feat(题单): 「截止时间」改成「布置期」，布置期内没加入的人也藏旧代码；老师能看全班情况，后台一次加好几道题

- 布置期（列名仍是 end_time，机房共库不改名）+ 新列 assigned_at：布置期内题单里这几道题，
  学生在布置开始之前交的代码先藏起来，不管加没加入，堵住「先抄再加入」；做对或到期放出来，不拦做题
- 「总分达到 N」奖章换成「做对 N 道」，草稿并进「不公开」（0026）
- /problem-sets 带布置期、必做题数、奖章获得时间；题目带做对时刻、错几次、旧代码藏着没有
- 新增 /problem-sets/:id/class-view（老师看一个班：真名 × 每题，加入前就做对过）、/problem-sets/locks
- 后台：批量加题、拖动排序、切必做；去掉状态、难度、分数、提示和单独的进度页

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

apps/api/src/db/0026_problemset_assignment.sql

@@ -0,0 +1,10 @@
+-- 题单的「截止时间」改成「布置到」：它从来不截止任何东西，只管布置期内藏学生以前的代码（防抄），
+-- 见 services/problemset.ts 的 problemSetLockCutoffs。列名 end_time 不改（机房和服务器共库，
+-- 改名会让没升级的那边直接报错）；旧值是按旧语义填的（3 个题单，都已过期），清掉。
+ALTER TABLE "problemset" ADD COLUMN "assigned_at" timestamp with time zone;--> statement-breakpoint
+UPDATE "problemset" SET "end_time" = NULL;--> statement-breakpoint
+-- 「状态」和「可见」两道闸合成一个「公开」：草稿等于不公开，归档等于公开（一直都还能进）
+UPDATE "problemset" SET "visible" = false WHERE "status" = 'draft';--> statement-breakpoint
+UPDATE "problemset" SET "status" = 'active' WHERE "status" <> 'active';--> statement-breakpoint
+-- 分数拿掉了，「总分达到 N」的奖章换成「做对 N 道」（线上那几套题每题 10 分，门槛不变）
+UPDATE "problemset_badge" SET "condition_type" = 'problem_count', "condition_value" = GREATEST(1, CEIL("condition_value" / 10.0)) WHERE "condition_type" = 'score';

apps/api/src/db/meta/_journal.json

@@ -183,6 +183,13 @@
       "when": 1791521256834,
       "tag": "0025_submission_problem_user_idx",
       "breakpoints": true
+    },
+    {
+      "idx": 26,
+      "version": "7",
+      "when": 1791553481647,
+      "tag": "0026_problemset_assignment",
+      "breakpoints": true
     }
   ]
 }

apps/api/src/db/schema.ts

@@ -417,7 +417,17 @@ export const problemset = pgTable(
     difficulty: text().notNull().$type<ProblemSetDifficulty>(),
     status: text().notNull().$type<ProblemSetStatus>(),
     createdById: integer("created_by_id").notNull(),
-    endTime: timestamp("end_time", { withTimezone: true, mode: "string" }),
+    /**
+     * 布置期：assignedAt 是这一轮布置开始的时刻，assignedUntil 是布置到哪天（东八区当天结束）。
+     * 布置期内，题单里这几道题学生在 assignedAt 之前交的代码先藏起来（防抄），见
+     * services/problemset.ts 的 problemSetLockCutoffs。不拦做题，过期照样做、照样记进度。
+     * 两个都为空 = 没布置。
+     *
+     * 列名还是 end_time（以前叫「截止时间」，名不副实）：机房那套和服务器共用这个库、
+     * 不一定同时升级，改列名会让没升级的那边一查题单就报错，所以只改代码里的名字
+     */
+    assignedUntil: timestamp("end_time", { withTimezone: true, mode: "string" }),
+    assignedAt: timestamp("assigned_at", { withTimezone: true, mode: "string" }),
   },
   (table) => [
     index("problemset_created_by_id_01b5197f").using(

apps/api/src/routes/admin/problemset.ts

@@ -1,18 +1,18 @@
 import {
-  addProblemToSetRequestSchema,
+  addProblemsToSetRequestSchema,
   createProblemSetBadgeRequestSchema,
   createProblemSetRequestSchema,
+  reorderProblemSetProblemsRequestSchema,
   updateProblemInSetRequestSchema,
   updateProblemSetBadgeRequestSchema,
   updateProblemSetRequestSchema,
-  updateProblemSetStatusRequestSchema,
+  type AddProblemsToSetResult,
   type AdminProblemSet,
   type AdminProblemSetBadge,
   type AdminProblemSetList,
   type AdminProblemSetProblem,
-  type AdminProblemSetProgress,
 } from "@oj2/contract"
-import { and, asc, count, desc, eq, ilike, inArray, isNull, or, sql } from "drizzle-orm"
+import { and, asc, count, desc, eq, ilike, inArray, isNull, max, or, sql } from "drizzle-orm"
 import { Hono } from "hono"
 
 import { requireTeacher, type AppEnv } from "../../auth/middleware"
@@ -20,7 +20,7 @@ import type { AuthUser } from "../../auth/session"
 import { db, schema } from "../../db"
 import { failure, parseBody, success } from "../../http"
 import { recalculateBadge, resyncProgress } from "../../services/problemset"
-import { asFilterValue, queryInteger, sampleUser } from "../helpers"
+import { queryInteger, sampleUser } from "../helpers"
 
 export const adminProblemSetRoutes = new Hono<AppEnv>()
 
@@ -49,11 +49,11 @@ async function serialize(row: typeof schema.problemset.$inferSelect) {
   return (await serializeMany([row]))[0]!
 }
 
-/** 批量版：列表接口走这个，固定 3 条查询，与行数无关（按行 serialize 就是 N+1） */
+/** 批量版：列表接口走这个，固定 4 条查询，与行数无关（按行 serialize 就是 N+1） */
 async function serializeMany(rows: (typeof schema.problemset.$inferSelect)[]) {
   if (rows.length === 0) return []
   const ids = rows.map((row) => row.id)
-  const [problems, participants, creators] = await Promise.all([
+  const [problems, participants, badges, creators] = await Promise.all([
     db
       .select({
         problemsetId: schema.problemsetProblem.problemsetId,
@@ -66,10 +66,19 @@ async function serializeMany(rows: (typeof schema.problemset.$inferSelect)[]) {
       .select({
         problemsetId: schema.problemsetProgress.problemsetId,
         value: count(),
+        completed: sql<number>`count(*) filter (where ${schema.problemsetProgress.isCompleted})::int`,
       })
       .from(schema.problemsetProgress)
       .where(inArray(schema.problemsetProgress.problemsetId, ids))
       .groupBy(schema.problemsetProgress.problemsetId),
+    db
+      .select({
+        problemsetId: schema.problemsetBadge.problemsetId,
+        value: count(),
+      })
+      .from(schema.problemsetBadge)
+      .where(inArray(schema.problemsetBadge.problemsetId, ids))
+      .groupBy(schema.problemsetBadge.problemsetId),
     db
       .select({
         id: schema.user.id,
@@ -81,27 +90,57 @@ async function serializeMany(rows: (typeof schema.problemset.$inferSelect)[]) {
       .where(inArray(schema.user.id, [...new Set(rows.map((row) => row.createdById))])),
   ])
   const problemsBySet = new Map(problems.map((item) => [item.problemsetId, item.value]))
-  const participantsBySet = new Map(participants.map((item) => [item.problemsetId, item.value]))
+  const participantsBySet = new Map(participants.map((item) => [item.problemsetId, item]))
+  const badgesBySet = new Map(badges.map((item) => [item.problemsetId, item.value]))
   const creatorById = new Map(creators.map((item) => [item.id, item]))
+  const now = Date.now()
   return rows.map((row) => {
     const creator = creatorById.get(row.createdById)
     return {
       id: row.id,
       title: row.title,
       description: row.description,
-      difficulty: row.difficulty,
-      status: row.status,
-      endTime: row.endTime,
+      assignedUntil: row.assignedUntil,
+      assignedAt: row.assignedAt,
+      assigning:
+        row.assignedAt !== null &&
+        row.assignedUntil !== null &&
+        Date.parse(row.assignedUntil) > now,
       visible: row.visible,
       createdBy: sampleUser(creator ?? { id: row.createdById, username: "" }, creator?.realName),
       createTime: row.createTime,
       lastUpdateTime: row.lastUpdateTime,
       problemsCount: problemsBySet.get(row.id) ?? 0,
-      participantCount: participantsBySet.get(row.id) ?? 0,
+      participantCount: participantsBySet.get(row.id)?.value ?? 0,
+      completedCount: participantsBySet.get(row.id)?.completed ?? 0,
+      badgeCount: badgesBySet.get(row.id) ?? 0,
     } satisfies AdminProblemSet
   })
 }
 
+/**
+ * 布置期怎么落库。老师给的是「布置到哪天」（东八区当天结束的时刻），开始时刻由服务端定：
+ *   - 不布置 → 两个都清掉；
+ *   - 现在正在布置 → 只改结束，开始不动（延长、缩短都不该把「以前的代码」的分界挪到现在）；
+ *   - 没在布置（从没布置过，或者上一轮已经过期）→ 开始记成现在，这就是「再布置一次」。
+ */
+function assignment(
+  requested: string | null,
+  current: { assignedAt: string | null; assignedUntil: string | null } | null,
+) {
+  if (requested === null) return { assignedAt: null, assignedUntil: null }
+  const until = Date.parse(requested)
+  if (!Number.isFinite(until) || until <= Date.now()) return "past" as const
+  const running =
+    current?.assignedAt != null &&
+    current.assignedUntil != null &&
+    Date.parse(current.assignedUntil) > Date.now()
+  return {
+    assignedAt: running ? current.assignedAt : new Date().toISOString(),
+    assignedUntil: new Date(until).toISOString(),
+  }
+}
+
 // ---------------------------------------------------------------- 题单本体
 
 adminProblemSetRoutes.get("/problem-sets", requireTeacher, async (c) => {
@@ -114,8 +153,6 @@ adminProblemSetRoutes.get("/problem-sets", requireTeacher, async (c) => {
   // 再也没法在界面上改回来。后台必须能看见自己管的全部题单。
   if (user.adminType !== "Super Admin") filters.push(eq(schema.problemset.createdById, user.id))
   const keyword = c.req.query("keyword")?.trim()
-  const difficulty = c.req.query("difficulty")?.trim()
-  const status = c.req.query("status")?.trim()
   if (keyword) {
     filters.push(
       or(
@@ -124,8 +161,6 @@ adminProblemSetRoutes.get("/problem-sets", requireTeacher, async (c) => {
       )!,
     )
   }
-  if (difficulty) filters.push(eq(schema.problemset.difficulty, asFilterValue(difficulty)))
-  if (status) filters.push(eq(schema.problemset.status, asFilterValue(status)))
   const where = filters.length ? and(...filters) : undefined
 
   const [totalRows, rows] = await Promise.all([
@@ -147,12 +182,19 @@ adminProblemSetRoutes.get("/problem-sets", requireTeacher, async (c) => {
 adminProblemSetRoutes.post("/problem-sets", requireTeacher, async (c) => {
   const parsed = await parseBody(c, createProblemSetRequestSchema)
   if (!parsed.success) return parsed.response
+  const period = assignment(parsed.data.assignedUntil, null)
+  if (period === "past") return failure(c, 400, "assign-in-past", "布置到的日期已经过了")
   const now = new Date().toISOString()
   const [created] = await db
     .insert(schema.problemset)
     .values({
-      ...parsed.data,
-      endTime: parsed.data.endTime ? new Date(parsed.data.endTime).toISOString() : null,
+      title: parsed.data.title,
+      description: parsed.data.description,
+      visible: parsed.data.visible,
+      ...period,
+      // 难度、状态两列还在表里、非空，但已经不用了（见契约 admin.ts 的说明）
+      difficulty: "Easy",
+      status: "active",
       createdById: c.get("user")!.id,
       createTime: now,
       lastUpdateTime: now,
@@ -172,11 +214,15 @@ adminProblemSetRoutes.put("/problem-sets/:id", requireTeacher, async (c) => {
   if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
   const parsed = await parseBody(c, updateProblemSetRequestSchema)
   if (!parsed.success) return parsed.response
+  const period = assignment(parsed.data.assignedUntil, row)
+  if (period === "past") return failure(c, 400, "assign-in-past", "布置到的日期已经过了")
   const [updated] = await db
     .update(schema.problemset)
     .set({
-      ...parsed.data,
-      endTime: parsed.data.endTime ? new Date(parsed.data.endTime).toISOString() : null,
+      title: parsed.data.title,
+      description: parsed.data.description,
+      visible: parsed.data.visible,
+      ...period,
       lastUpdateTime: new Date().toISOString(),
     })
     .where(eq(schema.problemset.id, row.id))
@@ -196,22 +242,6 @@ adminProblemSetRoutes.put("/problem-sets/:id/visibility", requireTeacher, async
   return success(c, await serialize(updated!))
 })
 
-adminProblemSetRoutes.put("/problem-sets/:id/status", requireTeacher, async (c) => {
-  const row = await loadOwned(c, c.get("user")!)
-  if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
-  const parsed = await parseBody(c, updateProblemSetStatusRequestSchema, "status 不合法")
-  if (!parsed.success) return parsed.response
-  const [updated] = await db
-    .update(schema.problemset)
-    .set({
-      status: parsed.data.status,
-      lastUpdateTime: new Date().toISOString(),
-    })
-    .where(eq(schema.problemset.id, row.id))
-    .returning()
-  return success(c, await serialize(updated!))
-})
-
 adminProblemSetRoutes.delete("/problem-sets/:id", requireTeacher, async (c) => {
   const row = await loadOwned(c, c.get("user")!)
   if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
@@ -245,59 +275,97 @@ adminProblemSetRoutes.get("/problem-sets/:id/problems", requireTeacher, async (c
           difficulty: problem.difficulty,
           order: item.order,
           isRequired: item.isRequired,
-          score: item.score,
-          hint: item.hint,
         }) satisfies AdminProblemSetProblem,
     ),
   )
 })
 
+/**
+ * 加题：一次可以给好几个题号（后台搜索框里粘一串「3065 3066 3067」），按给的顺序接在最后。
+ * 找不到的、本来就在里面的不报错，分开报回去，前端告诉老师哪几个没加上。
+ */
 adminProblemSetRoutes.post("/problem-sets/:id/problems", requireTeacher, async (c) => {
   const row = await loadOwned(c, c.get("user")!)
   if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
-  const parsed = await parseBody(c, addProblemToSetRequestSchema)
+  const parsed = await parseBody(c, addProblemsToSetRequestSchema)
   if (!parsed.success) return parsed.response
-  const [problem] = await db
-    .select({ id: schema.problem.id })
-    .from(schema.problem)
-    .where(
-      and(
-        sql`lower(${schema.problem.displayId}) = lower(${parsed.data.problemId})`,
-        eq(schema.problem.visible, true),
-        isNull(schema.problem.contestId),
+  const wanted = [...new Set(parsed.data.problemIds.map((id) => id.toLowerCase()))]
+  const [problems, existing, last] = await Promise.all([
+    db
+      .select({ id: schema.problem.id, displayId: schema.problem.displayId })
+      .from(schema.problem)
+      .where(
+        and(
+          inArray(sql<string>`lower(${schema.problem.displayId})`, wanted),
+          eq(schema.problem.visible, true),
+          isNull(schema.problem.contestId),
+        ),
       ),
-    )
-    .limit(1)
-  if (!problem) return failure(c, 404, "problem-not-found", "题目不存在或不可见")
+    db
+      .select({ problemId: schema.problemsetProblem.problemId })
+      .from(schema.problemsetProblem)
+      .where(eq(schema.problemsetProblem.problemsetId, row.id)),
+    db
+      .select({ value: max(schema.problemsetProblem.order) })
+      .from(schema.problemsetProblem)
+      .where(eq(schema.problemsetProblem.problemsetId, row.id)),
+  ])
+  const byDisplayId = new Map(problems.map((problem) => [problem.displayId.toLowerCase(), problem]))
+  const inSet = new Set(existing.map((item) => item.problemId))
+  const result: AddProblemsToSetResult = { added: [], missing: [], duplicate: [] }
+  const values: (typeof schema.problemsetProblem.$inferInsert)[] = []
+  let order = last[0]?.value ?? 0
+  for (const id of wanted) {
+    const problem = byDisplayId.get(id)
+    if (!problem) result.missing.push(id)
+    else if (inSet.has(problem.id)) result.duplicate.push(problem.displayId)
+    else {
+      inSet.add(problem.id)
+      order += 1
+      // 分数、提示两列还在表里但已经不用了：score 非空给 0
+      values.push({
+        problemsetId: row.id,
+        problemId: problem.id,
+        order,
+        isRequired: true,
+        score: 0,
+      })
+      result.added.push(problem.displayId)
+    }
+  }
+  if (values.length) {
+    await db.insert(schema.problemsetProblem).values(values)
+    // 题目集变了，已加入的人的分母、完成状态、奖章都得跟着变（旧栈靠 post_save 信号，
+    // 不在 views 里，别因为翻不到显式调用就以为它没做，见 services/problemset.ts）
+    await resyncProgress(row.id)
+  }
+  return success(c, result, values.length ? 201 : 200)
+})
 
-  const [duplicate] = await db
+// 必须注册在 /problems/:itemId 前面：Hono 按注册顺序匹配，order 会被当成 :itemId 吃掉
+adminProblemSetRoutes.put("/problem-sets/:id/problems/order", requireTeacher, async (c) => {
+  const row = await loadOwned(c, c.get("user")!)
+  if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
+  const parsed = await parseBody(c, reorderProblemSetProblemsRequestSchema)
+  if (!parsed.success) return parsed.response
+  const links = await db
     .select({ id: schema.problemsetProblem.id })
     .from(schema.problemsetProblem)
-    .where(
-      and(
-        eq(schema.problemsetProblem.problemsetId, row.id),
-        eq(schema.problemsetProblem.problemId, problem.id),
-      ),
-    )
-    .limit(1)
-  if (duplicate) return failure(c, 409, "problem-already-in-set", "题目已在该题单中")
-
-  const [created] = await db
-    .insert(schema.problemsetProblem)
-    .values({
-      problemsetId: row.id,
-      problemId: problem.id,
-      order: parsed.data.order,
-      isRequired: parsed.data.isRequired,
-      score: parsed.data.score,
-      hint: parsed.data.hint,
-    })
-    .returning({ id: schema.problemsetProblem.id })
-  // 题目集变了，已加入的人的 totalProblemsCount / 百分比都得跟着变，
-  // 否则学生看到的进度分母还是老的。旧栈是靠 ProblemSetProblem 的 post_save 信号做的，
-  // 不在 views 里，别因为翻不到显式调用就以为它没做（见 services/problemset.ts）。
-  await resyncProgress(row.id)
-  return success(c, { id: created!.id }, 201)
+    .where(eq(schema.problemsetProblem.problemsetId, row.id))
+  const have = new Set(links.map((link) => link.id))
+  const given = new Set(parsed.data.ids)
+  if (given.size !== have.size || [...given].some((id) => !have.has(id))) {
+    return failure(c, 409, "problems-changed", "题目列表变了，刷新一下再排")
+  }
+  await db.transaction(async (tx) => {
+    for (const [index, id] of parsed.data.ids.entries()) {
+      await tx
+        .update(schema.problemsetProblem)
+        .set({ order: index + 1 })
+        .where(eq(schema.problemsetProblem.id, id))
+    }
+  })
+  return success(c, null)
 })
 
 adminProblemSetRoutes.put("/problem-sets/:id/problems/:itemId", requireTeacher, async (c) => {
@@ -316,7 +384,8 @@ adminProblemSetRoutes.put("/problem-sets/:id/problems/:itemId", requireTeacher,
     )
     .returning({ id: schema.problemsetProblem.id })
   if (updated.length === 0) return failure(c, 404, "problem-not-in-set", "题目不在该题单中")
-  if (parsed.data.score !== undefined) await resyncProgress(row.id)
+  // 必做 / 选做变了，分母和「做完」跟着变
+  await resyncProgress(row.id)
   return success(c, null)
 })
 
@@ -453,84 +522,3 @@ adminProblemSetRoutes.delete("/problem-sets/:id/badges/:badgeId", requireTeacher
   await db.delete(schema.problemsetBadge).where(eq(schema.problemsetBadge.id, badge.id))
   return success(c, null)
 })
-
-// ---------------------------------------------------------------- 学生进度
-
-adminProblemSetRoutes.get("/problem-sets/:id/progress", requireTeacher, async (c) => {
-  const row = await loadOwned(c, c.get("user")!)
-  if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
-  const rows = await db
-    .select({
-      progress: schema.problemsetProgress,
-      username: schema.user.username,
-      realName: schema.userProfile.realName,
-    })
-    .from(schema.problemsetProgress)
-    .innerJoin(schema.user, eq(schema.problemsetProgress.userId, schema.user.id))
-    .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
-    .where(eq(schema.problemsetProgress.problemsetId, row.id))
-    .orderBy(desc(schema.problemsetProgress.joinTime))
-  return success(
-    c,
-    rows.map(
-      ({ progress, username, realName }) =>
-        ({
-          id: progress.id,
-          userId: progress.userId,
-          username,
-          // 真名有意下发：这是老师看本班完成情况的页面，已由 requireTeacher + 归属校验把关
-          realName,
-          joinTime: progress.joinTime,
-          completeTime: progress.completeTime,
-          isCompleted: progress.isCompleted,
-          progressPercentage: progress.progressPercentage,
-          completedProblemsCount: progress.completedProblemsCount,
-          totalProblemsCount: progress.totalProblemsCount,
-          totalScore: progress.totalScore,
-        }) satisfies AdminProblemSetProgress,
-    ),
-  )
-})
-
-adminProblemSetRoutes.delete("/problem-sets/:id/progress/:userId", requireTeacher, async (c) => {
-  const row = await loadOwned(c, c.get("user")!)
-  if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
-  const userId = queryInteger(c.req.param("userId"), 0, { min: 1 })
-  const deleted = await db.transaction(async (tx) => {
-    // 把人踢出题单，他基于这份题单拿到的奖章也该收回，否则奖章会悬空
-    const badges = await tx
-      .select({ id: schema.problemsetBadge.id })
-      .from(schema.problemsetBadge)
-      .where(eq(schema.problemsetBadge.problemsetId, row.id))
-    if (badges.length) {
-      await tx.delete(schema.userBadge).where(
-        and(
-          eq(schema.userBadge.userId, userId),
-          inArray(
-            schema.userBadge.badgeId,
-            badges.map((badge) => badge.id),
-          ),
-        ),
-      )
-    }
-    await tx
-      .delete(schema.problemsetSubmission)
-      .where(
-        and(
-          eq(schema.problemsetSubmission.problemsetId, row.id),
-          eq(schema.problemsetSubmission.userId, userId),
-        ),
-      )
-    return tx
-      .delete(schema.problemsetProgress)
-      .where(
-        and(
-          eq(schema.problemsetProgress.problemsetId, row.id),
-          eq(schema.problemsetProgress.userId, userId),
-        ),
-      )
-      .returning({ id: schema.problemsetProgress.id })
-  })
-  if (deleted.length === 0) return failure(c, 404, "progress-not-found", "用户未加入该题单")
-  return success(c, null)
-})

apps/api/src/routes/flowchart.ts

@@ -23,7 +23,7 @@ import { db, schema } from "../db"
 import { failure, readJson, success } from "../http"
 import { flowchartQueue } from "../queue"
 import { getBooleanOption } from "../services/options"
-import { problemSetJoinTimes } from "../services/problemset"
+import { problemSetLockCutoffs } from "../services/problemset"
 import { consumeToken } from "../services/throttling"
 import { buildWordFrequencies } from "../services/word-frequency"
 import { dayStart } from "../time"
@@ -49,36 +49,36 @@ function flowchartThrottleKey(userId: number) {
 }
 
 /**
- * 题单防抄：学生加入含这道题的题单之前画的图，先对他本人藏起来 —— 和代码提交同一道闸
- * （routes/submission.ts 的 canViewSubmission，规则见 problemSetJoinTimes）。原来流程图
- * 这边没有这一条，加入题单之前画到 A 的那张图点一下就能载回画布，交上去就是 A。
+ * 题单防抄：题单布置期内，学生在布置开始之前画的图先对他本人藏起来 —— 和代码提交同一道闸
+ * （routes/submission.ts 的 canViewSubmission，规则见 problemSetLockCutoffs）。原来流程图
+ * 这边没有这一条，以前画到 A 的那张图点一下就能载回画布，交上去就是 A。
  */
 function hiddenByProblemSet(
   user: AuthUser,
   row: { userId: number; problemId: number; createTime: string },
-  joinTimes: Map<number, string>,
+  cutoffs: Map<number, string>,
 ) {
   if (row.userId !== user.id || isTeacherOrAbove(user)) return false
-  const joinTime = joinTimes.get(row.problemId)
-  return joinTime !== undefined && Date.parse(row.createTime) < Date.parse(joinTime)
+  const cutoff = cutoffs.get(row.problemId)
+  return cutoff !== undefined && Date.parse(row.createTime) < Date.parse(cutoff)
 }
 
 function canView(
   user: AuthUser,
   row: { userId: number; problemId: number; createTime: string },
   problem: { createdById: number },
-  joinTimes: Map<number, string>,
+  cutoffs: Map<number, string>,
 ) {
-  if (hiddenByProblemSet(user, row, joinTimes)) return false
+  if (hiddenByProblemSet(user, row, cutoffs)) return false
   // 角色捷径只给老师：学生管理员算学生，不能看同学的流程图（同 submission.ts 的 canViewSubmission）
   return row.userId === user.id || isTeacherOrAbove(user) || problem.createdById === user.id
 }
 
 /** 只有学生看自己的提交时才需要查题单；其余情况给一张空表，省一次查询 */
-function joinTimesFor(user: AuthUser, rows: Array<{ userId: number; problemId: number }>) {
+function cutoffsFor(user: AuthUser, rows: Array<{ userId: number; problemId: number }>) {
   if (isTeacherOrAbove(user)) return Promise.resolve(new Map<number, string>())
   const own = rows.filter((row) => row.userId === user.id).map((row) => row.problemId)
-  return problemSetJoinTimes(user.id, [...new Set(own)])
+  return problemSetLockCutoffs(user.id, [...new Set(own)])
 }
 
 function flowchartData(
@@ -321,7 +321,7 @@ flowchartRoutes.get("/flowcharts", requireAuth, async (c) => {
       .offset(offset),
     displayId ? unknownDisplayIds(displayId, null) : [],
   ])
-  const joinTimes = await joinTimesFor(
+  const cutoffs = await cutoffsFor(
     user,
     rows.map((row) => row.flowchart),
   )
@@ -341,7 +341,7 @@ flowchartRoutes.get("/flowcharts", requireAuth, async (c) => {
           aiModel: flowchart.aiModel,
           processingTime: flowchart.processingTime,
           evaluationTime: flowchart.evaluationTime,
-          showLink: canView(user, flowchart, problem, joinTimes),
+          showLink: canView(user, flowchart, problem, cutoffs),
         }) satisfies FlowchartListItem,
     ),
     total: totalRows[0]?.value ?? 0,
@@ -656,7 +656,7 @@ flowchartRoutes.get("/flowcharts/:id", requireAuth, async (c) => {
     .where(eq(schema.flowchartSubmission.id, c.req.param("id")))
     .limit(1)
   const user = c.get("user")!
-  if (!row || !canView(user, row.flowchart, row.problem, await joinTimesFor(user, [row.flowchart])))
+  if (!row || !canView(user, row.flowchart, row.problem, await cutoffsFor(user, [row.flowchart])))
     return failure(c, 404, "flowchart-not-found", "Submission does not exist")
   return success(c, flowchartData(row.flowchart, row.username))
 })
@@ -669,7 +669,7 @@ flowchartRoutes.post("/flowcharts/:id/retry", requireAuth, async (c) => {
     .innerJoin(schema.problem, eq(schema.flowchartSubmission.problemId, schema.problem.id))
     .where(eq(schema.flowchartSubmission.id, c.req.param("id")))
     .limit(1)
-  if (!row || !canView(user, row.flowchart, row.problem, await joinTimesFor(user, [row.flowchart])))
+  if (!row || !canView(user, row.flowchart, row.problem, await cutoffsFor(user, [row.flowchart])))
     return failure(c, 404, "flowchart-not-found", "Submission does not exist")
   // 看得见不等于能重评：canView 放进来的出题人只能看。重评会清掉原来的
   // 评分再抽一次，别人的提交只有老师能动
@@ -737,7 +737,7 @@ flowchartRoutes.post("/flowcharts/:id/retry", requireAuth, async (c) => {
  * userId / problemId / createTime 三列是 hiddenByProblemSet 要的，别删。
  */
 async function myEvaluatedFlowcharts(user: AuthUser, problemId: number) {
-  const [rows, joinTimes] = await Promise.all([
+  const [rows, cutoffs] = await Promise.all([
     db
       .select({
         id: schema.flowchartSubmission.id,
@@ -756,9 +756,9 @@ async function myEvaluatedFlowcharts(user: AuthUser, problemId: number) {
         ),
       )
       .orderBy(asc(schema.flowchartSubmission.createTime)),
-    joinTimesFor(user, [{ userId: user.id, problemId }]),
+    cutoffsFor(user, [{ userId: user.id, problemId }]),
   ])
-  const visible = rows.filter((row) => !hiddenByProblemSet(user, row, joinTimes))
+  const visible = rows.filter((row) => !hiddenByProblemSet(user, row, cutoffs))
   return { visible, hidden: rows.length - visible.length }
 }
 

apps/api/src/routes/problemset.ts

@@ -1,44 +1,83 @@
 import {
   joinProblemSetRequestSchema,
+  STUDENT_ROLES,
   type ProblemSet,
   type ProblemSetBadge,
+  type ProblemSetClassView,
   type ProblemSetList,
+  type ProblemSetLock,
   type ProblemSetProblem,
-  type ProblemSetProgress,
-  type ProblemSetProgressList,
   type UserBadge,
 } from "@oj2/contract"
-import { and, asc, avg, count, desc, eq, gt, ilike, inArray, ne, or, sql } from "drizzle-orm"
+import { and, asc, count, desc, eq, ilike, inArray, isNull, notInArray, or, sql } from "drizzle-orm"
 import { Hono } from "hono"
 
 import { optionalAuth, requireAuth, requireTeacher, type AppEnv } from "../auth/middleware"
+import type { AuthUser } from "../auth/session"
 import { db, schema } from "../db"
 import { failure, parseBody, success } from "../http"
-import { computeProgress } from "../services/problemset"
-import { asFilterValue, asRecord, classPrefixCondition, queryInteger, sampleUser } from "./helpers"
+import { JudgeStatus, NON_FAILURE_RESULTS } from "../judge/status"
+import {
+  assigningSql,
+  computeProgress,
+  problemSetLockCutoffs,
+  problemSetLocksFor,
+} from "../services/problemset"
+import { asRecord, isTeacherOrAbove, queryInteger, sampleUser } from "./helpers"
 
 export const problemsetRoutes = new Hono<AppEnv>()
 
 type ProblemSetRow = typeof schema.problemset.$inferSelect
+type ProgressRow = typeof schema.problemsetProgress.$inferSelect
 
-function progressSummary(progress: typeof schema.problemsetProgress.$inferSelect | undefined) {
+const SOLVED_RESULTS = [JudgeStatus.ACCEPTED, JudgeStatus.AST_CHECK_FAILED]
+
+/** 必做题的 problemId；一道必做都没标的题单退回全部（和 computeProgress 同一个口径） */
+function gradedIds(links: { problemId: number; isRequired: boolean }[]) {
+  const required = links.filter((link) => link.isRequired)
+  return new Set((required.length ? required : links).map((link) => link.problemId))
+}
+
+function progressSummary(progress: ProgressRow | undefined) {
   return progress
     ? {
         isJoined: true,
-        progressPercentage: progress.progressPercentage,
+        joinTime: progress.joinTime,
         completedCount: progress.completedProblemsCount,
         totalCount: progress.totalProblemsCount,
+        solvedCount: Object.keys(asRecord(progress.progressDetail)).length,
         isCompleted: progress.isCompleted,
+        completeTime: progress.completeTime,
       }
     : {
         isJoined: false,
-        progressPercentage: 0,
+        joinTime: null,
         completedCount: 0,
         totalCount: 0,
+        solvedCount: 0,
         isCompleted: false,
+        completeTime: null,
       }
 }
 
+/**
+ * 学生能看到的题单：公开的。老师连没公开的也能打开 —— 后台编辑完要到前台看看学生
+ * 看到的样子、看全班情况，不该被 404 挡在外面。
+ */
+async function loadVisible(id: number, user: AuthUser | null | undefined) {
+  const [row] = await db
+    .select({ set: schema.problemset, assigning: assigningSql })
+    .from(schema.problemset)
+    .where(
+      and(
+        eq(schema.problemset.id, id),
+        isTeacherOrAbove(user) ? undefined : eq(schema.problemset.visible, true),
+      ),
+    )
+    .limit(1)
+  return row ?? null
+}
+
 async function problemSetCreators(ids: number[]) {
   const map = new Map<number, ReturnType<typeof sampleUser>>()
   if (ids.length === 0) return map
@@ -55,7 +94,7 @@ async function problemSetCreators(ids: number[]) {
   return map
 }
 
-function badgeData(badge: typeof schema.problemsetBadge.$inferSelect, earned?: boolean) {
+function badgeData(badge: typeof schema.problemsetBadge.$inferSelect, earnedTime?: string | null) {
   return {
     id: badge.id,
     problemSetId: badge.problemsetId,
@@ -64,70 +103,79 @@ function badgeData(badge: typeof schema.problemsetBadge.$inferSelect, earned?: b
     icon: badge.icon,
     conditionType: badge.conditionType,
     conditionValue: badge.conditionValue,
-    isEarned: earned,
+    isEarned: earnedTime === undefined ? undefined : earnedTime !== null,
+    earnedTime,
   } satisfies ProblemSetBadge
 }
 
 /**
  * 一次把整页题单的附属数据全查回来，再在内存里按 problemsetId 分组。
- *
- * 以前是每行 5 条查询（题目数 / 我的进度 / 奖章 / 已获奖章 / 创建者），
- * limit 最大 250 就是 1250 次往返。这里固定 5 条，与行数无关。
+ * 固定 6 条查询，与行数无关（按行查就是 N+1）。
  */
-async function serializeProblemSets(rows: ProblemSetRow[], userId?: number, includeBadges = false) {
+async function serializeProblemSets(
+  rows: { set: ProblemSetRow; assigning: boolean }[],
+  userId?: number,
+) {
   if (rows.length === 0) return []
-  const ids = rows.map((row) => row.id)
-  const [problemCounts, progresses, badges, earnedRows, creators] = await Promise.all([
-    db
-      .select({
-        problemsetId: schema.problemsetProblem.problemsetId,
-        value: count(),
-      })
-      .from(schema.problemsetProblem)
-      .where(inArray(schema.problemsetProblem.problemsetId, ids))
-      .groupBy(schema.problemsetProblem.problemsetId),
-    userId
-      ? db
-          .select()
-          .from(schema.problemsetProgress)
-          .where(
-            and(
-              inArray(schema.problemsetProgress.problemsetId, ids),
-              eq(schema.problemsetProgress.userId, userId),
-            ),
-          )
-      : Promise.resolve([] as (typeof schema.problemsetProgress.$inferSelect)[]),
-    includeBadges
-      ? db
-          .select()
-          .from(schema.problemsetBadge)
-          .where(inArray(schema.problemsetBadge.problemsetId, ids))
-          .orderBy(asc(schema.problemsetBadge.id))
-      : Promise.resolve([] as (typeof schema.problemsetBadge.$inferSelect)[]),
-    includeBadges && userId
-      ? db
-          .select({ id: schema.userBadge.badgeId })
-          .from(schema.userBadge)
-          .innerJoin(
-            schema.problemsetBadge,
-            eq(schema.userBadge.badgeId, schema.problemsetBadge.id),
-          )
-          .where(
-            and(
-              eq(schema.userBadge.userId, userId),
-              inArray(schema.problemsetBadge.problemsetId, ids),
-            ),
-          )
-      : Promise.resolve([] as { id: number }[]),
-    problemSetCreators([...new Set(rows.map((row) => row.createdById))]),
-  ])
-  const countBySet = new Map(problemCounts.map((item) => [item.problemsetId, item.value]))
+  const ids = rows.map((row) => row.set.id)
+  const [problemCounts, joinedCounts, progresses, badges, earnedRows, creators] = await Promise.all(
+    [
+      db
+        .select({
+          problemsetId: schema.problemsetProblem.problemsetId,
+          value: count(),
+          required: sql<number>`count(*) filter (where ${schema.problemsetProblem.isRequired})::int`,
+        })
+        .from(schema.problemsetProblem)
+        .where(inArray(schema.problemsetProblem.problemsetId, ids))
+        .groupBy(schema.problemsetProblem.problemsetId),
+      db
+        .select({ problemsetId: schema.problemsetProgress.problemsetId, value: count() })
+        .from(schema.problemsetProgress)
+        .where(inArray(schema.problemsetProgress.problemsetId, ids))
+        .groupBy(schema.problemsetProgress.problemsetId),
+      userId
+        ? db
+            .select()
+            .from(schema.problemsetProgress)
+            .where(
+              and(
+                inArray(schema.problemsetProgress.problemsetId, ids),
+                eq(schema.problemsetProgress.userId, userId),
+              ),
+            )
+        : Promise.resolve([] as ProgressRow[]),
+      db
+        .select()
+        .from(schema.problemsetBadge)
+        .where(inArray(schema.problemsetBadge.problemsetId, ids))
+        .orderBy(asc(schema.problemsetBadge.id)),
+      userId
+        ? db
+            .select({ id: schema.userBadge.badgeId, earnedTime: schema.userBadge.earnedTime })
+            .from(schema.userBadge)
+            .innerJoin(
+              schema.problemsetBadge,
+              eq(schema.userBadge.badgeId, schema.problemsetBadge.id),
+            )
+            .where(
+              and(
+                eq(schema.userBadge.userId, userId),
+                inArray(schema.problemsetBadge.problemsetId, ids),
+              ),
+            )
+        : Promise.resolve([] as { id: number; earnedTime: string }[]),
+      problemSetCreators([...new Set(rows.map((row) => row.set.createdById))]),
+    ],
+  )
+  const countBySet = new Map(problemCounts.map((item) => [item.problemsetId, item]))
+  const joinedBySet = new Map(joinedCounts.map((item) => [item.problemsetId, item.value]))
   const progressBySet = new Map(progresses.map((item) => [item.problemsetId, item]))
   const badgesBySet = new Map<number, (typeof schema.problemsetBadge.$inferSelect)[]>()
   for (const badge of badges)
     badgesBySet.set(badge.problemsetId, [...(badgesBySet.get(badge.problemsetId) ?? []), badge])
-  const earned = new Set(earnedRows.map((item) => item.id))
-  return rows.map((row) => {
+  const earned = new Map(earnedRows.map((item) => [item.id, item.earnedTime]))
+  return rows.map(({ set: row, assigning }) => {
     const progress = progressBySet.get(row.id)
     return {
       id: row.id,
@@ -136,17 +184,16 @@ async function serializeProblemSets(rows: ProblemSetRow[], userId?: number, incl
       createdBy:
         creators.get(row.createdById) ?? sampleUser({ id: row.createdById, username: "" }, null),
       createTime: row.createTime,
-      lastUpdateTime: row.lastUpdateTime,
-      difficulty: row.difficulty,
-      status: row.status,
-      endTime: row.endTime,
-      visible: row.visible,
-      problemsCount: countBySet.get(row.id) ?? 0,
-      completedCount: progress?.completedProblemsCount ?? 0,
+      assignedUntil: row.assignedUntil,
+      assigning,
+      problemsCount: countBySet.get(row.id)?.value ?? 0,
+      // 一道必做都没标的题单退回「全部都算必做」，和 computeProgress 同一个口径
+      requiredCount: countBySet.get(row.id)?.required || (countBySet.get(row.id)?.value ?? 0),
+      joinedCount: joinedBySet.get(row.id) ?? 0,
       userProgress: progressSummary(progress),
-      badges: includeBadges
-        ? (badgesBySet.get(row.id) ?? []).map((badge) => badgeData(badge, earned.has(badge.id)))
-        : undefined,
+      badges: (badgesBySet.get(row.id) ?? []).map((badge) =>
+        badgeData(badge, userId ? (earned.get(badge.id) ?? null) : undefined),
+      ),
     } satisfies ProblemSet
   })
 }
@@ -154,10 +201,8 @@ async function serializeProblemSets(rows: ProblemSetRow[], userId?: number, incl
 problemsetRoutes.get("/problem-sets", optionalAuth, async (c) => {
   const limit = queryInteger(c.req.query("limit"), 10, { min: 1, max: 250 })
   const offset = queryInteger(c.req.query("offset"), 0, { min: 0 })
-  const filters = [eq(schema.problemset.visible, true), ne(schema.problemset.status, "draft")]
+  const filters = [eq(schema.problemset.visible, true)]
   const keyword = c.req.query("keyword")?.trim()
-  const difficulty = c.req.query("difficulty")?.trim()
-  const status = c.req.query("status")?.trim()
   if (keyword)
     filters.push(
       or(
@@ -165,13 +210,11 @@ problemsetRoutes.get("/problem-sets", optionalAuth, async (c) => {
         ilike(schema.problemset.description, `%${keyword}%`),
       )!,
     )
-  if (difficulty) filters.push(eq(schema.problemset.difficulty, asFilterValue(difficulty)))
-  if (status) filters.push(eq(schema.problemset.status, asFilterValue(status)))
   const where = and(...filters)
   const [totalRows, rows] = await Promise.all([
     db.select({ value: count() }).from(schema.problemset).where(where),
     db
-      .select()
+      .select({ set: schema.problemset, assigning: assigningSql })
       .from(schema.problemset)
       .where(where)
       .orderBy(desc(schema.problemset.createTime))
@@ -179,49 +222,45 @@ problemsetRoutes.get("/problem-sets", optionalAuth, async (c) => {
       .offset(offset),
   ])
   return success(c, {
-    results: await serializeProblemSets(rows, c.get("user")?.id, true),
+    results: await serializeProblemSets(rows, c.get("user")?.id),
     total: totalRows[0]?.value ?? 0,
   } satisfies ProblemSetList)
 })
 
+// 字面量路由要排在 /problem-sets/:id 前面：Hono 按注册顺序匹配，不是静态优先
+// 题号（problemDisplayId）和主键（problemId）都认：提交列表那边手里只有题号
+problemsetRoutes.get("/problem-sets/locks", requireAuth, async (c) => {
+  const user = c.get("user")!
+  if (isTeacherOrAbove(user)) return success(c, [] as ProblemSetLock[])
+  let problemId = queryInteger(c.req.query("problemId"), 0, { min: 1 })
+  const displayId = c.req.query("problemDisplayId")?.trim()
+  if (!problemId && displayId) {
+    const [problem] = await db
+      .select({ id: schema.problem.id })
+      .from(schema.problem)
+      .where(and(eq(schema.problem.displayId, displayId), isNull(schema.problem.contestId)))
+      .limit(1)
+    problemId = problem?.id ?? 0
+  }
+  if (!problemId) return success(c, [] as ProblemSetLock[])
+  const rows = await problemSetLocksFor(user.id, problemId)
+  return success(c, rows satisfies ProblemSetLock[])
+})
+
 problemsetRoutes.get("/problem-sets/:id", optionalAuth, async (c) => {
-  const id = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const [row] = await db
-    .select()
-    .from(schema.problemset)
-    .where(
-      and(
-        eq(schema.problemset.id, id),
-        eq(schema.problemset.visible, true),
-        ne(schema.problemset.status, "draft"),
-      ),
-    )
-    .limit(1)
+  const row = await loadVisible(queryInteger(c.req.param("id"), 0, { min: 1 }), c.get("user"))
   if (!row) return failure(c, 404, "problem-set-not-found", "题单不存在")
   const [data] = await serializeProblemSets([row], c.get("user")?.id)
   return success(c, data)
 })
 
 problemsetRoutes.get("/problem-sets/:id/problems", optionalAuth, async (c) => {
-  const id = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const [problemSet] = await db
-    .select({ id: schema.problemset.id })
-    .from(schema.problemset)
-    .where(
-      and(
-        eq(schema.problemset.id, id),
-        eq(schema.problemset.visible, true),
-        ne(schema.problemset.status, "draft"),
-      ),
-    )
-    .limit(1)
-  if (!problemSet) return failure(c, 404, "problem-set-not-found", "题单不存在")
-  // 只取卡片要渲染的四列。取 schema.problem 整行会把题面、样例、答案、ast_rules、
-  // flowchart_data、sql_display 一起拉回来，题单页一个都不用。
-  //
-  // order 后面必须再跟一个 tiebreaker：并列时 Postgres 不保证次序，而卡片是按数组
-  // 下标编号的（#1 #2 #3），题单 8 / 11 / 14 实际就存在 order 重复，不定死的话
-  // 「第 3 题」指哪道题每次刷新都可能不一样。后台那条列表一直是这么排的。
+  const user = c.get("user")
+  const found = await loadVisible(queryInteger(c.req.param("id"), 0, { min: 1 }), user)
+  if (!found) return failure(c, 404, "problem-set-not-found", "题单不存在")
+  const id = found.set.id
+  // order 后面必须再跟一个 tiebreaker：并列时 Postgres 不保证次序，而题目是按数组下标
+  // 编号的（1、2、3），老题单里 order 大量重复，不定死的话「第 3 题」每次刷新都可能变
   const rows = await db
     .select({
       link: schema.problemsetProblem,
@@ -234,76 +273,86 @@ problemsetRoutes.get("/problem-sets/:id/problems", optionalAuth, async (c) => {
     .innerJoin(schema.problem, eq(schema.problemsetProblem.problemId, schema.problem.id))
     .where(eq(schema.problemsetProblem.problemsetId, id))
     .orderBy(asc(schema.problemsetProblem.order), asc(schema.problemsetProblem.id))
-  const progressRows = c.get("user")
-    ? await db
-        .select({ detail: schema.problemsetProgress.progressDetail })
-        .from(schema.problemsetProgress)
-        .where(
-          and(
-            eq(schema.problemsetProgress.problemsetId, id),
-            eq(schema.problemsetProgress.userId, c.get("user")!.id),
-          ),
-        )
-        .limit(1)
-    : []
-  const completed = asRecord(progressRows[0]?.detail)
+  const problemIds = rows.map((row) => row.problemId)
+  const [progressRows, wrongRows, cutoffs] = user
+    ? await Promise.all([
+        db
+          .select({ detail: schema.problemsetProgress.progressDetail })
+          .from(schema.problemsetProgress)
+          .where(
+            and(
+              eq(schema.problemsetProgress.problemsetId, id),
+              eq(schema.problemsetProgress.userId, user.id),
+            ),
+          )
+          .limit(1),
+        db
+          .select({ problemId: schema.submission.problemId, value: count() })
+          .from(schema.submission)
+          .where(
+            and(
+              eq(schema.submission.userId, user.id),
+              eq(schema.submission.problemsetId, id),
+              notInArray(schema.submission.result, NON_FAILURE_RESULTS),
+            ),
+          )
+          .groupBy(schema.submission.problemId),
+        isTeacherOrAbove(user)
+          ? new Map<number, string>()
+          : problemSetLockCutoffs(user.id, problemIds),
+      ])
+    : [[], [], new Map<number, string>()]
+  // 「以前做对过 · 旧代码先藏着」：这道题正被闸门挡着，而且分界之前确实做对过
+  const hiddenSolved =
+    user && cutoffs.size
+      ? await db
+          .select({ problemId: schema.submission.problemId })
+          .from(schema.submission)
+          .where(
+            and(
+              eq(schema.submission.userId, user.id),
+              inArray(schema.submission.problemId, [...cutoffs.keys()]),
+              inArray(schema.submission.result, SOLVED_RESULTS),
+              or(
+                ...[...cutoffs].map(
+                  ([problemId, cutoff]) =>
+                    sql`(${schema.submission.problemId} = ${problemId} and ${schema.submission.createTime} < ${cutoff})`,
+                ),
+              ),
+            ),
+          )
+          .groupBy(schema.submission.problemId)
+      : []
+  const hidden = new Set(hiddenSolved.map((row) => row.problemId))
+  const solved = asRecord(progressRows[0]?.detail)
+  const wrong = new Map(wrongRows.map((row) => [row.problemId, row.value]))
   return success(
     c,
-    rows.map(
-      ({ link, problemId, displayId, title, difficulty }) =>
-        ({
-          id: link.id,
-          problemSetId: link.problemsetId,
-          problem: { id: problemId, _id: displayId, title, difficulty },
-          order: link.order,
-          isRequired: link.isRequired,
-          score: link.score,
-          hint: link.hint,
-          isCompleted: String(problemId) in completed,
-        }) satisfies ProblemSetProblem,
-    ),
+    rows.map(({ link, problemId, displayId, title, difficulty }) => {
+      const entry = solved[String(problemId)]
+      const solvedTime = entry === undefined ? null : asRecord(entry).submit_time
+      return {
+        id: link.id,
+        problemSetId: link.problemsetId,
+        problem: { id: problemId, _id: displayId, title, difficulty },
+        order: link.order,
+        isRequired: link.isRequired,
+        isCompleted: entry !== undefined,
+        solvedTime: typeof solvedTime === "string" ? solvedTime : null,
+        wrongCount: wrong.get(problemId) ?? 0,
+        oldCodeHidden: hidden.has(problemId),
+      } satisfies ProblemSetProblem
+    }),
   )
 })
 
-async function recomputeProgress(
-  tx: Parameters<Parameters<typeof db.transaction>[0]>[0],
-  progress: typeof schema.problemsetProgress.$inferSelect,
-  detail: Record<string, unknown>,
-) {
-  const links = await tx
-    .select({
-      problemId: schema.problemsetProblem.problemId,
-      score: schema.problemsetProblem.score,
-      isRequired: schema.problemsetProblem.isRequired,
-    })
-    .from(schema.problemsetProblem)
-    .where(eq(schema.problemsetProblem.problemsetId, progress.problemsetId))
-  // 算法本身在 services/problemset.ts —— 后台改题目后的批量重算走的是同一份，
-  // 两边曾经各写一遍，结果后台那份少算了 total_score 和 is_completed
-  const update = computeProgress(detail, links, progress.completeTime)
-  await tx
-    .update(schema.problemsetProgress)
-    .set(update)
-    .where(eq(schema.problemsetProgress.id, progress.id))
-  return { ...progress, ...update }
-}
-
 problemsetRoutes.post("/problem-set-progress", requireAuth, async (c) => {
   const parsed = await parseBody(c, joinProblemSetRequestSchema, "Invalid problem set")
   if (!parsed.success) return parsed.response
   const user = c.get("user")!
-  const [problemSet] = await db
-    .select({ id: schema.problemset.id })
-    .from(schema.problemset)
-    .where(
-      and(
-        eq(schema.problemset.id, parsed.data.problemSetId),
-        eq(schema.problemset.visible, true),
-        ne(schema.problemset.status, "draft"),
-      ),
-    )
-    .limit(1)
-  if (!problemSet) return failure(c, 404, "problem-set-not-found", "题单不存在")
+  const found = await loadVisible(parsed.data.problemSetId, user)
+  if (!found) return failure(c, 404, "problem-set-not-found", "题单不存在")
+  const problemSet = found.set
   const [existing] = await db
     .select({ id: schema.problemsetProgress.id })
     .from(schema.problemsetProgress)
@@ -316,22 +365,21 @@ problemsetRoutes.post("/problem-set-progress", requireAuth, async (c) => {
     .limit(1)
   if (existing) return failure(c, 409, "already-joined", "已经加入该题单")
   await db.transaction(async (tx) => {
-    const [created] = await tx
-      .insert(schema.problemsetProgress)
-      .values({
-        problemsetId: problemSet.id,
-        userId: user.id,
-        joinTime: new Date().toISOString(),
-        completeTime: null,
-        isCompleted: false,
-        progressPercentage: 0,
-        completedProblemsCount: 0,
-        totalProblemsCount: 0,
-        totalScore: 0,
-        progressDetail: {},
+    const links = await tx
+      .select({
+        problemId: schema.problemsetProblem.problemId,
+        score: schema.problemsetProblem.score,
+        isRequired: schema.problemsetProblem.isRequired,
       })
-      .returning()
-    if (created) await recomputeProgress(tx, created, {})
+      .from(schema.problemsetProblem)
+      .where(eq(schema.problemsetProblem.problemsetId, problemSet.id))
+    // 算法本身在 services/problemset.ts —— 后台改题目后的批量重算走的是同一份
+    await tx.insert(schema.problemsetProgress).values({
+      problemsetId: problemSet.id,
+      userId: user.id,
+      joinTime: new Date().toISOString(),
+      ...computeProgress({}, links, null),
+    })
   })
   return success(c, null, 201)
 })
@@ -372,137 +420,198 @@ problemsetRoutes.get("/users/:username/badges", optionalAuth, async (c) => {
   )
 })
 
-problemsetRoutes.get("/problem-sets/:id/badges", async (c) => {
-  const id = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const [problemSet] = await db
-    .select({ id: schema.problemset.id })
-    .from(schema.problemset)
-    .where(
-      and(
-        eq(schema.problemset.id, id),
-        eq(schema.problemset.visible, true),
-        ne(schema.problemset.status, "draft"),
-      ),
-    )
-    .limit(1)
-  if (!problemSet) return failure(c, 404, "problem-set-not-found", "题单不存在")
-  const badges = await db
-    .select()
-    .from(schema.problemsetBadge)
-    .where(eq(schema.problemsetBadge.problemsetId, id))
-  return success(
-    c,
-    badges.map((badge) => badgeData(badge)),
-  )
-})
-
-problemsetRoutes.get("/problem-sets/:id/user-progress", requireTeacher, async (c) => {
-  const id = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const [problemSet] = await db
-    .select({ id: schema.problemset.id })
-    .from(schema.problemset)
-    .where(
-      and(
-        eq(schema.problemset.id, id),
-        eq(schema.problemset.visible, true),
-        ne(schema.problemset.status, "draft"),
-      ),
-    )
-    .limit(1)
-  // 所有老师都能看，不只是题单的创建者：系统里没有「班级归哪个老师」，课堂看板、数据统计
-  // 也是任何老师看任何班，这里和它们一致。后台那条（admin/problemset.ts 的 loadOwned）
-  // 能改能删，仍然只给创建者
-  if (!problemSet) {
-    return failure(c, 404, "problem-set-not-found", "题单不存在")
-  }
-  const limit = queryInteger(c.req.query("limit"), 10, { min: 1, max: 250 })
-  const offset = queryInteger(c.req.query("offset"), 0, { min: 0 })
-  const className = c.req.query("className")?.trim()
-  const completion = c.req.query("completionStatus")?.trim()
-  const filters = [eq(schema.problemsetProgress.problemsetId, id)]
-  // 只填数字（251）当班级号补上 ks；班级按 classPrefixCondition 匹配，
-  // 否则 251 会把 2511 班也算进来。别的输入照旧按用户名包含
-  if (className) {
-    const classPrefix = /^\d+$/.test(className) ? `ks${className}` : className
-    filters.push(classPrefixCondition(classPrefix) ?? ilike(schema.user.username, `%${className}%`))
-  }
-  if (completion === "completed") filters.push(eq(schema.problemsetProgress.isCompleted, true))
-  else if (completion === "in_progress")
-    filters.push(
-      and(
-        eq(schema.problemsetProgress.isCompleted, false),
-        gt(schema.problemsetProgress.completedProblemsCount, 0),
-      )!,
-    )
-  else if (completion === "not_started")
-    filters.push(eq(schema.problemsetProgress.completedProblemsCount, 0))
-  const where = and(...filters)
-  const [statsRows, rows, problemRows] = await Promise.all([
+/**
+ * 老师看一个班在这份题单里的情况：真名 × 每道题（几点做对 / 错几次 / 加入前就做对过）。
+ *
+ * 所有老师都能看，不只是题单的创建者：系统里没有「班级归哪个老师」，课堂看板、数据统计
+ * 也是任何老师看任何班，这里和它们一致。
+ *
+ * 班级不用老师选：从加入过的学生里数出有哪些班，最近有人加入的排第一个、默认就看它，
+ * 想看别的班再换（和比赛「全班情况」按参赛者推断班级是一个思路）。名单是那个班的全部学生，
+ * 没加入的也列出来，好点名。
+ */
+problemsetRoutes.get("/problem-sets/:id/class-view", requireTeacher, async (c) => {
+  const found = await loadVisible(queryInteger(c.req.param("id"), 0, { min: 1 }), c.get("user"))
+  if (!found) return failure(c, 404, "problem-set-not-found", "题单不存在")
+  const id = found.set.id
+  const studentRole = inArray(schema.user.adminType, [...STUDENT_ROLES])
+  const [links, joinedClasses] = await Promise.all([
     db
       .select({
-        total: count(),
-        completed: sql<number>`count(*) filter (where ${schema.problemsetProgress.isCompleted})::int`,
-        avgProgress: avg(schema.problemsetProgress.progressPercentage),
-      })
-      .from(schema.problemsetProgress)
-      .innerJoin(schema.user, eq(schema.problemsetProgress.userId, schema.user.id))
-      .where(where),
-    db
-      .select({
-        progress: schema.problemsetProgress,
-        user: schema.user,
-        realName: schema.userProfile.realName,
-      })
-      .from(schema.problemsetProgress)
-      .innerJoin(schema.user, eq(schema.problemsetProgress.userId, schema.user.id))
-      .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
-      .where(where)
-      .orderBy(
-        desc(schema.problemsetProgress.isCompleted),
-        desc(schema.problemsetProgress.progressPercentage),
-        asc(schema.problemsetProgress.joinTime),
-      )
-      .limit(limit)
-      .offset(offset),
-    db
-      .select({
-        id: schema.problem.id,
+        problemId: schema.problem.id,
         _id: schema.problem.displayId,
         title: schema.problem.title,
+        isRequired: schema.problemsetProblem.isRequired,
       })
       .from(schema.problemsetProblem)
       .innerJoin(schema.problem, eq(schema.problemsetProblem.problemId, schema.problem.id))
       .where(eq(schema.problemsetProblem.problemsetId, id))
       .orderBy(asc(schema.problemsetProblem.order), asc(schema.problemsetProblem.id)),
-  ])
-  const problemMap = new Map(problemRows.map((problem) => [String(problem.id), problem]))
-  const results = rows.map(
-    ({ progress, user: progressUser, realName }) =>
-      ({
-        id: progress.id,
-        problemSetId: progress.problemsetId,
-        user: sampleUser(progressUser, realName),
-        joinTime: progress.joinTime,
-        completeTime: progress.completeTime,
-        isCompleted: progress.isCompleted,
-        progressPercentage: progress.progressPercentage,
-        completedProblemsCount: progress.completedProblemsCount,
-        totalProblemsCount: progress.totalProblemsCount,
-        totalScore: progress.totalScore,
-        completedProblems: Object.keys(asRecord(progress.progressDetail)).flatMap(
-          (key) => problemMap.get(key) ?? [],
+    db
+      .select({
+        className: sql<string>`${schema.user.className}`,
+        joined: count(),
+        last: sql<string>`max(${schema.problemsetProgress.joinTime})`,
+      })
+      .from(schema.problemsetProgress)
+      .innerJoin(schema.user, eq(schema.user.id, schema.problemsetProgress.userId))
+      .where(
+        and(
+          eq(schema.problemsetProgress.problemsetId, id),
+          studentRole,
+          sql`coalesce(${schema.user.className}, '') <> ''`,
         ),
-      }) satisfies ProblemSetProgress,
-  )
-  const stats = statsRows[0]
+      )
+      .groupBy(schema.user.className)
+      .orderBy(sql`max(${schema.problemsetProgress.joinTime}) desc`),
+  ])
+  const sizes = joinedClasses.length
+    ? await db
+        .select({ className: sql<string>`${schema.user.className}`, value: count() })
+        .from(schema.user)
+        .where(
+          and(
+            inArray(
+              schema.user.className,
+              joinedClasses.map((row) => row.className),
+            ),
+            studentRole,
+            eq(schema.user.isDisabled, false),
+          ),
+        )
+        .groupBy(schema.user.className)
+    : []
+  const sizeOf = new Map(sizes.map((row) => [row.className, row.value]))
+  // 只有零星几个人加入的班（别的班的学生自己点进来的）排到后面去：至少 5 个、三分之一的人加入了
+  // 才算「这个班在做」，这样的班按最近一次有人加入排，默认看第一个
+  const classes = joinedClasses
+    .map((row) => ({
+      className: row.className,
+      joined: row.joined,
+      size: sizeOf.get(row.className) ?? row.joined,
+    }))
+    .map((row, recency) => ({ row, recency, doing: row.joined >= 5 && row.joined * 3 >= row.size }))
+    .sort((a, b) =>
+      a.doing !== b.doing
+        ? Number(b.doing) - Number(a.doing)
+        : a.doing
+          ? a.recency - b.recency
+          : b.row.joined - a.row.joined,
+    )
+    .map((item) => item.row)
+  const wanted = c.req.query("className")?.trim()
+  const className = wanted || classes[0]?.className || null
+  const graded = gradedIds(links)
+  const empty: ProblemSetClassView = {
+    classes,
+    className,
+    problems: links.map((link) => ({
+      id: link.problemId,
+      _id: link._id,
+      title: link.title,
+      isRequired: link.isRequired,
+      solved: 0,
+    })),
+    totalCount: graded.size,
+    students: [],
+  }
+  if (!className || links.length === 0) return success(c, empty)
+
+  const roster = await db
+    .select({
+      userId: schema.user.id,
+      username: schema.user.username,
+      realName: schema.userProfile.realName,
+      progress: schema.problemsetProgress,
+    })
+    .from(schema.user)
+    .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
+    .leftJoin(
+      schema.problemsetProgress,
+      and(
+        eq(schema.problemsetProgress.userId, schema.user.id),
+        eq(schema.problemsetProgress.problemsetId, id),
+      ),
+    )
+    .where(
+      and(eq(schema.user.className, className), studentRole, eq(schema.user.isDisabled, false)),
+    )
+    .orderBy(asc(schema.user.username))
+  if (roster.length === 0) return success(c, empty)
+  const userIds = roster.map((row) => row.userId)
+  const problemIds = links.map((link) => link.problemId)
+  const [wrongRows, beforeRows] = await Promise.all([
+    db
+      .select({
+        userId: schema.submission.userId,
+        problemId: schema.submission.problemId,
+        value: count(),
+      })
+      .from(schema.submission)
+      .where(
+        and(
+          eq(schema.submission.problemsetId, id),
+          inArray(schema.submission.userId, userIds),
+          notInArray(schema.submission.result, NON_FAILURE_RESULTS),
+        ),
+      )
+      .groupBy(schema.submission.userId, schema.submission.problemId),
+    // 加入之前就做对过（哪个入口都算）：老师据此知道谁可能是凭记忆默写的
+    db
+      .select({ userId: schema.submission.userId, problemId: schema.submission.problemId })
+      .from(schema.submission)
+      .innerJoin(
+        schema.problemsetProgress,
+        and(
+          eq(schema.problemsetProgress.userId, schema.submission.userId),
+          eq(schema.problemsetProgress.problemsetId, id),
+        ),
+      )
+      .where(
+        and(
+          inArray(schema.submission.userId, userIds),
+          inArray(schema.submission.problemId, problemIds),
+          inArray(schema.submission.result, SOLVED_RESULTS),
+          sql`${schema.submission.createTime} < ${schema.problemsetProgress.joinTime}`,
+        ),
+      )
+      .groupBy(schema.submission.userId, schema.submission.problemId),
+  ])
+  const key = (userId: number, problemId: number) => `${userId}:${problemId}`
+  const wrong = new Map(wrongRows.map((row) => [key(row.userId, row.problemId), row.value]))
+  const before = new Set(beforeRows.map((row) => key(row.userId, row.problemId)))
+  const solvedCount = new Map<number, number>()
+  const students = roster.map((row) => {
+    const detail = asRecord(row.progress?.progressDetail)
+    let completed = 0
+    const cells = links.map((link) => {
+      const entry = detail[String(link.problemId)]
+      const time = entry === undefined ? null : asRecord(entry).submit_time
+      if (entry !== undefined) {
+        solvedCount.set(link.problemId, (solvedCount.get(link.problemId) ?? 0) + 1)
+        if (graded.has(link.problemId)) completed += 1
+      }
+      return {
+        solvedTime: typeof time === "string" ? time : null,
+        wrongCount: wrong.get(key(row.userId, link.problemId)) ?? 0,
+        solvedBefore: before.has(key(row.userId, link.problemId)),
+      }
+    })
+    return {
+      userId: row.userId,
+      username: row.username,
+      realName: row.realName,
+      joinTime: row.progress?.joinTime ?? null,
+      completedCount: completed,
+      cells,
+    }
+  })
   return success(c, {
-    results,
-    total: stats?.total ?? 0,
-    statistics: {
-      total: stats?.total ?? 0,
-      completed: stats?.completed ?? 0,
-      avgProgress: Number(stats?.avgProgress ?? 0),
-    },
-    problems: problemRows,
-  } satisfies ProblemSetProgressList)
+    ...empty,
+    problems: empty.problems.map((problem) => ({
+      ...problem,
+      solved: solvedCount.get(problem.id) ?? 0,
+    })),
+    students,
+  } satisfies ProblemSetClassView)
 })

apps/api/src/routes/submission.ts

@@ -30,7 +30,7 @@ import {
 } from "../services/contest"
 import { CodeFormatError, formatCode } from "../services/format-code"
 import { getBooleanOption } from "../services/options"
-import { problemSetJoinTimes } from "../services/problemset"
+import { problemSetLockCutoffs } from "../services/problemset"
 import { consumeToken } from "../services/throttling"
 import { dayStart } from "../time"
 import { asFilterValue, asRecord, isAdminRole, isTeacherOrAbove, queryInteger } from "./helpers"
@@ -289,14 +289,14 @@ function canViewSubmission(
   user: AuthUser | null,
   row: { userId: number; problemId: number; createTime: string },
   problem: { createdById: number },
-  problemSetJoinTime?: Map<number, string>,
+  problemSetCutoffs?: Map<number, string>,
 ) {
   if (!user) return false
-  // 题单防作弊，见 problemSetJoinTimes。只对学生自己的提交生效，老师不受限。
+  // 题单防作弊，见 problemSetLockCutoffs。只对学生自己的提交生效，老师不受限。
   // 学生管理员算学生，同样受限（旧后端 `is_regular_user()` 放过了他）。
   if (row.userId === user.id && !isTeacherOrAbove(user)) {
-    const joinTime = problemSetJoinTime?.get(row.problemId)
-    if (joinTime !== undefined && Date.parse(row.createTime) < Date.parse(joinTime)) return false
+    const cutoff = problemSetCutoffs?.get(row.problemId)
+    if (cutoff !== undefined && Date.parse(row.createTime) < Date.parse(cutoff)) return false
   }
   // 看别人代码的角色捷径只给老师和超管。学生管理员算学生（STUDENT_ROLES）：他参赛、上榜、
   // 和同学做同一份作业，能读别人的提交就是开卷。旧后端这里是 `not user.is_regular_user()`，
@@ -399,11 +399,11 @@ async function submissionDetail(id: string, user: AuthUser) {
   if (!row) return null
   // 详情也要过闸门。旧后端只挡了列表里的链接，`SubmissionAPI.get`（views/oj.py:103）
   // 光走 check_user_permission——知道 submission id 直接访问照样拿得到代码，遮挡是虚的。
-  const joinTimes =
+  const cutoffs =
     isTeacherOrAbove(user) || row.submission.userId !== user.id
       ? undefined
-      : await problemSetJoinTimes(user.id, [row.submission.problemId])
-  if (!canViewSubmission(user, row.submission, row.problem, joinTimes)) return null
+      : await problemSetLockCutoffs(user.id, [row.submission.problemId])
+  if (!canViewSubmission(user, row.submission, row.problem, cutoffs)) return null
   // info（含每个测试点的 test_case 编号与 output_md5）只给管理员，对齐旧后端：
   // submission/views/oj.py 用 is_admin_role() 在 SubmissionModelSerializer 与
   // SubmissionSafeModelSerializer 之间二选一，把关的是角色，不是「是不是自己的提交」。
@@ -569,9 +569,9 @@ submissionRoutes.get("/submissions", optionalAuth, async (c) => {
     displayId ? unknownDisplayIds(displayId, null) : [],
   ])
   // 闸门只对学生自己的提交生效，所以只拿这一页里属于他自己的题目去查，一页一次查询
-  const [joinTimes, problemsetTitles] = await Promise.all([
+  const [cutoffs, problemsetTitles] = await Promise.all([
     user && !isTeacherOrAbove(user)
-      ? problemSetJoinTimes(user.id, [
+      ? problemSetLockCutoffs(user.id, [
           ...new Set(
             rows
               .filter((row) => row.submission.userId === user.id)
@@ -589,7 +589,7 @@ submissionRoutes.get("/submissions", optionalAuth, async (c) => {
           id: submission.id,
           problemDisplayId: problem.displayId,
           problemTitle: problem.title,
-          showLink: user ? canViewSubmission(user, submission, problem, joinTimes) : false,
+          showLink: user ? canViewSubmission(user, submission, problem, cutoffs) : false,
           createTime: submission.createTime,
           userId: submission.userId,
           username: submission.username,

apps/api/src/services/problemset.ts

@@ -1,4 +1,4 @@
-import { and, eq, gt, inArray, isNull, notInArray, or, sql } from "drizzle-orm"
+import { and, asc, eq, inArray, notInArray, sql } from "drizzle-orm"
 
 import { db, schema } from "../db"
 import { publishAchievementNotification } from "../events"
@@ -10,7 +10,7 @@ type ProgressRow = typeof schema.problemsetProgress.$inferSelect
 type ProblemLink = { problemId: number; score: number; isRequired: boolean }
 type BadgeCheck = Pick<
   ProgressRow,
-  "completedProblemsCount" | "totalProblemsCount" | "totalScore" | "progressDetail"
+  "completedProblemsCount" | "totalProblemsCount" | "progressDetail"
 >
 
 /**
@@ -132,7 +132,7 @@ export function eligibleForBadge(badge: BadgeRow, progress: BadgeCheck) {
   if (badge.conditionType === "problem_count") {
     return Object.keys(asRecord(progress.progressDetail)).length >= badge.conditionValue
   }
-  if (badge.conditionType === "score") return progress.totalScore >= badge.conditionValue
+  // 「总分达到 N」随分数一起拿掉了，0026 把它们换成了「做对 N 道」
   return false
 }
 
@@ -242,8 +242,8 @@ export async function recordSolvedProblem(
   problemId: number,
   /**
    * 做出来的那次代码提交。流程图画到 A/S 算完成时传 null：problemset_submission.submission_id
-   * 外键指向代码提交表，流程图提交的 id 进不去。不影响「解锁加入题单之前的提交」——
-   * 那道闸看的是 progress_detail（本文件下面的 problemSetJoinTimes）
+   * 外键指向代码提交表，流程图提交的 id 进不去。不影响防抄闸门的解锁 ——
+   * 那道闸看的是 progress_detail（本文件下面的 problemSetLockCutoffs）
    */
   submissionId: string | null,
   solvedAt: string,
@@ -390,50 +390,85 @@ export async function recordSolvedAndNotify(
   }
 }
 
+/** 题单现在是不是在布置期内。按数据库的钟算（`now()`），和防抄闸门同一个口径 */
+export const assigningSql = sql<boolean>`(${schema.problemset.assignedAt} is not null and ${schema.problemset.assignedUntil} > now())`
+
 /**
- * 题单防作弊闸门：查出这些题目里，哪些题的旧提交要对该用户藏起来，返回 problemId → 加入时间。
- * 代码提交（routes/submission.ts）和流程图提交（routes/flowchart.ts）共用这一道闸。
+ * 题单防抄闸门：查出这些题目里，哪些题的旧提交要对该用户藏起来，返回 problemId → 分界时刻
+ * （早于它的提交藏起来）。代码提交（routes/submission.ts）和流程图提交（routes/flowchart.ts）
+ * 共用这一道闸。
  *
- * 对齐旧后端 `submission/serializers.py:12` 的 `bulk_fetch_problemset_progress`。学生加入含
- * 某道题的题单后，他在加入之前留下的 AC 代码还摆在提交列表里，复制粘贴就能把题单刷完。
- * 备份快照里 1734 人次、188 名学生进过这个窗口（占已解题次的 22.5%），不是边角情况。
+ * 规则（2026-10 题单重设计，用户拍板）：题单**布置期内**，题单里这几道题，学生在**布置开始之前**
+ * 交的代码一律先藏起来 —— 不管他加没加入。老师常拿刚讲过的题攒复习题单：快照里 16% 的
+ * 「学生 × 题」加入前就做对过，不藏的话把自己以前的答案贴进去就完了。
  *
- * 解锁的三条路全写在 where 里，任一成立就查不出来、也就不遮挡：
- *   - 已经在题单里做出这道题（progress_detail 里有这道题的 key）
- *   - 题单过了截止时间（end_time；为空表示不设期限，只能靠做出来解锁）
- *   - 题单被归档（status 不是 active）
+ * 以前是「加入之后藏加入之前的」，于是先去提交记录里把旧答案复制下来、再点加入，闸就白设了；
+ * 现在分界是布置开始，没加入的人也藏，这个口子就没了。代价是别的班以前做过这几道题的人，
+ * 在这一两周里也看不到自己的旧代码，用户认了。
  *
- * 一道题可能同时落在多个已加入的题单里，取最晚的 join_time——「存在任一题单要求遮挡就遮挡」
- * 等价于「提交时间早于最晚的那次加入」。旧后端这里用 `.first()` 取任意一条，一题多题单时
- * 行为不确定，换成聚合顺手定死。
+ * 解锁的路全写在 where 里，任一成立就查不出来、也就不遮挡：
+ *   - 题单不在布置期（没布置，或者布置期过了）
+ *   - 题单没公开
+ *   - 已经在这份题单里做对了这道题（progress_detail 里有这道题的 key）
+ *
+ * 一道题可能同时落在几个正在布置的题单里，取最晚的布置开始 ——「任一题单要求遮挡就遮挡」。
  */
-export async function problemSetJoinTimes(userId: number, problemIds: number[]) {
-  const joinTimes = new Map<number, string>()
-  if (problemIds.length === 0) return joinTimes
+export async function problemSetLockCutoffs(userId: number, problemIds: number[]) {
+  const cutoffs = new Map<number, string>()
+  if (problemIds.length === 0) return cutoffs
   const rows = await db
     .select({
       problemId: schema.problemsetProblem.problemId,
       // 聚合表达式不走列的类型映射，但 OID 还是 1184 —— db/index.ts 给这个 OID 挂了
-      // 「转成 ISO 8601」的 parser，所以这里拿到的和 `mode:"string"` 的列同形状。
-      // 原来那个 `::text` 要撤掉：它的 OID 是 25、绕过那个 parser，反而会变成 PG 文本。
-      joinTime: sql<string>`max(${schema.problemsetProgress.joinTime})`,
+      // 「转成 ISO 8601」的 parser，所以这里拿到的和 `mode:"string"` 的列同形状
+      cutoff: sql<string>`max(${schema.problemset.assignedAt})`,
     })
-    .from(schema.problemsetProgress)
-    .innerJoin(schema.problemset, eq(schema.problemset.id, schema.problemsetProgress.problemsetId))
-    .innerJoin(
-      schema.problemsetProblem,
-      eq(schema.problemsetProblem.problemsetId, schema.problemset.id),
+    .from(schema.problemsetProblem)
+    .innerJoin(schema.problemset, eq(schema.problemset.id, schema.problemsetProblem.problemsetId))
+    .leftJoin(
+      schema.problemsetProgress,
+      and(
+        eq(schema.problemsetProgress.problemsetId, schema.problemset.id),
+        eq(schema.problemsetProgress.userId, userId),
+      ),
     )
     .where(
       and(
-        eq(schema.problemsetProgress.userId, userId),
         inArray(schema.problemsetProblem.problemId, problemIds),
-        eq(schema.problemset.status, "active"),
-        or(isNull(schema.problemset.endTime), gt(schema.problemset.endTime, sql`now()`)),
-        sql`not jsonb_exists(${schema.problemsetProgress.progressDetail}, ${schema.problemsetProblem.problemId}::text)`,
+        eq(schema.problemset.visible, true),
+        assigningSql,
+        sql`not coalesce(jsonb_exists(${schema.problemsetProgress.progressDetail}, ${schema.problemsetProblem.problemId}::text), false)`,
       ),
     )
     .groupBy(schema.problemsetProblem.problemId)
-  for (const row of rows) joinTimes.set(row.problemId, row.joinTime)
-  return joinTimes
+  for (const row of rows) cutoffs.set(row.problemId, row.cutoff)
+  return cutoffs
+}
+
+/** 这道题的旧代码为什么藏着：它落在哪些正在布置、我还没在里面做对的题单里 */
+export async function problemSetLocksFor(userId: number, problemId: number) {
+  return db
+    .select({
+      problemSetId: schema.problemset.id,
+      title: schema.problemset.title,
+      assignedUntil: sql<string>`${schema.problemset.assignedUntil}`,
+    })
+    .from(schema.problemsetProblem)
+    .innerJoin(schema.problemset, eq(schema.problemset.id, schema.problemsetProblem.problemsetId))
+    .leftJoin(
+      schema.problemsetProgress,
+      and(
+        eq(schema.problemsetProgress.problemsetId, schema.problemset.id),
+        eq(schema.problemsetProgress.userId, userId),
+      ),
+    )
+    .where(
+      and(
+        eq(schema.problemsetProblem.problemId, problemId),
+        eq(schema.problemset.visible, true),
+        assigningSql,
+        sql`not coalesce(jsonb_exists(${schema.problemsetProgress.progressDetail}, ${schema.problemsetProblem.problemId}::text), false)`,
+      ),
+    )
+    .orderBy(asc(schema.problemset.assignedUntil))
 }