diff --git a/packages/hydrooj/locales/zh.yaml b/packages/hydrooj/locales/zh.yaml
index b239ec8e6..8a9e979b7 100644
--- a/packages/hydrooj/locales/zh.yaml
+++ b/packages/hydrooj/locales/zh.yaml
@@ -439,6 +439,7 @@ Location: 位置
 Login to Attend Contest: 登录后参加比赛
 Login to Claim Homework: 登录后认领作业
 Login to Create a Discussion: 登录后创建讨论
+Login to join training plan: 登录以参加训练计划
 Login to Submit: 登录后递交
 Login: 登录
 Logout All Sessions: 注销所有会话
diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index e041003b9..3e92bd8bc 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "3.2.43",
+    "version": "3.3.0",
     "bin": "bin/hydrooj.js",
     "main": "src/loader",
     "module": "src/loader",
diff --git a/packages/hydrooj/src/handler/contest.ts b/packages/hydrooj/src/handler/contest.ts
index df38054c6..4265ae984 100644
--- a/packages/hydrooj/src/handler/contest.ts
+++ b/packages/hydrooj/src/handler/contest.ts
@@ -3,7 +3,7 @@ import moment from 'moment-timezone';
 import { ObjectID } from 'mongodb';
 import { Time } from '@hydrooj/utils/lib/utils';
 import {
-    ContestNotFoundError, ContestNotLiveError, InvalidTokenError,
+    ContestNotFoundError, ContestNotLiveError, ForbiddenError, InvalidTokenError,
     PermissionError, ValidationError,
 } from '../error';
 import { Tdoc } from '../interface';
@@ -74,6 +74,18 @@ export class ContestListHandler extends Handler {
 }
 
 export class ContestDetailHandler extends Handler {
+    @param('tid', Types.ObjectID)
+    @param('page', Types.PositiveInt, true)
+    async prepare(domainId: string, tid: ObjectID) {
+        const tdoc = await contest.get(domainId, tid);
+        if (tdoc.assign) {
+            const groups = await user.listGroup(domainId, this.user._id);
+            if (!Set.intersection(tdoc.assign, groups.map((i) => i.name)).size) {
+                throw new ForbiddenError('You are not assigned.');
+            }
+        }
+    }
+
     @param('tid', Types.ObjectID)
     @param('page', Types.PositiveInt, true)
     async get(domainId: string, tid: ObjectID, page = 1) {
@@ -238,9 +250,11 @@ export class ContestEditHandler extends Handler {
     @param('rated', Types.Boolean)
     @param('code', Types.String, true)
     @param('autoHide', Types.String, true)
+    @param('assign', Types.Array, true)
     async post(
         domainId: string, tid: ObjectID, beginAtDate: string, beginAtTime: string, duration: number,
-        title: string, content: string, rule: string, _pids: string, rated = false, _code = '', autoHide = false,
+        title: string, content: string, rule: string, _pids: string, rated = false,
+        _code = '', autoHide = false, assign: string[] = null,
     ) {
         if (autoHide) this.checkPerm(PERM.PERM_EDIT_PROBLEM);
         const pids = _pids.replace(/，/g, ',').split(',').map((i) => +i).filter((i) => i);
@@ -249,7 +263,7 @@ export class ContestEditHandler extends Handler {
         const endAt = beginAtMoment.clone().add(duration, 'hours').toDate();
         if (beginAtMoment.isSameOrAfter(endAt)) throw new ValidationError('duration');
         const beginAt = beginAtMoment.toDate();
-        await problem.getList(domainId, pids, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, true);
+        await problem.getList(domainId, pids, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, this.user.group, true);
         if (tid) {
             await contest.edit(domainId, tid, {
                 title, content, rule, beginAt, endAt, pids, rated,
@@ -267,13 +281,13 @@ export class ContestEditHandler extends Handler {
         await TaskModel.deleteMany(task);
         if (Date.now() <= endAt.getTime() && autoHide) {
             // eslint-disable-next-line no-await-in-loop
-            for (const pid of pids) await problem.edit(domainId, pid, { hidden: true });
+            await Promise.all(pids.map((pid) => problem.edit(domainId, pid, { hidden: true })));
             await TaskModel.add({
                 ...task,
                 executeAfter: endAt,
             });
         }
-        await contest.edit(domainId, tid, { _code, autoHide });
+        await contest.edit(domainId, tid, { assign, _code, autoHide });
         this.response.body = { tid };
         this.response.redirect = this.url('contest_detail', { tid });
     }
diff --git a/packages/hydrooj/src/handler/discussion.ts b/packages/hydrooj/src/handler/discussion.ts
index 761a6c234..10dd5b5e8 100644
--- a/packages/hydrooj/src/handler/discussion.ts
+++ b/packages/hydrooj/src/handler/discussion.ts
@@ -58,7 +58,11 @@ class DiscussionHandler extends Handler {
         // TODO(twd2): exclude problem/contest discussions?
         // TODO(iceboy): continuation based pagination.
         this.vnode = await discussion.getVnode(domainId, typeMapper[type], name, this.user._id);
-        if (this.vnode.hidden) this.checkPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        if (this.vnode.assign?.length) {
+            if (!Set.intersection(this.vnode.assign, this.user.group).size) {
+                throw new PermissionError(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+            }
+        }
         if (this.ddoc) {
             this.ddoc.parentType = this.ddoc.parentType || this.vnode.type;
             this.ddoc.parentId = this.ddoc.parentId || this.vnode.id;
@@ -78,9 +82,7 @@ class DiscussionMainHandler extends Handler {
         );
         const udict = await user.getList(domainId, ddocs.map((ddoc) => ddoc.owner));
         const [vndict, vnodes] = await Promise.all([
-            discussion.getListVnodes(
-                domainId, ddocs, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN),
-            ),
+            discussion.getListVnodes(domainId, ddocs, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN), this.user.group),
             discussion.getNodes(domainId),
         ]);
         this.response.template = 'discussion_main_or_node.html';
diff --git a/packages/hydrooj/src/handler/domain.ts b/packages/hydrooj/src/handler/domain.ts
index 4a23f0481..8e7ab1f06 100644
--- a/packages/hydrooj/src/handler/domain.ts
+++ b/packages/hydrooj/src/handler/domain.ts
@@ -3,7 +3,7 @@ import { Dictionary } from 'lodash';
 import moment from 'moment-timezone';
 import {
     DomainJoinAlreadyMemberError, DomainJoinForbiddenError, ForbiddenError,
-    InvalidJoinInvitationCodeError, RoleAlreadyExistError, ValidationError,
+    InvalidJoinInvitationCodeError, PermissionError, RoleAlreadyExistError, ValidationError,
 } from '../error';
 import type { DomainDoc } from '../interface';
 import avatar from '../lib/avatar';
@@ -19,6 +19,40 @@ import {
     Handler, param, post, query, Route, Types,
 } from '../service/server';
 import { log2 } from '../utils';
+import { registerResolver, registerValue } from './api';
+
+registerValue('GroupInfo', [
+    ['name', 'String!'],
+    ['uids', '[Int]!'],
+]);
+
+registerResolver('Query', 'domain(id: String)', 'Domain', async (args, ctx) => {
+    const ddoc = await domain.get(args.id);
+    if (!ddoc) return null;
+    const udoc = await user.getById(args.id, ctx.user._id);
+    if (!udoc.hasPerm(PERM.PERM_VIEW) && !udoc.hasPriv(PRIV.PRIV_VIEW_ALL_DOMAIN)) return null;
+    ctx.udoc = udoc;
+    return ddoc;
+});
+
+registerResolver('Domain', 'manage', 'DomainManage', async (args, ctx) => {
+    if (!ctx.udoc.hasPerm(PERM.PERM_EDIT_DOMAIN)) throw new PermissionError(PERM.PERM_EDIT_DOMAIN);
+    return {};
+});
+
+registerResolver('DomainManage', 'group', 'DomainGroup', (args, ctx) => ctx.parent);
+registerResolver(
+    'DomainGroup', 'list(uid: Int)', '[GroupInfo]',
+    (args, ctx) => user.listGroup(ctx.parent._id, args.uid),
+);
+registerResolver(
+    'DomainGroup', 'update(name: String!, uids: [Int]!)', 'Boolean',
+    async (args, ctx) => !!(await user.updateGroup(ctx.parent._id, args.name, args.uids)).upsertedCount,
+);
+registerResolver(
+    'DomainGroup', 'del(name: String!)', 'Boolean',
+    async (args, ctx) => !!(await user.delGroup(ctx.parent._id, args.name)).deletedCount,
+);
 
 class DomainRankHandler extends Handler {
     @query('page', Types.PositiveInt, true)
@@ -184,7 +218,7 @@ class DomainRoleHandler extends ManageHandler {
 
     @param('roles', Types.Array)
     async postDelete(domainId: string, roles: string[]) {
-        if (Set.intersection(new Set(roles), new Set(['root', 'default', 'guest'])).size > 0) {
+        if (Set.intersection(roles, ['root', 'default', 'guest']).size > 0) {
             throw new ValidationError('role', null, 'You cannot delete root, default or guest roles');
         }
         await domain.deleteRoles(domainId, roles);
@@ -231,6 +265,25 @@ class DomainJoinApplicationsHandler extends ManageHandler {
     }
 }
 
+class DomainUserGroupHandler extends ManageHandler {
+    async get() {
+        this.response.body = 'domain_group.html';
+    }
+
+    @param('name', Types.Name)
+    async postDel(domainId: string, name: string) {
+        await user.delGroup(domainId, name);
+        this.back();
+    }
+
+    @param('name', Types.Name)
+    @param('uids', Types.NumericArray)
+    async postUpdate(domainId: string, name: string, uids: number[]) {
+        await user.updateGroup(domainId, name, uids);
+        this.back();
+    }
+}
+
 class DomainJoinHandler extends Handler {
     joinSettings: any;
     noCheckPermView = true;
@@ -283,6 +336,7 @@ export async function apply() {
     Route('domain_user', '/domain/user', DomainUserHandler);
     Route('domain_permission', '/domain/permission', DomainPermissionHandler);
     Route('domain_role', '/domain/role', DomainRoleHandler);
+    Route('domain_group', '/domain/group', DomainUserGroupHandler);
     Route('domain_join_applications', '/domain/join_applications', DomainJoinApplicationsHandler);
     Route('domain_join', '/domain/join', DomainJoinHandler, PRIV.PRIV_USER_PROFILE);
     Route('domain_search', '/domain/search', DomainSearchHandler, PRIV.PRIV_USER_PROFILE);
diff --git a/packages/hydrooj/src/handler/home.ts b/packages/hydrooj/src/handler/home.ts
index 28acf1aa1..8a5e8a3aa 100644
--- a/packages/hydrooj/src/handler/home.ts
+++ b/packages/hydrooj/src/handler/home.ts
@@ -75,9 +75,7 @@ class HomeHandler extends Handler {
     async getDiscussion(domainId: string, limit = 20) {
         if (this.user.hasPerm(PERM.PERM_VIEW_DISCUSSION)) {
             const ddocs = await discussion.getMulti(domainId).limit(limit).toArray();
-            const vndict = await discussion.getListVnodes(
-                domainId, ddocs, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN),
-            );
+            const vndict = await discussion.getListVnodes(domainId, ddocs, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN), this.user.group);
             this.collectUser(ddocs.map((ddoc) => ddoc.owner));
             return ['discussion', ddocs, vndict];
         }
@@ -103,7 +101,7 @@ class HomeHandler extends Handler {
             for (const psdoc of psdocs) psdict[psdoc.docId] = psdoc;
             const pdict = await ProblemModel.getList(
                 domainId, psdocs.map((pdoc) => pdoc.docId),
-                this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, false,
+                this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, this.user.group, false,
             );
             const pdocs = Object.keys(pdict).filter((i) => +i).map((i) => pdict[i]);
             return ['problem', pdocs, psdict];
diff --git a/packages/hydrooj/src/handler/homework.ts b/packages/hydrooj/src/handler/homework.ts
index af7009513..7d92c7e3b 100644
--- a/packages/hydrooj/src/handler/homework.ts
+++ b/packages/hydrooj/src/handler/homework.ts
@@ -4,7 +4,8 @@ import moment from 'moment-timezone';
 import { ObjectID } from 'mongodb';
 import { Time } from '@hydrooj/utils/lib/utils';
 import {
-    ContestNotFoundError, HomeworkNotLiveError, ValidationError,
+    ContestNotFoundError, ForbiddenError, HomeworkNotLiveError,
+    ValidationError,
 } from '../error';
 import { PenaltyRules } from '../interface';
 import paginate from '../lib/paginate';
@@ -40,6 +41,17 @@ class HomeworkMainHandler extends Handler {
 }
 
 class HomeworkDetailHandler extends Handler {
+    @param('tid', Types.ObjectID)
+    async prepare(domainId: string, tid: ObjectID) {
+        const tdoc = await contest.get(domainId, tid);
+        if (tdoc.rule !== 'homework') throw new ContestNotFoundError(domainId, tid);
+        if (tdoc.assign) {
+            if (!Set.intersection(tdoc.assign, this.user.group).size) {
+                throw new ForbiddenError('You are not assigned.');
+            }
+        }
+    }
+
     @param('tid', Types.ObjectID)
     @param('page', Types.PositiveInt, true)
     async get(domainId: string, tid: ObjectID, page = 1) {
@@ -156,7 +168,7 @@ class HomeworkEditHandler extends Handler {
         const endAt = penaltySince.clone().add(extensionDays, 'days');
         if (beginAt.isSameOrAfter(penaltySince)) throw new ValidationError('endAtDate', 'endAtTime');
         if (penaltySince.isAfter(endAt)) throw new ValidationError('extensionDays');
-        await problem.getList(domainId, pids, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, true);
+        await problem.getList(domainId, pids, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, this.user.group, true);
         if (!tid) {
             tid = await contest.add(domainId, title, content, this.user._id,
                 'homework', beginAt.toDate(), endAt.toDate(), pids, rated,
diff --git a/packages/hydrooj/src/handler/problem.ts b/packages/hydrooj/src/handler/problem.ts
index f28aeaa75..73f354b5d 100644
--- a/packages/hydrooj/src/handler/problem.ts
+++ b/packages/hydrooj/src/handler/problem.ts
@@ -1,17 +1,18 @@
 import AdmZip from 'adm-zip';
 import { statSync } from 'fs-extra';
-import { flatten, intersection, isSafeInteger } from 'lodash';
+import { intersection, isSafeInteger } from 'lodash';
 import { FilterQuery, ObjectID } from 'mongodb';
 import { sortFiles } from '@hydrooj/utils/lib/utils';
 import {
     BadRequestError, ContestNotAttendedError, ContestNotEndedError,
     ContestNotFoundError, ContestNotLiveError,
     ForbiddenError, NoProblemError, NotFoundError,
-    PermissionError, ProblemNotFoundError, SolutionNotFoundError, ValidationError,
+    PermissionError, ProblemNotFoundError, SolutionNotFoundError,
+    ValidationError,
 } from '../error';
 import {
-    ProblemConfig,
-    ProblemDoc, ProblemStatusDoc, Tdoc, User,
+    ProblemConfig, ProblemDoc, ProblemStatusDoc,
+    Tdoc, User,
 } from '../interface';
 import paginate from '../lib/paginate';
 import { isPid, parsePid as convertPid } from '../lib/validator';
@@ -32,7 +33,7 @@ import {
 } from '../service/server';
 import { registerResolver, registerValue } from './api';
 
-export const parseCategory = (value: string) => flatten(value.replace(/，/g, ',').split(',')).map((e) => e.trim());
+export const parseCategory = (value: string) => value.replace(/，/g, ',').split(',').map((e) => e.trim());
 export const parsePid = (value: string) => (isSafeInteger(value) ? +value : value);
 
 registerValue('FileInfo', [
@@ -58,9 +59,7 @@ registerValue('Problem', [
     ['difficulty', 'Int'],
     ['tag', '[String]'],
     ['hidden', 'Boolean'],
-]);
-registerValue('ProblemManage', [
-    ['delete', 'Boolean!'],
+    ['assign', '[String]'],
 ]);
 
 registerResolver(
@@ -68,7 +67,12 @@ registerResolver(
     async (arg, ctx) => {
         const pdoc = await problem.get(ctx.domainId, arg.pid || arg.id);
         if (!pdoc) return null;
-        if (pdoc.hidden && !ctx.user.own(pdoc)) ctx.checkPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        if (pdoc.hidden) ctx.checkPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        if (pdoc.assign.length && !ctx.user.own(pdoc)) {
+            if (!Set.intersection(new Set(pdoc.assign), new Set(ctx.user.group)).size) {
+                throw new PermissionError(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+            }
+        }
         ctx.pdoc = pdoc;
         return pdoc;
     },
@@ -89,10 +93,33 @@ registerResolver(
     },
 );
 registerResolver(
-    'ProblemManage', 'edit(title: String, content: String, tag: [String], hidden: Boolean)', 'Problem!',
+    'ProblemManage', 'edit(title: String, content: String, tag: [String], hidden: Boolean, assign: [String])', 'Problem!',
     (arg, ctx) => problem.edit(ctx.domainId, ctx.pdoc.docId, arg),
 );
 
+function buildQuery(udoc: User) {
+    const q: FilterQuery<ProblemDoc> = {
+        $or: [
+            {
+                $and: [
+                    {
+                        $or: [
+                            { assign: { $size: 0 } },
+                            { assign: { $in: udoc.group } },
+                        ],
+                    },
+                ],
+            },
+            { owner: udoc._id },
+            { maintainer: udoc._id },
+        ],
+    };
+    if (udoc.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN)) {
+        q.$or[0].$and.push({ hidden: false });
+    }
+    return q;
+}
+
 export class ProblemHandler extends Handler {
     async cleanup() {
         if (this.response.template === 'problem_main.html' && this.request.json) {
@@ -123,7 +150,7 @@ export class ProblemMainHandler extends ProblemHandler {
     async get(domainId: string, page = 1, q = '', category = []) {
         this.response.template = 'problem_main.html';
         // eslint-disable-next-line @typescript-eslint/no-shadow
-        const query: FilterQuery<ProblemDoc> = {};
+        const query = buildQuery(this.user);
         const psdict = {};
         const search = global.Hydro.lib.problemSearch;
         let sort: string[];
@@ -145,9 +172,6 @@ export class ProblemMainHandler extends ProblemHandler {
                 sort = result;
             } else query.$text = { $search: q };
         }
-        if (!this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN)) {
-            query.$or = [{ hidden: false }, { owner: this.user._id }, { maintainer: this.user._id }];
-        }
         await bus.serial('problem/list', query, this);
         // eslint-disable-next-line prefer-const
         let [pdocs, ppcount, pcount] = fail
@@ -160,7 +184,7 @@ export class ProblemMainHandler extends ProblemHandler {
         if (sort) pdocs = pdocs.sort((a, b) => sort.indexOf(`${a.domainId}/${a.docId}`) - sort.indexOf(`${b.domainId}/${b.docId}`));
         if (q) {
             const pdoc = await problem.get(domainId, +q || q, problem.PROJECTION_LIST);
-            if (pdoc && (!pdoc.hidden || this.user.own(pdoc) || this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN))) {
+            if (pdoc && problem.canViewBy(pdoc, this.user)) {
                 const count = pdocs.length;
                 pdocs = pdocs.filter((doc) => doc.docId !== pdoc.docId);
                 pdocs.unshift(pdoc);
@@ -252,9 +276,8 @@ export class ProblemMainHandler extends ProblemHandler {
 export class ProblemRandomHandler extends ProblemHandler {
     @param('category', Types.Name, true, null, parseCategory)
     async get(domainId: string, category: string[] = []) {
-        const q: FilterQuery<ProblemDoc> = category.length ? { $and: [] } : {};
-        for (const tag of category) q.$and.push({ tag });
-        if (!this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN)) q.hidden = false;
+        const q = buildQuery(this.user);
+        if (category.length) q.$and = category.map((tag) => ({ tag }));
         await bus.serial('problem/list', q, this);
         const pid = await problem.random(domainId, q);
         if (!pid) throw new NoProblemError();
@@ -284,8 +307,8 @@ export class ProblemDetailHandler extends ProblemHandler {
             if (!showAccept) this.pdoc.nAccept = 0;
             if (contest.isNotStarted(this.tdoc)) throw new ContestNotLiveError(tid);
             if (!contest.isDone(this.tdoc) && !this.tsdoc?.attend) throw new ContestNotAttendedError(tid);
-        } else if (this.pdoc.hidden && !this.user.own(this.pdoc)) {
-            this.checkPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        } else if (!problem.canViewBy(this.pdoc, this.user)) {
+            throw new PermissionError(PERM.PERM_VIEW_PROBLEM_HIDDEN);
         }
         let ddoc = this.domain;
         if (this.pdoc.reference) {
@@ -462,13 +485,14 @@ export class ProblemEditHandler extends ProblemManageHandler {
     @post('hidden', Types.Boolean)
     @post('tag', Types.Content, true, null, parseCategory)
     @post('difficulty', Types.PositiveInt, (i) => +i <= 10, true)
+    @post('assign', Types.CommaSeperatedArray)
     async post(
         domainId: string, pid: string | number, title: string, content: string,
-        newPid: string = '', hidden = false, tag: string[] = [], difficulty = 0,
+        newPid: string = '', hidden = false, tag: string[] = [], difficulty = 0, assign: string[] = [],
     ) {
         if (newPid !== this.pdoc.pid && await problem.get(domainId, newPid)) throw new BadRequestError('new pid exists');
         const $update: Partial<ProblemDoc> = {
-            title, content, pid: newPid, hidden, tag: tag ?? [], difficulty,
+            title, content, pid: newPid, hidden, assign, tag: tag ?? [], difficulty,
         };
         let pdoc = await problem.get(domainId, pid);
         pdoc = await problem.edit(domainId, pdoc.docId, $update);
@@ -765,9 +789,13 @@ export class ProblemCreateHandler extends Handler {
     @post('hidden', Types.Boolean)
     @post('difficulty', Types.PositiveInt, (i) => +i <= 10, true)
     @post('tag', Types.Content, true, null, parseCategory)
-    async post(domainId: string, title: string, content: string, pid: string, hidden = false, difficulty = 0, tag: string[] = []) {
+    @post('assign', Types.CommaSeperatedArray)
+    async post(
+        domainId: string, title: string, content: string, pid: string,
+        hidden = false, difficulty = 0, tag: string[] = [], assign: string[] = [],
+    ) {
         if (pid && await problem.get(domainId, pid)) throw new BadRequestError('invalid pid');
-        const docId = await problem.add(domainId, pid, title, content, this.user._id, tag ?? [], hidden);
+        const docId = await problem.add(domainId, pid, title, content, this.user._id, tag ?? [], hidden, assign);
         if (difficulty) await problem.edit(domainId, docId, { difficulty });
         this.response.body = { pid: pid || docId };
         this.response.redirect = this.url('problem_files', { pid: pid || docId });
diff --git a/packages/hydrooj/src/handler/record.ts b/packages/hydrooj/src/handler/record.ts
index be0b6c127..6616db1d3 100644
--- a/packages/hydrooj/src/handler/record.ts
+++ b/packages/hydrooj/src/handler/record.ts
@@ -69,13 +69,13 @@ class RecordListHandler extends Handler {
         const rdocs = invalid
             ? [] as RecordDoc[]
             : await cursor.skip((page - 1) * limit).limit(limit).toArray();
-        const canViewProblem = this.user.hasPerm(PERM.PERM_VIEW_PROBLEM);
-        const canViewProblemHidden = (!!tid) || this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        const canViewProblem = tid || this.user.hasPerm(PERM.PERM_VIEW_PROBLEM);
+        const canViewHiddenProblem = this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id;
         const [udict, pdict] = full ? [{}, {}]
             : await Promise.all([
                 user.getList(domainId, rdocs.map((rdoc) => rdoc.uid)),
                 canViewProblem
-                    ? problem.getList(domainId, rdocs.map((rdoc) => rdoc.pid), canViewProblemHidden || this.user._id, false)
+                    ? problem.getList(domainId, rdocs.map((rdoc) => rdoc.pid), canViewHiddenProblem, this.user.group, false)
                     : Object.fromEntries([rdocs.map((rdoc) => [rdoc.pid, { ...problem.default, pid: rdoc.pid }])]),
             ]);
         this.response.body = {
@@ -132,10 +132,9 @@ class RecordDetailHandler extends Handler {
             rdoc.compilerTexts = [];
         }
 
-        let canView = pdoc && this.user.own(pdoc);
-        canView ||= !pdoc?.hidden && this.user.hasPerm(PERM.PERM_VIEW_PROBLEM);
-        canView ||= !!rdoc.contest || this.user._id === rdoc.uid;
-        if (!canView) this.checkPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        if (pdoc && !(rdoc.contest && this.user._id === rdoc.uid)) {
+            if (!problem.canViewBy(pdoc, this.user)) throw new PermissionError(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        }
 
         this.response.body = {
             udoc, rdoc, pdoc, tdoc,
@@ -250,7 +249,7 @@ class RecordMainConnectionHandler extends ConnectionHandler {
         ]);
         const tdoc = this.tid ? this.tdoc || await contest.get(rdoc.domainId, new ObjectID(this.tid)) : null;
         if (pdoc && !rdoc.contest) {
-            if (pdoc.hidden && !this.user.own(pdoc) && !this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN)) pdoc = null;
+            if (problem.canViewBy(pdoc, this.user)) pdoc = null;
             if (!this.user.hasPerm(PERM.PERM_VIEW_PROBLEM)) pdoc = null;
         }
         if (this.pretest) this.send({ rdoc });
@@ -293,11 +292,9 @@ class RecordDetailConnectionHandler extends ConnectionHandler {
             rdoc.compilerTexts = [];
         }
 
-        let canView = pdoc && this.user.own(pdoc);
-        canView ||= !pdoc?.hidden && this.user.hasPerm(PERM.PERM_VIEW_PROBLEM);
-        canView ||= this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN);
-        canView ||= !!rdoc.contest || this.user._id === rdoc.uid;
-        if (!canView) throw new PermissionError(PERM.PERM_READ_RECORD_CODE);
+        if (!(rdoc.contest && this.user._id === rdoc.uid)) {
+            if (!problem.canViewBy(pdoc, this.user)) throw new PermissionError(PERM.PERM_VIEW_PROBLEM_HIDDEN);
+        }
 
         this.rid = rid.toString();
         this.cleanup = bus.on('record/change', this.onRecordChange.bind(this));
diff --git a/packages/hydrooj/src/handler/training.ts b/packages/hydrooj/src/handler/training.ts
index b781a33ef..d5011f04e 100644
--- a/packages/hydrooj/src/handler/training.ts
+++ b/packages/hydrooj/src/handler/training.ts
@@ -97,9 +97,10 @@ class TrainingDetailHandler extends Handler {
         const tdoc = await training.get(domainId, tid);
         await bus.serial('training/get', tdoc, this);
         const pids = training.getPids(tdoc.dag);
+        const canViewHidden = this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id;
         const [owner, pdict] = await Promise.all([
             user.getById(domainId, tdoc.owner),
-            problem.getList(domainId, pids, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id, true),
+            problem.getList(domainId, pids, canViewHidden, this.user.group, true),
         ]);
         const psdict = await problem.getListStatus(domainId, this.user._id, pids);
         const donePids = new Set<number>();
@@ -119,7 +120,7 @@ class TrainingDetailHandler extends Handler {
         for (const node of tdoc.dag) {
             ndict[node._id] = node;
             const totalCount = node.pids.length;
-            const doneCount = Set.intersection(new Set(node.pids), donePids).size;
+            const doneCount = Set.intersection(node.pids, donePids).size;
             const nsdoc = {
                 progress: totalCount ? Math.floor(100 * (doneCount / totalCount)) : 100,
                 isDone: training.isDone(node, doneNids, donePids),
diff --git a/packages/hydrooj/src/handler/user.ts b/packages/hydrooj/src/handler/user.ts
index e8d5203a9..76a4f313b 100644
--- a/packages/hydrooj/src/handler/user.ts
+++ b/packages/hydrooj/src/handler/user.ts
@@ -303,7 +303,12 @@ class UserDetailHandler extends Handler {
         const canViewHidden = this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id;
         await Promise.all([domainId, ...(union?.union || [])].map(async (did) => {
             const psdocs = await problem.getMultiStatus(did, { uid, status: STATUS.STATUS_ACCEPTED }).toArray();
-            pdocs.push(...Object.values(await problem.getList(did, psdocs.map((i) => i.docId), canViewHidden, false, undefined, true)));
+            pdocs.push(...Object.values(
+                await problem.getList(
+                    did, psdocs.map((i) => i.docId), canViewHidden,
+                    this.user.group, false, undefined, true,
+                ),
+            ));
         }));
         for (const pdoc of pdocs) {
             for (const tag of pdoc.tag) {
diff --git a/packages/hydrooj/src/interface.ts b/packages/hydrooj/src/interface.ts
index 4bba9c4cc..cc46bf6e4 100644
--- a/packages/hydrooj/src/interface.ts
+++ b/packages/hydrooj/src/interface.ts
@@ -97,32 +97,33 @@ export interface GDoc {
 export type ownerInfo = { owner: number, maintainer?: number[] };
 
 export interface User extends Record<string, any> {
-    _id: number,
-    _udoc: Udoc,
-    _dudoc: any,
-    _salt: string,
-    _hash: string,
-    _regip: string,
-    _loginip: string,
-    _tfa: string,
+    _id: number;
+    _udoc: Udoc;
+    _dudoc: any;
+    _salt: string;
+    _hash: string;
+    _regip: string;
+    _loginip: string;
+    _tfa: string;
 
-    mail: string,
-    uname: string,
-    hashType: string,
-    priv: number,
-    regat: Date,
-    loginat: Date,
-    perm: bigint,
-    scope: bigint,
-    role: string,
-    tfa: boolean,
+    mail: string;
+    uname: string;
+    hashType: string;
+    priv: number;
+    regat: Date;
+    loginat: Date;
+    perm: bigint;
+    scope: bigint;
+    role: string;
+    group?: string[];
+    tfa: boolean;
     own<T extends ownerInfo>(doc: T, checkPerm: bigint): boolean
     own<T extends ownerInfo>(doc: T, exact: boolean): boolean
     own<T extends ownerInfo>(doc: T): boolean
     own<T extends { owner: number, maintainer?: number[] }>(doc: T): boolean;
-    hasPerm: (...perm: bigint[]) => boolean,
-    hasPriv: (...priv: number[]) => boolean,
-    checkPassword: (password: string) => void,
+    hasPerm: (...perm: bigint[]) => boolean;
+    hasPriv: (...priv: number[]) => boolean;
+    checkPassword: (password: string) => void;
 }
 
 export type Udict = NumericDictionary<User>;
@@ -244,7 +245,8 @@ declare module './model/problem' {
         tag: string[];
         data: FileInfo[];
         additional_file: FileInfo[];
-        hidden: boolean;
+        hidden?: boolean;
+        assign: string[];
         html?: boolean;
         stats?: any;
         difficulty?: number;
diff --git a/packages/hydrooj/src/model/discussion.ts b/packages/hydrooj/src/model/discussion.ts
index 67e77b61b..607c84a6d 100644
--- a/packages/hydrooj/src/model/discussion.ts
+++ b/packages/hydrooj/src/model/discussion.ts
@@ -275,17 +275,16 @@ export function getNodes(domainId: string) {
     return document.getMulti(domainId, document.TYPE_DISCUSSION_NODE).toArray();
 }
 
-export async function getListVnodes(domainId: string, ddocs: any, getHidden: boolean) {
-    const tasks = [];
+export async function getListVnodes(domainId: string, ddocs: any, getHidden = false, assign: string[] = []) {
     const res = {};
     async function task(ddoc: DiscussionDoc) {
         const vnode = await getVnode(domainId, ddoc.parentType, ddoc.parentId.toString());
         if (!res[ddoc.parentType]) res[ddoc.parentType] = {};
-        if (vnode.hidden && !getHidden) return;
+        if (!getHidden && vnode.hidden) return;
+        if (vnode.assign?.length && Set.intersection(vnode.assign, assign).size) return;
         res[ddoc.parentType][ddoc.parentId] = vnode;
     }
-    for (const ddoc of ddocs) tasks.push(task(ddoc));
-    await Promise.all(tasks);
+    await Promise.all(ddocs.map((ddoc) => task(ddoc)));
     return res;
 }
 
diff --git a/packages/hydrooj/src/model/problem.ts b/packages/hydrooj/src/model/problem.ts
index d8ee27210..382e39cc7 100644
--- a/packages/hydrooj/src/model/problem.ts
+++ b/packages/hydrooj/src/model/problem.ts
@@ -6,7 +6,7 @@ import type { Readable } from 'stream';
 import { streamToBuffer } from '@hydrooj/utils/lib/utils';
 import { ProblemNotFoundError, ValidationError } from '../error';
 import type {
-    Document, ProblemDict, ProblemStatusDoc,
+    Document, ProblemDict, ProblemStatusDoc, User,
 } from '../interface';
 import { parseConfig } from '../lib/testdataConfig';
 import * as bus from '../service/bus';
@@ -31,7 +31,7 @@ export class ProblemModel {
     static PROJECTION_LIST: Field[] = [
         '_id', 'domainId', 'docType', 'docId', 'pid',
         'owner', 'title', 'nSubmit', 'nAccept', 'difficulty',
-        'tag', 'hidden', 'stats',
+        'tag', 'assign', 'stats',
     ];
 
     static PROJECTION_PUBLIC: Field[] = [
@@ -57,6 +57,7 @@ export class ProblemModel {
         additional_file: [],
         stats: {},
         hidden: true,
+        assign: [],
         config: '',
         difficulty: 0,
     };
@@ -78,27 +79,31 @@ export class ProblemModel {
         additional_file: [],
         stats: {},
         hidden: true,
+        assign: [],
         config: '',
         difficulty: 0,
     };
 
     static async add(
         domainId: string, pid: string = '', title: string, content: string, owner: number,
-        tag: string[] = [], hidden = false,
+        tag: string[] = [], hidden = false, assign: string[] = [],
     ) {
         const [doc] = await ProblemModel.getMulti(domainId, {})
             .sort({ docId: -1 }).limit(1).project({ docId: 1 })
             .toArray();
-        const result = await ProblemModel.addWithId(domainId, (doc?.docId || 0) + 1, pid, title, content, owner, tag, hidden);
+        const result = await ProblemModel.addWithId(
+            domainId, (doc?.docId || 0) + 1, pid,
+            title, content, owner, tag, hidden, assign,
+        );
         return result;
     }
 
     static async addWithId(
         domainId: string, docId: number, pid: string = '', title: string,
-        content: string, owner: number, tag: string[] = [], hidden = false,
+        content: string, owner: number, tag: string[] = [], hidden = false, assign: string[] = [],
     ) {
         const args: Partial<ProblemDoc> = {
-            title, tag, hidden, nSubmit: 0, nAccept: 0, sort: sortable(pid || `P${docId}`),
+            title, tag, hidden, assign, nSubmit: 0, nAccept: 0, sort: sortable(pid || `P${docId}`),
         };
         if (pid) args.pid = pid;
         await bus.serial('problem/before-add', domainId, content, owner, docId, args);
@@ -279,8 +284,8 @@ export class ProblemModel {
     }
 
     static async getList(
-        domainId: string, pids: number[],
-        getHidden: number | boolean = false, doThrow = true, projection = ProblemModel.PROJECTION_PUBLIC,
+        domainId: string, pids: number[], canViewHidden: number | boolean = false,
+        group: string[] = [], doThrow = true, projection = ProblemModel.PROJECTION_PUBLIC,
         indexByDocIdOnly = false,
     ): Promise<ProblemDict> {
         const r: Record<number, ProblemDoc> = {};
@@ -288,7 +293,12 @@ export class ProblemModel {
         const q: any = { $or: [{ docId: { $in: pids } }, { pid: { $in: pids } }] };
         let pdocs = await document.getMulti(domainId, document.TYPE_PROBLEM, q)
             .project(buildProjection(projection)).toArray();
-        if (getHidden !== true) pdocs = pdocs.filter((i) => !i.hidden || i.owner === getHidden);
+        if (group.length > 0) {
+            pdocs = pdocs.filter((i) => !i.assign?.length || Set.intersection(group, i.assign).size);
+        }
+        if (canViewHidden !== true) {
+            pdocs = pdocs.filter((i) => i.owner === canViewHidden || !i.hidden);
+        }
         for (const pdoc of pdocs) {
             try {
                 // eslint-disable-next-line no-await-in-loop
@@ -352,6 +362,14 @@ export class ProblemModel {
     static setStar(domainId: string, pid: number, uid: number, star: boolean) {
         return document.setStatus(domainId, document.TYPE_PROBLEM, pid, uid, { star });
     }
+
+    static canViewBy(pdoc: ProblemDoc, udoc: User) {
+        if (!udoc.hasPerm(PERM.PERM_VIEW_PROBLEM)) return false;
+        if (udoc.own(pdoc)) return true;
+        if (pdoc.hidden && !udoc.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN)) return false;
+        if (!pdoc.assign.length) return true;
+        return !!Set.intersection(pdoc.assign, udoc.group).size;
+    }
 }
 
 bus.on('problem/addTestdata', async (domainId, docId, name) => {
diff --git a/packages/hydrooj/src/model/task.ts b/packages/hydrooj/src/model/task.ts
index 58c2856ec..de3b2e11b 100644
--- a/packages/hydrooj/src/model/task.ts
+++ b/packages/hydrooj/src/model/task.ts
@@ -158,7 +158,7 @@ bus.once('app/started', async () => {
         while (true) {
             // eslint-disable-next-line no-await-in-loop
             const res = await collEvent.findOneAndUpdate(
-                { ack: { $not: { $elemMatch: { $eq: id } } } },
+                { ack: { $nin: [id] } },
                 { $push: { ack: id } },
             );
             // eslint-disable-next-line no-await-in-loop
diff --git a/packages/hydrooj/src/model/user.ts b/packages/hydrooj/src/model/user.ts
index 6071dc4eb..81179a4c3 100644
--- a/packages/hydrooj/src/model/user.ts
+++ b/packages/hydrooj/src/model/user.ts
@@ -67,6 +67,7 @@ class User implements _User {
     scope: bigint;
     _files: FileInfo[];
     tfa: boolean;
+    group?: string[];
     [key: string]: any;
 
     constructor(udoc: Udoc, dudoc, scope = PERM.PERM_ALL) {
@@ -91,6 +92,7 @@ class User implements _User {
         this.scope = typeof scope === 'string' ? BigInt(scope) : scope;
         this.role = dudoc.role || 'default';
         this.tfa = !!udoc.tfa;
+        if (dudoc.group) this.group = [...dudoc.group, this._id.toString()];
 
         for (const key in setting.SETTINGS_BY_KEY) {
             this[key] = udoc[key] ?? (setting.SETTINGS_BY_KEY[key].value || system.get(`preference.${key}`));
@@ -175,6 +177,8 @@ class UserModel {
         const udoc = await (_id < -999 ? collV : coll).findOne({ _id });
         if (!udoc) return null;
         const dudoc = await domain.getDomainUser(domainId, udoc);
+        const groups = await UserModel.listGroup(domainId, _id);
+        dudoc.group = groups.map((i) => i.name);
         if (typeof scope === 'string') scope = BigInt(scope);
         const res = await new User(udoc, dudoc, scope).init();
         cache.set(`id/${res._id}/${domainId}`, res);
@@ -373,10 +377,6 @@ class UserModel {
         ]);
     }
 
-    static createGroup(domainId: string, name: string, uids: number[]) {
-        return collGroup.insertOne({ domainId, name, uids });
-    }
-
     static async listGroup(domainId: string, uid?: number) {
         const groups = await collGroup.find(uid ? { domainId, uids: uid } : { domainId }).toArray();
         if (uid) {
diff --git a/packages/hydrooj/src/service/server.ts b/packages/hydrooj/src/service/server.ts
index 2fe51c313..f295cd742 100644
--- a/packages/hydrooj/src/service/server.ts
+++ b/packages/hydrooj/src/service/server.ts
@@ -84,6 +84,7 @@ export interface Types {
     Range: (range: Array<string | number> | Dictionary<any>) => Type,
     Array: Type,
     NumericArray: Type,
+    CommaSeperatedArray: Type,
     Set: Type,
 }
 
@@ -163,6 +164,10 @@ export const Types: Types = {
         if (v instanceof Array) return !v.map(Number).includes(NaN);
         return !Number.isNaN(+v);
     }],
+    CommaSeperatedArray: [
+        (v) => v.toString().replace(/，/g, ',').split(',').map((e) => e.trim()).filter((i) => i),
+        (v) => v.toString(),
+    ],
     Set: [(v) => {
         if (v instanceof Array) return new Set(v);
         return v ? new Set([v]) : new Set();
diff --git a/packages/hydrooj/src/upgrade.ts b/packages/hydrooj/src/upgrade.ts
index fc728347d..15ce46852 100644
--- a/packages/hydrooj/src/upgrade.ts
+++ b/packages/hydrooj/src/upgrade.ts
@@ -664,6 +664,14 @@ const scripts: UpgradeScript[] = [
         await db.collection('oplog').deleteMany({ type: 'user.login' });
         return true;
     },
+    async function _57_58() {
+        const _FRESH_INSTALL_IGNORE = 1;
+        await db.collection('document').updateMany(
+            { docType: document.TYPE_PROBLEM, assign: null },
+            { $set: { assign: [] } },
+        );
+        return true;
+    },
 ];
 
 export default scripts;
diff --git a/packages/ui-default/package.json b/packages/ui-default/package.json
index 3bfbd8876..5f87d1f2f 100644
--- a/packages/ui-default/package.json
+++ b/packages/ui-default/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.27.17",
+  "version": "4.27.18",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "hydro.js",
diff --git a/packages/utils/lib/utils.ts b/packages/utils/lib/utils.ts
index 5933486e1..1186fdee5 100644
--- a/packages/utils/lib/utils.ts
+++ b/packages/utils/lib/utils.ts
@@ -27,7 +27,7 @@ declare global {
     }
     interface SetConstructor {
         isSuperset: (set: Set<any>, subset: Set<any>) => boolean;
-        intersection: <T>(setA: Set<T>, setB: Set<T>) => Set<T>;
+        intersection: <T>(setA: Set<T> | Array<T>, setB: Set<T> | Array<T>) => Set<T>;
         union: <T>(setA: Set<T>, setB: Set<T>) => Set<T>;
     }
 }
@@ -130,9 +130,11 @@ Set.union = function Union<T>(setA: Set<T>, setB: Set<T>) {
     return union;
 };
 
-Set.intersection = function Intersection<T>(setA: Set<T>, setB: Set<T>) {
+Set.intersection = function Intersection<T>(A: Set<T> | Array<T> = [], B: Set<T> | Array<T> = []) {
     const intersection = new Set<T>();
-    for (const elem of setB) if (setA.has(elem)) intersection.add(elem);
+    if (A instanceof Array) A = new Set(A);
+    if (B instanceof Array) B = new Set(B);
+    for (const elem of B) if (A.has(elem)) intersection.add(elem);
     return intersection;
 };
 
diff --git a/packages/utils/package.json b/packages/utils/package.json
index 0501535af..7d1bbe4eb 100644
--- a/packages/utils/package.json
+++ b/packages/utils/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@hydrooj/utils",
-    "version": "1.1.10",
+    "version": "1.1.11",
     "description": "hydrooj utils",
     "main": "package.json",
     "repository": "https://github.com/hydro-dev/Hydro.git",