diff --git a/packages/hydrooj/src/handler/discussion.ts b/packages/hydrooj/src/handler/discussion.ts
index c3c9005f1..44dc54748 100644
--- a/packages/hydrooj/src/handler/discussion.ts
+++ b/packages/hydrooj/src/handler/discussion.ts
@@ -1,7 +1,7 @@
 import { isSafeInteger } from 'lodash';
 import { ObjectId } from 'mongodb';
 import {
-    DiscussionLockedError, DiscussionNotFoundError, DocumentNotFoundError,
+    DiscussionLockedError, DiscussionNodeNotFoundError, DiscussionNotFoundError, DocumentNotFoundError,
     PermissionError,
 } from '../error';
 import { DiscussionDoc, DiscussionReplyDoc, DiscussionTailReplyDoc } from '../interface';
@@ -30,7 +30,7 @@ class DiscussionHandler extends Handler {
     vnode?: any;
 
     @param('type', Types.Range(Object.keys(typeMapper)), true)
-    @param('name', Types.Name, true)
+    @param('name', Types.String, true)
     @param('did', Types.ObjectId, true)
     @param('drid', Types.ObjectId, true)
     @param('drrid', Types.ObjectId, true)
@@ -55,15 +55,10 @@ class DiscussionHandler extends Handler {
                 }
             }
         }
-        // TODO(twd2): do more visibility check eg. contest
         // 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.assign?.length && !this.user.own(this.vnode)) {
-            if (!Set.intersection(this.vnode.assign, this.user.group).size) {
-                throw new PermissionError(PERM.PERM_VIEW_PROBLEM_HIDDEN);
-            }
-        }
+        if (!discussion.checkVNodeVisibility(typeMapper[type], this.vnode, this.user)) throw new DiscussionNodeNotFoundError(this.vnode.id);
         if (this.ddoc) {
             this.ddoc.parentType ||= this.vnode.type;
             this.ddoc.parentId ||= this.vnode.id;
@@ -73,11 +68,13 @@ class DiscussionHandler extends Handler {
 
 class DiscussionMainHandler extends Handler {
     @param('page', Types.PositiveInt, true)
-    async get(domainId: string, page = 1) {
+    @param('all', Types.Boolean)
+    async get(domainId: string, page = 1, all = false) {
         // Limit to known types
         const parentType = { $in: Object.keys(typeMapper).map((i) => typeMapper[i]) };
+        all &&= this.user.hasPerm(PERM.PERM_MOD_BADGE);
         const [ddocs, dpcount] = await paginate(
-            discussion.getMulti(domainId, { parentType }),
+            discussion.getMulti(domainId, { parentType, ...all ? {} : { hidden: false } }),
             page,
             system.get('pagination.discussion'),
         );
@@ -95,15 +92,16 @@ class DiscussionMainHandler extends Handler {
 
 class DiscussionNodeHandler extends DiscussionHandler {
     @param('type', Types.Range(Object.keys(typeMapper)))
-    @param('name', Types.Name)
+    @param('name', Types.String)
     @param('page', Types.PositiveInt, true)
     async get(domainId: string, type: string, _name: string, page = 1) {
         let name: ObjectId | string | number;
         if (ObjectId.isValid(_name)) name = new ObjectId(_name);
         else if (isSafeInteger(parseInt(_name, 10))) name = parseInt(_name, 10);
         else name = _name;
+        const hidden = this.user.own(this.vnode) || this.user.hasPerm(PERM.PERM_EDIT_DISCUSSION) ? {} : { hidden: false };
         const [ddocs, dpcount] = await paginate(
-            discussion.getMulti(domainId, { parentType: typeMapper[type], parentId: name }),
+            discussion.getMulti(domainId, { parentType: typeMapper[type], parentId: name, ...hidden }),
             page,
             system.get('pagination.discussion'),
         );
@@ -152,9 +150,10 @@ class DiscussionCreateHandler extends DiscussionHandler {
         await this.limitRate('add_discussion', 3600, 60);
         if (highlight) this.checkPerm(PERM.PERM_HIGHLIGHT_DISCUSSION);
         if (pin) this.checkPerm(PERM.PERM_PIN_DISCUSSION);
+        const hidden = this.vnode.hidden ?? false;
         const did = await discussion.add(
             domainId, typeMapper[type], this.vnode.id, this.user._id,
-            title, content, this.request.ip, highlight, pin,
+            title, content, this.request.ip, highlight, pin, hidden,
         );
         this.response.body = { did };
         this.response.redirect = this.url('discussion_detail', { did });
@@ -397,9 +396,10 @@ class DiscussionEditHandler extends DiscussionHandler {
         else this.checkPerm(PERM.PERM_EDIT_DISCUSSION_SELF);
         if (!this.user.hasPerm(PERM.PERM_HIGHLIGHT_DISCUSSION)) highlight = this.ddoc.highlight;
         if (!this.user.hasPerm(PERM.PERM_PIN_DISCUSSION)) pin = this.ddoc.pin;
+        const hidden = this.vnode.hidden ?? false;
         await Promise.all([
             discussion.edit(domainId, did, {
-                title, highlight, pin, content, editor: this.user._id, edited: true,
+                title, highlight, pin, content, editor: this.user._id, edited: true, hidden,
             }),
             oplog.log(this, 'discussion.edit', this.ddoc),
         ]);
diff --git a/packages/hydrooj/src/interface.ts b/packages/hydrooj/src/interface.ts
index 6995455ac..78840446e 100644
--- a/packages/hydrooj/src/interface.ts
+++ b/packages/hydrooj/src/interface.ts
@@ -462,6 +462,7 @@ declare module './model/discussion' {
         sort: number;
         lastRCount: number;
         lock?: boolean;
+        hidden?: boolean;
     }
 }
 
diff --git a/packages/hydrooj/src/model/discussion.ts b/packages/hydrooj/src/model/discussion.ts
index a436ca1d4..7f1ac1ec5 100644
--- a/packages/hydrooj/src/model/discussion.ts
+++ b/packages/hydrooj/src/model/discussion.ts
@@ -9,10 +9,12 @@ import * as bus from '../service/bus';
 import db from '../service/db';
 import { NumberKeys } from '../typeutils';
 import { buildProjection } from '../utils';
+import { PERM } from './builtin';
 import * as contest from './contest';
 import * as document from './document';
 import problem from './problem';
 import * as training from './training';
+import { User } from './user';
 
 export interface DiscussionDoc extends Document { }
 export type Field = keyof DiscussionDoc;
@@ -20,7 +22,7 @@ export type Field = keyof DiscussionDoc;
 export const PROJECTION_LIST: Field[] = [
     '_id', 'domainId', 'docType', 'docId', 'highlight',
     'nReply', 'views', 'pin', 'updateAt', 'owner',
-    'parentId', 'parentType', 'title',
+    'parentId', 'parentType', 'title', 'hidden',
 ];
 export const PROJECTION_PUBLIC: Field[] = [
     ...PROJECTION_LIST, 'content', 'edited', 'react', 'maintainer',
@@ -43,7 +45,7 @@ export const coll = db.collection('discussion.history');
 export async function add(
     domainId: string, parentType: number, parentId: ObjectId | number | string,
     owner: number, title: string, content: string,
-    ip: string | null = null, highlight: boolean, pin: boolean,
+    ip: string | null = null, highlight: boolean, pin: boolean, hidden = false,
 ): Promise<ObjectId> {
     const time = new Date();
     const payload: Partial<DiscussionDoc> = {
@@ -61,6 +63,7 @@ export async function add(
         updateAt: time,
         views: 0,
         sort: 100,
+        hidden,
     };
     await bus.parallel('discussion/before-add', payload);
     const res = await document.add(
@@ -271,9 +274,8 @@ export function flushNodes(domainId: string) {
 
 export async function getVnode(domainId: string, type: number, id: string, uid?: number) {
     if (type === document.TYPE_PROBLEM) {
-        let pdoc = await problem.get(domainId, Number.isSafeInteger(+id) ? +id : id, problem.PROJECTION_LIST);
+        const pdoc = await problem.get(domainId, Number.isSafeInteger(+id) ? +id : id, problem.PROJECTION_LIST);
         if (!pdoc) throw new DiscussionNodeNotFoundError(id);
-        if (pdoc.hidden) pdoc = problem.default;
         return { ...pdoc, type, id: pdoc.docId };
     }
     if ([document.TYPE_CONTEST, document.TYPE_TRAINING, document.TYPE_HOMEWORK].includes(type as any)) {
@@ -285,6 +287,7 @@ export async function getVnode(domainId: string, type: number, id: string, uid?:
             const tsdoc = await model.getStatus(domainId, _id, uid);
             tdoc.attend = tsdoc?.attend || tsdoc?.enroll;
         }
+        if (type === document.TYPE_CONTEST) tdoc.hidden = !(contest.isDone(tdoc));
         return { ...tdoc, type, id: _id };
     }
     return {
@@ -292,6 +295,7 @@ export async function getVnode(domainId: string, type: number, id: string, uid?:
         ...await getNode(domainId, id),
         type,
         id,
+        owner: 1,
     };
 }
 
@@ -312,6 +316,16 @@ export async function getListVnodes(domainId: string, ddocs: any, getHidden = fa
     return res;
 }
 
+export function checkVNodeVisibility(type: number, vnode: any, user: User) {
+    if (type === document.TYPE_PROBLEM) {
+        if (vnode.hidden && !(user.own(vnode) || user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN))) return false;
+    }
+    if ([document.TYPE_CONTEST, document.TYPE_TRAINING, document.TYPE_HOMEWORK].includes(type as any)) {
+        if (!user.own(vnode) && vnode.assign?.length && !Set.intersection(vnode.assign, user.group).size) return false;
+    }
+    return true;
+}
+
 export function apply(ctx: Context) {
     ctx.on('problem/delete', async (domainId, docId) => {
         const dids = await document.getMulti(
@@ -328,6 +342,13 @@ export function apply(ctx: Context) {
             document.deleteMulti(domainId, document.TYPE_DISCUSSION_REPLY, { docId: { $in: drids } }),
         ]);
     });
+    ctx.on('problem/edit', async (result) => {
+        const dids = await document.getMulti(
+            result.domainId, document.TYPE_DISCUSSION,
+            { parentType: document.TYPE_PROBLEM, parentId: result.docId },
+        ).project({ docId: 1 }).map((ddoc) => ddoc.docId).toArray();
+        return await coll.updateMany({ _id: { $in: dids } }, { $set: { hidden: result.hidden } });
+    });
 }
 
 global.Hydro.model.discussion = {
@@ -367,4 +388,5 @@ global.Hydro.model.discussion = {
     getNodes,
     getVnode,
     getListVnodes,
+    checkVNodeVisibility,
 };
diff --git a/packages/ui-default/templates/partials/discussion_list.html b/packages/ui-default/templates/partials/discussion_list.html
index eb8acb14c..4255f3c89 100644
--- a/packages/ui-default/templates/partials/discussion_list.html
+++ b/packages/ui-default/templates/partials/discussion_list.html
@@ -35,6 +35,9 @@
               @
               {{ datetimeSpan(ddoc.updateAt)|safe }}
             </li>
+            {%- if ddoc.hidden -%}
+              <li class="text-orange">({{ _('Hidden') }})</li>
+            {%- endif -%}
           </ul>
         </div>
       </div>