feat(挑战): 这节课做完了给「还能挑战」，挑战中编辑器顶上一条紫色的，老师看板上看得出谁在挑战

做完这节课（或题库里自己做对）之后列出还能挑战的题；去挑战后编辑器顶上写着要求，
没做到标出是哪几行，做到了写本班第几个、全站第几个。课堂看板做到的格子贴一枚紫色筹码、
在挑战的加一圈紫边，题卡片写挑战成功几人。出题页多一块「挑战」，能从做对的代码里找候选。

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

apps/web/src/admin/api.ts

@@ -1,6 +1,7 @@
 import { toAdminType, toProblemPermission } from "@oj2/contract"
 import type {
   AddContestProblemRequest,
+  ChallengeSuggestionsResponse,
   AddProblemsToSetRequest,
   BatchProblemTagRequest,
   BatchProblemVisibleRequest,
@@ -353,6 +354,16 @@ export function checkAstRules(data: AstCheckRequest) {
   return api.post<AstCheckResponse>("admin/ast-check", data satisfies AstCheckRequest)
 }
 
+// 出题页「挑战」的候选：拿这道题历史上做对的代码挖
+export function getChallengeSuggestions(problemId: number, language: string) {
+  return api.post<ChallengeSuggestionsResponse>(
+    `admin/problems/${problemId}/challenge-suggestions`,
+    {
+      language,
+    },
+  )
+}
+
 // AI 按题面和标准答案想几组测试输入（输出由标准答案跑）
 export function generateTestInputs(data: GenerateTestInputsRequest) {
   return api.post<GenerateTestInputsResponse>(

apps/web/src/admin/problem/components/AstRulesEditor.vue

@@ -15,6 +15,11 @@ interface Props {
   languages: LANGUAGE[]
   /** 各语言的标准答案（学生那段代码，不套模板）：拿来自测规则 */
   answers: Partial<Record<LANGUAGE, string>>
+  /**
+   * 挑战的判定规则（ChallengeEditor 里一条挑战一个）。和语法要求是同一套规则，但口径不同：
+   * 不满足不算错、说法由挑战自己写、标准答案不这么写是常事（挑战就是另一种写法）
+   */
+  challenge?: boolean
 }
 
 const props = defineProps<Props>()
@@ -294,8 +299,13 @@ watch(supportedLanguages, (langs) => {
 <template>
   <div class="astRules">
     <div class="head">
-      <span class="label">语法要求</span>
-      <div v-if="supportedLanguages.length" class="langs" role="tablist" aria-label="语言">
+      <span class="label">{{ challenge ? "判定" : "语法要求" }}</span>
+      <div
+        v-if="supportedLanguages.length && !challenge"
+        class="langs"
+        role="tablist"
+        aria-label="语言"
+      >
         <button
           v-for="lang in supportedLanguages"
           :key="lang"
@@ -310,7 +320,8 @@ watch(supportedLanguages, (langs) => {
         </button>
       </div>
       <div class="grow"></div>
-      <n-text depth="3" class="note">提交时逐条检查，不满足算错</n-text>
+      <n-text v-if="!challenge" depth="3" class="note">提交时逐条检查，不满足算错</n-text>
+      <n-text v-else depth="3" class="note">几条都满足才算做到</n-text>
     </div>
     <n-text v-if="unsupportedLanguages.length" depth="3" class="note">
       {{ unsupportedLanguages.join("、") }} 检查不了语法要求（判题机只认
@@ -402,6 +413,7 @@ watch(supportedLanguages, (langs) => {
           </div>
           <div class="ruleRow sub">
             <n-input
+              v-if="!challenge"
               :value="rule.message"
               size="tiny"
               class="message"
@@ -412,7 +424,19 @@ watch(supportedLanguages, (langs) => {
               "
               @update:value="(v: string) => updateRule(lang, index, 'message', v)"
             />
-            <span v-if="checkOf(lang, index)?.passed === true" class="ok">✓ 标准答案过了</span>
+            <template v-if="challenge">
+              <n-text v-if="checkOf(lang, index)?.passed === true" depth="3" class="note">
+                标准答案这样写也满足
+              </n-text>
+              <n-text v-else-if="checkOf(lang, index)?.passed === false" depth="3" class="note">
+                标准答案不是这样写的{{
+                  checkOf(lang, index)!.actual !== undefined
+                    ? `（数到 ${checkOf(lang, index)!.actual} 次）`
+                    : ""
+                }}
+              </n-text>
+            </template>
+            <span v-else-if="checkOf(lang, index)?.passed === true" class="ok">✓ 标准答案过了</span>
             <span v-else-if="checkOf(lang, index)?.passed === false" class="bad">
               ✗ 标准答案自己没过{{
                 checkOf(lang, index)!.actual !== undefined

apps/web/src/admin/problem/components/ChallengeEditor.vue

@@ -0,0 +1,265 @@
+<script setup lang="ts">
+import {
+  AST_SUPPORTED_LANGUAGES,
+  CHALLENGE_RULES_MAX,
+  CHALLENGE_WORDING_MAX,
+  CHALLENGES_PER_LANGUAGE_MAX,
+  type AstRules,
+  type ChallengeInput,
+  type ChallengeSuggestionsResponse,
+} from "@oj2/contract"
+import { errorMessage } from "utils/api"
+import type { LANGUAGE } from "utils/types"
+import { getChallengeSuggestions } from "../../api"
+import AstRulesEditor from "./AstRulesEditor.vue"
+
+/**
+ * 出题页的「挑战」：做对之后，同一道题加一条写法上的限制再做一遍（设计稿 StkAdmin）。
+ * 判定就是语法要求那套规则，所以每条挑战底下直接摆一个规则编辑器（只开这一种语言）。
+ *
+ * 「从做对的代码里找」把这道题历史上做对的代码挖一遍，列出「一批人用另一种写法也做对了」
+ * 的地方。机械挖出来的会有坏的（拆掉 elif 换成一串 if 也算「不用 elif」），所以每条带一份
+ * 做到的人的真实代码，好不好老师看了再加。新建的题还没人做过，不给这个按钮。
+ */
+const props = defineProps<{
+  modelValue: Record<string, ChallengeInput[]> | null
+  languages: LANGUAGE[]
+  answers: Partial<Record<LANGUAGE, string>>
+  /** 编辑已有的题才有；新建的题没有做对的代码可挖 */
+  problemId: number | null
+}>()
+const emit = defineEmits<{
+  (e: "update:modelValue", value: Record<string, ChallengeInput[]> | null): void
+}>()
+
+const languages = computed(() =>
+  props.languages.filter((lang) => AST_SUPPORTED_LANGUAGES.includes(lang)),
+)
+const tab = ref<string>(languages.value[0] ?? "Python")
+watch(languages, (list) => {
+  if (!list.includes(tab.value as LANGUAGE)) tab.value = list[0] ?? "Python"
+})
+
+const list = computed(() => props.modelValue?.[tab.value] ?? [])
+
+function update(next: ChallengeInput[]) {
+  const value = { ...props.modelValue }
+  if (next.length) value[tab.value] = next
+  else delete value[tab.value]
+  emit("update:modelValue", Object.keys(value).length ? value : null)
+}
+
+function patch(index: number, change: Partial<ChallengeInput>) {
+  update(list.value.map((item, i) => (i === index ? { ...item, ...change } : item)))
+}
+
+function remove(index: number) {
+  update(list.value.filter((_, i) => i !== index))
+}
+
+function add(item: ChallengeInput = { wording: "", rules: [] }) {
+  update([...list.value, item])
+}
+
+/** AstRulesEditor 按语言分组收发，这里只给它一种语言 */
+function rulesModel(item: ChallengeInput): AstRules {
+  return { [tab.value]: item.rules }
+}
+function onRules(index: number, value: AstRules | null) {
+  patch(index, { rules: (value?.[tab.value] ?? []).slice(0, CHALLENGE_RULES_MAX) })
+}
+
+const full = computed(() => list.value.length >= CHALLENGES_PER_LANGUAGE_MAX)
+
+// ---------------------------------------------------------------- 候选
+
+const suggestions = ref<Record<string, ChallengeSuggestionsResponse>>({})
+const loading = ref(false)
+const error = ref("")
+
+async function findSuggestions() {
+  if (!props.problemId) return
+  loading.value = true
+  error.value = ""
+  try {
+    suggestions.value = {
+      ...suggestions.value,
+      [tab.value]: await getChallengeSuggestions(props.problemId, tab.value),
+    }
+  } catch (err) {
+    error.value = errorMessage(err, "没找成")
+  } finally {
+    loading.value = false
+  }
+}
+
+const current = computed(() => suggestions.value[tab.value] ?? null)
+
+/** 已经加上的不再列 */
+const shown = computed(() => {
+  const taken = list.value.map((item) => JSON.stringify(item.rules))
+  return (current.value?.suggestions ?? []).filter(
+    (item) => !taken.includes(JSON.stringify(item.rules)),
+  )
+})
+</script>
+
+<template>
+  <div class="challenge-editor">
+    <n-radio-group v-if="languages.length > 1" v-model:value="tab" size="small">
+      <n-radio-button v-for="lang in languages" :key="lang" :value="lang">
+        {{ lang }}{{ modelValue?.[lang]?.length ? ` ${modelValue[lang]!.length} 条` : "" }}
+      </n-radio-button>
+    </n-radio-group>
+
+    <div v-for="(item, index) in list" :key="`${tab}-${item.id ?? index}`" class="item">
+      <div class="itemHead">
+        <span class="index">{{ index + 1 }}</span>
+        <n-input
+          :value="item.wording"
+          :maxlength="CHALLENGE_WORDING_MAX"
+          placeholder="给学生看的说法，例如「整首歌只用 1 次 print」"
+          :status="item.wording.trim() ? undefined : 'warning'"
+          @update:value="(value: string) => patch(index, { wording: value })"
+        />
+        <n-button size="small" quaternary @click="remove(index)">删掉</n-button>
+      </div>
+      <AstRulesEditor
+        :model-value="rulesModel(item)"
+        :languages="[tab as LANGUAGE]"
+        :answers="answers"
+        challenge
+        @update:model-value="(value) => onRules(index, value)"
+      />
+    </div>
+
+    <n-text v-if="!languages.length" depth="3" class="note">
+      只有 Python、C、C++ 能配挑战，先在「学生怎么写」里勾上其中一种。
+    </n-text>
+    <template v-else>
+      <div class="actions">
+        <n-button size="small" :disabled="full" @click="add()">+ 自己写一条</n-button>
+        <n-button
+          v-if="problemId"
+          size="small"
+          :loading="loading"
+          :disabled="full"
+          @click="findSuggestions"
+        >
+          从做对的代码里找
+        </n-button>
+      </div>
+      <n-text v-if="error" type="error" class="note">{{ error }}</n-text>
+
+      <div v-if="current" class="suggestions">
+        <n-text depth="3" class="note">
+          {{ current.acCount }} 个人用 {{ tab }} 做对过，下面是有一批人换了种写法也做对的地方
+        </n-text>
+        <n-text v-if="!shown.length" depth="3" class="note">没找到别的写法</n-text>
+        <div v-for="item in shown" :key="JSON.stringify(item.rules)" class="suggestion">
+          <div class="suggestionHead">
+            <div class="suggestionText">
+              <b>{{ item.wording }}</b>
+              <n-text depth="3" class="note">
+                {{ item.did }} 人这样做对<template v-if="item.firstShare !== null"
+                  >，第一次做对时 {{ item.firstShare }}% 这样写</template
+                >
+              </n-text>
+            </div>
+            <n-button
+              size="small"
+              :disabled="full"
+              @click="add({ wording: item.wording, rules: item.rules })"
+            >
+              加上
+            </n-button>
+          </div>
+          <pre class="example">{{ item.example }}</pre>
+        </div>
+      </div>
+    </template>
+  </div>
+</template>
+
+<style scoped>
+.challenge-editor {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+
+.item {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  padding: 10px 12px;
+  border: 1px solid rgba(91, 52, 196, 0.3);
+  border-radius: 6px;
+}
+
+.itemHead {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.index {
+  flex-shrink: 0;
+  width: 22px;
+  height: 22px;
+  border-radius: 11px;
+  background-color: rgba(91, 52, 196, 0.12);
+  color: #5b34c4;
+  font-size: 12px;
+  font-weight: 600;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.actions {
+  display: flex;
+  gap: 8px;
+}
+
+.note {
+  font-size: 12px;
+}
+
+.suggestions {
+  display: flex;
+  flex-direction: column;
+}
+
+.suggestion {
+  padding: 10px 0;
+  border-top: 1px solid rgba(128, 128, 128, 0.15);
+}
+
+.suggestionHead {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 12px;
+}
+
+.suggestionText {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+  min-width: 0;
+}
+
+.example {
+  margin: 6px 0 0;
+  padding: 6px 10px;
+  border: 1px solid rgba(128, 128, 128, 0.2);
+  border-radius: 4px;
+  font-family: ui-monospace, "Cascadia Mono", Consolas, "Microsoft YaHei", monospace;
+  font-size: 12.5px;
+  line-height: 1.6;
+  white-space: pre;
+  overflow-x: auto;
+  max-height: 180px;
+}
+</style>

apps/web/src/admin/problem/detail.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { TEST_CASE_MAX_CASES, type RunnableLanguage } from "@oj2/contract"
+import { TEST_CASE_MAX_CASES, type ChallengeInput, type RunnableLanguage } from "@oj2/contract"
 import { useThemeVars } from "naive-ui"
 import PageHeader from "admin/components/PageHeader.vue"
 import { getProblemTagList } from "shared/api"
@@ -19,6 +19,7 @@ import {
   uploadTestcases,
 } from "../api"
 import AstRulesEditor from "./components/AstRulesEditor.vue"
+import ChallengeEditor from "./components/ChallengeEditor.vue"
 import CaseTable from "./components/CaseTable.vue"
 import CodePreview from "./components/CodePreview.vue"
 import PreviewStrip from "./components/PreviewStrip.vue"
@@ -108,6 +109,8 @@ interface CodeForm {
   answers: Record<RunnableLanguage, string>
   templates: Record<RunnableLanguage, TemplateParts>
   astRules: AstRules | null
+  /** 做对之后的挑战，按语言分组（见契约 challengeSchema） */
+  challenges: Record<string, ChallengeInput[]> | null
   flowchartMode: FlowchartMode
   mermaidCode: string
   /** 画布画的参考流程图；null 是老题（只有手写的 Mermaid）或者还没画 */
@@ -135,6 +138,7 @@ const blankForm = (): CodeForm => ({
   answers: { Python: "", C: "", "C++": "" },
   templates: { Python: blankParts(), C: blankParts(), "C++": blankParts() },
   astRules: null,
+  challenges: null,
   flowchartMode: "none",
   mermaidCode: "",
   flowchartDoc: null,
@@ -428,6 +432,14 @@ watch(
 const showHidden = ref(false)
 const astChecks = ref<AstCheckState>({})
 
+const challengeSummary = computed(() => {
+  const parts = form.languages
+    .map((lang) => [lang, form.challenges?.[lang]?.length ?? 0] as const)
+    .filter(([, n]) => n > 0)
+    .map(([lang, n]) => `${lang} ${n} 条`)
+  return parts.length ? parts.join(" · ") : "没有"
+})
+
 const answersForAst = computed(() => ({ ...form.answers }) as Partial<Record<LANGUAGE, string>>)
 const templatesForPreview = computed(
   () => ({ ...form.templates }) as Partial<Record<LANGUAGE, TemplateParts>>,
@@ -493,6 +505,7 @@ const open = reactive({
   answer: true,
   cases: true,
   write: false,
+  challenge: false,
   flowchart: false,
   more: false,
 })
@@ -612,6 +625,15 @@ async function loadProblem(data: AdminProblem) {
     answers,
     templates,
     astRules: data.astRules ?? null,
+    // scannedAt 是后端记账用的，表单里不带；id 带着，规则没改就沿用（做到记录跟着 id 走）
+    challenges: data.challenges
+      ? Object.fromEntries(
+          Object.entries(data.challenges).map(([lang, list]) => [
+            lang,
+            list.map(({ id, wording, rules }) => ({ id, wording, rules })),
+          ]),
+        )
+      : null,
     flowchartMode: data.allowFlowchart ? "draw" : data.showFlowchart ? "show" : "none",
     mermaidCode: data.mermaidCode ?? "",
     flowchartDoc: parseDoc(data.flowchartData),
@@ -719,6 +741,15 @@ const blockers = computed<Blocker[]>(() => {
           })
       })
   }
+  for (const lang of form.languages) {
+    form.challenges?.[lang]?.forEach((item, i) => {
+      if (!item.wording.trim() || !item.rules.length)
+        list.push({
+          text: `把挑战 ${lang} 第 ${i + 1} 条${item.wording.trim() ? "的规则" : "的说法"}写上`,
+          section: "challenge",
+        })
+    })
+  }
   if (form.flowchartMode === "show") {
     if (legacyMermaid.value) {
       if (!mermaidOk.value)
@@ -804,6 +835,7 @@ async function save() {
           : null,
       flowchartHint: form.flowchartHint.trim(),
       astRules: form.astRules,
+      challenges: form.challenges,
       sqlConfig: null,
       sqlDisplay: null,
       contestId: props.contestID ? Number(props.contestID) : null,
@@ -1197,6 +1229,24 @@ onMounted(async () => {
         </template>
       </section>
 
+      <!-- 挑战 -->
+      <section id="section-challenge" class="card">
+        <button type="button" class="cardHead" @click="open.challenge = !open.challenge">
+          <h3>挑战</h3>
+          <span v-if="!open.challenge" class="summary">{{ challengeSummary }}</span>
+          <n-text v-else depth="3" class="note">选填，学生做对以后才看得到</n-text>
+          <span class="grow"></span>
+          <span class="caret">{{ open.challenge ? "⌃" : "›" }}</span>
+        </button>
+        <ChallengeEditor
+          v-if="open.challenge"
+          v-model="form.challenges"
+          :languages="form.languages"
+          :answers="answersForAst"
+          :problem-id="props.initial?.id ?? null"
+        />
+      </section>
+
       <!-- 流程图 -->
       <section id="section-flowchart" class="card">
         <button type="button" class="cardHead" @click="open.flowchart = !open.flowchart">