diff --git a/CLAUDE.md b/CLAUDE.md
index d4b191c..b8fedcc 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -106,26 +106,46 @@ dev 直接起不来。
 这些整数是**落库的值**：12 万条历史提交的 `submission.result` 就是它们，判题沙箱回的也是
 这套编码，所以只能新增、不能改已有的含义。题目表情 reaction 的语义 key 同理。
 
-### 契约收紧要挑地方：闸在写入侧，不在读出侧
+### 出参不 `parse`，用 `satisfies`
 
-`packages/contract` 的 schema 前后端共用，而且**后端在读路径上 `parse`**
-（`submissionDetailSchema` / `exerciseSchema` / `contestRankItemSchema` 都是）。
-所以收紧一个字段不只是「类型更准」，是给全部历史数据加了一道闸：
+**后端的响应一律 `satisfies XxxType`，不要写 `xxxSchema.parse({...})`。**
+出参是后端自己刚拼出来的字面量，TS 已经在编译期校验过；再 `parse` 一遍拿不到任何新
+信息，唯一可能失败的输入是**库里的历史数据**，而失败的代价是 500。这一层原来有 136 处，
+已经全部撤掉，撤的时候当场炸出两个一直存在的线上 500：
 
-- 对不上就 500 —— `exerciseSchema` 按题型收紧过，库里一行脏数据能让整条学生练习
-  列表打不开，坏的不是那一道题；
-- 更坏的是**不 500**：`info` 当时写成 `union([完整形状, z.object({})])`，对不上的
-  一律落进空对象那支且 parse 成功，管理员详情页的测试点表格**静默消失**。全量核出来
-  9163/124192 条中招，RE 8480/8480、TLE 338/338、MLE 1/1 全中 —— 沙箱在非正常退出
-  的测试点上写 `output_md5: null`，而契约写的是 `z.string()`。
+- `adminProblemSchema.lastUpdateTime` 写的是 `z.string()`，但 `problem.last_update_time`
+  是全库唯一可空的列（961 道题里 470 道是 NULL）——**后台打开任何一道没编辑过的老题都是 500**；
+- `embeddedSubmissionSchema` 从 `submissionDetailSchema` 继承了 `problemDisplayId` 却没
+  omit，而路由只填了同义的 `problem`——**凡是收到过站内信的人，消息页都打不开**（列表为空
+  时才碰巧不炸，所以一直没人报）。
 
-所以：**JSONB 原文（`submission.info` / `statistic_info` / `exercise.data`）的形状
-真相在写入侧** —— 判题机、`services/exercise.ts` 的 `exerciseDataError` —— 闸就设在
-那里，读出侧放行。下一条 AST 规则的 `astRulesError()` 是同一个道理的另一个实例。
+两个都是「读出侧校验」自己造出来的故障，不是它拦住的故障。历史上还有两次同类：
+`exerciseSchema` 按题型收紧后一行脏数据让整条练习列表 500；`info` 写成
+`union([完整形状, z.object({})])` 后对不上的一律落进空对象那支且 parse **成功**，
+管理员详情页的测试点表格静默消失（全量核出 9163/124192 条中招，RE 8480/8480 全中——
+沙箱在非正常退出的测试点上写 `output_md5: null`，而契约写的是 `z.string()`）。
 
-真要收紧读出侧的字段，先拿根目录那份生产备份跑一遍全量，**重点看空值，不是键集合**：
-上面那次翻车就是键集合全对、空值没看。前端那侧（`utils/contract.ts` 为什么只挂三处）
-见 `apps/web/CLAUDE.md`。
+**闸设在写入侧，一共三处形态：**
+
+1. **入参 `safeParse`**（58 处，全部保留）—— 请求体进来的那一刻校验，对不上回 400。
+2. **`db/schema.ts` 的 `.$type<>()`** —— 枚举型的列（`submission.result` / `.language`、
+   `problem.difficulty` / `.languages`、`achievement.rarity`、`exercise.type`…）和几个
+   形状确定的 JSONB（`problem.template` / `.astRules` / `.sqlConfig` / `.sqlDisplay`、
+   `acm_contest_rank.submission_info`）直接在列上收窄，只影响 TS、不产生任何 SQL。
+   这些断言**逐列拿根目录那份生产备份核过**（12.4 万条提交的 `result` 全在 `-2..6,10`、
+   961 道题的 `languages` 全是合法数组、10050 条榜单条目形状全对）。
+   加这类断言前先照样核一遍，别凭直觉。
+3. **语义校验函数** —— `astRulesError()`、`services/exercise.ts` 的 `exerciseDataError`。
+
+**JSONB 原文（`submission.info` / `statistic_info` / `exercise.data`）仍然一律放行**，
+读出侧不收窄：它们的形状真相在判题机那边。
+
+query 里的筛选值要和收窄过的列比较时走 `routes/helpers.ts` 的 `asFilterValue()` ——
+那是纯类型交接，**不加校验**：在那儿拦一道会把「筛出空列表」变成「筛条件被忽略、
+返回全部」。前端那侧（`utils/contract.ts` 为什么只挂三处）见 `apps/web/CLAUDE.md`。
+
+唯一还留着 `parse` 的地方是 `judge/events.ts` 的 `parseSubmissionEvent` ——
+那是从 Redis 收回来的报文，真边界，且失败返回 `null` 而不是 500。
 
 ### AST 代码规则有两张表，必须同增同减
 
diff --git a/apps/api/src/db/schema.ts b/apps/api/src/db/schema.ts
index 51acabb..0217f9c 100644
--- a/apps/api/src/db/schema.ts
+++ b/apps/api/src/db/schema.ts
@@ -15,6 +15,17 @@
 // 详见 CLAUDE.md「改 schema 走 drizzle migration」）：
 //   * bigint identity 的 maxValue 用字符串，不能写成 JS number 字面量（会丢精度）。
 //   * 索引不写 `.desc()`，生成 SQL 时方向会被丢掉。
+//   * `.$type<...>()` 的收窄（见下）—— `pull` 只会吐出 text/integer/jsonb，重新 pull
+//     会把这些断言全抹掉，之后出参的 `satisfies` 会当场编译不过（这是好事，别拿
+//     `as` 糊过去，把断言补回来）。
+//
+// 2026-09-10：出参不再 `xxxSchema.parse()` 而是 `satisfies`（原来 136 处），
+// 收窄的责任因此挪到了列上：枚举型的列和几个形状确定的 JSONB 都挂了 `.$type<>()`。
+// `$type` 只是 TS 层的断言、不产生任何 SQL，所以它成立与否得靠数据说话 ——
+// 下面每一处都拿根目录那份生产备份逐列核过（12.4 万条提交的 result 全在 -2..6,10、
+// 961 道题的 languages 全是合法数组、10050 条榜单条目形状全对，无一例外）。
+// **再给别的列加 $type 之前，照样先核一遍全量数据。** 兑现这些断言的是写入侧的
+// `safeParse`，不是读出侧。前因后果见 CLAUDE.md「出参不 `parse`，用 `satisfies`」。
 //
 // 关于 10 张表的 bigint id（problemset*、achievement、user_achievement、user_stat、
 // user_badge、ai_analysis）：这是历史巧合不是设计——这些 app 的 0001_initial 生成时
@@ -22,7 +33,26 @@
 // problem、contest、submission）都是 int4。现存最大 id 一万出头，确实都用不上 bigint，
 // 但 2026-08-26 评估后决定**不改**：省 4 字节/行毫无意义，ALTER TYPE 要重写整表并拿
 // ACCESS EXCLUSIVE 锁，而且其中 6 处 id 被外键绑着得连坐。别再提这件事了。
-import type { AdminType, ProblemPermission } from "@oj2/contract"
+import type {
+	AchievementOperator,
+	AchievementRarity,
+	AdminType,
+	AstRules,
+	BadgeConditionType,
+	ContestSubmissionInfo,
+	ExerciseType,
+	FlowchartStatus,
+	JudgeStatus,
+	ProblemDifficulty,
+	ProblemLanguage,
+	ProblemPermission,
+	ProblemSetDifficulty,
+	ProblemSetStatus,
+	ReactionKey,
+	SqlConfig,
+	SqlDisplay,
+	TutorialType,
+} from "@oj2/contract"
 import { pgTable, index, foreignKey, primaryKey, bigint, text, jsonb, timestamp, integer, boolean, serial, doublePrecision, varchar, unique, uniqueIndex } from "drizzle-orm/pg-core"
 import { sql } from "drizzle-orm"
 
@@ -75,10 +105,10 @@ export const achievement = pgTable("achievement", {
 	name: text().notNull(),
 	description: text().notNull(),
 	icon: text().notNull(),
-	rarity: text().notNull(),
+	rarity: text().notNull().$type<AchievementRarity>(),
 	hidden: boolean().default(false).notNull(),
 	metric: text().notNull(),
-	operator: text().notNull(),
+	operator: text().notNull().$type<AchievementOperator>(),
 	threshold: integer().notNull(),
 	visible: boolean().default(true).notNull(),
 	unlockCount: integer("unlock_count").default(0).notNull(),
@@ -111,7 +141,7 @@ export const flowchartSubmission = pgTable("flowchart_submission", {
 	id: text().primaryKey().notNull(),
 	mermaidCode: text("mermaid_code").notNull(),
 	flowchartData: jsonb("flowchart_data").notNull(),
-	status: integer().notNull(),
+	status: integer().notNull().$type<FlowchartStatus>(),
 	createTime: timestamp("create_time", { withTimezone: true, mode: 'string' }).notNull(),
 	aiScore: doublePrecision("ai_score"),
 	aiGrade: varchar("ai_grade", { length: 10 }),
@@ -189,7 +219,7 @@ export const judgeServer = pgTable("judge_server", {
 
 export const exercise = pgTable("exercise", {
 	id: integer().primaryKey().generatedByDefaultAsIdentity({ name: "exercise_id_seq", startWith: 1, increment: 1, minValue: 1, maxValue: 2147483647, cache: 1 }),
-	type: varchar({ length: 16 }).notNull(),
+	type: varchar({ length: 16 }).notNull().$type<ExerciseType>(),
 	data: jsonb().notNull(),
 	order: integer().notNull(),
 	createdAt: timestamp("created_at", { withTimezone: true, mode: 'string' }).notNull(),
@@ -219,8 +249,8 @@ export const problemset = pgTable("problemset", {
 	createTime: timestamp("create_time", { withTimezone: true, mode: 'string' }).notNull(),
 	lastUpdateTime: timestamp("last_update_time", { withTimezone: true, mode: 'string' }).notNull(),
 	visible: boolean().notNull(),
-	difficulty: text().notNull(),
-	status: text().notNull(),
+	difficulty: text().notNull().$type<ProblemSetDifficulty>(),
+	status: text().notNull().$type<ProblemSetStatus>(),
 	createdById: integer("created_by_id").notNull(),
 	endTime: timestamp("end_time", { withTimezone: true, mode: 'string' }),
 }, (table) => [
@@ -324,7 +354,7 @@ export const problemsetSubmission = pgTable("problemset_submission", {
 
 export const reaction = pgTable("reaction", {
 	id: integer().primaryKey().generatedByDefaultAsIdentity({ name: "reaction_id_seq", startWith: 1, increment: 1, minValue: 1, maxValue: 2147483647, cache: 1 }),
-	type: varchar({ length: 20 }).notNull(),
+	type: varchar({ length: 20 }).notNull().$type<ReactionKey>(),
 	createTime: timestamp("create_time", { withTimezone: true, mode: 'string' }).notNull(),
 	problemId: integer("problem_id").notNull(),
 	userId: integer("user_id").notNull(),
@@ -354,14 +384,14 @@ export const problem = pgTable("problem", {
 	testCaseId: text("test_case_id").notNull(),
 	testCaseScore: jsonb("test_case_score").notNull(),
 	hint: text(),
-	languages: jsonb().notNull(),
-	template: jsonb().notNull(),
+	languages: jsonb().notNull().$type<ProblemLanguage[]>(),
+	template: jsonb().notNull().$type<Record<string, string>>(),
 	createTime: timestamp("create_time", { withTimezone: true, mode: 'string' }).notNull(),
 	lastUpdateTime: timestamp("last_update_time", { withTimezone: true, mode: 'string' }),
 	timeLimit: integer("time_limit").notNull(),
 	memoryLimit: integer("memory_limit").notNull(),
 	visible: boolean().default(true).notNull(),
-	difficulty: text().notNull(),
+	difficulty: text().notNull().$type<ProblemDifficulty>(),
 	source: text(),
 	// You can use { mode: "bigint" } if numbers are exceeding js number limitations
 	submissionNumber: bigint("submission_number", { mode: "number" }).default(0).notNull(),
@@ -386,9 +416,9 @@ export const problem = pgTable("problem", {
 	flowchartHint: text("flowchart_hint"),
 	mermaidCode: text("mermaid_code"),
 	showFlowchart: boolean("show_flowchart").default(false).notNull(),
-	astRules: jsonb("ast_rules"),
-	sqlConfig: jsonb("sql_config"),
-	sqlDisplay: jsonb("sql_display"),
+	astRules: jsonb("ast_rules").$type<AstRules>(),
+	sqlConfig: jsonb("sql_config").$type<SqlConfig>(),
+	sqlDisplay: jsonb("sql_display").$type<SqlDisplay>(),
 }, (table) => [
 	index("problem_contest_visible_idx").using("btree", table.contestId.asc().nullsLast().op("bool_ops"), table.visible.asc().nullsLast().op("int4_ops")),
 	index("problem_created_by_id_cb362143").using("btree", table.createdById.asc().nullsLast().op("int4_ops")),
@@ -439,9 +469,9 @@ export const submission = pgTable("submission", {
 	createTime: timestamp("create_time", { withTimezone: true, mode: 'string' }).notNull(),
 	userId: integer("user_id").notNull(),
 	code: text().notNull(),
-	result: integer().default(6).notNull(),
+	result: integer().default(6).notNull().$type<JudgeStatus>(),
 	info: jsonb().default({}).notNull(),
-	language: text().notNull(),
+	language: text().notNull().$type<ProblemLanguage>(),
 	/**
 	 * 已停用，见 problem.share_submission 的说明。历史上 12.3 万条提交里有 40 条
 	 * 为真（2022 年 39 条、2023 年 1 条），入口在更早的那版前端上，ojnext 和 OJ2
@@ -560,7 +590,7 @@ export const tutorial = pgTable("tutorial", {
 	order: integer().notNull(),
 	createdById: integer("created_by_id").notNull(),
 	code: text(),
-	type: varchar({ length: 10 }).notNull(),
+	type: varchar({ length: 10 }).notNull().$type<TutorialType>(),
 }, (table) => [
 	index("tutorial_created_by_id_07973cab").using("btree", table.createdById.asc().nullsLast().op("int4_ops")),
 	foreignKey({
@@ -635,7 +665,7 @@ export const userBadge = pgTable("user_badge", {
 
 export const userProfile = pgTable("user_profile", {
 	id: serial().primaryKey().notNull(),
-	acmProblemsStatus: jsonb("acm_problems_status").default({}).notNull(),
+	acmProblemsStatus: jsonb("acm_problems_status").default({}).notNull().$type<Record<string, unknown>>(),
 	avatar: text().notNull(),
 	mood: text(),
 	acceptedNumber: integer("accepted_number").default(0).notNull(),
@@ -656,7 +686,7 @@ export const acmContestRank = pgTable("acm_contest_rank", {
 	submissionNumber: integer("submission_number").default(0).notNull(),
 	acceptedNumber: integer("accepted_number").default(0).notNull(),
 	totalTime: integer("total_time").default(0).notNull(),
-	submissionInfo: jsonb("submission_info").default({}).notNull(),
+	submissionInfo: jsonb("submission_info").default({}).notNull().$type<Record<string, ContestSubmissionInfo>>(),
 	contestId: integer("contest_id").notNull(),
 	userId: integer("user_id").notNull(),
 }, (table) => [
@@ -705,7 +735,7 @@ export const problemsetBadge = pgTable("problemset_badge", {
 	name: text().notNull(),
 	description: text().notNull(),
 	icon: text().notNull(),
-	conditionType: text("condition_type").notNull(),
+	conditionType: text("condition_type").notNull().$type<BadgeConditionType>(),
 	conditionValue: integer("condition_value").notNull(),
 	// You can use { mode: "bigint" } if numbers are exceeding js number limitations
 	problemsetId: bigint("problemset_id", { mode: "number" }).notNull(),
diff --git a/apps/api/src/events.ts b/apps/api/src/events.ts
index 3db2d5a..f05eed2 100644
--- a/apps/api/src/events.ts
+++ b/apps/api/src/events.ts
@@ -1,4 +1,4 @@
-import { flowchartUpdateSchema, type FlowchartUpdate } from "@oj2/contract"
+import type { FlowchartUpdate } from "@oj2/contract"
 
 import { redis } from "./redis"
 
@@ -72,7 +72,7 @@ export function userEventTopic(userId: number) {
 }
 
 export async function publishFlowchartUpdate(userId: number, data: FlowchartUpdate) {
-  await redis.publish(userEventChannel, JSON.stringify({ userId, data: flowchartUpdateSchema.parse(data) }))
+  await redis.publish(userEventChannel, JSON.stringify({ userId, data }))
 }
 
 export async function publishAchievementNotification(
diff --git a/apps/api/src/flowchart/run.ts b/apps/api/src/flowchart/run.ts
index 59874f4..a269b23 100644
--- a/apps/api/src/flowchart/run.ts
+++ b/apps/api/src/flowchart/run.ts
@@ -1,4 +1,4 @@
-import { flowchartUpdateSchema } from "@oj2/contract"
+import type { FlowchartUpdate } from "@oj2/contract"
 import { eq } from "drizzle-orm"
 
 import { db, schema } from "../db"
@@ -71,7 +71,7 @@ export async function evaluateFlowchart(
       processingTime: (performance.now() - started) / 1000,
       evaluationTime: new Date().toISOString(),
     }).where(eq(schema.flowchartSubmission.id, row.flowchart.id))
-    await publishFlowchartUpdate(row.flowchart.userId, flowchartUpdateSchema.parse({
+    await publishFlowchartUpdate(row.flowchart.userId, {
       type: "flowchart_evaluation_completed",
       submissionId: row.flowchart.id,
       score: result.score,
@@ -79,7 +79,7 @@ export async function evaluateFlowchart(
       feedback: result.feedback,
       suggestions: result.suggestions,
       criteriaDetails: result.criteria,
-    }))
+    } satisfies FlowchartUpdate)
   } catch (error) {
     // 原来这里把 error.message 原样推给学生、前端还直接 message.error 弹出来 ——
     // AI provider 的地址、内部报错就这么进了浏览器。真实原因留在服务端日志里，
@@ -91,10 +91,10 @@ export async function evaluateFlowchart(
     // 就算成功，AI 侧的偶发失败（限流、超时、网络抖动）永远等不到重试。
     if (!isFinalAttempt) throw error
     await db.update(schema.flowchartSubmission).set({ status: 3 }).where(eq(schema.flowchartSubmission.id, row.flowchart.id))
-    await publishFlowchartUpdate(row.flowchart.userId, flowchartUpdateSchema.parse({
+    await publishFlowchartUpdate(row.flowchart.userId, {
       type: "flowchart_evaluation_failed",
       submissionId: row.flowchart.id,
-    }))
+    } satisfies FlowchartUpdate)
     throw error
   }
 }
diff --git a/apps/api/src/judge/events.ts b/apps/api/src/judge/events.ts
index ba4bec7..d45a865 100644
--- a/apps/api/src/judge/events.ts
+++ b/apps/api/src/judge/events.ts
@@ -1,7 +1,4 @@
-import {
-  submissionUpdateSchema,
-  type SubmissionUpdate,
-} from "@oj2/contract"
+import { submissionUpdateSchema, type SubmissionUpdate } from "@oj2/contract"
 
 import { redis } from "../redis"
 
@@ -20,10 +17,7 @@ export async function publishSubmissionUpdate(
   userId: number,
   data: SubmissionUpdate,
 ) {
-  const event: SubmissionEvent = {
-    userId,
-    data: submissionUpdateSchema.parse(data),
-  }
+  const event: SubmissionEvent = { userId, data }
   await redis.publish(submissionUpdateChannel, JSON.stringify(event))
 }
 
diff --git a/apps/api/src/judge/run.ts b/apps/api/src/judge/run.ts
index 62a974e..f5a7142 100644
--- a/apps/api/src/judge/run.ts
+++ b/apps/api/src/judge/run.ts
@@ -1,6 +1,6 @@
 import { createHash } from "node:crypto"
 
-import { astRuleSchema } from "@oj2/contract"
+import { astRuleSchema, type ContestSubmissionInfo } from "@oj2/contract"
 import { and, eq, inArray } from "drizzle-orm"
 
 import { config } from "../config"
@@ -248,15 +248,12 @@ async function persistResult(
         .for("update")
       if (!rank) throw new Error("Contest rank could not be created")
 
-      const rankInfo = objectValue(rank.submissionInfo)
-      const previousInfo = objectValue(rankInfo[String(problemId)])
-      const alreadyAccepted = previousInfo.is_ac === true
+      const rankInfo = rank.submissionInfo
+      const previousInfo = rankInfo[String(problemId)]
+      const alreadyAccepted = previousInfo?.is_ac === true
       if (!alreadyAccepted) {
-        const errorNumber =
-          typeof previousInfo.error_number === "number"
-            ? previousInfo.error_number
-            : 0
-        const nextInfo: Record<string, unknown> = {
+        const errorNumber = previousInfo?.error_number ?? 0
+        const nextInfo: ContestSubmissionInfo = {
           is_ac: acceptedNow,
           ac_time: 0,
           error_number:
diff --git a/apps/api/src/judge/sql/index.ts b/apps/api/src/judge/sql/index.ts
index 53e46e0..1963cba 100644
--- a/apps/api/src/judge/sql/index.ts
+++ b/apps/api/src/judge/sql/index.ts
@@ -1,3 +1,5 @@
+import type { SqlDisplay } from "@oj2/contract"
+
 import { selfCommand } from "../../runtime"
 import { JudgeStatus, type JudgeStatusValue } from "../status"
 import { DISPLAY_BUDGET_MS, trustedBudgetMs, type CaseResult } from "./engine"
@@ -175,7 +177,9 @@ export function runSqlCase(job: Extract<SqlJob, { kind: "judge" }>) {
 }
 
 export function buildSqlDisplay(initSql: string, refSql: string, mode: "query" | "modify") {
-  return runJob<{ tables: unknown[]; expected: unknown }>(
+  // 子进程产出的形状由 engine.ts 的 dumpDisplayTables / runDisplay 决定，就是契约里的
+  // SqlDisplay —— 同一个仓库里的两端，不在这儿再 parse 一遍
+  return runJob<SqlDisplay>(
     { kind: "display", initSql, refSql, mode },
     { trustedMs: DISPLAY_BUDGET_MS, studentMs: null },
   )
diff --git a/apps/api/src/judge/status.ts b/apps/api/src/judge/status.ts
index cf22c9b..553c0b8 100644
--- a/apps/api/src/judge/status.ts
+++ b/apps/api/src/judge/status.ts
@@ -48,14 +48,14 @@ export function judgeStatusName(result: number) {
  * 它们从分母里摘掉 —— 否则全班同时交卷的那几秒，分母涨了分子没涨，正确率凭空掉一截。
  * 人数口径不受影响：交了但还在判的学生仍然算「交过」，不该被点名成「没做」。
  */
-export const UNJUDGED_RESULTS: number[] = [JudgeStatus.PENDING, JudgeStatus.JUDGING]
+export const UNJUDGED_RESULTS: JudgeStatusValue[] = [JudgeStatus.PENDING, JudgeStatus.JUDGING]
 
 /**
  * **不**计入「这道题失败了几次」的状态。除了通过（含 AST_CHECK_FAILED，那也是答案对了）
  * 和还没判完的两个，还排掉 SYSTEM_ERROR —— 判题机自己崩了不是学生的问题，
  * 不该推着 AI 提示的解锁进度往前走。
  */
-export const NON_FAILURE_RESULTS: number[] = [
+export const NON_FAILURE_RESULTS: JudgeStatusValue[] = [
   JudgeStatus.ACCEPTED,
   JudgeStatus.AST_CHECK_FAILED,
   JudgeStatus.PENDING,
diff --git a/apps/api/src/routes/account.ts b/apps/api/src/routes/account.ts
index 78a5c16..ceb4fb9 100644
--- a/apps/api/src/routes/account.ts
+++ b/apps/api/src/routes/account.ts
@@ -2,15 +2,16 @@ import { randomBytes } from "node:crypto"
 import { extname, resolve } from "node:path"
 
 import {
-  STUDENT_ROLES,
-  activityRankItemSchema,
-  metricsSchema,
-  problemRankSchema,
-  myRankSchema,
   rankProfileSchema,
   registerRequestSchema,
+  STUDENT_ROLES,
   updateProfileRequestSchema,
-  userRankSchema,
+  type ActivityRankItem,
+  type Metrics,
+  type MyRank,
+  type ProblemRank,
+  type RankProfile,
+  type UserRank,
 } from "@oj2/contract"
 import {
   and,
@@ -144,7 +145,7 @@ accountRoutes.get("/users/:id/metrics", async (c) => {
     .from(schema.submission)
     .where(and(eq(schema.submission.userId, userId), isNull(schema.submission.contestId)))
   if (!row?.total || !row.first || !row.latest) return failure(c, 404, "no-submissions", "暂无提交")
-  return success(c, metricsSchema.parse({ now: new Date().toISOString(), first: row.first, latest: row.latest }))
+  return success(c, { now: new Date().toISOString(), first: row.first, latest: row.latest } satisfies Metrics)
 })
 
 /**
@@ -199,25 +200,25 @@ accountRoutes.get("/rankings/users", optionalAuth, async (c) => {
     isTeacherOrAbove(c.get("user")) ? onlineUserIds() : null,
   ])
 
-  return success(c, userRankSchema.parse({
+  return success(c, {
     results: rows.map((row) => serializeRankRow(row, online)),
     total: Math.min(totalRow?.value ?? 0, LEADERBOARD_SIZE),
     me,
-  }))
+  } satisfies UserRank)
 })
 
 function serializeRankRow({ profile, user }: {
   profile: typeof schema.userProfile.$inferSelect
   user: typeof schema.user.$inferSelect
 }, online: Set<number> | null = null) {
-  return rankProfileSchema.parse({
+  return {
     id: profile.id,
     user: sampleUser(user, profile.realName),
     acceptedNumber: profile.acceptedNumber,
     submissionNumber: profile.submissionNumber,
     mood: profile.mood,
     isOnline: online ? online.has(user.id) : null,
-  })
+  } satisfies RankProfile
 }
 
 /**
@@ -251,10 +252,10 @@ async function myLeaderboardRank(userId: number | undefined) {
       ),
     )))
 
-  return myRankSchema.parse({
+  return {
     ...serializeRankRow(mine),
     rank: (ahead?.value ?? 0) + 1,
-  })
+  } satisfies MyRank
 }
 
 accountRoutes.get("/rankings/activity", async (c) => {
@@ -279,7 +280,7 @@ accountRoutes.get("/rankings/activity", async (c) => {
     ))
     .groupBy(schema.submission.userId, schema.user.username)
     .orderBy(desc(countDistinct(schema.submission.problemId))).limit(10)
-  return success(c, rows.map((row) => activityRankItemSchema.parse({ username: row.username, count: row.value })))
+  return success(c, rows.map((row) => ({ username: row.username, count: row.value } satisfies ActivityRankItem)))
 })
 
 accountRoutes.get("/problems/:displayId/rank", requireAuth, async (c) => {
@@ -303,7 +304,7 @@ accountRoutes.get("/problems/:displayId/rank", requireAuth, async (c) => {
     const [rankRow] = await db.select({ value: count() }).from(schema.submission).where(and(classWhere, lte(schema.submission.createTime, first.value)))
     rank = rankRow?.value ?? -1
   }
-  return success(c, problemRankSchema.parse({ className, rank, classAcCount: classCount?.value ?? 0, allAcCount: all?.value ?? 0 }))
+  return success(c, { className, rank, classAcCount: classCount?.value ?? 0, allAcCount: all?.value ?? 0 } satisfies ProblemRank)
 })
 
 /**
diff --git a/apps/api/src/routes/achievement.ts b/apps/api/src/routes/achievement.ts
index 82db138..29dd3ec 100644
--- a/apps/api/src/routes/achievement.ts
+++ b/apps/api/src/routes/achievement.ts
@@ -1,9 +1,9 @@
 import {
-  achievementListSchema,
-  achievementSchema,
-  achievementSummarySchema,
   markAchievementsReadSchema,
-  pendingAchievementSchema,
+  type Achievement,
+  type AchievementList,
+  type AchievementSummary,
+  type PendingAchievement,
 } from "@oj2/contract"
 import { and, asc, count, desc, eq, inArray } from "drizzle-orm"
 import { Hono } from "hono"
@@ -27,13 +27,13 @@ async function resolveUser(requested: string | undefined, currentId: number) {
 }
 
 function pendingData(row: { achievement: typeof schema.achievement.$inferSelect }) {
-  return pendingAchievementSchema.parse({
+  return {
     id: row.achievement.id,
     name: row.achievement.name,
     description: row.achievement.description,
     icon: row.achievement.icon,
     rarity: row.achievement.rarity,
-  })
+  } satisfies PendingAchievement
 }
 
 achievementRoutes.get("/achievements", requireAuth, async (c) => {
@@ -52,7 +52,7 @@ achievementRoutes.get("/achievements", requireAuth, async (c) => {
     const record = unlocked.get(achievement.id)
     const masked = achievement.hidden && !record
     const progress = metrics[achievement.metric]
-    return achievementSchema.parse({
+    return {
       id: achievement.id,
       name: masked ? "???" : achievement.name,
       description: masked ? "达成条件保密" : achievement.description,
@@ -67,9 +67,9 @@ achievementRoutes.get("/achievements", requireAuth, async (c) => {
       backfilled: record?.backfilled ?? false,
       progress: masked ? null : typeof progress === "number" ? progress : 0,
       unlockRate: active > 0 ? Math.round(achievement.unlockCount / active * 1000) / 10 : 0,
-    })
+    } satisfies Achievement
   })
-  return success(c, achievementListSchema.parse({ username: target.username, achievements: result }))
+  return success(c, { username: target.username, achievements: result } satisfies AchievementList)
 })
 
 achievementRoutes.get("/achievements/summary", requireAuth, async (c) => {
@@ -85,7 +85,7 @@ achievementRoutes.get("/achievements/summary", requireAuth, async (c) => {
   const rarities = ["bronze", "silver", "gold", "platinum"] as const
   const total = achievements.length
   const unlocked = unlockedRows.length
-  return success(c, achievementSummarySchema.parse({
+  return success(c, {
     username: target.username,
     total,
     unlocked,
@@ -97,7 +97,7 @@ achievementRoutes.get("/achievements/summary", requireAuth, async (c) => {
       unlocked: unlockedRows.filter((item) => item.achievement.rarity === rarity).length,
     })),
     recent: unlockedRows.slice(0, 10).map(pendingData),
-  }))
+  } satisfies AchievementSummary)
 })
 
 achievementRoutes.get("/achievements/pending", requireAuth, async (c) => {
diff --git a/apps/api/src/routes/admin/account.ts b/apps/api/src/routes/admin/account.ts
index f42c1f1..537b2fb 100644
--- a/apps/api/src/routes/admin/account.ts
+++ b/apps/api/src/routes/admin/account.ts
@@ -1,16 +1,16 @@
 import {
-  STUDENT_ROLES,
   adminTypeSchema,
-  adminUserListSchema,
-  adminUserRankSchema,
-  adminUserSchema,
   deleteUsersRequestSchema,
   importUsersRequestSchema,
-  rankProfileSchema,
-  resetPasswordResponseSchema,
+  STUDENT_ROLES,
   updateUserRequestSchema,
   type AdminType,
+  type AdminUser,
+  type AdminUserList,
+  type AdminUserRank,
   type ProblemPermission,
+  type RankProfile,
+  type ResetPasswordResponse,
 } from "@oj2/contract"
 import { randomInt } from "node:crypto"
 import { z } from "zod"
@@ -66,7 +66,7 @@ function serialize(row: {
   user: typeof schema.user.$inferSelect
   realName: string | null
 }, isOnline: boolean) {
-  return adminUserSchema.parse({
+  return {
     id: row.user.id,
     username: row.user.username,
     email: row.user.email,
@@ -79,7 +79,7 @@ function serialize(row: {
     isOnline,
     rawPassword: row.user.rawPassword,
     className: row.user.className,
-  })
+  } satisfies AdminUser
 }
 
 function selectUser(id: number) {
@@ -122,16 +122,19 @@ adminAccountRoutes.get("/rankings/users", requireSuperAdmin, async (c) => {
       .limit(limit).offset(offset),
   ])
 
-  return success(c, adminUserRankSchema.parse({
-    results: rows.map(({ profile, user }) => rankProfileSchema.parse({
+  return success(c, {
+    results: rows.map(({ profile, user }) => ({
       id: profile.id,
       user: sampleUser(user, profile.realName),
       acceptedNumber: profile.acceptedNumber,
       submissionNumber: profile.submissionNumber,
       mood: profile.mood,
-    })),
+      // 这张榜不下发在线状态（null = 「调用方不该知道」，见契约里 isOnline 的注释）。
+      // 原来是靠 schema 的 .default(null) 填出来的，改成显式写死。
+      isOnline: null,
+    } satisfies RankProfile)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AdminUserRank)
 })
 
 adminAccountRoutes.get("/users", requireSuperAdmin, async (c) => {
@@ -181,10 +184,10 @@ adminAccountRoutes.get("/users", requireSuperAdmin, async (c) => {
       .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id)).where(where)
       .orderBy(...order, asc(schema.user.id)).limit(limit).offset(offset),
   ])
-  return success(c, adminUserListSchema.parse({
+  return success(c, {
     results: rows.map((row) => serialize(row, online.has(row.user.id))),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AdminUserList)
 })
 
 adminAccountRoutes.get("/users/:id", requireSuperAdmin, async (c) => {
@@ -447,5 +450,5 @@ adminAccountRoutes.post("/users/:id/reset-password", requireSuperAdmin, async (c
   }).where(eq(schema.user.id, id))
   // 旧密码登出来的会话立刻作废，理由同 PUT /users/:id
   await revokeUserSessions(id, "session-ended")
-  return success(c, resetPasswordResponseSchema.parse({ password }))
+  return success(c, { password } satisfies ResetPasswordResponse)
 })
diff --git a/apps/api/src/routes/admin/achievement.ts b/apps/api/src/routes/admin/achievement.ts
index 454656a..4c6d431 100644
--- a/apps/api/src/routes/admin/achievement.ts
+++ b/apps/api/src/routes/admin/achievement.ts
@@ -1,8 +1,8 @@
 import {
-  achievementMetricSchema,
-  adminAchievementSchema,
   createAchievementRequestSchema,
   updateAchievementRequestSchema,
+  type AchievementMetric,
+  type AdminAchievement,
 } from "@oj2/contract"
 import { asc, eq } from "drizzle-orm"
 import { Hono } from "hono"
@@ -17,7 +17,7 @@ import { queryInteger } from "../helpers"
 export const adminAchievementRoutes = new Hono<AppEnv>()
 
 function serialize(row: typeof schema.achievement.$inferSelect) {
-  return adminAchievementSchema.parse({
+  return {
     id: row.id,
     name: row.name,
     description: row.description,
@@ -32,12 +32,12 @@ function serialize(row: typeof schema.achievement.$inferSelect) {
     unlockCount: row.unlockCount,
     order: row.order,
     createTime: row.createTime,
-  })
+  } satisfies AdminAchievement
 }
 
 /** 下拉框的可选项就是代码里注册了什么，见 services/achievement-metrics.ts 的说明 */
 adminAchievementRoutes.get("/achievement-metrics", requireSuperAdmin, (c) =>
-  success(c, ACHIEVEMENT_METRICS.map((item) => achievementMetricSchema.parse(item))))
+  success(c, ACHIEVEMENT_METRICS satisfies AchievementMetric[]))
 
 adminAchievementRoutes.get("/achievements", requireSuperAdmin, async (c) => {
   const rows = await db.select().from(schema.achievement)
diff --git a/apps/api/src/routes/admin/ai.ts b/apps/api/src/routes/admin/ai.ts
index 1acb996..b2360bb 100644
--- a/apps/api/src/routes/admin/ai.ts
+++ b/apps/api/src/routes/admin/ai.ts
@@ -1,8 +1,8 @@
-import {
-  adminAiReportListSchema,
-  adminAiReportListItemSchema,
-  adminAiReportSchema,
-  toggleAiReportPinResponseSchema,
+import type {
+  AdminAiReport,
+  AdminAiReportList,
+  AdminAiReportListItem,
+  ToggleAiReportPinResponse,
 } from "@oj2/contract"
 import { and, count, desc, eq, ilike } from "drizzle-orm"
 import { Hono } from "hono"
@@ -22,13 +22,13 @@ function excerpt(analysis: string | null) {
 }
 
 function listItem(row: { id: number; username: string; createTime: string; analysis: string; isPinned: boolean }) {
-  return adminAiReportListItemSchema.parse({
+  return {
     id: row.id,
     username: row.username,
     createTime: row.createTime,
     analysisExcerpt: excerpt(row.analysis),
     isPinned: row.isPinned,
-  })
+  } satisfies AdminAiReportListItem
 }
 
 const listColumns = {
@@ -53,10 +53,10 @@ adminAiRoutes.get("/ai/reports", requireTeacher, async (c) => {
       .innerJoin(schema.user, eq(schema.aiAnalysis.userId, schema.user.id))
       .where(and(eq(schema.aiAnalysis.isPinned, true), where))
       .orderBy(desc(schema.aiAnalysis.createTime))
-    return success(c, adminAiReportListSchema.parse({
+    return success(c, {
       results: rows.map(listItem),
       total: rows.length,
-    }))
+    } satisfies AdminAiReportList)
   }
 
   const limit = queryInteger(c.req.query("limit"), 10, { min: 1, max: 250 })
@@ -68,10 +68,10 @@ adminAiRoutes.get("/ai/reports", requireTeacher, async (c) => {
       .innerJoin(schema.user, eq(schema.aiAnalysis.userId, schema.user.id)).where(where)
       .orderBy(desc(schema.aiAnalysis.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, adminAiReportListSchema.parse({
+  return success(c, {
     results: rows.map(listItem),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AdminAiReportList)
 })
 
 adminAiRoutes.get("/ai/reports/:id", requireTeacher, async (c) => {
@@ -86,7 +86,7 @@ adminAiRoutes.get("/ai/reports/:id", requireTeacher, async (c) => {
     .where(eq(schema.aiAnalysis.id, queryInteger(c.req.param("id"), 0, { min: 1 }))).limit(1)
   if (!row) return failure(c, 404, "report-not-found", "AIAnalysis not found")
   // data / systemPrompt / userPrompt 一律不下发：里面是喂给模型的原始学情数据与提示词
-  return success(c, adminAiReportSchema.parse(row))
+  return success(c, row satisfies AdminAiReport)
 })
 
 adminAiRoutes.post("/ai/reports/:id/pin", requireTeacher, async (c) => {
@@ -104,5 +104,5 @@ adminAiRoutes.post("/ai/reports/:id/pin", requireTeacher, async (c) => {
     }
     await tx.update(schema.aiAnalysis).set({ isPinned: next }).where(eq(schema.aiAnalysis.id, id))
   })
-  return success(c, toggleAiReportPinResponseSchema.parse({ isPinned: next }))
+  return success(c, { isPinned: next } satisfies ToggleAiReportPinResponse)
 })
diff --git a/apps/api/src/routes/admin/announcement.ts b/apps/api/src/routes/admin/announcement.ts
index a975991..630542e 100644
--- a/apps/api/src/routes/admin/announcement.ts
+++ b/apps/api/src/routes/admin/announcement.ts
@@ -1,8 +1,8 @@
 import {
-  adminAnnouncementListSchema,
-  adminAnnouncementSchema,
   createAnnouncementRequestSchema,
   updateAnnouncementRequestSchema,
+  type AdminAnnouncement,
+  type AdminAnnouncementList,
 } from "@oj2/contract"
 import { count, desc, eq } from "drizzle-orm"
 import { Hono } from "hono"
@@ -19,7 +19,7 @@ function serialize(row: {
   user: typeof schema.user.$inferSelect
   realName: string | null
 }) {
-  return adminAnnouncementSchema.parse({
+  return {
     id: row.announcement.id,
     title: row.announcement.title,
     tag: row.announcement.tag,
@@ -29,7 +29,7 @@ function serialize(row: {
     createdBy: sampleUser(row.user, row.realName),
     createTime: row.announcement.createTime,
     lastUpdateTime: row.announcement.lastUpdateTime,
-  })
+  } satisfies AdminAnnouncement
 }
 
 function selectOne(id: number) {
@@ -55,11 +55,11 @@ adminAnnouncementRoutes.get("/announcements", requireSuperAdmin, async (c) => {
       .limit(limit)
       .offset(offset),
   ])
-  return success(c, adminAnnouncementListSchema.parse({
+  return success(c, {
     // 列表 schema omit 掉了 content，Zod 会 strip 掉多出来的键，这里不必手工再挑一遍
     results: rows.map(serialize),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AdminAnnouncementList)
 })
 
 adminAnnouncementRoutes.post("/announcements", requireSuperAdmin, async (c) => {
diff --git a/apps/api/src/routes/admin/conf.ts b/apps/api/src/routes/admin/conf.ts
index 2ad8337..6d3a6a5 100644
--- a/apps/api/src/routes/admin/conf.ts
+++ b/apps/api/src/routes/admin/conf.ts
@@ -1,12 +1,12 @@
 import {
-  dashboardInfoSchema,
-  judgeServerListSchema,
-  judgeServerSchema,
-  orphanTestCaseSchema,
   updateJudgeServerRequestSchema,
   updateWebsiteConfigRequestSchema,
-  uploadImageResponseSchema,
-  websiteConfigSchema,
+  type DashboardInfo,
+  type JudgeServer,
+  type JudgeServerList,
+  type OrphanTestCase,
+  type UploadImageResponse,
+  type WebsiteConfig,
 } from "@oj2/contract"
 import { randomInt } from "node:crypto"
 import { mkdir, readdir, rm, stat } from "node:fs/promises"
@@ -57,7 +57,7 @@ const OPTION_KEYS = {
 
 adminConfRoutes.get("/website", requireSuperAdmin, async (c) => {
   const options = await getWebsiteOptions()
-  return success(c, websiteConfigSchema.parse({
+  return success(c, {
     websiteBaseUrl: options.website_base_url,
     websiteName: options.website_name,
     websiteNameShortcut: options.website_name_shortcut,
@@ -66,7 +66,7 @@ adminConfRoutes.get("/website", requireSuperAdmin, async (c) => {
     submissionListShowAll: options.submission_list_show_all,
     classList: options.class_list,
     enableMaxkb: options.enable_maxkb,
-  }))
+  } satisfies WebsiteConfig)
 })
 
 adminConfRoutes.post("/website", requireSuperAdmin, async (c) => {
@@ -96,14 +96,14 @@ adminConfRoutes.post("/website", requireSuperAdmin, async (c) => {
 
 adminConfRoutes.get("/judge-servers", requireSuperAdmin, async (c) => {
   const rows = await db.select().from(schema.judgeServer).orderBy(desc(schema.judgeServer.lastHeartbeat))
-  return success(c, judgeServerListSchema.parse({
+  return success(c, {
     // 后台要显示 token 才能拿去配判题机。这个接口是超管专属的
     token: config.judgeServerToken,
-    servers: rows.map((row) => judgeServerSchema.parse({
+    servers: rows.map((row) => ({
       ...row,
       status: isAlive(row.lastHeartbeat) ? "normal" : "abnormal",
-    })),
-  }))
+    } satisfies JudgeServer)),
+  } satisfies JudgeServerList)
 })
 
 adminConfRoutes.put("/judge-servers/:id", requireSuperAdmin, async (c) => {
@@ -146,7 +146,7 @@ adminConfRoutes.get("/orphan-test-cases", requireSuperAdmin, async (c) => {
   const ids = await orphanTestCaseIds()
   const rows = await Promise.all(ids.map(async (id) => {
     const info = await stat(resolve(config.testCaseDirectory, id)).catch(() => null)
-    return orphanTestCaseSchema.parse({ id, createTime: info ? info.mtimeMs / 1000 : 0 })
+    return { id, createTime: info ? info.mtimeMs / 1000 : 0 } satisfies OrphanTestCase
   }))
   return success(c, rows)
 })
@@ -180,12 +180,12 @@ adminConfRoutes.get("/dashboard", requireSuperAdmin, async (c) => {
       .where(gte(schema.judgeServer.lastHeartbeat, aliveSince())),
   ])
   // 旧接口还回了 env.FORCE_HTTPS / STATIC_CDN_HOST，前端从未读过，不再下发
-  return success(c, dashboardInfoSchema.parse({
+  return success(c, {
     userCount: users?.value ?? 0,
     todaySubmissionCount: submissions?.value ?? 0,
     recentContestCount: contests?.value ?? 0,
     judgeServerCount: servers?.value ?? 0,
-  }))
+  } satisfies DashboardInfo)
 })
 
 adminConfRoutes.get("/random-usernames", requireSuperAdmin, async (c) => {
@@ -218,16 +218,16 @@ adminConfRoutes.post("/upload-image", requireAdmin, async (c) => {
   const form = await c.req.formData().catch(() => null)
   const image = form?.get("image")
   if (!(image instanceof File)) {
-    return success(c, uploadImageResponseSchema.parse({ success: false, msg: "Upload failed", filePath: "" }))
+    return success(c, { success: false, msg: "Upload failed", filePath: "" } satisfies UploadImageResponse)
   }
   const suffix = image.name.slice(image.name.lastIndexOf(".")).toLowerCase()
   if (!IMAGE_SUFFIXES.includes(suffix)) {
-    return success(c, uploadImageResponseSchema.parse({ success: false, msg: "Unsupported file format", filePath: "" }))
+    return success(c, { success: false, msg: "Unsupported file format", filePath: "" } satisfies UploadImageResponse)
   }
   // 旧后端没有大小限制，靠 nginx 兜。这里显式限一道：文件写在本地磁盘上，
   // 一个超大文件就能把机房那台机器的盘写满，而写满之后判题也一起挂
   if (image.size > MAX_IMAGE_BYTES) {
-    return success(c, uploadImageResponseSchema.parse({ success: false, msg: "图片不能超过 10MB", filePath: "" }))
+    return success(c, { success: false, msg: "图片不能超过 10MB", filePath: "" } satisfies UploadImageResponse)
   }
   // 文件名完全由服务端生成，不带用户提供的任何一段 —— 原名里的 ../ 或空字节都进不来
   const name = `${randomFileName()}${suffix}`
@@ -236,13 +236,13 @@ adminConfRoutes.post("/upload-image", requireAdmin, async (c) => {
     await Bun.write(resolve(config.uploadDirectory, name), image)
   } catch (error) {
     console.error("Failed to save uploaded image", error)
-    return success(c, uploadImageResponseSchema.parse({ success: false, msg: "Upload Error", filePath: "" }))
+    return success(c, { success: false, msg: "Upload Error", filePath: "" } satisfies UploadImageResponse)
   }
-  return success(c, uploadImageResponseSchema.parse({
+  return success(c, {
     success: true,
     msg: "Success",
     filePath: `${config.uploadUriPrefix}/${name}`,
-  }))
+  } satisfies UploadImageResponse)
 })
 
 function randomFileName() {
diff --git a/apps/api/src/routes/admin/contest.ts b/apps/api/src/routes/admin/contest.ts
index 5624068..3c68452 100644
--- a/apps/api/src/routes/admin/contest.ts
+++ b/apps/api/src/routes/admin/contest.ts
@@ -1,10 +1,10 @@
 import {
-  acmHelperItemSchema,
-  adminContestListSchema,
-  adminContestSchema,
   createContestRequestSchema,
   updateAcmHelperRequestSchema,
   updateContestRequestSchema,
+  type AcmHelperItem,
+  type AdminContest,
+  type AdminContestList,
 } from "@oj2/contract"
 import { and, count, desc, eq, ilike, inArray } from "drizzle-orm"
 import { Hono } from "hono"
@@ -31,7 +31,7 @@ async function serialize(row: {
   user: typeof schema.user.$inferSelect
   realName: string | null
 }) {
-  return adminContestSchema.parse({
+  return {
     id: row.contest.id,
     title: row.contest.title,
     description: row.contest.description,
@@ -45,7 +45,7 @@ async function serialize(row: {
     createdBy: sampleUser(row.user, row.realName),
     status: contestStatus(row.contest),
     contestType: row.contest.password ? "Password Protected" : "Public",
-  })
+  } satisfies AdminContest
 }
 
 function selectContest(id: number) {
@@ -84,10 +84,10 @@ adminContestRoutes.get("/contests", requireTeacher, async (c) => {
       .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
       .where(where).orderBy(desc(schema.contest.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, adminContestListSchema.parse({
+  return success(c, {
     results: await Promise.all(rows.map(serialize)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AdminContestList)
 })
 
 adminContestRoutes.get("/contests/:id", requireTeacher, async (c) => {
@@ -266,8 +266,7 @@ adminContestRoutes.get("/contests/:id/acm-helper", requireTeacher, async (c) =>
   const results = []
   for (const rank of ranks) {
     if (rank.acceptedNumber <= 0) continue
-    for (const [problemId, raw] of Object.entries(objectValue(rank.submissionInfo))) {
-      const info = objectValue(raw)
+    for (const [problemId, info] of Object.entries(rank.submissionInfo)) {
       if (info.is_ac !== true) continue
       results.push({
         id: rank.id,
@@ -285,7 +284,7 @@ adminContestRoutes.get("/contests/:id/acm-helper", requireTeacher, async (c) =>
   }
   // 按 AC 用时倒序：最后才做出来的排前面，那是最值得看的
   results.sort((left, right) => right._acTime - left._acTime)
-  return success(c, results.map(({ _acTime, ...item }) => acmHelperItemSchema.parse(item)))
+  return success(c, results.map(({ _acTime, ...item }) => item) satisfies AcmHelperItem[])
 })
 
 adminContestRoutes.put("/contests/:id/acm-helper", requireTeacher, async (c) => {
@@ -306,9 +305,9 @@ adminContestRoutes.put("/contests/:id/acm-helper", requireTeacher, async (c) =>
   )).limit(1)
   if (!rank) return failure(c, 404, "rank-not-found", "Rank id does not exist")
 
-  const info = objectValue(rank.submissionInfo)
-  const entry = objectValue(info[parsed.data.problemId])
-  if (!info[parsed.data.problemId]) {
+  const info = rank.submissionInfo
+  const entry = info[parsed.data.problemId]
+  if (!entry) {
     return failure(c, 404, "problem-not-in-rank", "Problem id does not exist")
   }
   entry.checked = parsed.data.checked
diff --git a/apps/api/src/routes/admin/learn.ts b/apps/api/src/routes/admin/learn.ts
index 7a21f33..fc514bd 100644
--- a/apps/api/src/routes/admin/learn.ts
+++ b/apps/api/src/routes/admin/learn.ts
@@ -1,13 +1,13 @@
 import {
   STUDENT_ROLES,
   TUTORIAL_READ_SECONDS,
-  learnExerciseAttemptSchema,
-  learnExerciseProgressListSchema,
-  learnExerciseProgressSchema,
-  learnStudentProgressListSchema,
-  learnStudentProgressSchema,
-  learnTutorialProgressListSchema,
-  learnTutorialProgressSchema,
+  type LearnExerciseAttempt,
+  type LearnExerciseProgress,
+  type LearnExerciseProgressList,
+  type LearnStudentProgress,
+  type LearnStudentProgressList,
+  type LearnTutorialProgress,
+  type LearnTutorialProgressList,
 } from "@oj2/contract"
 import { and, asc, count, desc, eq, inArray, like, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -120,16 +120,16 @@ adminLearnRoutes.get("/learn-analytics/students", requireTeacher, async (c) => {
         .where(inArray(schema.exercise.tutorialId, tutorialIds))
     : [{ value: 0 }]
 
-  return success(c, learnStudentProgressListSchema.parse({
+  return success(c, {
     tutorialCount: tutorialIds.length,
     exerciseCount: exerciseCountRow?.value ?? 0,
-    results: rows.map((row) => learnStudentProgressSchema.parse({
+    results: rows.map((row) => ({
       ...row,
       exerciseTried: attempts.get(row.userId)?.tried ?? 0,
       exerciseSolved: attempts.get(row.userId)?.solved ?? 0,
       exerciseAttempts: attempts.get(row.userId)?.attempts ?? 0,
-    })),
-  }))
+    } satisfies LearnStudentProgress)),
+  } satisfies LearnStudentProgressList)
 })
 
 adminLearnRoutes.get("/learn-analytics/tutorials", requireTeacher, async (c) => {
@@ -166,13 +166,13 @@ adminLearnRoutes.get("/learn-analytics/tutorials", requireTeacher, async (c) =>
     .groupBy(schema.tutorial.id, schema.tutorial.title, schema.tutorial.order)
     .orderBy(asc(schema.tutorial.order))
 
-  return success(c, learnTutorialProgressListSchema.parse({
+  return success(c, {
     studentCount,
-    results: rows.map(({ readSeconds, ...row }) => learnTutorialProgressSchema.parse({
+    results: rows.map(({ readSeconds, ...row }) => ({
       ...row,
       avgSeconds: row.readers ? Math.round(readSeconds / row.readers) : 0,
-    })),
-  }))
+    } satisfies LearnTutorialProgress)),
+  } satisfies LearnTutorialProgressList)
 })
 
 /**
@@ -216,13 +216,13 @@ adminLearnRoutes.get("/learn-analytics/exercises", requireTeacher, async (c) =>
     .groupBy(schema.exercise.id, schema.tutorial.id, schema.tutorial.title, schema.tutorial.order)
     .orderBy(asc(schema.tutorial.order), asc(schema.exercise.order))
 
-  return success(c, learnExerciseProgressListSchema.parse({
+  return success(c, {
     studentCount: studentCountRow?.value ?? 0,
-    results: rows.map((row) => learnExerciseProgressSchema.parse({
+    results: rows.map((row) => ({
       ...row,
       avgAttemptsToSolve: rounded(Number(row.avgAttemptsToSolve), 1),
-    })),
-  }))
+    } satisfies LearnExerciseProgress)),
+  } satisfies LearnExerciseProgressList)
 })
 
 /** 单道练习的逐人明细。后台表格展开某一行时才拉，不跟着列表一起下发 */
@@ -249,5 +249,5 @@ adminLearnRoutes.get("/learn-analytics/exercises/:id/attempts", requireTeacher,
     // 没做对的排前面，错得最多的最前 —— 展开这一行的人是来找卡住的学生的
     .orderBy(asc(schema.exerciseAttempt.solved), desc(schema.exerciseAttempt.wrongAttempts))
 
-  return success(c, rows.map((row) => learnExerciseAttemptSchema.parse(row)))
+  return success(c, rows satisfies LearnExerciseAttempt[])
 })
diff --git a/apps/api/src/routes/admin/problem.ts b/apps/api/src/routes/admin/problem.ts
index 451a606..11a4fa9 100644
--- a/apps/api/src/routes/admin/problem.ts
+++ b/apps/api/src/routes/admin/problem.ts
@@ -1,18 +1,19 @@
 import {
   addContestProblemRequestSchema,
-  adminProblemListItemSchema,
-  adminProblemListSchema,
-  adminProblemSchema,
   createProblemRequestSchema,
-  makeProblemPublicRequestSchema,
-  updateProblemRequestSchema,
   generateSqlTestCaseRequestSchema,
-  generateSqlTestCaseResponseSchema,
+  makeProblemPublicRequestSchema,
   sqlPreviewRequestSchema,
-  sqlTestCaseScriptSchema,
-  uploadTestCaseResponseSchema,
+  updateProblemRequestSchema,
+  type AdminProblem,
+  type AdminProblemList,
+  type AdminProblemListItem,
   type AstRules,
+  type GenerateSqlTestCaseResponse,
   type SqlConfig,
+  type SqlDisplay,
+  type SqlTestCaseScript,
+  type UploadTestCaseResponse,
 } from "@oj2/contract"
 import { and, count, desc, eq, ilike, inArray, isNull, ne, or, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -30,7 +31,7 @@ import { config } from "../../config"
 import { readFile } from "node:fs/promises"
 import { resolve } from "node:path"
 import { getTopReactions } from "../../services/reaction"
-import { objectValue, queryInteger, sampleUser, stringArray } from "../helpers"
+import { objectValue, queryInteger, sampleUser } from "../helpers"
 
 export const adminProblemRoutes = new Hono<AppEnv>()
 
@@ -130,7 +131,7 @@ async function serialize(row: ProblemRow) {
       .where(eq(schema.user.id, row.createdById)).limit(1),
     tagNames(row.id),
   ])
-  return adminProblemSchema.parse({
+  return {
     id: row.id,
     _id: row.displayId,
     title: row.title,
@@ -141,8 +142,8 @@ async function serialize(row: ProblemRow) {
     testCaseId: row.testCaseId,
     testCaseScore: Array.isArray(row.testCaseScore) ? row.testCaseScore : [],
     hint: row.hint,
-    languages: stringArray(row.languages),
-    template: objectValue(row.template),
+    languages: row.languages,
+    template: row.template,
     createTime: row.createTime,
     lastUpdateTime: row.lastUpdateTime,
     timeLimit: row.timeLimit,
@@ -164,9 +165,9 @@ async function serialize(row: ProblemRow) {
     astRules: row.astRules,
     answers: Array.isArray(row.answers) ? row.answers : [],
     prompt: row.prompt,
-    sqlConfig: row.sqlConfig ? objectValue(row.sqlConfig) : null,
-    sqlDisplay: row.sqlDisplay ? objectValue(row.sqlDisplay) : null,
-  })
+    sqlConfig: row.sqlConfig,
+    sqlDisplay: row.sqlDisplay,
+  } satisfies AdminProblem
 }
 
 /** 公共校验，对齐旧 `ProblemBase.common_checks` */
@@ -205,7 +206,7 @@ async function generateSqlDisplay(
   testCaseId: string,
   answers: Record<string, unknown>[],
   sqlConfig: SqlConfig,
-): Promise<{ error: string } | { display: unknown }> {
+): Promise<{ error: string } | { display: SqlDisplay }> {
   const info = await readInfo(testCaseId)
   if (!info) return { error: "测试点信息读取失败，请重新上传测试点" }
   if (!info.sql) return { error: "测试点不是 SQL 类型，请重新上传 SQL 测试点压缩包" }
@@ -294,9 +295,9 @@ adminProblemRoutes.get("/problems", requireProblemPermission, async (c) => {
   // 只有公开题列表下发最高票评价，比赛题列表不下发 —— 与旧后端一致
   const problemIds = rows.map(({ problem }) => problem.id)
   const [topReactions, tags] = await Promise.all([getTopReactions(problemIds), tagNamesFor(problemIds)])
-  return success(c, adminProblemListSchema.parse({
+  return success(c, {
     results: rows.map(({ problem, user: creator, realName }) =>
-      adminProblemListItemSchema.parse({
+      ({
         id: problem.id,
         _id: problem.displayId,
         title: problem.title,
@@ -309,9 +310,9 @@ adminProblemRoutes.get("/problems", requireProblemPermission, async (c) => {
         allowFlowchart: problem.allowFlowchart,
         showFlowchart: problem.showFlowchart,
         topReaction: topReactions.get(problem.id) ?? null,
-      })),
+      } satisfies AdminProblemListItem)),
     total: totalRow[0]?.value ?? 0,
-  }))
+  } satisfies AdminProblemList)
 })
 
 adminProblemRoutes.get("/problems/:id", requireProblemPermission, async (c) => {
@@ -331,7 +332,7 @@ adminProblemRoutes.post("/problems", requireProblemPermission, async (c) => {
   }
   const checked = commonChecks(parsed.data)
   if ("error" in checked) return failure(c, 400, "invalid-problem", checked.error)
-  let sqlDisplay: unknown = null
+  let sqlDisplay: SqlDisplay | null = null
   if (checked.sql) {
     const built = await generateSqlDisplay(parsed.data.testCaseId, parsed.data.answers, parsed.data.sqlConfig!)
     if ("error" in built) return failure(c, 400, "invalid-problem", built.error)
@@ -388,7 +389,7 @@ adminProblemRoutes.put("/problems/:id", requireProblemPermission, async (c) => {
   if (duplicate) return failure(c, 409, "display-id-exists", "Display ID already exists")
 
   // SQL 题每次保存都重算展示数据：测试点或标准答案可能刚改过，留着旧的就会和判题结果对不上
-  let sqlDisplay: unknown = null
+  let sqlDisplay: SqlDisplay | null = null
   if (checked.sql) {
     const built = await generateSqlDisplay(parsed.data.testCaseId, parsed.data.answers, parsed.data.sqlConfig!)
     if ("error" in built) return failure(c, 400, "invalid-problem", built.error)
@@ -467,9 +468,9 @@ adminProblemRoutes.get("/contests/:contestId/problems", requireProblemPermission
       .where(where).orderBy(desc(schema.problem.createTime)).limit(limit).offset(offset),
   ])
   const tags = await tagNamesFor(rows.map(({ problem }) => problem.id))
-  return success(c, adminProblemListSchema.parse({
+  return success(c, {
     results: rows.map(({ problem, user: creator, realName }) =>
-      adminProblemListItemSchema.parse({
+      ({
         id: problem.id,
         _id: problem.displayId,
         title: problem.title,
@@ -482,9 +483,9 @@ adminProblemRoutes.get("/contests/:contestId/problems", requireProblemPermission
         allowFlowchart: problem.allowFlowchart,
         showFlowchart: problem.showFlowchart,
         topReaction: null,
-      })),
+      } satisfies AdminProblemListItem)),
     total: totalRow[0]?.value ?? 0,
-  }))
+  } satisfies AdminProblemList)
 })
 
 adminProblemRoutes.post("/contests/:contestId/problems", requireProblemPermission, async (c) => {
@@ -500,7 +501,7 @@ adminProblemRoutes.post("/contests/:contestId/problems", requireProblemPermissio
   }
   const checked = commonChecks(parsed.data)
   if ("error" in checked) return failure(c, 400, "invalid-problem", checked.error)
-  let sqlDisplay: unknown = null
+  let sqlDisplay: SqlDisplay | null = null
   if (checked.sql) {
     const built = await generateSqlDisplay(parsed.data.testCaseId, parsed.data.answers, parsed.data.sqlConfig!)
     if ("error" in built) return failure(c, 400, "invalid-problem", built.error)
@@ -652,10 +653,10 @@ adminProblemRoutes.post("/test-cases", requireProblemPermission, async (c) => {
   const sql = ["1", "true", "True"].includes(String(form?.get("sql") ?? ""))
   try {
     const result = await processTestCaseZip(new Uint8Array(await file.arrayBuffer()), { sql })
-    return success(c, uploadTestCaseResponseSchema.parse({
+    return success(c, {
       id: result.testCaseId,
       info: result.info,
-    }), 201)
+    } satisfies UploadTestCaseResponse, 201)
   } catch (error) {
     if (error instanceof TestCaseError) return failure(c, 400, "invalid-test-case", error.message)
     console.error("Failed to process test case zip", error)
@@ -701,7 +702,7 @@ adminProblemRoutes.get("/problems/:id/sql-scripts", requireProblemPermission, as
   if (!info.sql) return failure(c, 409, "not-sql-test-case", "该题的测试点不是 SQL 类型")
   try {
     const scripts = await readSqlScripts(problem.testCaseId)
-    return success(c, scripts.map((script) => sqlTestCaseScriptSchema.parse(script)))
+    return success(c, scripts satisfies SqlTestCaseScript[])
   } catch (error) {
     console.error("Failed to read SQL test case scripts", error)
     return failure(c, 500, "test-case-error", "测试点脚本读取失败")
@@ -735,7 +736,7 @@ SELECT 语句，或增删改题的 UPDATE/DELETE/INSERT 语句）和题型。
 请只返回 SQL 脚本本身，连 \`\`\` 都不需要，不要任何解释文字。`,
       `题型：${parsed.data.mode}\n标准答案：\n${parsed.data.refSql}`,
     )
-    return success(c, generateSqlTestCaseResponseSchema.parse({ sql }))
+    return success(c, { sql } satisfies GenerateSqlTestCaseResponse)
   } catch (error) {
     console.error("SQL test case generation failed", error)
     return failure(c, 502, "ai-unavailable", "生成失败，请稍后再试")
diff --git a/apps/api/src/routes/admin/problemset.ts b/apps/api/src/routes/admin/problemset.ts
index 567ded3..991c41c 100644
--- a/apps/api/src/routes/admin/problemset.ts
+++ b/apps/api/src/routes/admin/problemset.ts
@@ -1,16 +1,16 @@
 import {
   addProblemToSetRequestSchema,
-  adminProblemSetBadgeSchema,
-  adminProblemSetListSchema,
-  adminProblemSetProblemSchema,
-  adminProblemSetProgressSchema,
-  adminProblemSetSchema,
   createProblemSetBadgeRequestSchema,
   createProblemSetRequestSchema,
   updateProblemInSetRequestSchema,
   updateProblemSetBadgeRequestSchema,
   updateProblemSetRequestSchema,
   updateProblemSetStatusRequestSchema,
+  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 { Hono } from "hono"
@@ -20,7 +20,7 @@ import type { AuthUser } from "../../auth/session"
 import { db, schema } from "../../db"
 import { failure, success } from "../../http"
 import { recalculateBadge, resyncProgress } from "../../services/problemset"
-import { queryInteger, sampleUser } from "../helpers"
+import { asFilterValue, queryInteger, sampleUser } from "../helpers"
 
 export const adminProblemSetRoutes = new Hono<AppEnv>()
 
@@ -65,7 +65,7 @@ async function serializeMany(rows: (typeof schema.problemset.$inferSelect)[]) {
   const creatorById = new Map(creators.map((item) => [item.id, item]))
   return rows.map((row) => {
     const creator = creatorById.get(row.createdById)
-    return adminProblemSetSchema.parse({
+    return {
       id: row.id,
       title: row.title,
       description: row.description,
@@ -78,7 +78,7 @@ async function serializeMany(rows: (typeof schema.problemset.$inferSelect)[]) {
       lastUpdateTime: row.lastUpdateTime,
       problemsCount: problemsBySet.get(row.id) ?? 0,
       participantCount: participantsBySet.get(row.id) ?? 0,
-    })
+    } satisfies AdminProblemSet
   })
 }
 
@@ -102,8 +102,8 @@ adminProblemSetRoutes.get("/problem-sets", requireTeacher, async (c) => {
       ilike(schema.problemset.description, `%${keyword}%`),
     )!)
   }
-  if (difficulty) filters.push(eq(schema.problemset.difficulty, difficulty))
-  if (status) filters.push(eq(schema.problemset.status, status))
+  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([
@@ -111,10 +111,10 @@ adminProblemSetRoutes.get("/problem-sets", requireTeacher, async (c) => {
     db.select().from(schema.problemset).where(where)
       .orderBy(desc(schema.problemset.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, adminProblemSetListSchema.parse({
+  return success(c, {
     results: await serializeMany(rows),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AdminProblemSetList)
 })
 
 adminProblemSetRoutes.post("/problem-sets", requireTeacher, async (c) => {
@@ -194,7 +194,7 @@ adminProblemSetRoutes.get("/problem-sets/:id/problems", requireTeacher, async (c
     .innerJoin(schema.problem, eq(schema.problemsetProblem.problemId, schema.problem.id))
     .where(eq(schema.problemsetProblem.problemsetId, row.id))
     .orderBy(asc(schema.problemsetProblem.order), asc(schema.problemsetProblem.id))
-  return success(c, rows.map(({ item, problem }) => adminProblemSetProblemSchema.parse({
+  return success(c, rows.map(({ item, problem }) => ({
     id: item.id,
     problemsetId: item.problemsetId,
     problemId: item.problemId,
@@ -205,7 +205,7 @@ adminProblemSetRoutes.get("/problem-sets/:id/problems", requireTeacher, async (c
     isRequired: item.isRequired,
     score: item.score,
     hint: item.hint,
-  })))
+  } satisfies AdminProblemSetProblem)))
 })
 
 adminProblemSetRoutes.post("/problem-sets/:id/problems", requireTeacher, async (c) => {
@@ -289,7 +289,7 @@ async function badgesWithCount(badges: BadgeRow[]) {
     .from(schema.userBadge).where(inArray(schema.userBadge.badgeId, badges.map((badge) => badge.id)))
     .groupBy(schema.userBadge.badgeId)
   const countByBadge = new Map(earned.map((item) => [item.badgeId, item.value]))
-  return badges.map((badge) => adminProblemSetBadgeSchema.parse({
+  return badges.map((badge) => ({
     id: badge.id,
     problemsetId: badge.problemsetId,
     name: badge.name,
@@ -298,7 +298,7 @@ async function badgesWithCount(badges: BadgeRow[]) {
     conditionType: badge.conditionType,
     conditionValue: badge.conditionValue,
     earnedCount: countByBadge.get(badge.id) ?? 0,
-  }))
+  } satisfies AdminProblemSetBadge))
 }
 
 adminProblemSetRoutes.get("/problem-sets/:id/badges", requireTeacher, async (c) => {
@@ -375,7 +375,7 @@ adminProblemSetRoutes.get("/problem-sets/:id/progress", requireTeacher, async (c
     .where(eq(schema.problemsetProgress.problemsetId, row.id))
     .orderBy(desc(schema.problemsetProgress.joinTime))
   return success(c, rows.map(({ progress, username, realName }) =>
-    adminProblemSetProgressSchema.parse({
+    ({
       id: progress.id,
       userId: progress.userId,
       username,
@@ -388,7 +388,7 @@ adminProblemSetRoutes.get("/problem-sets/:id/progress", requireTeacher, async (c
       completedProblemsCount: progress.completedProblemsCount,
       totalProblemsCount: progress.totalProblemsCount,
       totalScore: progress.totalScore,
-    })))
+    } satisfies AdminProblemSetProgress)))
 })
 
 adminProblemSetRoutes.delete("/problem-sets/:id/progress/:userId", requireTeacher, async (c) => {
diff --git a/apps/api/src/routes/admin/tag.ts b/apps/api/src/routes/admin/tag.ts
index 5ce53b9..6052f3a 100644
--- a/apps/api/src/routes/admin/tag.ts
+++ b/apps/api/src/routes/admin/tag.ts
@@ -1,13 +1,13 @@
 import {
-  acTrendSchema,
-  adminTagSchema,
   batchProblemTagRequestSchema,
-  batchProblemTagResponseSchema,
   generateFlowchartRequestSchema,
-  generateFlowchartResponseSchema,
   renameTagRequestSchema,
-  renameTagResponseSchema,
-  stuckProblemSchema,
+  type AcTrend,
+  type AdminTag,
+  type BatchProblemTagResponse,
+  type GenerateFlowchartResponse,
+  type RenameTagResponse,
+  type StuckProblem,
 } from "@oj2/contract"
 import { and, asc, countDistinct, count, desc, eq, gte, ilike, inArray, isNull, lte, ne, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -46,7 +46,7 @@ adminTagRoutes.get("/problem-tags", requireProblemPermission, async (c) => {
     // 后台标签管理要看到 problemCount=0 的标签（正是要清理的那些），
     // 所以这里用 leftJoin 且不加 having —— oj 侧的 /problem-tags 才过滤 >0
     .orderBy(desc(countDistinct(schema.problemTags.problemId)), asc(schema.problemTag.name))
-  return success(c, rows.map((row) => adminTagSchema.parse(row)))
+  return success(c, rows satisfies AdminTag[])
 })
 
 adminTagRoutes.put("/problem-tags/:id", requireProblemPermission, async (c) => {
@@ -63,7 +63,7 @@ adminTagRoutes.put("/problem-tags/:id", requireProblemPermission, async (c) => {
 
   if (!target) {
     await db.update(schema.problemTag).set({ name }).where(eq(schema.problemTag.id, id))
-    return success(c, renameTagResponseSchema.parse({ merged: false, id, name, affectedCount: 0 }))
+    return success(c, { merged: false, id, name, affectedCount: 0 } satisfies RenameTagResponse)
   }
 
   // 改名撞上已有标签，视为合并：题目关系转移过去，原标签删除
@@ -86,9 +86,9 @@ adminTagRoutes.put("/problem-tags/:id", requireProblemPermission, async (c) => {
     await tx.delete(schema.problemTag).where(eq(schema.problemTag.id, id))
     return links.length
   })
-  return success(c, renameTagResponseSchema.parse({
+  return success(c, {
     merged: true, id: target.id, name: target.name, affectedCount: affected,
-  }))
+  } satisfies RenameTagResponse)
 })
 
 adminTagRoutes.delete("/problem-tags/:id", requireProblemPermission, async (c) => {
@@ -152,10 +152,10 @@ adminTagRoutes.post("/problems/batch-tag", requireProblemPermission, async (c) =
     if (rows.length) await tx.insert(schema.problemTags).values(rows)
   })
 
-  return success(c, batchProblemTagResponseSchema.parse({
+  return success(c, {
     problemCount: problems.length,
     tagCount: tagIds.length,
-  }))
+  } satisfies BatchProblemTagResponse)
 })
 
 // ---------------------------------------------------------------- 题目可见性
@@ -209,14 +209,14 @@ adminTagRoutes.get("/problem-analytics/stuck", requireTeacher, async (c) => {
     .having(sql`count(distinct ${schema.submission.userId}) ${failedFilter} > 0`)
     .orderBy(desc(sql`count(distinct ${schema.submission.userId}) ${failedFilter}`))
     .limit(40)
-  return success(c, rows.map((row) => stuckProblemSchema.parse({
+  return success(c, rows.map((row) => ({
     problemId: row.displayId,
     problemTitle: row.title,
     total: row.total,
     failed: row.failed,
     failedUsers: row.failedUsers,
     acRate: row.total ? rounded((row.accepted / row.total) * 100, 1) : 0,
-  })))
+  } satisfies StuckProblem)))
 })
 
 adminTagRoutes.get("/problem-analytics/ac-trend", requireTeacher, async (c) => {
@@ -263,7 +263,7 @@ adminTagRoutes.get("/problem-analytics/ac-trend", requireTeacher, async (c) => {
     // 每一年都得有数据，且每年提交量都超过门槛 —— 否则趋势没有可比性
     if (![...required].every((y) => years.has(y))) continue
     if (!entry.yearly.every((row) => row.total > minPerYear)) continue
-    result.push(acTrendSchema.parse({
+    result.push({
       problemId: entry.displayId,
       problemTitle: entry.title,
       yearly: entry.yearly
@@ -274,7 +274,7 @@ adminTagRoutes.get("/problem-analytics/ac-trend", requireTeacher, async (c) => {
           acRate: row.total ? rounded((row.accepted / row.total) * 100, 1) : 0,
         }))
         .sort((left, right) => left.year - right.year),
-    }))
+    } satisfies AcTrend)
   }
   return success(c, result)
 })
@@ -292,7 +292,7 @@ adminTagRoutes.post("/problems/flowchart", requireProblemPermission, async (c) =
 请只返回 mermaid 代码，连 \`\`\` 都不需要。`,
       parsed.data.python,
     )
-    return success(c, generateFlowchartResponseSchema.parse({ flowchart }))
+    return success(c, { flowchart } satisfies GenerateFlowchartResponse)
   } catch (error) {
     console.error("Flowchart generation failed", error)
     return failure(c, 502, "ai-unavailable", "生成失败，请稍后再试")
diff --git a/apps/api/src/routes/admin/tutorial.ts b/apps/api/src/routes/admin/tutorial.ts
index f65a36f..da4ef56 100644
--- a/apps/api/src/routes/admin/tutorial.ts
+++ b/apps/api/src/routes/admin/tutorial.ts
@@ -1,12 +1,12 @@
 import {
-  adminExerciseSchema,
-  adminTutorialGroupsSchema,
-  adminTutorialSchema,
   createExerciseRequestSchema,
   createTutorialRequestSchema,
   setTutorialVisibilityRequestSchema,
   updateExerciseRequestSchema,
   updateTutorialRequestSchema,
+  type AdminExercise,
+  type AdminTutorial,
+  type AdminTutorialGroups,
 } from "@oj2/contract"
 import { asc, desc, eq } from "drizzle-orm"
 import { Hono } from "hono"
@@ -24,7 +24,7 @@ function serializeTutorial(row: {
   user: typeof schema.user.$inferSelect
   realName: string | null
 }) {
-  return adminTutorialSchema.parse({
+  return {
     id: row.tutorial.id,
     title: row.tutorial.title,
     content: row.tutorial.content,
@@ -35,7 +35,7 @@ function serializeTutorial(row: {
     createdBy: sampleUser(row.user, row.realName),
     createdAt: row.tutorial.createdAt,
     updatedAt: row.tutorial.updatedAt,
-  })
+  } satisfies AdminTutorial
 }
 
 function selectTutorial(id: number) {
@@ -57,10 +57,10 @@ adminTutorialRoutes.get("/tutorials", requireSuperAdmin, async (c) => {
     .orderBy(asc(schema.tutorial.order), desc(schema.tutorial.createdAt))
   const all = rows.map(serializeTutorial)
   // 分组返回，形状对齐旧 TutorialAdminAPI.get；列表 schema omit 掉了 content/code，Zod 会 strip
-  return success(c, adminTutorialGroupsSchema.parse({
+  return success(c, {
     python: all.filter((item) => item.type === "python"),
     c: all.filter((item) => item.type === "c"),
-  }))
+  } satisfies AdminTutorialGroups)
 })
 
 adminTutorialRoutes.post("/tutorials", requireSuperAdmin, async (c) => {
@@ -126,12 +126,12 @@ adminTutorialRoutes.delete("/tutorials/:id", requireSuperAdmin, async (c) => {
 // ---------------------------------------------------------------- 练习
 
 function serializeExercise(row: typeof schema.exercise.$inferSelect) {
-  return adminExerciseSchema.parse({
+  return {
     id: row.id,
     type: row.type,
     data: objectValue(row.data),
     order: row.order,
-  })
+  } satisfies AdminExercise
 }
 
 // 练习挂在教程下，路径嵌套 —— 旧后端是 ?tutorial_id= 查询参数，
diff --git a/apps/api/src/routes/ai.ts b/apps/api/src/routes/ai.ts
index e83bc8e..57fdb98 100644
--- a/apps/api/src/routes/ai.ts
+++ b/apps/api/src/routes/ai.ts
@@ -1,16 +1,17 @@
 import {
-  HINT_MIN_FAILURES,
-  aiAnalysisRecordSchema,
   aiAnalysisRequestSchema,
-  aiDetailSchema,
   aiHintRequestSchema,
   classAnalysisRequestSchema,
   classPkAnalysisRequestSchema,
-  durationDataSchema,
-  heatmapItemSchema,
-  loginSummarySchema,
-  solvedListSchema,
-  solvedProblemSchema,
+  HINT_MIN_FAILURES,
+  type AiAnalysisRecord,
+  type AiDetail,
+  type DurationData,
+  type Grade,
+  type HeatmapItem,
+  type LoginSummary,
+  type SolvedList,
+  type SolvedProblem,
 } from "@oj2/contract"
 import { and, asc, count, countDistinct, eq, gte, inArray, isNull, lte, min, sql } from "drizzle-orm"
 import { Hono, type Context } from "hono"
@@ -19,7 +20,7 @@ import { requireAuth, type AppEnv } from "../auth/middleware"
 import { getPreviousLogin, type AuthUser } from "../auth/session"
 import { config } from "../config"
 import { db, schema } from "../db"
-import { JudgeStatus, judgeStatusName } from "../judge/status"
+import { JudgeStatus, judgeStatusName, type JudgeStatusValue } from "../judge/status"
 import { failure, success } from "../http"
 import { completeChat, streamChat } from "../services/ai"
 import { consumeToken } from "../services/throttling"
@@ -27,7 +28,7 @@ import { countFailedSubmissions, isTeacherOrAbove, objectValue, queryInteger, ro
 
 export const aiRoutes = new Hono<AppEnv>()
 
-const accepted = [0, 10]
+const accepted: JudgeStatusValue[] = [JudgeStatus.ACCEPTED, JudgeStatus.AST_CHECK_FAILED]
 const difficultyNames: Record<string, string> = { Low: "简单", Mid: "中等", High: "困难" }
 
 /**
@@ -61,15 +62,15 @@ const calendarDay = new Intl.DateTimeFormat("en-CA", {
   timeZone: CALENDAR_TZ, year: "numeric", month: "2-digit", day: "2-digit",
 })
 
-function grade(rank: number | null, count: number, reference = count) {
+function grade(rank: number | null, count: number, reference = count): Grade {
   if (!rank || count <= 0) return "C"
   const percentile = (rank - 1) / count * 100
-  let value = percentile < 10 ? "S" : percentile < 35 ? "A" : percentile < 75 ? "B" : "C"
+  let value: Grade = percentile < 10 ? "S" : percentile < 35 ? "A" : percentile < 75 ? "B" : "C"
   if (reference < 10) value = value === "S" ? "A" : value === "A" ? "B" : value
   return value
 }
 
-function averageGrade(grades: string[]) {
+function averageGrade(grades: Grade[]): Grade {
   const weights: Record<string, number> = { S: 4, A: 3, B: 2, C: 1 }
   const values = grades.flatMap((item) => weights[item] ?? [])
   if (!values.length) return ""
@@ -149,12 +150,12 @@ async function buildSolved(user: AuthUser, start: string, end: string, firstAc:
     const period = ranks(periodRows, item.problemId)
     const rank = all.findIndex((row) => row.userId === user.id) + 1 || null
     const periodRank = period.findIndex((row) => row.userId === user.id) + 1 || null
-    return solvedProblemSchema.parse({
+    return {
       problem: { title: problem.problem.title, displayId: problem.problem.displayId, contestTitle: problem.contestTitle ?? "", contestId: problem.problem.contestId },
       acTime: item.first, rank, acCount: all.length, grade: grade(periodRank, period.length, all.length), periodRank, periodAcCount: period.length,
       difficulty: difficultyNames[problem.problem.difficulty] ?? "中等",
       attempts: attemptsByProblem.get(item.problemId) ?? 1,
-    })
+    } satisfies SolvedProblem
   }).sort((a, b) => Date.parse(a.acTime) - Date.parse(b.acTime))
   return { solved, problems, scopeIds }
 }
@@ -169,7 +170,7 @@ async function listSolved(user: AuthUser, start: string, end: string, limit: num
     )),
   ])
   const { solved } = await buildSolved(user, start, end, firstAc)
-  return solvedListSchema.parse({ results: solved, total: totalRows[0]?.value ?? 0 })
+  return { results: solved, total: totalRows[0]?.value ?? 0 } satisfies SolvedList
 }
 
 async function buildDetail(user: AuthUser, start: string, end: string) {
@@ -195,7 +196,7 @@ async function buildDetail(user: AuthUser, start: string, end: string) {
     eq(schema.submission.userId, user.id),
     gte(schema.submission.createTime, start), lte(schema.submission.createTime, end),
   ))
-  const settledFail = (result: number) =>
+  const settledFail = (result: JudgeStatusValue) =>
     !accepted.includes(result) && result !== JudgeStatus.PENDING && result !== JudgeStatus.JUDGING
   const errorCounts = new Map<number, number>()
   for (const row of submissions) {
@@ -207,10 +208,10 @@ async function buildDetail(user: AuthUser, start: string, end: string) {
     .sort((a, b) => b.count - a.count || a.result - b.result)
   const firstAc = await firstAcQuery(user, start, end)
   const problemIds = firstAc.map((item) => item.problemId)
-  if (!problemIds.length) return aiDetailSchema.parse({
+  if (!problemIds.length) return {
     user: user.username, className: user.className, start, end, solvedCount: 0, attempts: [], flowcharts: [], grade: "", tags: {}, difficulty: {}, contestCount: 0,
     activity, errors, rankScope: "global",
-  })
+  } satisfies AiDetail
   const [{ solved, problems, scopeIds }, tagRows, flowRows] = await Promise.all([
     buildSolved(user, start, end, firstAc),
     db.select({ problemId: schema.problemTags.problemId, name: schema.problemTag.name }).from(schema.problemTags)
@@ -244,13 +245,13 @@ async function buildDetail(user: AuthUser, start: string, end: string) {
       avgScore: rounded(scores.length ? scores.reduce((sum, value) => sum + value, 0) / scores.length : 0, 0),
     }
   }).sort((a, b) => b.latestSubmissionTime.localeCompare(a.latestSubmissionTime))
-  return aiDetailSchema.parse({
+  return {
     user: user.username, className: user.className, start, end, flowcharts,
     solvedCount: solved.length, attempts: solved.map((item) => item.attempts),
     grade: averageGrade(solved.map((item) => item.grade)), tags: topTags, difficulty,
     contestCount: new Set(solved.flatMap((item) => item.problem.contestId ?? [])).size,
     activity, errors, rankScope: scopeIds ? "class" : "global",
-  })
+  } satisfies AiDetail
 }
 
 aiRoutes.get("/ai/detail", requireAuth, async (c) => {
@@ -357,7 +358,7 @@ async function buildDuration(user: AuthUser, endText: string, duration: string)
     const inRange = rows.filter((row) => row.time >= from && row.time <= to)
     const acceptedRows = inRange.filter((row) => accepted.includes(row.result))
     const solved = [...new Set(acceptedRows.map((row) => row.problemId))]
-    return durationDataSchema.parse({
+    return {
       unit: config.unit,
       index: config.count - 1 - index,
       start: bucket.start.toISOString(),
@@ -366,7 +367,7 @@ async function buildDuration(user: AuthUser, endText: string, duration: string)
       problemCount: solved.length,
       acceptedCount: acceptedRows.length,
       submissionCount: inRange.length,
-    })
+    } satisfies DurationData
   })
 }
 
@@ -407,7 +408,7 @@ aiRoutes.get("/ai/heatmap", requireAuth, async (c) => {
       const day = new Date(monday.getFullYear(), monday.getMonth(), monday.getDate() + offset)
       value += counts.get(dateKey(day)) ?? 0
     }
-    return heatmapItemSchema.parse({ timestamp: monday.getTime(), value })
+    return { timestamp: monday.getTime(), value } satisfies HeatmapItem
   }))
 })
 
@@ -442,7 +443,7 @@ aiRoutes.get("/ai/login-summary", requireAuth, async (c) => {
       analysisError = error instanceof Error ? error.message : String(error)
     }
   }
-  return success(c, loginSummarySchema.parse({ summary, analysis, analysisError }))
+  return success(c, { summary, analysis, analysisError } satisfies LoginSummary)
 })
 
 aiRoutes.get("/ai/pinned", requireAuth, async (c) => {
@@ -450,10 +451,10 @@ aiRoutes.get("/ai/pinned", requireAuth, async (c) => {
     .innerJoin(schema.user, eq(schema.aiAnalysis.userId, schema.user.id))
     .where(and(eq(schema.aiAnalysis.userId, c.get("user")!.id), eq(schema.aiAnalysis.isPinned, true))).limit(1)
   if (!row) return success(c, null)
-  return success(c, aiAnalysisRecordSchema.parse({
+  return success(c, {
     id: row.analysis.id, provider: row.analysis.provider, model: row.analysis.model, data: objectValue(row.analysis.data),
     analysis: row.analysis.analysis, createTime: row.analysis.createTime, isPinned: row.analysis.isPinned, username: row.username,
-  }))
+  } satisfies AiAnalysisRecord)
 })
 
 aiRoutes.post("/ai/analysis", requireAuth, async (c) => {
diff --git a/apps/api/src/routes/classroom.ts b/apps/api/src/routes/classroom.ts
index 08d59b3..d8d7022 100644
--- a/apps/api/src/routes/classroom.ts
+++ b/apps/api/src/routes/classroom.ts
@@ -1,10 +1,10 @@
 import {
-  STUDENT_ROLES,
   classComparisonRequestSchema,
-  classComparisonResponseSchema,
-  classComparisonSchema,
-  classRankItemSchema,
-  classUserRankSchema,
+  STUDENT_ROLES,
+  type ClassComparison,
+  type ClassComparisonResponse,
+  type ClassRankItem,
+  type ClassUserRank,
 } from "@oj2/contract"
 import { and, eq, gte, inArray, like, lte, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -94,7 +94,7 @@ classroomRoutes.get("/rankings/classes", async (c) => {
       acRate: totalSubmission > 0 ? rounded(totalAc / totalSubmission * 100) : 0,
     }
   }).sort((a, b) => b.totalAc - a.totalAc || a.totalSubmission - b.totalSubmission)
-  return success(c, result.map((item, index) => classRankItemSchema.parse({ ...item, rank: index + 1 })))
+  return success(c, result.map((item, index) => ({ ...item, rank: index + 1 } satisfies ClassRankItem)))
 })
 
 classroomRoutes.get("/me/class-rank", requireAuth, async (c) => {
@@ -121,7 +121,7 @@ classroomRoutes.get("/me/class-rank", requireAuth, async (c) => {
     const start = Math.min(Math.max(0, myRank - 6), ranks.length - 10)
     selected = ranks.slice(start, start + 10)
   }
-  return success(c, classUserRankSchema.parse({ className: user.className, myRank, total: ranks.length, ranks: selected }))
+  return success(c, { className: user.className, myRank, total: ranks.length, ranks: selected } satisfies ClassUserRank)
 })
 
 classroomRoutes.post("/classes/comparison", async (c) => {
@@ -166,7 +166,7 @@ classroomRoutes.post("/classes/comparison", async (c) => {
     const middle = topCount + bottomCount < userCount ? ac.slice(topCount, -bottomCount) : ac
     const totalAc = ac.reduce((sum, value) => sum + value, 0)
     const totalSubmission = submissions.reduce((sum, value) => sum + value, 0)
-    const base: Record<string, number | string> = {
+    const base: ClassComparison = {
       className,
       userCount,
       totalAc,
@@ -197,21 +197,18 @@ classroomRoutes.post("/classes/comparison", async (c) => {
     }
     return base
   })
-  const maxMedian = Math.max(1, ...comparisons.map((item) => Number(item.medianAc)))
-  const maxMiddle = Math.max(1, ...comparisons.map((item) => Number(item.middle80Avg)))
+  const maxMedian = Math.max(1, ...comparisons.map((item) => item.medianAc))
+  const maxMiddle = Math.max(1, ...comparisons.map((item) => item.middle80Avg))
   for (const item of comparisons) {
     item.compositeScore = rounded(
-      0.4 * (Number(item.medianAc) / maxMedian * 100) +
-      0.15 * (Number(item.middle80Avg) / maxMiddle * 100) +
-      0.2 * Number(item.activeRate) +
-      0.15 * Number(item.passRate) +
-      0.1 * Number(item.excellentRate),
+      0.4 * (item.medianAc / maxMedian * 100) +
+      0.15 * (item.middle80Avg / maxMiddle * 100) +
+      0.2 * item.activeRate +
+      0.15 * item.passRate +
+      0.1 * item.excellentRate,
       1,
     )
   }
-  comparisons.sort((a, b) => Number(b.compositeScore) - Number(a.compositeScore) || Number(b.medianAc) - Number(a.medianAc))
-  return success(c, classComparisonResponseSchema.parse({
-    comparisons: comparisons.map((item) => classComparisonSchema.parse(item)),
-    hasTimeRange,
-  }))
+  comparisons.sort((a, b) => b.compositeScore - a.compositeScore || b.medianAc - a.medianAc)
+  return success(c, { comparisons, hasTimeRange } satisfies ClassComparisonResponse)
 })
diff --git a/apps/api/src/routes/content.ts b/apps/api/src/routes/content.ts
index bb85b7d..aba4337 100644
--- a/apps/api/src/routes/content.ts
+++ b/apps/api/src/routes/content.ts
@@ -1,20 +1,22 @@
 import {
-  announcementListItemSchema,
-  announcementListSchema,
-  announcementSchema,
   createMessageRequestSchema,
-  exerciseSchema,
-  messageListSchema,
-  messageSchema,
-  reactionKeySchema,
-  reactionStateSchema,
-  setReactionRequestSchema,
   embeddedSubmissionSchema,
   exerciseAttemptRequestSchema,
+  reactionKeySchema,
+  setReactionRequestSchema,
   tutorialProgressPingSchema,
-  tutorialProgressSchema,
-  tutorialSchema,
-  tutorialSummarySchema,
+  type Announcement,
+  type AnnouncementList,
+  type AnnouncementListItem,
+  type EmbeddedSubmission,
+  type Exercise,
+  type Message,
+  type MessageList,
+  type ReactionCounts,
+  type ReactionState,
+  type Tutorial,
+  type TutorialProgress,
+  type TutorialSummary,
 } from "@oj2/contract"
 import { and, asc, count, desc, eq, inArray, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -38,8 +40,8 @@ contentRoutes.get("/announcements", async (c) => {
       .where(eq(schema.announcement.visible, true))
       .orderBy(desc(schema.announcement.top), desc(schema.announcement.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, announcementListSchema.parse({
-    results: rows.map(({ announcement, user, realName }) => announcementListItemSchema.parse({
+  return success(c, {
+    results: rows.map(({ announcement, user, realName }) => ({
       id: announcement.id,
       title: announcement.title,
       tag: announcement.tag,
@@ -47,9 +49,9 @@ contentRoutes.get("/announcements", async (c) => {
       createdBy: sampleUser(user, realName),
       createTime: announcement.createTime,
       lastUpdateTime: announcement.lastUpdateTime,
-    })),
+    } satisfies AnnouncementListItem)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies AnnouncementList)
 })
 
 contentRoutes.get("/announcements/:id", async (c) => {
@@ -59,7 +61,7 @@ contentRoutes.get("/announcements/:id", async (c) => {
     .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
     .where(and(eq(schema.announcement.id, id), eq(schema.announcement.visible, true))).limit(1)
   if (!row) return failure(c, 404, "announcement-not-found", "Announcement does not exist")
-  return success(c, announcementSchema.parse({
+  return success(c, {
     id: row.announcement.id,
     title: row.announcement.title,
     tag: row.announcement.tag,
@@ -68,7 +70,7 @@ contentRoutes.get("/announcements/:id", async (c) => {
     createdBy: sampleUser(row.user, row.realName),
     createTime: row.announcement.createTime,
     lastUpdateTime: row.announcement.lastUpdateTime,
-  }))
+  } satisfies Announcement)
 })
 
 contentRoutes.get("/messages", requireAuth, async (c) => {
@@ -84,13 +86,13 @@ contentRoutes.get("/messages", requireAuth, async (c) => {
       .innerJoin(schema.problem, eq(schema.submission.problemId, schema.problem.id))
       .where(eq(schema.message.recipientId, user.id)).orderBy(desc(schema.message.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, messageListSchema.parse({
-    results: rows.map(({ message, sender, realName, submission, displayId }) => messageSchema.parse({
+  return success(c, {
+    results: rows.map(({ message, sender, realName, submission, displayId }) => ({
       id: message.id,
       sender: sampleUser(sender, realName),
       createTime: message.createTime,
       message: message.message,
-      submission: embeddedSubmissionSchema.parse({
+      submission: {
         id: submission.id,
         createTime: submission.createTime,
         userId: submission.userId,
@@ -104,10 +106,10 @@ contentRoutes.get("/messages", requireAuth, async (c) => {
         // 展示用题号而非数字主键，站内信页面拿它拼 /problem/<题号>
         problem: displayId,
         showLink: true,
-      }),
-    })),
+      } satisfies EmbeddedSubmission,
+    } satisfies Message)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies MessageList)
 })
 
 /**
@@ -140,15 +142,16 @@ contentRoutes.post("/messages", requireSuperAdmin, async (c) => {
 async function reactionState(problemId: number, userId: number) {
   const [mine] = await db.select({ type: schema.reaction.type }).from(schema.reaction)
     .where(and(eq(schema.reaction.problemId, problemId), eq(schema.reaction.userId, userId))).limit(1)
-  if (!mine) return reactionStateSchema.parse({ mine: null, counts: null })
+  if (!mine) return { mine: null, counts: null } satisfies ReactionState
   const rows = await db.select({ type: schema.reaction.type, value: count() }).from(schema.reaction)
     .where(eq(schema.reaction.problemId, problemId)).groupBy(schema.reaction.type)
-  const counts = Object.fromEntries(reactionKeySchema.options.map((key) => [key, 0]))
-  for (const row of rows) {
-    const key = reactionKeySchema.safeParse(row.type)
-    if (key.success) counts[key.data] = row.value
-  }
-  return reactionStateSchema.parse({ mine: mine.type, counts })
+  // fromEntries 推不出这个键集，但 options 就是 ReactionKey 的全集，断言是成立的。
+  // row.type 不必再 safeParse：reaction.type 列上挂着 $type<ReactionKey>()
+  const counts = Object.fromEntries(
+    reactionKeySchema.options.map((key) => [key, 0]),
+  ) as ReactionCounts
+  for (const row of rows) counts[row.type] = row.value
+  return { mine: mine.type, counts } satisfies ReactionState
 }
 
 contentRoutes.get("/problems/:id/reaction", requireAuth, async (c) => {
@@ -183,7 +186,7 @@ contentRoutes.get("/tutorials", async (c) => {
   const type = c.req.query("type") === "c" ? "c" : "python"
   const rows = await db.select({ id: schema.tutorial.id, title: schema.tutorial.title }).from(schema.tutorial)
     .where(and(eq(schema.tutorial.isPublic, true), eq(schema.tutorial.type, type))).orderBy(asc(schema.tutorial.order))
-  return success(c, rows.map((row) => tutorialSummarySchema.parse(row)))
+  return success(c, rows satisfies TutorialSummary[])
 })
 
 contentRoutes.get("/tutorials/:id", async (c) => {
@@ -193,7 +196,7 @@ contentRoutes.get("/tutorials/:id", async (c) => {
     .leftJoin(schema.userProfile, eq(schema.userProfile.userId, schema.user.id))
     .where(and(eq(schema.tutorial.id, id), eq(schema.tutorial.isPublic, true))).limit(1)
   if (!row) return failure(c, 404, "tutorial-not-found", "Tutorial does not exist")
-  return success(c, tutorialSchema.parse({
+  return success(c, {
     id: row.tutorial.id,
     title: row.tutorial.title,
     content: row.tutorial.content,
@@ -204,7 +207,7 @@ contentRoutes.get("/tutorials/:id", async (c) => {
     createdBy: sampleUser(row.user, row.realName),
     createdAt: row.tutorial.createdAt,
     updatedAt: row.tutorial.updatedAt,
-  }))
+  } satisfies Tutorial)
 })
 
 // ---------------------------------------------------------------- 自学留痕
@@ -252,7 +255,7 @@ contentRoutes.get("/learn/progress", requireAuth, async (c) => {
   ])
   const exercises = new Map(exerciseRows.map((row) => [row.tutorialId, row]))
 
-  return success(c, rows.map((row) => tutorialProgressSchema.parse({
+  return success(c, rows.map((row) => ({
     tutorialId: row.tutorialId,
     viewCount: row.viewCount ?? 0,
     totalSeconds: row.totalSeconds ?? 0,
@@ -260,7 +263,7 @@ contentRoutes.get("/learn/progress", requireAuth, async (c) => {
     lastViewedAt: row.lastViewedAt,
     exerciseTotal: exercises.get(row.tutorialId)?.total ?? 0,
     exerciseSolved: exercises.get(row.tutorialId)?.solved ?? 0,
-  })))
+  } satisfies TutorialProgress)))
 })
 
 /**
@@ -369,5 +372,5 @@ contentRoutes.get("/tutorials/:id/exercises", async (c) => {
     .where(and(eq(schema.tutorial.id, id), eq(schema.tutorial.isPublic, true))).limit(1)
   if (!tutorial) return failure(c, 404, "tutorial-not-found", "Tutorial does not exist")
   const rows = await db.select().from(schema.exercise).where(eq(schema.exercise.tutorialId, id)).orderBy(asc(schema.exercise.order))
-  return success(c, rows.map((row) => exerciseSchema.parse({ id: row.id, type: row.type, data: objectValue(row.data), order: row.order })))
+  return success(c, rows.map((row) => ({ id: row.id, type: row.type, data: objectValue(row.data), order: row.order } satisfies Exercise)))
 })
diff --git a/apps/api/src/routes/contest.ts b/apps/api/src/routes/contest.ts
index 76d509d..2be88a4 100644
--- a/apps/api/src/routes/contest.ts
+++ b/apps/api/src/routes/contest.ts
@@ -1,13 +1,13 @@
 import {
-  STUDENT_ROLES,
-  contestAccessSchema,
-  contestListSchema,
   contestPasswordRequestSchema,
-  contestRankItemSchema,
-  contestRankSchema,
-  contestSchema,
-  problemDetailSchema,
-  problemListItemSchema,
+  STUDENT_ROLES,
+  type Contest,
+  type ContestAccess,
+  type ContestList,
+  type ContestRank,
+  type ContestRankItem,
+  type ProblemDetail,
+  type ProblemListItem,
 } from "@oj2/contract"
 import { and, asc, count, desc, eq, gte, ilike, inArray, lte, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -27,7 +27,7 @@ import {
   requireContestAccess,
   type ContestEnv,
 } from "../services/contest"
-import { objectValue, publicTemplates, queryInteger, sampleUser, stringArray } from "./helpers"
+import { objectValue, publicTemplates, queryInteger, sampleUser } from "./helpers"
 
 export const contestRoutes = new Hono<ContestEnv>()
 
@@ -47,7 +47,7 @@ function serializeContest(
   createdBy: ReturnType<typeof sampleUser>,
   includeNow = false,
 ) {
-  return contestSchema.parse({
+  return {
     id: contest.id,
     title: contest.title,
     description: contest.description,
@@ -60,7 +60,7 @@ function serializeContest(
     status: contestStatus(contest),
     contestType: contest.password ? "Password Protected" : "Public",
     now: includeNow ? new Date().toISOString() : undefined,
-  })
+  } satisfies Contest
 }
 
 contestRoutes.get("/contests", async (c) => {
@@ -82,13 +82,13 @@ contestRoutes.get("/contests", async (c) => {
     db.select().from(schema.contest).where(where).orderBy(desc(schema.contest.startTime)).limit(limit).offset(offset),
   ])
   const byId = await creators([...new Set(rows.map((row) => row.createdById))])
-  return success(c, contestListSchema.parse({
+  return success(c, {
     results: rows.map((row) => serializeContest(
       row,
       byId.get(row.createdById) ?? sampleUser({ id: row.createdById, username: "" }, null),
     )),
     total: totalRow[0]?.value ?? 0,
-  }))
+  } satisfies ContestList)
 })
 
 // optionalAuth 是为了下面那句 findAccessibleContest 认得出「这是出题人自己」——
@@ -120,7 +120,7 @@ contestRoutes.get("/contests/:id/access", requireAuth, async (c) => {
   const contest = await findAccessibleContest(c.get("user"), queryInteger(c.req.param("id"), 0, { min: 1 }))
   if (!contest || !contest.password) return failure(c, 404, "contest-not-found", "Contest does not exist")
   const access = await canAccessContest(c, contest, "details")
-  return success(c, contestAccessSchema.parse({ access: access.ok }))
+  return success(c, { access: access.ok } satisfies ContestAccess)
 })
 
 /**
@@ -165,7 +165,7 @@ contestRoutes.get("/contests/:id/problems", optionalAuth, requireContestAccess("
   const tags = await contestProblemTags(rows.map((row) => row.problem.id))
   const allowed = contestDetailsAllowed(c.get("user"), contest)
   const statuses = await contestProblemStatuses(c.get("user")?.id)
-  return success(c, rows.map(({ problem, user, realName }) => problemListItemSchema.parse({
+  return success(c, rows.map(({ problem, user, realName }) => ({
     id: problem.id,
     _id: problem.displayId,
     title: problem.title,
@@ -179,7 +179,7 @@ contestRoutes.get("/contests/:id/problems", optionalAuth, requireContestAccess("
     showFlowchart: problem.showFlowchart,
     hasAstRules: problem.astRules !== null,
     myStatus: myStatusOf(statuses, problem.id),
-  })))
+  } satisfies ProblemListItem)))
 })
 
 contestRoutes.get("/contests/:id/problems/:displayId", optionalAuth, requireContestAccess("problems"), async (c) => {
@@ -192,7 +192,7 @@ contestRoutes.get("/contests/:id/problems/:displayId", optionalAuth, requireCont
   const tags = await contestProblemTags([row.problem.id])
   const allowed = contestDetailsAllowed(c.get("user"), contest)
   const statuses = await contestProblemStatuses(c.get("user")?.id)
-  return success(c, problemDetailSchema.parse({
+  return success(c, {
     id: row.problem.id,
     _id: row.problem.displayId,
     title: row.problem.title,
@@ -201,7 +201,7 @@ contestRoutes.get("/contests/:id/problems/:displayId", optionalAuth, requireCont
     outputDescription: row.problem.outputDescription,
     samples: Array.isArray(row.problem.samples) ? row.problem.samples : [],
     hint: row.problem.hint,
-    languages: stringArray(row.problem.languages),
+    languages: row.problem.languages,
     template: publicTemplates(row.problem.template),
     createTime: row.problem.createTime,
     lastUpdateTime: row.problem.lastUpdateTime,
@@ -224,11 +224,11 @@ contestRoutes.get("/contests/:id/problems/:displayId", optionalAuth, requireCont
     mermaidCode: row.problem.allowFlowchart ? null : row.problem.mermaidCode,
     flowchartData: row.problem.allowFlowchart ? null : objectValue(row.problem.flowchartData),
     flowchartHint: row.problem.flowchartHint,
-    sqlConfig: row.problem.sqlConfig ? objectValue(row.problem.sqlConfig) : null,
-    sqlDisplay: row.problem.sqlDisplay ? objectValue(row.problem.sqlDisplay) : null,
+    sqlConfig: row.problem.sqlConfig,
+    sqlDisplay: row.problem.sqlDisplay,
     // 代码要求：只给渲染好的文案，规则原文不下发给学生
     astRequirements: astRequirements(row.problem.astRules),
-  }))
+  } satisfies ProblemDetail)
 })
 
 contestRoutes.get("/contests/:id/rank", optionalAuth, requireContestAccess("ranks"), async (c) => {
@@ -247,8 +247,8 @@ contestRoutes.get("/contests/:id/rank", optionalAuth, requireContestAccess("rank
       .orderBy(desc(schema.acmContestRank.acceptedNumber), asc(schema.acmContestRank.totalTime), asc(schema.acmContestRank.id)).limit(limit).offset(offset),
   ])
   const admin = isContestAdmin(c.get("user"), contest)
-  return success(c, contestRankSchema.parse({
-    results: rows.map(({ rank, user, realName }) => contestRankItemSchema.parse({
+  return success(c, {
+    results: rows.map(({ rank, user, realName }) => ({
       id: rank.id,
       // 唯一显式打开真名的地方，对齐旧后端 contest/serializers.py:84
       // `UsernameSerializer(obj.user, need_real_name=self.is_contest_admin)`
@@ -256,9 +256,9 @@ contestRoutes.get("/contests/:id/rank", optionalAuth, requireContestAccess("rank
       submissionNumber: rank.submissionNumber,
       acceptedNumber: rank.acceptedNumber,
       totalTime: rank.totalTime,
-      submissionInfo: objectValue(rank.submissionInfo),
+      submissionInfo: rank.submissionInfo,
       contestId: rank.contestId,
-    })),
+    } satisfies ContestRankItem)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies ContestRank)
 })
diff --git a/apps/api/src/routes/flowchart.ts b/apps/api/src/routes/flowchart.ts
index a440748..1565c87 100644
--- a/apps/api/src/routes/flowchart.ts
+++ b/apps/api/src/routes/flowchart.ts
@@ -2,13 +2,13 @@ import { randomBytes } from "node:crypto"
 
 import {
   createFlowchartRequestSchema,
-  createFlowchartResponseSchema,
-  flowchartCurrentSchema,
-  flowchartDetailSchema,
-  flowchartListItemSchema,
-  flowchartListSchema,
-  flowchartStatisticsSchema,
-  flowchartSubmissionSchema,
+  type CreateFlowchartResponse,
+  type FlowchartCurrent,
+  type FlowchartDetail,
+  type FlowchartList,
+  type FlowchartListItem,
+  type FlowchartStatistics,
+  type FlowchartSubmission,
 } from "@oj2/contract"
 import { and, asc, count, desc, eq, ilike, isNull, sql } from "drizzle-orm"
 import { Hono } from "hono"
@@ -45,7 +45,7 @@ function flowchartData(
   flowchart: typeof schema.flowchartSubmission.$inferSelect,
   username: string,
 ) {
-  return flowchartSubmissionSchema.parse({
+  return {
     id: flowchart.id,
     username,
     problemId: flowchart.problemId,
@@ -62,7 +62,7 @@ function flowchartData(
     aiModel: flowchart.aiModel,
     processingTime: flowchart.processingTime,
     evaluationTime: flowchart.evaluationTime,
-  })
+  } satisfies FlowchartSubmission
 }
 
 flowchartRoutes.post("/flowcharts", requireAuth, async (c) => {
@@ -106,7 +106,7 @@ flowchartRoutes.post("/flowcharts", requireAuth, async (c) => {
     await db.update(schema.flowchartSubmission).set({ status: 3 }).where(eq(schema.flowchartSubmission.id, id))
     return failure(c, 502, "queue-unavailable", "Evaluation queue is unavailable")
   }
-  return success(c, createFlowchartResponseSchema.parse({ submissionId: id, status: "pending" }), 201)
+  return success(c, { submissionId: id, status: "pending" } satisfies CreateFlowchartResponse, 201)
 })
 
 flowchartRoutes.get("/flowcharts", requireAuth, async (c) => {
@@ -121,7 +121,7 @@ flowchartRoutes.get("/flowcharts", requireAuth, async (c) => {
   // submission_list_show_all 时非管理员看不到列表。流程图这边一直漏了这道门，
   // 学生把语言切成「流程图」、用户名随便填一个字就能翻出全班的 AI 评分。
   if (!(await getBooleanOption("submission_list_show_all", true)) && !isAdminRole(user)) {
-    return success(c, flowchartListSchema.parse({ results: [], total: 0 }))
+    return success(c, { results: [], total: 0 } satisfies FlowchartList)
   }
   if (displayId) filters.push(sql`lower(${schema.problem.displayId}) = lower(${displayId})`)
   if (c.req.query("myself") === "1" || (!username && user.adminType === "Regular User")) filters.push(eq(schema.flowchartSubmission.userId, user.id))
@@ -136,8 +136,8 @@ flowchartRoutes.get("/flowcharts", requireAuth, async (c) => {
       .innerJoin(schema.problem, eq(schema.flowchartSubmission.problemId, schema.problem.id)).where(where)
       .orderBy(desc(schema.flowchartSubmission.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, flowchartListSchema.parse({
-    results: rows.map(({ flowchart, username, problem }) => flowchartListItemSchema.parse({
+  return success(c, {
+    results: rows.map(({ flowchart, username, problem }) => ({
       id: flowchart.id,
       username,
       problem: problem.displayId,
@@ -151,9 +151,9 @@ flowchartRoutes.get("/flowcharts", requireAuth, async (c) => {
       processingTime: flowchart.processingTime,
       evaluationTime: flowchart.evaluationTime,
       showLink: canView(user, flowchart, problem),
-    })),
+    } satisfies FlowchartListItem)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies FlowchartList)
 })
 
 const FLOWCHART_COMPLETED = 2
@@ -242,7 +242,7 @@ flowchartRoutes.get("/flowcharts/statistics", requireTeacher, async (c) => {
       realName: stripClassPrefix(row.username, row.className),
     })),
   }
-  if (rows.length === 0) return success(c, flowchartStatisticsSchema.parse(empty))
+  if (rows.length === 0) return success(c, empty satisfies FlowchartStatistics)
 
   const gradeDistribution: Record<string, number> = {}
   const criteriaTotals = new Map<string, { sum: number; count: number; max: number }>()
@@ -289,7 +289,7 @@ flowchartRoutes.get("/flowcharts/statistics", requireTeacher, async (c) => {
     criteriaAverages[key] = { avg: rounded(bucket.sum / bucket.count, 1), max: bucket.max }
   }
 
-  return success(c, flowchartStatisticsSchema.parse({
+  return success(c, {
     totalCount: rows.length,
     // 分母是有分数的条数，不是总条数 —— 对齐 Django 的 Avg()，它跳过 NULL
     avgScore: scoreCount ? rounded(scoreSum / scoreCount, 1) : 0,
@@ -304,7 +304,7 @@ flowchartRoutes.get("/flowcharts/statistics", requireTeacher, async (c) => {
         username: row.username,
         realName: stripClassPrefix(row.username, row.className),
       })),
-  }))
+  } satisfies FlowchartStatistics)
 })
 
 flowchartRoutes.get("/flowcharts/:id", requireAuth, async (c) => {
@@ -351,7 +351,7 @@ flowchartRoutes.post("/flowcharts/:id/retry", requireAuth, async (c) => {
     await db.update(schema.flowchartSubmission).set({ status: 3 }).where(eq(schema.flowchartSubmission.id, row.flowchart.id))
     return failure(c, 502, "queue-unavailable", "Evaluation queue is unavailable")
   }
-  return success(c, createFlowchartResponseSchema.parse({ submissionId: row.flowchart.id, status: "pending" }))
+  return success(c, { submissionId: row.flowchart.id, status: "pending" } satisfies CreateFlowchartResponse)
 })
 
 flowchartRoutes.get("/problems/:id/flowchart/current", requireAuth, async (c) => {
@@ -359,7 +359,7 @@ flowchartRoutes.get("/problems/:id/flowchart/current", requireAuth, async (c) =>
   const rows = await db.select({ score: schema.flowchartSubmission.aiScore, grade: schema.flowchartSubmission.aiGrade })
     .from(schema.flowchartSubmission).where(and(eq(schema.flowchartSubmission.userId, c.get("user")!.id), eq(schema.flowchartSubmission.problemId, problemId), eq(schema.flowchartSubmission.status, 2)))
     .orderBy(desc(schema.flowchartSubmission.createTime))
-  return success(c, flowchartCurrentSchema.parse({ count: rows.length, score: rows[0]?.score ?? 0, grade: rows[0]?.grade ?? "" }))
+  return success(c, { count: rows.length, score: rows[0]?.score ?? 0, grade: rows[0]?.grade ?? "" } satisfies FlowchartCurrent)
 })
 
 flowchartRoutes.get("/problems/:id/flowchart/history", requireAuth, async (c) => {
@@ -371,5 +371,5 @@ flowchartRoutes.get("/problems/:id/flowchart/history", requireAuth, async (c) =>
     .orderBy(asc(schema.flowchartSubmission.createTime))
   const selected = page === 0 ? rows.at(-1) : rows[page - 1]
   if (page > rows.length) return failure(c, 400, "page-out-of-range", "Page out of range")
-  return success(c, flowchartDetailSchema.parse({ submission: selected ? flowchartData(selected.flowchart, selected.username) : null, count: rows.length }))
+  return success(c, { submission: selected ? flowchartData(selected.flowchart, selected.username) : null, count: rows.length } satisfies FlowchartDetail)
 })
diff --git a/apps/api/src/routes/helpers.ts b/apps/api/src/routes/helpers.ts
index 256fa1d..f46f286 100644
--- a/apps/api/src/routes/helpers.ts
+++ b/apps/api/src/routes/helpers.ts
@@ -1,9 +1,4 @@
-import {
-  ADMIN_ROLES,
-  TEACHER_ROLES,
-  sampleUserSchema,
-  type SampleUser,
-} from "@oj2/contract"
+import { ADMIN_ROLES, TEACHER_ROLES, type SampleUser } from "@oj2/contract"
 
 import { and, count, eq, notInArray } from "drizzle-orm"
 
@@ -26,11 +21,11 @@ export function sampleUser(
   realName: string | null | undefined,
   options: { includeRealName?: boolean } = {},
 ): SampleUser {
-  return sampleUserSchema.parse({
+  return {
     id: source.id,
     username: source.username,
     realName: options.includeRealName === true ? (realName ?? null) : null,
-  })
+  } satisfies SampleUser
 }
 
 /**
@@ -49,18 +44,23 @@ export function stripClassPrefix(
   return username.startsWith(prefix) ? username.slice(prefix.length) : username
 }
 
+/**
+ * 拿 query 里的筛选值去比对 `$type` 收窄过的列（`submission.result`、`problem.difficulty` 这些）。
+ *
+ * 值来自 URL，不受控：前端下拉框以外的任何字符串都可能进来。对不上枚举时 SQL 一行都匹配不到，
+ * 和列没收窄之前的行为完全一致 —— 所以这里只做类型上的交接，**不加校验**：
+ * 在这儿拦一道会把「筛出空列表」变成「筛条件被忽略、返回全部」，那是另一种行为。
+ */
+export function asFilterValue<T extends string | number>(value: string | number): T {
+  return value as T
+}
+
 export function objectValue(value: unknown): Record<string, unknown> {
   return value && typeof value === "object" && !Array.isArray(value)
     ? (value as Record<string, unknown>)
     : {}
 }
 
-export function stringArray(value: unknown): string[] {
-  return Array.isArray(value)
-    ? value.filter((item): item is string => typeof item === "string")
-    : []
-}
-
 export function queryInteger(
   value: string | undefined,
   fallback: number,
diff --git a/apps/api/src/routes/problem.ts b/apps/api/src/routes/problem.ts
index bed20ee..9a99dab 100644
--- a/apps/api/src/routes/problem.ts
+++ b/apps/api/src/routes/problem.ts
@@ -1,11 +1,4 @@
-import {
-	problemAuthorSchema,
-	problemDetailSchema,
-	problemListItemSchema,
-	problemListSchema,
-	tagSchema,
-	yearlyAcSchema,
-} from "@oj2/contract"
+import type { ProblemAuthor, ProblemDetail, ProblemList, ProblemListItem, Tag, YearlyAc } from "@oj2/contract"
 import {
 	and,
 	asc,
@@ -28,7 +21,7 @@ import { db, schema } from "../db"
 import { astRequirements } from "../judge/ast"
 import { failure, success } from "../http"
 import { JudgeStatus } from "../judge/status"
-import { countFailedSubmissions, objectValue as toObject, queryInteger, sampleUser } from "./helpers"
+import { asFilterValue, countFailedSubmissions, objectValue as toObject, queryInteger, sampleUser } from "./helpers"
 
 export const problemRoutes = new Hono<AppEnv>()
 
@@ -38,10 +31,6 @@ function objectValue(value: unknown): Record<string, unknown> {
 		: {}
 }
 
-function stringArray(value: unknown): string[] {
-	return Array.isArray(value) ? value.filter((item): item is string => typeof item === "string") : []
-}
-
 function publicTemplates(value: unknown) {
 	const templates: Record<string, string> = {}
 	for (const [language, raw] of Object.entries(objectValue(value))) {
@@ -76,7 +65,7 @@ function listItem(
 	statuses: Record<string, unknown>,
 ) {
 	const status = toObject(statuses[String(row.problem.id)]).status
-	return problemListItemSchema.parse({
+	return {
 		id: row.problem.id,
 		_id: row.problem.displayId,
 		title: row.problem.title,
@@ -90,7 +79,7 @@ function listItem(
 		showFlowchart: row.problem.showFlowchart,
 		hasAstRules: row.problem.astRules !== null,
 		myStatus: typeof status === "number" ? status : null,
-	})
+	} satisfies ProblemListItem
 }
 
 problemRoutes.get("/problems", optionalAuth, async (c) => {
@@ -103,7 +92,7 @@ problemRoutes.get("/problems", optionalAuth, async (c) => {
 	const tag = c.req.query("tag")?.trim()
 	if (author) filters.push(eq(schema.user.username, author))
 	if (keyword) filters.push(or(ilike(schema.problem.title, `%${keyword}%`), ilike(schema.problem.displayId, `%${keyword}%`))!)
-	if (difficulty) filters.push(eq(schema.problem.difficulty, difficulty))
+	if (difficulty) filters.push(eq(schema.problem.difficulty, asFilterValue(difficulty)))
 	if (tag) {
 		filters.push(inArray(schema.problem.id, db.select({ id: schema.problemTags.problemId }).from(schema.problemTags)
 			.innerJoin(schema.problemTag, eq(schema.problemTags.problemtagId, schema.problemTag.id))
@@ -140,10 +129,10 @@ problemRoutes.get("/problems", optionalAuth, async (c) => {
 		getProblemTags(rows.map((row) => row.problem.id)),
 		getProblemStatuses(c.get("user")?.id),
 	])
-	return success(c, problemListSchema.parse({
+	return success(c, {
 		results: rows.map((row) => listItem(row, tags, statuses)),
 		total: totalRow?.value ?? 0,
-	}))
+	} satisfies ProblemList)
 })
 
 problemRoutes.get("/problem-tags", async (c) => {
@@ -161,7 +150,7 @@ problemRoutes.get("/problem-tags", async (c) => {
 		.where(keyword ? ilike(schema.problemTag.name, `%${keyword}%`) : undefined)
 		.groupBy(schema.problemTag.id, schema.problemTag.name).having(sql`count(${schema.problemTags.problemId}) > 0`)
 		.orderBy(asc(schema.problemTag.name))
-	return success(c, rows.map((row) => tagSchema.parse(row)))
+	return success(c, rows satisfies Tag[])
 })
 
 problemRoutes.get("/problems/random", async (c) => {
@@ -177,7 +166,7 @@ problemRoutes.get("/problem-authors", async (c) => {
 		.from(schema.problem).innerJoin(schema.user, eq(schema.problem.createdById, schema.user.id))
 		.where(and(isNull(schema.problem.contestId), eq(schema.user.isDisabled, false), showAll ? undefined : eq(schema.problem.visible, true)))
 		.groupBy(schema.user.username).orderBy(desc(count(schema.problem.id)))
-	return success(c, rows.map((row) => problemAuthorSchema.parse(row)))
+	return success(c, rows satisfies ProblemAuthor[])
 })
 
 problemRoutes.get("/problems/:id/beat-count", optionalAuth, async (c) => {
@@ -232,7 +221,7 @@ problemRoutes.get("/problems/:displayId/yearly-ac", async (c) => {
 		accepted: sql<number>`count(*) filter (where ${schema.submission.result} in (0, 10))::int`,
 	}).from(schema.submission).where(and(eq(schema.submission.problemId, problem.id), isNull(schema.submission.contestId), notInArray(schema.submission.result, [6, 7])))
 		.groupBy(year).orderBy(year)
-	return success(c, rows.map((row) => yearlyAcSchema.parse({ ...row, acRate: row.total > 0 ? Math.round(row.accepted / row.total * 10_000) / 100 : 0 })))
+	return success(c, rows.map((row) => ({ ...row, acRate: row.total > 0 ? Math.round(row.accepted / row.total * 10_000) / 100 : 0 } satisfies YearlyAc)))
 })
 
 problemRoutes.get("/problems/:displayId", optionalAuth, async (c) => {
@@ -283,7 +272,7 @@ problemRoutes.get("/problems/:displayId", optionalAuth, async (c) => {
 	}
 
 	const samples = Array.isArray(row.problem.samples) ? row.problem.samples : []
-	const data = problemDetailSchema.parse({
+	const data = {
 		id: row.problem.id,
 		_id: row.problem.displayId,
 		title: row.problem.title,
@@ -292,7 +281,7 @@ problemRoutes.get("/problems/:displayId", optionalAuth, async (c) => {
 		outputDescription: row.problem.outputDescription,
 		samples,
 		hint: row.problem.hint,
-		languages: stringArray(row.problem.languages),
+		languages: row.problem.languages,
 		template: publicTemplates(row.problem.template),
 		createTime: row.problem.createTime,
 		lastUpdateTime: row.problem.lastUpdateTime,
@@ -316,11 +305,11 @@ problemRoutes.get("/problems/:displayId", optionalAuth, async (c) => {
 			? null
 			: objectValue(row.problem.flowchartData),
 		flowchartHint: row.problem.flowchartHint,
-		sqlConfig: row.problem.sqlConfig ? objectValue(row.problem.sqlConfig) : null,
-		sqlDisplay: row.problem.sqlDisplay ? objectValue(row.problem.sqlDisplay) : null,
+		sqlConfig: row.problem.sqlConfig,
+		sqlDisplay: row.problem.sqlDisplay,
 		// 代码要求：只给渲染好的文案，规则原文不下发给学生
 		astRequirements: astRequirements(row.problem.astRules),
-	})
+	} satisfies ProblemDetail
 
 	return success(c, data)
 })
diff --git a/apps/api/src/routes/problemset.ts b/apps/api/src/routes/problemset.ts
index 4c2376b..89a5719 100644
--- a/apps/api/src/routes/problemset.ts
+++ b/apps/api/src/routes/problemset.ts
@@ -1,13 +1,13 @@
 import {
-  problemSetBadgeSchema,
-  problemSetListSchema,
-  problemSetProblemSchema,
-  problemSetProgressListSchema,
-  problemSetProgressSchema,
-  problemSetSchema,
-  updateProblemSetProgressRequestSchema,
   joinProblemSetRequestSchema,
-  userBadgeSchema,
+  updateProblemSetProgressRequestSchema,
+  type ProblemSet,
+  type ProblemSetBadge,
+  type ProblemSetList,
+  type ProblemSetProblem,
+  type ProblemSetProgress,
+  type ProblemSetProgressList,
+  type UserBadge,
 } from "@oj2/contract"
 import {
   and,
@@ -32,7 +32,7 @@ import { failure, success } from "../http"
 import { JudgeStatus } from "../judge/status"
 import { updateAchievementsForProblemSet } from "../services/achievements"
 import { computeProgress, eligibleForBadge } from "../services/problemset"
-import { objectValue, queryInteger, sampleUser } from "./helpers"
+import { asFilterValue, objectValue, queryInteger, sampleUser } from "./helpers"
 
 export const problemsetRoutes = new Hono<AppEnv>()
 
@@ -65,7 +65,7 @@ async function problemSetCreators(ids: number[]) {
 }
 
 function badgeData(badge: typeof schema.problemsetBadge.$inferSelect, earned?: boolean) {
-  return problemSetBadgeSchema.parse({
+  return {
     id: badge.id,
     problemsetId: badge.problemsetId,
     name: badge.name,
@@ -74,7 +74,7 @@ function badgeData(badge: typeof schema.problemsetBadge.$inferSelect, earned?: b
     conditionType: badge.conditionType,
     conditionValue: badge.conditionValue,
     isEarned: earned,
-  })
+  } satisfies ProblemSetBadge
 }
 
 /**
@@ -113,7 +113,7 @@ async function serializeProblemSets(
   const earned = new Set(earnedRows.map((item) => item.id))
   return rows.map((row) => {
     const progress = progressBySet.get(row.id)
-    return problemSetSchema.parse({
+    return {
       id: row.id,
       title: row.title,
       description: row.description,
@@ -128,7 +128,7 @@ async function serializeProblemSets(
       completedCount: progress?.completedProblemsCount ?? 0,
       userProgress: progressSummary(progress),
       badges: includeBadges ? (badgesBySet.get(row.id) ?? []).map((badge) => badgeData(badge, earned.has(badge.id))) : undefined,
-    })
+    } satisfies ProblemSet
   })
 }
 
@@ -140,17 +140,17 @@ problemsetRoutes.get("/problem-sets", optionalAuth, async (c) => {
   const difficulty = c.req.query("difficulty")?.trim()
   const status = c.req.query("status")?.trim()
   if (keyword) filters.push(or(ilike(schema.problemset.title, `%${keyword}%`), ilike(schema.problemset.description, `%${keyword}%`))!)
-  if (difficulty) filters.push(eq(schema.problemset.difficulty, difficulty))
-  if (status) filters.push(eq(schema.problemset.status, status))
+  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().from(schema.problemset).where(where).orderBy(desc(schema.problemset.createTime)).limit(limit).offset(offset),
   ])
-  return success(c, problemSetListSchema.parse({
+  return success(c, {
     results: await serializeProblemSets(rows, c.get("user")?.id, true),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies ProblemSetList)
 })
 
 problemsetRoutes.get("/problem-sets/:id", optionalAuth, async (c) => {
@@ -189,7 +189,7 @@ problemsetRoutes.get("/problem-sets/:id/problems", optionalAuth, async (c) => {
       .where(and(eq(schema.problemsetProgress.problemsetId, id), eq(schema.problemsetProgress.userId, c.get("user")!.id))).limit(1)
     : []
   const completed = objectValue(progressRows[0]?.detail)
-  return success(c, rows.map(({ link, problemId, displayId, title, difficulty }) => problemSetProblemSchema.parse({
+  return success(c, rows.map(({ link, problemId, displayId, title, difficulty }) => ({
     id: link.id,
     problemsetId: link.problemsetId,
     problem: { id: problemId, _id: displayId, title, difficulty },
@@ -198,7 +198,7 @@ problemsetRoutes.get("/problem-sets/:id/problems", optionalAuth, async (c) => {
     score: link.score,
     hint: link.hint,
     isCompleted: String(problemId) in completed,
-  })))
+  } satisfies ProblemSetProblem)))
 })
 
 async function recomputeProgress(
@@ -344,13 +344,13 @@ problemsetRoutes.get("/users/:username/badges", optionalAuth, async (c) => {
     .from(schema.userBadge).innerJoin(schema.problemsetBadge, eq(schema.userBadge.badgeId, schema.problemsetBadge.id))
     .innerJoin(schema.problemset, eq(schema.problemsetBadge.problemsetId, schema.problemset.id))
     .where(eq(schema.userBadge.userId, target.id)).orderBy(desc(schema.userBadge.earnedTime))
-  return success(c, rows.map(({ userBadge, badge, problemSet }) => userBadgeSchema.parse({
+  return success(c, rows.map(({ userBadge, badge, problemSet }) => ({
     id: userBadge.id,
     userId: userBadge.userId,
     badge: badgeData(badge),
     earnedTime: userBadge.earnedTime,
     problemset: { id: problemSet.id, title: problemSet.title },
-  })))
+  } satisfies UserBadge)))
 })
 
 problemsetRoutes.get("/problem-sets/:id/badges", async (c) => {
@@ -399,7 +399,7 @@ problemsetRoutes.get("/problem-sets/:id/user-progress", requireTeacher, async (c
       .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 }) => problemSetProgressSchema.parse({
+  const results = rows.map(({ progress, user: progressUser, realName }) => ({
     id: progress.id,
     problemsetId: progress.problemsetId,
     user: sampleUser(progressUser, realName),
@@ -411,12 +411,12 @@ problemsetRoutes.get("/problem-sets/:id/user-progress", requireTeacher, async (c
     totalProblemsCount: progress.totalProblemsCount,
     totalScore: progress.totalScore,
     completedProblems: Object.keys(objectValue(progress.progressDetail)).flatMap((key) => problemMap.get(key) ?? []),
-  }))
+  } satisfies ProblemSetProgress))
   const stats = statsRows[0]
-  return success(c, problemSetProgressListSchema.parse({
+  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)
 })
diff --git a/apps/api/src/routes/site.ts b/apps/api/src/routes/site.ts
index c68b1ad..586dbaf 100644
--- a/apps/api/src/routes/site.ts
+++ b/apps/api/src/routes/site.ts
@@ -1,4 +1,4 @@
-import { onlineCountSchema, quoteSchema, websiteConfigSchema } from "@oj2/contract"
+import type { OnlineCount, Quote, WebsiteConfig } from "@oj2/contract"
 import { asc, desc, eq } from "drizzle-orm"
 import { Hono } from "hono"
 import { resolve } from "node:path"
@@ -14,7 +14,7 @@ export const siteRoutes = new Hono()
 
 siteRoutes.get("/site", async (c) => {
   const options = await getWebsiteOptions()
-  return success(c, websiteConfigSchema.parse({
+  return success(c, {
     websiteBaseUrl: options.website_base_url,
     websiteName: options.website_name,
     websiteNameShortcut: options.website_name_shortcut,
@@ -23,7 +23,7 @@ siteRoutes.get("/site", async (c) => {
     submissionListShowAll: options.submission_list_show_all,
     classList: options.class_list,
     enableMaxkb: options.enable_maxkb,
-  }))
+  } satisfies WebsiteConfig)
 })
 
 /**
@@ -31,7 +31,7 @@ siteRoutes.get("/site", async (c) => {
  * 而榜单页本身就允许匿名看。谁在线是另一回事，只在 /rankings/users 里对老师下发。
  */
 siteRoutes.get("/site/online", async (c) => {
-  return success(c, onlineCountSchema.parse({ count: await onlineCount() }))
+  return success(c, { count: await onlineCount() } satisfies OnlineCount)
 })
 
 // 数据集读不到时的兜底（本机 dev 没挂 data/hitokoto 就会走这里）
@@ -47,11 +47,6 @@ const fallbackQuotes = [
 let categoryPaths: string[] | null = null
 const sentenceCache = new Map<string, Quote[]>()
 
-interface Quote {
-  hitokoto: string
-  from: string
-}
-
 async function loadSentences(path: string) {
   const cached = sentenceCache.get(path)
   if (cached) return cached
@@ -78,10 +73,10 @@ async function randomQuote() {
 
 siteRoutes.get("/quotes/random", async (c) => {
   try {
-    return success(c, quoteSchema.parse(await randomQuote()))
+    return success(c, (await randomQuote()) satisfies Quote)
   } catch {
     const item = fallbackQuotes[Math.floor(Math.random() * fallbackQuotes.length)]!
-    return success(c, quoteSchema.parse(item))
+    return success(c, item satisfies Quote)
   }
 })
 
diff --git a/apps/api/src/routes/submission.ts b/apps/api/src/routes/submission.ts
index 36036fb..9913c24 100644
--- a/apps/api/src/routes/submission.ts
+++ b/apps/api/src/routes/submission.ts
@@ -2,14 +2,14 @@ import { randomBytes } from "node:crypto"
 
 import {
   createSubmissionRequestSchema,
-  createSubmissionResponseSchema,
   formatCodeRequestSchema,
-  formatCodeResponseSchema,
-  submissionDetailSchema,
-  submissionListItemSchema,
-  submissionListSchema,
-  submissionStatisticsItemsSchema,
-  submissionStatisticsSchema,
+  type CreateSubmissionResponse,
+  type FormatCodeResponse,
+  type SubmissionDetail,
+  type SubmissionList,
+  type SubmissionListItem,
+  type SubmissionStatistics,
+  type SubmissionStatisticsItems,
 } from "@oj2/contract"
 import { and, count, desc, eq, gt, ilike, inArray, isNull, or, sql, type SQL } from "drizzle-orm"
 import { Hono } from "hono"
@@ -23,7 +23,7 @@ import {
 import type { AuthUser } from "../auth/session"
 import { db, schema } from "../db"
 import { failure, success } from "../http"
-import { JudgeStatus, UNJUDGED_RESULTS } from "../judge/status"
+import { JudgeStatus, UNJUDGED_RESULTS, type JudgeStatusValue } from "../judge/status"
 import { judgeQueue } from "../queue"
 import {
   canAccessContest,
@@ -36,22 +36,10 @@ import {
 import { CodeFormatError, formatCode } from "../services/format-code"
 import { getBooleanOption } from "../services/options"
 import { consumeToken } from "../services/throttling"
-import {
-  isAdminRole,
-  queryInteger,
-  rounded,
-  stripClassPrefix,
-  todayStart,
-} from "./helpers"
+import { asFilterValue, isAdminRole, queryInteger, rounded, stripClassPrefix, todayStart } from "./helpers"
 
 export const submissionRoutes = new Hono<ContestEnv>()
 
-function stringArray(value: unknown): string[] {
-  return Array.isArray(value)
-    ? value.filter((item): item is string => typeof item === "string")
-    : []
-}
-
 function objectValue(value: unknown): Record<string, unknown> {
   return value && typeof value === "object" && !Array.isArray(value)
     ? (value as Record<string, unknown>)
@@ -100,7 +88,7 @@ submissionRoutes.post("/submissions", requireAuth, async (c) => {
     .limit(1)
 
   if (!problem) return failure(c, 404, "problem-not-found", "Problem does not exist")
-  if (!stringArray(problem.languages).includes(parsed.data.language)) {
+  if (!problem.languages.includes(parsed.data.language)) {
     return failure(
       c,
       400,
@@ -162,7 +150,7 @@ submissionRoutes.post("/submissions", requireAuth, async (c) => {
 
   return success(
     c,
-    createSubmissionResponseSchema.parse({ submissionId }),
+    { submissionId } satisfies CreateSubmissionResponse,
     201,
   )
 })
@@ -258,9 +246,11 @@ const FAILURE_MESSAGE_LIMIT = 400
  * statistic_info 的那一段，提交详情页读的也是它。
  */
 async function lastFailureByUser(where: SQL | undefined, userIds: number[]) {
+  // result 手写成 JudgeStatusValue：这条裸 SQL 读的就是 submission.result 那一列，
+  // 口径要和列上的 $type 一致
   const byUser = new Map<
     number,
-    { id: string; problem: string; result: number; error: string | null }
+    { id: string; problem: string; result: JudgeStatusValue; error: string | null }
   >()
   if (!userIds.length) return byUser
 
@@ -269,7 +259,7 @@ async function lastFailureByUser(where: SQL | undefined, userIds: number[]) {
     user_id: number
     id: string
     problem: string
-    result: number
+    result: JudgeStatusValue
     error: string | null
   }>(sql`
     select user_id, id, problem, result, error from (
@@ -606,7 +596,7 @@ submissionRoutes.get("/submissions/statistics", requireTeacher, async (c) => {
 
   return success(
     c,
-    submissionStatisticsSchema.parse({
+    {
       submissionCount,
       acceptedCount,
       judgingCount,
@@ -615,7 +605,7 @@ submissionRoutes.get("/submissions/statistics", requireTeacher, async (c) => {
       data,
       dataUnaccepted,
       dataAttempted,
-    }),
+    } satisfies SubmissionStatistics,
   )
 })
 
@@ -661,10 +651,10 @@ submissionRoutes.get("/submissions/statistics/items", requireTeacher, async (c)
   const truncated = rows.length > STATISTICS_ITEMS_LIMIT
   return success(
     c,
-    submissionStatisticsItemsSchema.parse({
+    {
       items: rows.slice(0, STATISTICS_ITEMS_LIMIT),
       truncated,
-    }),
+    } satisfies SubmissionStatisticsItems,
   )
 })
 
@@ -696,7 +686,7 @@ submissionRoutes.post("/code/format", requireAuth, async (c) => {
   if (!parsed.success) return failure(c, 400, "invalid-request", "Invalid format payload")
   try {
     const code = await formatCode(parsed.data.code, parsed.data.language)
-    return success(c, formatCodeResponseSchema.parse({ code }))
+    return success(c, { code } satisfies FormatCodeResponse)
   } catch (error) {
     if (error instanceof CodeFormatError) {
       return failure(c, error.kind === "syntax" ? 400 : 500, error.kind === "syntax" ? "format-error" : "format-tool-error", error.message)
@@ -831,7 +821,7 @@ async function submissionDetail(id: string, user: AuthUser) {
   // 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」。
   const full = isAdminRole(user)
-  return submissionDetailSchema.parse({
+  return {
     id: row.submission.id,
     createTime: row.submission.createTime,
     userId: row.submission.userId,
@@ -847,7 +837,7 @@ async function submissionDetail(id: string, user: AuthUser) {
     // problem 表本来就 join 了，不额外查库
     problemDisplayId: row.problem.displayId,
     showLink: true,
-  })
+  } satisfies SubmissionDetail
 }
 
 /**
@@ -926,7 +916,7 @@ submissionRoutes.get("/submissions", optionalAuth, async (c) => {
   // 「非管理员即受限」，不能写成「是普通用户才受限」——
   // 后者对匿名用户（user 为 null）会短路，匿名反而能看到全部提交，权限大于登录学生。
   if (!(await getBooleanOption("submission_list_show_all", true)) && !isAdminRole(user)) {
-    return success(c, submissionListSchema.parse({ results: [], total: 0 }))
+    return success(c, { results: [], total: 0 } satisfies SubmissionList)
   }
   const filters = [isNull(schema.submission.contestId)]
   const displayId = c.req.query("problemId")?.trim()
@@ -936,8 +926,8 @@ submissionRoutes.get("/submissions", optionalAuth, async (c) => {
   if (displayId) filters.push(sql`lower(${schema.problem.displayId}) = lower(${displayId})`)
   if (c.req.query("myself") === "1" && user) filters.push(eq(schema.submission.userId, user.id))
   else if (username) filters.push(usernameFilter(username))
-  if (result !== undefined && result !== "" && Number.isInteger(Number(result))) filters.push(eq(schema.submission.result, Number(result)))
-  if (language) filters.push(eq(schema.submission.language, language))
+  if (result !== undefined && result !== "" && Number.isInteger(Number(result))) filters.push(eq(schema.submission.result, asFilterValue(Number(result))))
+  if (language) filters.push(eq(schema.submission.language, asFilterValue(language)))
   if (c.req.query("today") === "1") filters.push(sql`${schema.submission.createTime} >= ${todayStart()}`)
   const where = and(...filters)
   // count 不 join problem：problem 只有按题号筛选时才出现在 where 里，无条件 join 会让
@@ -960,8 +950,8 @@ submissionRoutes.get("/submissions", optionalAuth, async (c) => {
     // 来源题单的标题。一页里不同题单最多几个，按主键查一次就够
     problemsetTitleMap(rows.map((row) => row.submission.problemsetId)),
   ])
-  return success(c, submissionListSchema.parse({
-    results: rows.map(({ submission, problem }) => submissionListItemSchema.parse({
+  return success(c, {
+    results: rows.map(({ submission, problem }) => ({
       id: submission.id,
       problem: problem.displayId,
       problemTitle: problem.title,
@@ -976,9 +966,9 @@ submissionRoutes.get("/submissions", optionalAuth, async (c) => {
       problemSet: submission.problemsetId !== null && problemsetTitles.has(submission.problemsetId)
         ? { id: submission.problemsetId, title: problemsetTitles.get(submission.problemsetId)! }
         : null,
-    })),
+    } satisfies SubmissionListItem)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies SubmissionList)
 })
 
 submissionRoutes.get("/contests/:contestId/submissions", optionalAuth, requireContestAccess("submissions", "contestId"), async (c) => {
@@ -993,7 +983,7 @@ submissionRoutes.get("/contests/:contestId/submissions", optionalAuth, requireCo
   if (displayId) filters.push(sql`lower(${schema.problem.displayId}) = lower(${displayId})`)
   if (c.req.query("myself") === "1" && user) filters.push(eq(schema.submission.userId, user.id))
   else if (username) filters.push(usernameFilter(username))
-  if (result !== undefined && result !== "" && Number.isInteger(Number(result))) filters.push(eq(schema.submission.result, Number(result)))
+  if (result !== undefined && result !== "" && Number.isInteger(Number(result))) filters.push(eq(schema.submission.result, asFilterValue(Number(result))))
   if (contestStatus(contest) !== "1") filters.push(sql`${schema.submission.createTime} >= ${contest.startTime}`)
   const where = and(...filters)
   // count 不 join problem：problem 只有按题号筛选时才出现在 where 里，无条件 join 会让
@@ -1013,8 +1003,8 @@ submissionRoutes.get("/contests/:contestId/submissions", optionalAuth, requireCo
   // `isNull(problem.contestId)`（admin/problemset.ts:232）——而这条列表只出比赛提交，
   // 两边交集恒空，挂上去就是每页白跑一次查询，而比赛进行中这条列表是被刷得最狠的。
   // 旧后端 ContestSubmissionListAPI 照抄了 bulk_fetch，那边同样是死代码。
-  return success(c, submissionListSchema.parse({
-    results: rows.map(({ submission, problem }) => submissionListItemSchema.parse({
+  return success(c, {
+    results: rows.map(({ submission, problem }) => ({
       id: submission.id,
       problem: problem.displayId,
       problemTitle: problem.title,
@@ -1028,9 +1018,9 @@ submissionRoutes.get("/contests/:contestId/submissions", optionalAuth, requireCo
       // 比赛提交没有来源题单：题单只收非比赛题（admin/problemset.ts 加题时卡了
       // isNull(problem.contestId)），提交接口那边也只在 contestId 为空时才认这个字段
       problemSet: null,
-    })),
+    } satisfies SubmissionListItem)),
     total: totalRows[0]?.value ?? 0,
-  }))
+  } satisfies SubmissionList)
 })
 
 submissionRoutes.get("/submissions/:id", requireAuth, async (c) => {
diff --git a/apps/api/src/services/profile.ts b/apps/api/src/services/profile.ts
index a4fb244..39b5db6 100644
--- a/apps/api/src/services/profile.ts
+++ b/apps/api/src/services/profile.ts
@@ -1,4 +1,4 @@
-import { sessionUserSchema, userProfileSchema } from "@oj2/contract"
+import type { SessionUser, UserProfile } from "@oj2/contract"
 import { and, eq } from "drizzle-orm"
 
 import { db, schema } from "../db"
@@ -12,9 +12,9 @@ export async function getUserProfileById(userId: number, showRealName: boolean)
     .limit(1)
 
   if (!row) return null
-  return userProfileSchema.parse({
+  return {
     id: row.profile.id,
-    user: sessionUserSchema.parse({
+    user: {
       id: row.user.id,
       username: row.user.username,
       email: row.user.email,
@@ -24,12 +24,12 @@ export async function getUserProfileById(userId: number, showRealName: boolean)
       lastLogin: row.user.lastLogin,
       isDisabled: row.user.isDisabled,
       className: row.user.className,
-    }),
+    } satisfies SessionUser,
     realName: showRealName ? row.profile.realName : null,
     acmProblemsStatus: row.profile.acmProblemsStatus,
     avatar: row.profile.avatar,
     mood: row.profile.mood,
     acceptedNumber: row.profile.acceptedNumber,
     submissionNumber: row.profile.submissionNumber,
-  })
+  } satisfies UserProfile
 }
diff --git a/apps/api/src/websocket.ts b/apps/api/src/websocket.ts
index f0136b9..b4fd7bd 100644
--- a/apps/api/src/websocket.ts
+++ b/apps/api/src/websocket.ts
@@ -1,4 +1,4 @@
-import { flowchartUpdateSchema, submissionUpdateSchema } from "@oj2/contract"
+import { submissionUpdateSchema, type FlowchartUpdate } from "@oj2/contract"
 import { and, eq } from "drizzle-orm"
 
 import { touchSession } from "./auth/session"
@@ -345,11 +345,11 @@ async function handleMessage(
       return
     }
     const replay = flowchart.status === 2
-      ? { type: "flowchart_evaluation_completed", submissionId: flowchart.id, score: flowchart.score ?? undefined, grade: flowchart.grade ?? undefined }
+      ? { type: "flowchart_evaluation_completed" as const, submissionId: flowchart.id, score: flowchart.score ?? undefined, grade: flowchart.grade ?? undefined }
       : flowchart.status === 3
-        ? { type: "flowchart_evaluation_failed", submissionId: flowchart.id }
-        : { type: "flowchart_evaluation_update", submissionId: flowchart.id }
-    ws.send(JSON.stringify(flowchartUpdateSchema.parse(replay)))
+        ? { type: "flowchart_evaluation_failed" as const, submissionId: flowchart.id }
+        : { type: "flowchart_evaluation_update" as const, submissionId: flowchart.id }
+    ws.send(JSON.stringify(replay satisfies FlowchartUpdate))
     return
   }
 
diff --git a/apps/web/CLAUDE.md b/apps/web/CLAUDE.md
index f7f0d6a..ea63f72 100644
--- a/apps/web/CLAUDE.md
+++ b/apps/web/CLAUDE.md
@@ -120,9 +120,12 @@ return contract("GET /problems/:id", problemDetailSchema, value)
 - `exercise.data` 按题型收紧后，后端读路径（`routes/content.ts` 硬 parse）变成
   一道闸，一行脏数据能让整条练习列表 500。
 
-所以：**同一个 schema 后端也在 `parse`**（`submissionDetailSchema` /
-`exerciseSchema` / `contestRankItemSchema` 都是），收紧任何字段之前，拿根目录
-那份生产备份把全量数据跑一遍，尤其要看**空值**而不只是键集合。
+**后端出参已经不 `parse` 了**（原来 136 处，全部改成 `satisfies`；撤的时候炸出两个
+一直存在的线上 500，见 `../CLAUDE.md` 的「出参不 `parse`，用 `satisfies`」）。
+所以现在收紧一个字段的直接后果落在 **`tsc` 编译期**，而不再是运行时 500 —— 这是好事，
+但别因此就放心大胆收：契约里的形状仍然要对得上库里的存量数据，前端拿到对不上的值
+一样会渲染错。收紧任何字段之前，拿根目录那份生产备份把全量数据跑一遍，
+尤其要看**空值**而不只是键集合。
 
 ### Key Utilities
 
diff --git a/packages/contract/src/admin.ts b/packages/contract/src/admin.ts
index 1116d49..0a70bc7 100644
--- a/packages/contract/src/admin.ts
+++ b/packages/contract/src/admin.ts
@@ -6,6 +6,7 @@ import { achievementRaritySchema } from "./achievement"
 import { rankProfileSchema } from "./account"
 import { paginatedSchema, sampleUserSchema } from "./common"
 import { reactionKeySchema } from "./content"
+import { problemLanguageSchema } from "./language"
 import {
   astRulesSchema,
   problemDifficultySchema,
@@ -671,7 +672,12 @@ export const adminProblemSchema = z.object({
   languages: z.array(z.string()),
   template: z.record(z.string(), z.string()),
   createTime: z.string(),
-  lastUpdateTime: z.string(),
+  /**
+   * `problem.last_update_time` 是全库唯一可空的那一列（961 道题里 470 道是 NULL：
+   * 从来没被编辑过的老题）。公共的 problemDetailSchema 早就是 nullable，这里漏了，
+   * 于是后台打开任何一道没编辑过的题都会 500 在 parse 上。
+   */
+  lastUpdateTime: z.string().nullable(),
   timeLimit: z.number().int(),
   memoryLimit: z.number().int(),
   visible: z.boolean(),
@@ -718,7 +724,9 @@ export const createProblemRequestSchema = z.object({
   testCaseScore: z.array(problemTestCaseScoreSchema),
   timeLimit: z.number().int().min(1).max(1000 * 60),
   memoryLimit: z.number().int().min(1).max(1024),
-  languages: z.array(z.string()).min(1),
+  // 收窄到语言联合而不是裸 string[]：`problem.languages` 列上挂着
+  // `$type<ProblemLanguage[]>()`，那个断言得有人兑现 —— 闸就设在这里（写入侧）。
+  languages: z.array(problemLanguageSchema).min(1),
   template: z.record(z.string(), z.string()),
   visible: z.boolean(),
   difficulty: z.enum(["Low", "Mid", "High"]),
diff --git a/packages/contract/src/submission.ts b/packages/contract/src/submission.ts
index d4b48cf..c1fd972 100644
--- a/packages/contract/src/submission.ts
+++ b/packages/contract/src/submission.ts
@@ -149,7 +149,10 @@ export const submissionDetailSchema = z.object({
  * 将来有人「顺手」把空值改成真值就不会变成泄露，因为这里压根没有这些字段。
  */
 export const embeddedSubmissionSchema = submissionDetailSchema
-  .omit({ info: true, contestId: true, problemId: true })
+  // problemDisplayId 也要去掉：下面的 problem 就是它，同一个值留两份，
+  // 而路由只填了 problem —— 这里漏 omit 的那阵子，凡是收到过站内信的人
+  // 打开消息页都是 500（parse 抛在缺失的 problemDisplayId 上，列表为空时才碰巧不炸）。
+  .omit({ info: true, contestId: true, problemId: true, problemDisplayId: true })
   // 旧 SubmissionSafeModelSerializer 里 problem 是
   // `SlugRelatedField(slug_field="_id")`，即**展示用题号**而非数字主键。
   // 站内信页面拿它拼 `/problem/<题号>` 链接，给数字 id 会拼出打不开的地址。