bots

Towns Protocol Bot SDK Reference

Critical Rules

MUST follow these rules - violations cause silent failures:

1. User IDs are Ethereum addresses - Always 0x... format, never usernames
2. Mentions require BOTH - <@{userId}> format in text AND mentions array in options
3. Two-wallet architecture:
   • bot.viem.account.address = Gas wallet (signs & pays fees) - MUST fund with Base ETH
   • bot.appAddress = Treasury (optional, for transfers)
4. Slash commands DON'T trigger onMessage - They're exclusive handlers
5. Interactive forms use type property - Not case (e.g., type: 'form')
6. Never trust txHash alone - Verify receipt.status === 'success' before granting access

Quick Reference

Key Imports

import { makeTownsBot, getSmartAccountFromUserId } from '@towns-protocol/bot'
import type { BotCommand, BotHandler } from '@towns-protocol/bot'
import { Permission } from '@towns-protocol/web3'
import { parseEther, formatEther, erc20Abi, zeroAddress } from 'viem'
import { readContract, waitForTransactionReceipt } from 'viem/actions'
import { execute } from 'viem/experimental/erc7821'

Handler Methods

Method	Signature	Notes
sendMessage	(channelId, text, opts?) → { eventId }	opts: { threadId?, replyId?, mentions?, attachments? }
editMessage	(channelId, eventId, text)	Bot's own messages only
removeEvent	(channelId, eventId)	Bot's own messages only
sendReaction	(channelId, messageId, emoji)
sendInteractionRequest	(channelId, payload)	Forms, transactions, signatures
hasAdminPermission	(userId, spaceId) → boolean
ban / unban	(userId, spaceId)	Needs ModifyBanning permission

Bot Properties

Property	Description
bot.viem	Viem client for blockchain
bot.viem.account.address	Gas wallet - MUST fund with Base ETH
bot.appAddress	Treasury wallet (optional)
bot.botId	Bot identifier

For detailed guides, see references/:

• Messaging API - Mentions, threads, attachments, formatting
• Blockchain Operations - Read/write contracts, verify transactions
• Interactive Components - Forms, transaction requests
• Deployment - Local dev, Render, tunnels
• Debugging - Troubleshooting guide

---

Bot Setup

Project Initialization

bunx towns-bot init my-bot
cd my-bot
bun install

Environment Variables

APP_PRIVATE_DATA=<base64_credentials>   # From app.towns.com/developer
JWT_SECRET=<webhook_secret>              # Min 32 chars
PORT=3000
BASE_RPC_URL=https://base-mainnet.g.alchemy.com/v2/KEY  # Recommended

Basic Bot Template

import { makeTownsBot } from '@towns-protocol/bot'
import type { BotCommand } from '@towns-protocol/bot'

const commands = [
  { name: 'help', description: 'Show help' },
  { name: 'ping', description: 'Check if alive' }
] as const satisfies BotCommand[]

const bot = await makeTownsBot(
  process.env.APP_PRIVATE_DATA!,
  process.env.JWT_SECRET!,
  { commands }
)

bot.onSlashCommand('ping', async (handler, event) => {
  const latency = Date.now() - event.createdAt.getTime()
  await handler.sendMessage(event.channelId, 'Pong! ' + latency + 'ms')
})

export default bot.start()

Config Validation

import { z } from 'zod'

const EnvSchema = z.object({
  APP_PRIVATE_DATA: z.string().min(1),
  JWT_SECRET: z.string().min(32),
  DATABASE_URL: z.string().url().optional()
})

const env = EnvSchema.safeParse(process.env)
if (!env.success) {
  console.error('Invalid config:', env.error.issues)
  process.exit(1)
}

---

Event Handlers

onMessage

Triggers on regular messages (NOT slash commands).

bot.onMessage(async (handler, event) => {
  // event: { userId, spaceId, channelId, eventId, message, isMentioned, threadId?, replyId? }

  if (event.isMentioned) {
    await handler.sendMessage(event.channelId, 'You mentioned me!')
  }
})

onSlashCommand

Triggers on /command. Does NOT trigger onMessage.

bot.onSlashCommand('weather', async (handler, { args, channelId }) => {
  // /weather San Francisco → args: ['San', 'Francisco']
  const location = args.join(' ')
  if (!location) {
    await handler.sendMessage(channelId, 'Usage: /weather <location>')
    return
  }
  // ... fetch weather
})

onReaction

bot.onReaction(async (handler, event) => {
  // event: { reaction, messageId, channelId }
  if (event.reaction === '👋') {
    await handler.sendMessage(event.channelId, 'I saw your wave!')
  }
})

onTip

Requires "All Messages" mode in Developer Portal.

bot.onTip(async (handler, event) => {
  // event: { senderAddress, receiverAddress, amount (bigint), currency }
  if (event.receiverAddress === bot.appAddress) {
    await handler.sendMessage(event.channelId,
      'Thanks for ' + formatEther(event.amount) + ' ETH!')
  }
})

onInteractionResponse

bot.onInteractionResponse(async (handler, event) => {
  switch (event.response.payload.content?.case) {
    case 'form':
      const form = event.response.payload.content.value
      for (const c of form.components) {
        if (c.component.case === 'button' && c.id === 'yes') {
          await handler.sendMessage(event.channelId, 'You clicked Yes!')
        }
      }
      break
    case 'transaction':
      const tx = event.response.payload.content.value
      if (tx.txHash) {
        // IMPORTANT: Verify on-chain before granting access
        // See references/BLOCKCHAIN.md for full verification pattern
        await handler.sendMessage(event.channelId,
          'TX: https://basescan.org/tx/' + tx.txHash)
      }
      break
  }
})

Event Context Validation

Always validate context before using:

bot.onSlashCommand('cmd', async (handler, event) => {
  if (!event.spaceId || !event.channelId) {
    console.error('Missing context:', { userId: event.userId })
    return
  }
  // Safe to proceed
})

---

Common Mistakes

Mistake	Fix
insufficient funds for gas	Fund bot.viem.account.address with Base ETH
Mention not highlighting	Include BOTH <@userId> in text AND mentions array
Slash command not working	Add to commands array in makeTownsBot
Handler not triggering	Check message forwarding mode in Developer Portal
writeContract failing	Use execute() for external contracts
Granting access on txHash	Verify receipt.status === 'success' first
Message lines overlapping	Use \n\n (double newlines), not \n
Missing event context	Validate spaceId/channelId before using

---

Resources

• Developer Portal: https://app.towns.com/developer
• Documentation: https://docs.towns.com/build/bots
• SDK: https://www.npmjs.com/package/@towns-protocol/bot
• Chain ID: 8453 (Base Mainnet)