOpen = ref(false)
 
-  // ==================== 登录表单状态 ====================
-  // class 为 null 表示还没选，别用空串 —— 空串是「没有我所在的班级」那一项的值。
-  // username 同理用 null：空串在 n-select 里是「选了一个空值」，占位符不显示。
-  const loginForm = reactive({
-    class: null as string | null,
-    username: null as string | null,
-    password: "",
-  })
-
-  const loginLoading = ref(false)
-  const loginError = ref("")
-
-  // ==================== 注册表单状态 ====================
-  const signupForm = reactive({
-    username: "",
-    email: "",
-    password: "",
-    passwordAgain: "",
-  })
-
-  const signupLoading = ref(false)
-  const signupError = ref("")
-
-  // ==================== 模态框操作 ====================
-  /**
-   * 打开登录模态框
-   */
   function openLoginModal() {
     loginModalOpen.value = true
   }
 
-  /**
-   * 关闭登录模态框
-   */
   function closeLoginModal() {
     loginModalOpen.value = false
   }
 
-  /**
-   * 打开注册模态框
-   */
   function openSignupModal() {
     signupModalOpen.value = true
   }
 
-  /**
-   * 关闭注册模态框
-   */
   function closeSignupModal() {
     signupModalOpen.value = false
   }
 
-  /**
-   * 从登录切换到注册
-   */
   function switchToSignup() {
     closeLoginModal()
     openSignupModal()
   }
 
-  /**
-   * 从注册切换到登录
-   */
   function switchToLogin() {
     closeSignupModal()
     openLoginModal()
   }
 
-  // ==================== 登录表单操作 ====================
-  /**
-   * 设置登录加载状态
-   */
-  function setLoginLoading(loading: boolean) {
-    loginLoading.value = loading
-  }
-
-  /**
-   * 设置登录错误信息
-   */
-  function setLoginError(error: string) {
-    loginError.value = error
-  }
-
-  /**
-   * 清空登录错误
-   */
-  function clearLoginError() {
-    loginError.value = ""
-  }
-
-  // ==================== 注册表单操作 ====================
-  /**
-   * 设置注册加载状态
-   */
-  function setSignupLoading(loading: boolean) {
-    signupLoading.value = loading
-  }
-
-  /**
-   * 设置注册错误信息
-   */
-  function setSignupError(error: string) {
-    signupError.value = error
-  }
-
-  /**
-   * 清空注册错误
-   */
-  function clearSignupError() {
-    signupError.value = ""
-  }
-
   return {
-    // 模态框状态
     loginModalOpen,
     signupModalOpen,
-
-    // 登录表单状态
-    loginForm,
-    loginLoading,
-    loginError,
-
-    // 注册表单状态
-    signupForm,
-    signupLoading,
-    signupError,
-
-    // 模态框操作
     openLoginModal,
     closeLoginModal,
     openSignupModal,
     closeSignupModal,
     switchToSignup,
     switchToLogin,
-
-    // 登录表单操作
-    setLoginLoading,
-    setLoginError,
-    clearLoginError,
-
-    // 注册表单操作
-    setSignupLoading,
-    setSignupError,
-    clearSignupError,
   }
 })
diff --git a/apps/web/src/shared/store/user.ts b/apps/web/src/shared/store/user.ts
index 04d96fc..f99d6d9 100644
--- a/apps/web/src/shared/store/user.ts
+++ b/apps/web/src/shared/store/user.ts
@@ -95,11 +95,14 @@ export const useUserStore = defineStore("user", () => {
   function clearProfile() {
     profile.value = null
     demoSwitch.value = false
-    // 登录框记的班级要跨退登活下来：机房一台机器对一个班，下课登出、下节课再来
-    // 还是同一个班，清掉的话每个人都得重新选一遍。它是机器的属性，不是谁的隐私。
-    const loginClass = storage.get(STORAGE_KEY.LOGIN_CLASS)
+    // 登录框记的班级和登法要跨退登活下来：机房一台机器对一个班，下课登出、下节课再来
+    // 还是同一个班，清掉的话每个人都得重新选一遍；老师的电脑同理，下次还是写用户名。
+    // 它们是机器的属性，不是谁的隐私。
+    const keep = [STORAGE_KEY.LOGIN_CLASS, STORAGE_KEY.LOGIN_MODE].map(
+      (key) => [key, storage.get(key)] as const,
+    )
     storage.clear()
-    if (loginClass !== null) storage.set(STORAGE_KEY.LOGIN_CLASS, loginClass)
+    for (const [key, value] of keep) if (value !== null) storage.set(key, value)
   }
 
   // 退登的两步（吊销服务端会话、清本地状态）绑在一起：只清本地会留一个还活着
diff --git a/apps/web/src/utils/constants.ts b/apps/web/src/utils/constants.ts
index abd5a46..d951a86 100644
--- a/apps/web/src/utils/constants.ts
+++ b/apps/web/src/utils/constants.ts
@@ -157,6 +157,7 @@ export const STORAGE_KEY = {
   ADMIN_SIDER_COLLAPSED: "adminSiderCollapsed",
   DEMO_MODE: "demoMode",
   LOGIN_CLASS: "loginClass",
+  LOGIN_MODE: "loginMode",
   RANK_CLASS: "rankClass",
 }