Chat Widget

Implementation Guide

Step 1: Data Models

Create two tables: support_chats and support_messages.

support_chats

id              - primary key (UUID recommended)
user_id         - foreign key to users (UNIQUE - one chat per user)
last_message_at - timestamp (for sorting chats by recency)
admin_viewed_at - timestamp (tracks when admin last viewed)
archived_at     - timestamp (null = active, set = archived)
created_at
updated_at

support_messages

id              - primary key (UUID recommended)
chat_id         - foreign key to support_chats
content         - text (required)
sender_type     - enum: 'user' | 'admin'
read_at         - timestamp (null = unread)
created_at
updated_at

Key indexes:

• support_chats.user_id (unique)
• support_chats.last_message_at (for sorting)
• support_chats.archived_at (for filtering)
• support_messages.chat_id
• support_messages.(chat_id, created_at) (composite, for ordering)

Model relationships:

User has_one SupportChat
SupportChat belongs_to User
SupportChat has_many SupportMessages
SupportMessage belongs_to SupportChat

Model methods to implement:

Chat model:

function touch_last_message()
  update last_message_at = now()

function unread_for_admin?()
  return exists message where sender_type = 'user'
    and created_at > admin_viewed_at

function mark_viewed_by_admin()
  update admin_viewed_at = now()

function archive()
  update archived_at = now()

function unarchive()
  update archived_at = null

function archived?()
  return archived_at != null

Message model:

after_create:
  chat.touch_last_message()
  if sender_type == 'user' and chat.archived?:
    chat.unarchive()  // Auto-reactivate on new user message

after_create_commit:
  broadcast_to_chat_channel(message_data)
  if sender_type == 'user':
    broadcast_to_admin_notification_channel(message_data, chat_info)
  if sender_type == 'admin':
    schedule_email_notification(delay: 5.minutes)

Step 2: API Endpoints

User-facing:

GET  /support_chat       - Get or create user's chat with messages
PATCH /support_chat/mark_read - Mark admin messages as read

Admin-facing:

GET  /admin/chats              - List chats (query: archived=true/false)
GET  /admin/chats/:id          - Get chat with messages
POST /admin/chats/:id/archive  - Archive chat
POST /admin/chats/:id/unarchive - Restore chat

Controller logic:

User GET /support_chat:

function show()
  chat = current_user.support_chat || create_chat(user: current_user)
  return {
    id: chat.id,
    messages: chat.messages.map(m => serialize_message(m))
  }

Admin GET /admin/chats:

function index()
  chats = SupportChat
    .where(archived_at: params.archived ? not_null : null)
    .includes(:user, :messages)
    .order(last_message_at: desc)

  return chats.map(c => {
    id: c.id,
    user_email: c.user.email,
    last_message_preview: c.messages.last?.content.truncate(100),
    last_message_sender: c.messages.last?.sender_type,
    message_count: c.messages.count,
    unread: c.unread_for_admin?,
    archived: c.archived?
  })

Step 3: WebSocket Channels

Create two channels for real-time communication.

ChatChannel (specific to each chat):

class ChatChannel
  on_subscribe(chat_id):
    chat = find_chat(chat_id)
    if not authorized(chat):
      reject()
      return
    stream_from "support_chat:#{chat_id}"

  function authorized(chat):
    return chat.user_id == current_user.id OR current_user.is_admin

  action send_message(content):
    if content.blank: return
    sender_type = current_user.is_admin ? 'admin' : 'user'
    chat.messages.create(content: content, sender_type: sender_type)

AdminNotificationChannel (global for all admins):

class AdminNotificationChannel
  on_subscribe:
    if not current_user.is_admin:
      reject()
      return
    stream_from "admin_support_notifications"

Broadcasting (from Message model):

function broadcast_message():
  message_data = {
    id: id,
    content: content,
    sender_type: sender_type,
    read_at: read_at,
    created_at: created_at
  }

  // Broadcast to chat subscribers (user + any viewing admins)
  broadcast("support_chat:#{chat.id}", {
    type: "new_message",
    message: message_data
  })

  // Notify all admins when user sends message
  if sender_type == 'user':
    broadcast("admin_support_notifications", {
      type: "new_user_message",
      chat_id: chat.id,
      user_email: chat.user.email,
      message: message_data
    })

Step 4: Frontend - User Widget

Create a floating chat widget with these components:

Component structure:

ChatWidget (root container)
├── ChatButton (fixed position, bottom-right)
│   ├── Icon (message bubble when closed, X when open)
│   └── UnreadBadge (shows count, caps at "9+")
└── ChatPanel (slides up when open)
    ├── Header (title + connection status dot)
    ├── MessageList (scrollable)
    │   └── MessageBubble (styled by sender_type)
    └── InputArea
        ├── Textarea (auto-expanding)
        └── SendButton

State management hook:

function useSupportChat():
  state:
    chat: Chat | null
    connected: boolean
    loading: boolean

  refs:
    consumer: WebSocketConsumer
    subscription: ChannelSubscription
    seenMessageIds: Set<string>  // For deduplication

  on_mount:
    fetch('/support_chat')
      .then(data => {
        chat = data
        seenMessageIds.addAll(data.messages.map(m => m.id))
      })

  when chat.id changes:
    subscription = consumer.subscribe('ChatChannel', { chat_id: chat.id })
    subscription.on_received(data => {
      if data.type == 'new_message':
        if seenMessageIds.has(data.message.id): return  // Dedupe
        seenMessageIds.add(data.message.id)
        chat.messages.push(data.message)
        if data.message.sender_type == 'admin':
          play_notification_sound()
    })
    subscription.on_connected(() => connected = true)
    subscription.on_disconnected(() => connected = false)

  on_unmount:
    subscription.unsubscribe()

  function sendMessage(content):
    subscription.perform('send_message', { content: content.trim() })

  function markAsRead():
    fetch('/support_chat/mark_read', { method: 'PATCH' })
    // Update local state to mark admin messages as read

  return { chat, connected, loading, sendMessage, markAsRead }

Widget behavior:

• Show floating button at bottom-right corner (fixed position)
• Display unread count badge (count messages where sender_type='admin' and read_at=null)
• Toggle panel open/closed on button click
• Auto-call markAsRead() when panel opens
• Auto-scroll to bottom when new messages arrive
• Show connection status indicator (green dot = connected)
• Keyboard: Enter to send, Shift+Enter for newline

Message styling:

• User messages: right-aligned, primary color background
• Admin messages: left-aligned, secondary/muted background
• Show timestamp on each message

Step 5: Frontend - Admin Dashboard

Create two pages: chat list and chat detail.

Chat List Page:

Header: "Support Chats"
Tabs: [Active] [Archived]

Chat cards (sorted by last_message_at desc):
┌─────────────────────────────────────────┐
│ [Unread indicator] [email protected]     │
│ Last message preview text...            │
│ 5 messages · 2 minutes ago              │
└─────────────────────────────────────────┘

Features:

• Tab filtering (active vs archived)
• Unread indicator (highlight border or badge)
• Click to navigate to detail
• Show "You: " prefix if last message was from admin

Chat Detail Page:

Header: [email protected] [Archive/Restore button]
Back link

Messages (grouped by date):
──── Monday, January 29 ────
[User bubble]  Message content
               10:30 AM

          [Admin bubble] Reply content
                         10:35 AM

Input area (same as widget)

Features:

• Group messages by date with dividers
• User messages left, admin messages right (opposite of user widget)
• Show sender label ("You" for admin, user email/name for user)
• Archive/restore toggle button
• Same WebSocket subscription as user widget for real-time updates
• Call mark_viewed_by_admin() when page loads (server-side)

Step 6: Email Notifications

Send email to user when admin replies and user hasn't seen it.

Job/worker:

class SupportReplyNotificationJob
  perform(message):
    if message.sender_type != 'admin': return
    if message.read_at != null: return  // Already read, skip

    send_email(
      to: message.chat.user.email,
      subject: "New reply from Support",
      body: "You have a new message from our support team..."
    )

Scheduling:

• Schedule job with 5-minute delay when admin sends message
• This gives user time to see message in-app before email
• Job checks if still unread before sending

Step 7: TypeScript Types

interface SupportMessage {
  id: string
  content: string
  sender_type: 'user' | 'admin'
  read_at: string | null  // ISO8601
  created_at: string      // ISO8601
}

interface SupportChat {
  id: string
  messages: SupportMessage[]
}

interface SupportChatListItem {
  id: string
  user_id: string
  user_email: string
  last_message_at: string | null
  last_message_preview: string | null
  last_message_sender: 'user' | 'admin' | null
  message_count: number
  unread: boolean
  archived: boolean
}

interface AdminSupportChat {
  id: string
  user_id: string
  user_email: string
  archived: boolean
  messages: SupportMessage[]
}

// WebSocket message types
interface ChatChannelMessage {
  type: 'new_message'
  message: SupportMessage
}

interface AdminNotificationMessage {
  type: 'new_user_message'
  chat_id: string
  user_email: string
  message: SupportMessage
}

Key Design Decisions

1. One chat per user - Simplifies UX, user always has same conversation history
2. Soft-delete via archiving - Preserves history, allows restore
3. Auto-unarchive - When user sends message to archived chat, reactivate it
4. Delayed email notifications - 5 min delay prevents spam for rapid replies
5. Message deduplication - Track seen IDs to prevent duplicates from send + broadcast echo
6. Separate admin channel - Allows future features like global unread count, desktop notifications

Testing Checklist

After implementation:

• User can open widget and send message
• Admin sees message in real-time on dashboard
• Admin can reply and user sees it instantly
• Unread badge shows correct count
• Badge clears when widget opens
• Connection indicator reflects actual status
• Archive/restore works correctly
• Auto-unarchive triggers on user message
• Email sends after 5 min if message unread
• Email does NOT send if user already read message
• Messages appear in chronological order
• No duplicate messages appear

Common Pitfalls

1. Forgetting deduplication - Messages sent by current user echo back via broadcast
2. Race conditions on read status - Use database transactions
3. WebSocket auth - Verify user can access the specific chat
4. Stale connection status - Handle reconnection gracefully
5. Missing indexes - Add composite index on (chat_id, created_at)
6. Email timing - Use background job, not synchronous send

Framework-Specific Guidance

Ruby on Rails

Models:

# app/models/support_chat.rb
class SupportChat < ApplicationRecord
  belongs_to :user
  has_many :support_messages, dependent: :destroy

  scope :active, -> { where(archived_at: nil) }
  scope :archived, -> { where.not(archived_at: nil) }
  scope :recent_first, -> { order(last_message_at: :desc) }

  def touch_last_message
    update_column(:last_message_at, Time.current)
  end

  def unread_for_admin?
    support_messages.where(sender_type: :user)
      .where("created_at > ?", admin_viewed_at || Time.at(0)).exists?
  end

  def archive!
    update_column(:archived_at, Time.current)
  end

  def unarchive!
    update_column(:archived_at, nil)
  end
end

# app/models/support_message.rb
class SupportMessage < ApplicationRecord
  belongs_to :support_chat
  enum :sender_type, { user: 0, admin: 1 }
  validates :content, presence: true

  after_create :update_chat_timestamp
  after_create :auto_unarchive, if: :user?
  after_create_commit :broadcast_message
  after_create_commit :schedule_notification, if: :admin?

  private

  def broadcast_message
    ActionCable.server.broadcast("support_chat:#{support_chat_id}", {
      type: "new_message",
      message: { id:, content:, sender_type:, read_at:, created_at: }
    })
  end

  def schedule_notification
    SupportReplyNotificationJob.set(wait: 5.minutes).perform_later(self)
  end
end

Channel:

# app/channels/support_chat_channel.rb
class SupportChatChannel < ApplicationCable::Channel
  def subscribed
    @chat = SupportChat.find(params[:chat_id])
    reject unless @chat.user_id == current_user.id || current_user.admin?
    stream_from "support_chat:#{@chat.id}"
  end

  def send_message(data)
    @chat.support_messages.create!(
      content: data["content"],
      sender_type: current_user.admin? ? :admin : :user
    )
  end
end

Migration:

create_table :support_chats, id: :uuid do |t|
  t.references :user, type: :uuid, null: false, foreign_key: true, index: { unique: true }
  t.datetime :last_message_at
  t.datetime :admin_viewed_at
  t.datetime :archived_at
  t.timestamps
end

create_table :support_messages, id: :uuid do |t|
  t.references :support_chat, type: :uuid, null: false, foreign_key: true
  t.text :content, null: false
  t.integer :sender_type, default: 0
  t.datetime :read_at
  t.timestamps
end
add_index :support_messages, [:support_chat_id, :created_at]

React (with any backend)

Hook:

// hooks/useSupportChat.ts
import { useEffect, useState, useRef, useCallback } from 'react'

export function useSupportChat(websocketUrl: string) {
  const [chat, setChat] = useState<Chat | null>(null)
  const [connected, setConnected] = useState(false)
  const wsRef = useRef<WebSocket | null>(null)
  const seenIds = useRef(new Set<string>())

  useEffect(() => {
    fetch('/api/support_chat').then(r => r.json()).then(data => {
      setChat(data)
      data.messages.forEach((m: Message) => seenIds.current.add(m.id))
    })
  }, [])

  useEffect(() => {
    if (!chat?.id) return
    const ws = new WebSocket(`${websocketUrl}?chat_id=${chat.id}`)
    wsRef.current = ws

    ws.onopen = () => setConnected(true)
    ws.onclose = () => setConnected(false)
    ws.onmessage = (event) => {
      const data = JSON.parse(event.data)
      if (data.type === 'new_message' && !seenIds.current.has(data.message.id)) {
        seenIds.current.add(data.message.id)
        setChat(prev => prev ? { ...prev, messages: [...prev.messages, data.message] } : prev)
      }
    }
    return () => ws.close()
  }, [chat?.id])

  const sendMessage = useCallback((content: string) => {
    wsRef.current?.send(JSON.stringify({ action: 'send_message', content }))
  }, [])

  return { chat, connected, sendMessage }
}

Widget Component:

// components/ChatWidget.tsx
export function ChatWidget() {
  const [isOpen, setIsOpen] = useState(false)
  const { chat, connected, sendMessage } = useSupportChat('/ws/chat')
  const [input, setInput] = useState('')
  const messagesEndRef = useRef<HTMLDivElement>(null)

  const unreadCount = chat?.messages.filter(
    m => m.sender_type === 'admin' && !m.read_at
  ).length ?? 0

  useEffect(() => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
  }, [chat?.messages])

  const handleSend = () => {
    if (!input.trim()) return
    sendMessage(input.trim())
    setInput('')
  }

  return (
    <div className="fixed bottom-4 right-4 z-50">
      {isOpen ? (
        <div className="w-80 h-96 bg-white rounded-lg shadow-xl flex flex-col">
          <header className="p-3 border-b flex justify-between items-center">
            <span>Support Chat</span>
            <span className={`w-2 h-2 rounded-full ${connected ? 'bg-green-500' : 'bg-gray-400'}`} />
          </header>
          <div className="flex-1 overflow-y-auto p-3 space-y-2">
            {chat?.messages.map(m => (
              <div key={m.id} className={`p-2 rounded ${m.sender_type === 'user' ? 'bg-blue-100 ml-auto' : 'bg-gray-100'}`}>
                {m.content}
              </div>
            ))}
            <div ref={messagesEndRef} />
          </div>
          <div className="p-3 border-t flex gap-2">
            <input value={input} onChange={e => setInput(e.target.value)}
              onKeyDown={e => e.key === 'Enter' && !e.shiftKey && handleSend()}
              className="flex-1 border rounded px-2" placeholder="Type a message..." />
            <button onClick={handleSend} className="px-3 py-1 bg-blue-500 text-white rounded">Send</button>
          </div>
        </div>
      ) : (
        <button onClick={() => setIsOpen(true)} className="w-14 h-14 bg-blue-500 rounded-full text-white relative">
          💬
          {unreadCount > 0 && (
            <span className="absolute -top-1 -right-1 bg-red-500 text-xs w-5 h-5 rounded-full flex items-center justify-center">
              {unreadCount > 9 ? '9+' : unreadCount}
            </span>
          )}
        </button>
      )}
    </div>
  )
}

Next.js (App Router)

API Route:

// app/api/support-chat/route.ts
import { getServerSession } from 'next-auth'
import { prisma } from '@/lib/prisma'

export async function GET() {
  const session = await getServerSession()
  if (!session?.user) return Response.json({ error: 'Unauthorized' }, { status: 401 })

  let chat = await prisma.supportChat.findUnique({
    where: { userId: session.user.id },
    include: { messages: { orderBy: { createdAt: 'asc' } } }
  })

  if (!chat) {
    chat = await prisma.supportChat.create({
      data: { userId: session.user.id },
      include: { messages: true }
    })
  }

  return Response.json(chat)
}

WebSocket with Pusher/Ably (serverless-friendly):

// For serverless, use Pusher, Ably, or similar
import Pusher from 'pusher'
const pusher = new Pusher({ appId, key, secret, cluster })

// When message is created:
await pusher.trigger(`support-chat-${chatId}`, 'new-message', messageData)

// Client-side with pusher-js:
const channel = pusher.subscribe(`support-chat-${chatId}`)
channel.bind('new-message', (data) => { /* update state */ })

PHP/Laravel

Models:

// app/Models/SupportChat.php
class SupportChat extends Model
{
    protected $casts = ['last_message_at' => 'datetime', 'archived_at' => 'datetime'];

    public function user() { return $this->belongsTo(User::class); }
    public function messages() { return $this->hasMany(SupportMessage::class); }

    public function scopeActive($query) { return $query->whereNull('archived_at'); }
    public function scopeArchived($query) { return $query->whereNotNull('archived_at'); }

    public function isUnreadForAdmin(): bool {
        return $this->messages()
            ->where('sender_type', 'user')
            ->where('created_at', '>', $this->admin_viewed_at ?? '1970-01-01')
            ->exists();
    }
}

// app/Models/SupportMessage.php
class SupportMessage extends Model
{
    protected static function booted() {
        static::created(function ($message) {
            $message->supportChat->update(['last_message_at' => now()]);
            broadcast(new NewSupportMessage($message))->toOthers();

            if ($message->sender_type === 'admin') {
                SendSupportReplyNotification::dispatch($message)->delay(now()->addMinutes(5));
            }
        });
    }
}

Broadcasting Event:

// app/Events/NewSupportMessage.php
class NewSupportMessage implements ShouldBroadcast
{
    public function __construct(public SupportMessage $message) {}

    public function broadcastOn() {
        return new PrivateChannel('support-chat.' . $this->message->support_chat_id);
    }

    public function broadcastAs() { return 'new-message'; }
}

Vue.js

Composable:

// composables/useSupportChat.ts
import { ref, onMounted, onUnmounted } from 'vue'

export function useSupportChat() {
  const chat = ref<Chat | null>(null)
  const connected = ref(false)
  let ws: WebSocket | null = null
  const seenIds = new Set<string>()

  onMounted(async () => {
    const res = await fetch('/api/support-chat')
    chat.value = await res.json()
    chat.value?.messages.forEach(m => seenIds.add(m.id))

    ws = new WebSocket(`/ws/chat?id=${chat.value?.id}`)
    ws.onopen = () => connected.value = true
    ws.onclose = () => connected.value = false
    ws.onmessage = (e) => {
      const data = JSON.parse(e.data)
      if (data.type === 'new_message' && !seenIds.has(data.message.id)) {
        seenIds.add(data.message.id)
        chat.value?.messages.push(data.message)
      }
    }
  })

  onUnmounted(() => ws?.close())

  const sendMessage = (content: string) => {
    ws?.send(JSON.stringify({ action: 'send_message', content }))
  }

  return { chat, connected, sendMessage }
}

Database Recommendations

PostgreSQL (Recommended)

• Use UUID primary keys for security (non-guessable IDs)
• Use timestamptz for all datetime columns
• Add GIN index on content for full-text search (optional)

MySQL

• Use CHAR(36) or BINARY(16) for UUIDs
• Use DATETIME(6) for microsecond precision
• Consider utf8mb4 charset for emoji support

SQLite (Development/Small Scale)

• Works fine for prototyping
• Store UUIDs as TEXT
• No native datetime type, store as ISO8601 strings

MongoDB (Document Store)

• Embed messages in chat document if message count is bounded
• Or use separate collection with chat_id reference
• Use TTL index on archived chats for auto-cleanup (optional)

Email Processing Recommendations

Transactional Email Services

• Postmark - Best deliverability, simple API
• SendGrid - Good free tier, robust
• AWS SES - Cheapest at scale
• Resend - Modern DX, React email templates

Implementation Pattern

// Always use background jobs for email
Job: SendSupportReplyNotification
  delay: 5 minutes after admin message

  perform(message_id):
    message = find_message(message_id)

    // Guard clauses - don't send if:
    if message.sender_type != 'admin': return
    if message.read_at != null: return        // Already read
    if message.chat.archived?: return         // Chat archived

    send_email(
      to: message.chat.user.email,
      template: 'support_reply',
      data: { message_preview: message.content.truncate(200) }
    )

Email Template Tips

• Include message preview (truncated)
• Add direct link to open chat (if web app)
• Keep subject simple: "New reply from [App] Support"
• Include unsubscribe link for compliance

Real-Time Technology Options

Fallback Strategy

If WebSocket unavailable, implement polling:

// Poll every 5 seconds when disconnected
if (!websocket.connected) {
  setInterval(() => {
    fetch('/api/support-chat/messages?since=' + lastMessageTime)
      .then(newMessages => appendMessages(newMessages))
  }, 5000)
}

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.