diff --git a/packages/hydrooj/locales/zh.yaml b/packages/hydrooj/locales/zh.yaml
index f62a33105..510455e71 100644
--- a/packages/hydrooj/locales/zh.yaml
+++ b/packages/hydrooj/locales/zh.yaml
@@ -28,6 +28,7 @@ __langname: 简体中文
 'Copy failed :(': '复制失败 :('
 'Current dataset: {0}': '当前测试数据: {0}'
 'Discussion: Terms Of Service': 讨论区服务条款
+'First Blood Notice\n{0} solved problem {1} ({2})': '题目一血提示\n{0} 解决了题目 {1} ({2})'
 'Format: category 1, sub category 1.1, sub category 1.2, ..., sub category 1.x, ..., category n, sub category n.1, sub category n.2, ..., sub category n.m, ...': 格式：分类1, 子分类1.1, 子分类1.2, ..., 子分类1.x, ..., 分类n, 子分类n.1, 子分类n.2, ..., 子分类n.m, ...
 'Join {0}': '加入 {0}'
 'No': 否
diff --git a/packages/hydrooj/src/handler/home.ts b/packages/hydrooj/src/handler/home.ts
index 4f4635100..c2e39fac5 100644
--- a/packages/hydrooj/src/handler/home.ts
+++ b/packages/hydrooj/src/handler/home.ts
@@ -568,19 +568,22 @@ class HomeMessagesHandler extends Handler {
         const messages = await message.getByUser(this.user._id);
         const uids = new Set<number>([
             ...messages.map((mdoc) => mdoc.from),
-            ...messages.map((mdoc) => mdoc.to),
+            ...messages.flatMap((mdoc) => mdoc.to),
         ]);
         const udict = await user.getList('system', Array.from(uids));
         // TODO(twd2): improve here:
         const parsed = {};
         for (const m of messages) {
-            const target = m.from === this.user._id ? m.to : m.from;
-            parsed[target] ||= {
-                _id: target,
-                udoc: { ...udict[target], avatarUrl: avatar(udict[target].avatar) },
-                messages: [],
-            };
-            parsed[target].messages.push(m);
+            const raw = m.from === this.user._id ? m.to : m.from;
+            const targetArr = Array.isArray(raw) ? raw : [raw];
+            for (const target of targetArr) {
+                parsed[target] ||= {
+                    _id: target,
+                    udoc: { ...udict[target], avatarUrl: avatar(udict[target].avatar) },
+                    messages: [],
+                };
+                parsed[target].messages.push(m);
+            }
         }
         await user.setById(this.user._id, { unreadMsg: 0 });
         this.response.body = { messages: parsed };
@@ -601,19 +604,10 @@ class HomeMessagesHandler extends Handler {
     @param('messageId', Types.ObjectId)
     async postDeleteMessage({ }, messageId: ObjectId) {
         const msg = await message.get(messageId);
-        if ([msg.from, msg.to].includes(this.user._id)) await message.del(messageId);
+        if (msg.from === this.user._id) await message.del(messageId);
         else throw new PermissionError();
         this.back();
     }
-
-    @param('messageId', Types.ObjectId)
-    async postRead({ }, messageId: ObjectId) {
-        const msg = await message.get(messageId);
-        if ([msg.from, msg.to].includes(this.user._id)) {
-            await message.setFlag(messageId, message.FLAG_UNREAD);
-        } else throw new PermissionError();
-        this.back();
-    }
 }
 
 export const inject = { geoip: { required: false }, oauth: {} };
diff --git a/packages/hydrooj/src/handler/user.ts b/packages/hydrooj/src/handler/user.ts
index f93f44e66..a8aecdbc4 100644
--- a/packages/hydrooj/src/handler/user.ts
+++ b/packages/hydrooj/src/handler/user.ts
@@ -174,7 +174,7 @@ class UserWebauthnHandler extends Handler {
 
     async post({ domainId, result, redirect }) {
         const challenge = this.session.challenge;
-        if (!challenge) throw new ForbiddenError();
+        if (!challenge) throw new ForbiddenError('no-challenge');
         const tdoc = await token.get(challenge, token.TYPE_WEBAUTHN);
         if (!tdoc) throw new InvalidTokenError(token.TYPE_TEXTS[token.TYPE_WEBAUTHN]);
         const udoc = await (tdoc.uid === 'login'
diff --git a/packages/hydrooj/src/interface.ts b/packages/hydrooj/src/interface.ts
index ab12ae17c..b4eef3de6 100644
--- a/packages/hydrooj/src/interface.ts
+++ b/packages/hydrooj/src/interface.ts
@@ -311,7 +311,7 @@ export interface DomainDoc extends Record<string, any> {
 // Message
 export interface MessageDoc {
     from: number;
-    to: number;
+    to: number | number[];
     content: string;
     flag: number;
 }
diff --git a/packages/hydrooj/src/model/contest.ts b/packages/hydrooj/src/model/contest.ts
index c2c5739fc..51d4bf4c2 100644
--- a/packages/hydrooj/src/model/contest.ts
+++ b/packages/hydrooj/src/model/contest.ts
@@ -1,8 +1,9 @@
 import { sumBy } from 'lodash';
 import { Filter, ObjectId } from 'mongodb';
 import {
-    Counter, formatSeconds, getAlphabeticId, Time,
+    Counter, formatSeconds, getAlphabeticId, sleep, Time,
 } from '@hydrooj/utils/lib/utils';
+import { Context } from '../context';
 import {
     ContestAlreadyAttendedError, ContestNotFoundError,
     ContestScoreboardHiddenError, ValidationError,
@@ -11,14 +12,17 @@ import {
     BaseUserDict, ContestPrintDoc, ContestRule, ContestRules, ProblemDict, RecordDoc,
     ScoreboardConfig, ScoreboardNode, ScoreboardRow, SubtaskResult, Tdoc,
 } from '../interface';
+import avatar from '../lib/avatar';
 import bus from '../service/bus';
 import db from '../service/db';
 import type { Handler } from '../service/server';
 import { Optional } from '../typeutils';
 import { PERM, STATUS, STATUS_SHORT_TEXTS } from './builtin';
 import * as document from './document';
-import problem from './problem';
-import user, { User } from './user';
+import MessageModel from './message';
+import problem, { ProblemModel } from './problem';
+import RecordModel from './record';
+import UserModel, { User } from './user';
 
 export enum PrintTaskStatus {
     pending = 'pending',
@@ -233,7 +237,7 @@ const acm = buildContestRule({
     async scoreboard(config, _, tdoc, pdict, cursor) {
         const rankedTsdocs = await db.ranked(cursor, (a, b) => (a.score || 0) === (b.score || 0) && (a.time || 0) === (b.time || 0));
         const uids = rankedTsdocs.map(([, tsdoc]) => tsdoc.uid);
-        const udict = await user.getListForRender(tdoc.domainId, uids, config.showDisplayName ? ['displayName'] : []);
+        const udict = await UserModel.getListForRender(tdoc.domainId, uids, config.showDisplayName ? ['displayName'] : []);
         // Find first accept
         const first = {};
         const data = await document.collStatus.aggregate([
@@ -407,7 +411,7 @@ const oi = buildContestRule({
     async scoreboard(config, _, tdoc, pdict, cursor) {
         const rankedTsdocs = await db.ranked(cursor, (a, b) => (a.score || 0) === (b.score || 0));
         const uids = rankedTsdocs.map(([, tsdoc]) => tsdoc.uid);
-        const udict = await user.getListForRender(tdoc.domainId, uids, config.showDisplayName ? ['displayName'] : []);
+        const udict = await UserModel.getListForRender(tdoc.domainId, uids, config.showDisplayName ? ['displayName'] : []);
         const psdict = {};
         const first = {};
         const useRelativeTime = !!tdoc.duration;
@@ -776,7 +780,7 @@ const homework = buildContestRule({
     async scoreboard(config, _, tdoc, pdict, cursor) {
         const rankedTsdocs = await db.ranked(cursor, (a, b) => a.score === b.score);
         const uids = rankedTsdocs.map(([, tsdoc]) => tsdoc.uid);
-        const udict = await user.getListForRender(tdoc.domainId, uids, config.showDisplayName ? ['displayName'] : []);
+        const udict = await UserModel.getListForRender(tdoc.domainId, uids, config.showDisplayName ? ['displayName'] : []);
         const columns = await this.scoreboardHeader(config, _, tdoc, pdict);
         const rows: ScoreboardRow[] = [
             columns,
@@ -851,16 +855,30 @@ export async function getRelated(domainId: string, pid: number, rule?: string) {
 }
 
 export async function addBalloon(domainId: string, tid: ObjectId, uid: number, rid: ObjectId, pid: number) {
-    const balloon = await collBalloon.findOne({
-        domainId, tid, pid, uid,
-    });
-    if (balloon) return null;
-    const bdcount = await collBalloon.countDocuments({ domainId, tid, pid });
+    const balloon = await collBalloon.find({ domainId, tid, pid }).project({ uid: 1 }).toArray();
+    if (balloon.find((i) => i.uid === uid)) return null;
+    let isFirst = !balloon.length;
+    if (isFirst) {
+        let pending: RecordDoc[] = [];
+        do {
+            if (pending.length) await sleep(500); // eslint-disable-line no-await-in-loop
+            pending = await RecordModel.getMulti(domainId, { // eslint-disable-line no-await-in-loop
+                pid, contest: tid, _id: { $lt: rid }, status: {
+                    $in: [
+                        STATUS.STATUS_WAITING, STATUS.STATUS_COMPILING,
+                        STATUS.STATUS_JUDGING, STATUS.STATUS_FETCHED,
+                        STATUS.STATUS_ACCEPTED,
+                    ],
+                },
+            }).limit(1).toArray();
+        } while (pending.length && !pending.some((i) => i.status === STATUS.STATUS_ACCEPTED));
+        if (pending.some((i) => i.status === STATUS.STATUS_ACCEPTED)) isFirst = false;
+    }
     const newBdoc = {
-        _id: rid, domainId, tid, pid, uid, ...(!bdcount ? { first: true } : {}),
+        _id: rid, domainId, tid, pid, uid, ...(isFirst ? { first: true } : {}),
     };
     await collBalloon.insertOne(newBdoc);
-    bus.broadcast('contest/balloon', domainId, tid, newBdoc);
+    bus.emit('contest/balloon', domainId, tid, newBdoc);
     return rid;
 }
 
@@ -1090,7 +1108,34 @@ export function getMultiPrintTask(domainId: string, tid: ObjectId, query = {}) {
         .sort({ _id: 1 });
 }
 
+export async function apply(ctx: Context) {
+    ctx.on('contest/balloon', (domainId, tid, bdoc) => {
+        if (!bdoc.first) return;
+        (async () => {
+            const tsdocs = await getMultiStatus(domainId, { docId: tid, subscribe: 1 }).toArray();
+            const uids = Array.from<number>(new Set(tsdocs.map((tsdoc) => tsdoc.uid)));
+            const [team, tdoc, pdoc] = await Promise.all([
+                UserModel.getById(domainId, bdoc.uid),
+                get(domainId, tid),
+                ProblemModel.get(domainId, bdoc.pid),
+            ]);
+            await MessageModel.send(1, uids, JSON.stringify({
+                message: 'First Blood Notice\n{0} solved problem {1} ({2})',
+                avatar: avatar(team.avatar),
+                params: [team.uname, getAlphabeticId(tdoc.pids.indexOf(bdoc.pid)), pdoc.title],
+            }), MessageModel.FLAG_I18N);
+        })();
+    });
+    await ctx.db.ensureIndexes(
+        collBalloon,
+        { key: { domainId: 1, tid: 1, pid: 1, uid: 1 }, unique: true, name: 'basic' },
+        { key: { domainId: 1, tid: 1, pid: 1 }, unique: true, name: 'first', partialFilterExpression: { first: true } },
+    );
+}
+
 global.Hydro.model.contest = {
+    apply,
+
     RULES,
     PrintTaskStatus,
     buildContestRule,
diff --git a/packages/hydrooj/src/model/message.ts b/packages/hydrooj/src/model/message.ts
index 2ffcd4d68..673973340 100644
--- a/packages/hydrooj/src/model/message.ts
+++ b/packages/hydrooj/src/model/message.ts
@@ -22,9 +22,9 @@ class MessageModel {
         content: string, flag: number = MessageModel.FLAG_UNREAD,
     ) {
         if (!Array.isArray(to)) to = [to];
-        const base = { from, content, flag };
+        const base = { from, content, flag, to };
         if (!to.length) return base;
-        await MessageModel.coll.insertMany(to.map((t) => ({ ...base, to: t })));
+        await MessageModel.coll.insertOne(base);
         bus.broadcast('user/message', to, base);
         if (flag & MessageModel.FLAG_UNREAD) await user.inc(to, 'unreadMsg', 1);
         return base;
@@ -52,14 +52,6 @@ class MessageModel {
             .toArray();
     }
 
-    static async setFlag(messageId: ObjectId, flag: number) {
-        return await MessageModel.coll.findOneAndUpdate(
-            { _id: messageId },
-            { $bit: { flag: { xor: flag } } },
-            { returnDocument: 'after' },
-        );
-    }
-
     static async del(_id: ObjectId) {
         return await MessageModel.coll.deleteOne({ _id });
     }
diff --git a/packages/hydrooj/src/service/db.ts b/packages/hydrooj/src/service/db.ts
index 626229360..f4904bd6d 100644
--- a/packages/hydrooj/src/service/db.ts
+++ b/packages/hydrooj/src/service/db.ts
@@ -120,7 +120,11 @@ export class MongoService extends Service {
             index.background = true;
             if (!i) {
                 logger.info('Indexing %s.%s with key %o', coll.collectionName, index.name, index.key);
-                await coll.createIndexes([index]);
+                try {
+                    await coll.createIndexes([index]);
+                } catch (e) {
+                    logger.error('Failed to index %s.%s with key %o: %s', coll.collectionName, index.name, index.key, e);
+                }
                 continue;
             }
             const isDifferent = () => {
@@ -137,7 +141,11 @@ export class MongoService extends Service {
                 }
                 logger.info('Re-Index %s.%s with key %o', coll.collectionName, index.name, index.key);
                 await coll.dropIndex(i.name);
-                await coll.createIndexes([index]);
+                try {
+                    await coll.createIndexes([index]);
+                } catch (e) {
+                    logger.error('Failed to re-index %s.%s with key %o: %s', coll.collectionName, index.name, index.key, e);
+                }
             }
         }
     }
diff --git a/packages/ui-default/components/message/index.page.ts b/packages/ui-default/components/message/index.page.ts
index 9a3727e85..f34787620 100644
--- a/packages/ui-default/components/message/index.page.ts
+++ b/packages/ui-default/components/message/index.page.ts
@@ -9,17 +9,22 @@ import { i18n, tpl } from 'vj/utils';
 import Sock from '../socket';
 
 let previous: VjNotification;
-const onmessage = (msg) => {
-  console.log('Received message', msg);
+const processI18n = (msg) => {
   if (msg.mdoc.flag & FLAG_I18N) {
     try {
       msg.mdoc.content = JSON.parse(msg.mdoc.content);
       if (msg.mdoc.content.url) msg.mdoc.url = msg.mdoc.content.url;
+      if (msg.mdoc.content.avatar) msg.mdoc.avatar = msg.mdoc.content.avatar;
       msg.mdoc.content = i18n(msg.mdoc.content.message, ...msg.mdoc.content.params);
     } catch (e) {
       msg.mdoc.content = i18n(msg.mdoc.content);
     }
   }
+  return msg;
+};
+const onmessage = (msg) => {
+  console.log('Received message', msg);
+  msg = processI18n(msg);
   if (msg.mdoc.flag & FLAG_ALERT) {
     // Is alert
     new InfoDialog({
@@ -48,6 +53,7 @@ const onmessage = (msg) => {
       ? {
         type: 'info',
         message: msg.mdoc.flag & FLAG_RICHTEXT ? i18n('You received a system message, click here to view.') : msg.mdoc.content,
+        ...(msg.mdoc.avatar ? { avatar: msg.mdoc.avatar } : {}),
       } : {
         title: msg.udoc.uname,
         avatar: msg.udoc.avatarUrl,
@@ -72,6 +78,8 @@ const initWorkerMode = (endpoint) => {
     const { payload, type } = message.data;
     if (type === 'message') {
       if (onmessage(payload)) worker.port.postMessage({ type: 'ack', id: payload.mdoc._id });
+    } else if (type === 'i18n') {
+      worker.port.postMessage({ type: 'ack', id: `${payload.mdoc._id}-i18n`, payload: processI18n(payload) });
     } else if (type === 'open-page') {
       console.log('opening page');
       window.open('/home/messages');
diff --git a/packages/ui-default/components/message/worker.ts b/packages/ui-default/components/message/worker.ts
index a4e186dfc..d2fa7baac 100644
--- a/packages/ui-default/components/message/worker.ts
+++ b/packages/ui-default/components/message/worker.ts
@@ -1,7 +1,7 @@
 /// <reference no-default-lib="true" />
 /// <reference lib="webworker" />
 import ReconnectingWebsocket from 'reconnecting-websocket';
-import { FLAG_INFO } from 'vj/constant/message';
+import { FLAG_I18N, FLAG_INFO } from 'vj/constant/message';
 declare const self: SharedWorkerGlobalScope;
 
 console.log('SharedWorker init');
@@ -17,6 +17,7 @@ interface RequestInitSharedConnPayload {
 interface RequestAckPayload {
   type: 'ack';
   id: string;
+  payload?: any;
 }
 interface RequestUnloadPayload {
   type: 'unload';
@@ -28,28 +29,37 @@ function broadcastMsg(message: any) {
   for (const p of ports) p.postMessage(message);
 }
 
-function onMessage(payload: any) {
-  broadcastMsg({ type: 'message', payload });
+function onMessage(message: any) {
+  broadcastMsg({ type: 'message', payload: message });
   let acked = false;
-  ack[payload.mdoc._id] = () => { acked = true; };
+  let payload = message;
+  ack[message.mdoc._id] = () => { acked = true; };
+  ack[`${message.mdoc._id}-i18n`] = (v) => { payload = v; };
+  if (message.mdoc.flag & FLAG_I18N) broadcastMsg({ type: 'i18n', payload: message });
   setTimeout(() => {
-    delete ack[payload.mdoc._id];
+    delete ack[message.mdoc._id];
+    delete ack[`${message.mdoc._id}-i18n`];
     if (acked) return;
-    if (payload.mdoc.flag & FLAG_INFO) return;
+    if (message.mdoc.flag & FLAG_INFO) return;
     if (Notification?.permission !== 'granted') {
       console.log('Notification permission denied');
       return;
     }
+    console.log('Sending as system notification');
     // eslint-disable-next-line no-new
     new Notification(
-      payload.udoc.uname || 'Hydro Notification',
-      {
+      payload.udoc._id === 1 ? payload.mdoc.content.split('\n')[0] : payload.udoc.uname || 'Hydro Notification',
+      payload.udoc._id === 1 ? {
+        tag: `notification-${payload.mdoc._id}`,
+        icon: payload.mdoc.avatar || '/android-chrome-192x192.png',
+        body: payload.mdoc.content.split('\n').slice(1).join('\n'),
+      } : {
         tag: `message-${payload.mdoc._id}`,
         icon: payload.udoc.avatarUrl || '/android-chrome-192x192.png',
         body: payload.mdoc.content,
       },
     );
-  }, 5000);
+  }, 3000);
 }
 
 function initConn(path: string, port: MessagePort, cookie: any) {
@@ -92,7 +102,7 @@ self.onconnect = function (e) {
 
   port.addEventListener('message', (msg: { data: RequestPayload }) => {
     if (msg.data.type === 'conn') initConn(msg.data.path, port, msg.data.cookie);
-    if (msg.data.type === 'ack') ack[msg.data.id]?.();
+    if (msg.data.type === 'ack') ack[msg.data.id]?.(msg.data.payload);
     if (msg.data.type === 'unload') ports.delete(port);
   });
 
diff --git a/packages/ui-default/components/notification/index.ts b/packages/ui-default/components/notification/index.ts
index 3aace4689..a9e878023 100644
--- a/packages/ui-default/components/notification/index.ts
+++ b/packages/ui-default/components/notification/index.ts
@@ -38,11 +38,12 @@ export default class Notification {
     if (avatar) this.type += ' avatar';
     if (title) this.type += ' title';
     this.action = action || (() => { });
-    this.$dom = $(tpl`<div class="notification ${type} hide"></div>`);
-    if (avatar) $(tpl`<img width="64" height="64" class="avatar" src="${avatar}"></img>`).appendTo(this.$dom);
+    this.$dom = $(tpl`<div class="notification ${this.type} hide"></div>`);
+    if (avatar) $(tpl`<img width="32" height="32" class="avatar" src="${avatar}"></img>`).appendTo(this.$dom);
+    const content = message.split('\n').map((line) => tpl`<p>${line}</p>`).join('');
     if (title) {
-      $(tpl`<div class="notification-content"><h2>${title}</h2><p>${message}</p></div>`).appendTo(this.$dom);
-    } else $(tpl`<p>${message}</p>`).appendTo(this.$dom);
+      $(tpl`<div class="notification-content"><h2>${title}</h2>${{ templateRaw: true, html: content }}</div>`).appendTo(this.$dom);
+    } else $(`<div>${content}</div>`).appendTo(this.$dom);
     this.$dom.on('click', this.handleClick.bind(this));
     this.$n = this.$dom
       .css('z-index', zIndexManager.getNext())
diff --git a/packages/ui-default/components/notification/notification.page.styl b/packages/ui-default/components/notification/notification.page.styl
index 239b8c32b..c7e76e7ca 100644
--- a/packages/ui-default/components/notification/notification.page.styl
+++ b/packages/ui-default/components/notification/notification.page.styl
@@ -21,6 +21,15 @@
     opacity: 0
     transform: translateY(20px) scale(0.9)
 
+  &.avatar
+    display: flex
+    align-items: center
+
+  .avatar
+    display: inline-block
+    vertical-align: top
+    margin-right: rem(10px)
+
   &:before
     display: inline-block
     font-family: $icon-font-name !important
@@ -30,6 +39,9 @@
     vertical-align: top
     margin-top: rem((20px - $font-size-icon) / 2)
 
+  &.avatar:before
+    display: none !important
+
   for key, value in $notification-color
     &.{key}
       border-left: 5px solid value
@@ -37,7 +49,7 @@
         color: value
 
   for key, value in $notification-icon
-    &.{key}:before
+    &:not(.avatar).{key}:before
       content: value
 
 +mobile()
diff --git a/packages/ui-default/pages/contest_balloon.page.tsx b/packages/ui-default/pages/contest_balloon.page.tsx
index 8696404d7..da2064da1 100644
--- a/packages/ui-default/pages/contest_balloon.page.tsx
+++ b/packages/ui-default/pages/contest_balloon.page.tsx
@@ -85,7 +85,8 @@ async function handleSetColor(tdoc) {
     Notification.error(`${e.message} ${e.params?.[0]}`);
   }
   Notification.info(i18n('Successfully updated.'));
-  pjax.request({ url: '', push: false });
+  if ($('[data-fragment-id="constest_balloon-tbody"]').length) pjax.request({ url: '', push: false });
+  else window.location.reload();
 }
 
 const page = new NamedPage('contest_balloon', () => {