Slack

Slack is the only channel here with two credentials that do different things. Which one you configure decides what the channel can do, and the module tells you which mode it is in rather than guessing.

Copy this

PIGEON_SLACK_BOT_TOKEN=xoxb-...
PIGEON_SLACK_CHANNEL=C01ABC2DEF

export default defineNuxtConfig({
  modules: ['nuxt-pigeon'],
  nuxtPigeon: {
    channels: {
      slack: true,
    },
  },
})

export default defineEventHandler(async () => {
  const message = await slack.send('*Deploy failed* on `main`')

  await slack.send('Fixed it', { threadTs: message.id })

  return { ts: message.id }
})

The two modes

If both are configured the bot token wins, because it can do strictly more. A token without a channel is an error, not a quiet fallback to the webhook: you set a token to get an id back, and the webhook would hand you a message you cannot touch again.

Every option

Receiving

This is the part that costs people an evening, so it is spelled out in full. Slack has four switches that each silently disable delivery on their own, and none of them produces an error anywhere.

PIGEON_SLACK_SIGNING_SECRET=...

nuxtPigeon: {
  channels: {
    slack: { receive: true },
  },
}

pnpm dev --tunnel

https://your-tunnel.trycloudflare.com/api/_pigeon/slack

/invite @your-bot

Nothing arrives? In this order

Every one of these fails silently. Work down the list, it is sorted by how often it is the answer.

1. Is Socket Mode off? Settings → Socket Mode. With it on, Slack delivers everything over a WebSocket and nothing over HTTP. Your Request URL is ignored, your route is never called, and no error appears anywhere. This is the one that costs the evening.
2. Did you reinstall after changing scopes? A yellow banner at the top of the app page means your token is older than your permissions.
3. Is the bot in the channel? /invite @your-bot.
4. Did the tunnel address change? Every restart of --tunnel gives you a new one, and Slack still has the old one. Paste the new one into Event Subscriptions again.
5. Is the event actually subscribed? app_mention fires only when the bot is mentioned. Writing a normal message in the channel needs message.channels.
6. Is the signing secret right? A wrong one means every delivery is rejected before your handler, which looks exactly like nothing arriving.

The listener

export default defineNitroPlugin(() => {
  slack.listen(async (envelope) => {
    // Yours come back too. Without this you have built a loop.
    if (envelope.event?.bot_id) return

    if (envelope.event?.type === 'app_mention') {
      await slack.send('You rang?', { threadTs: envelope.event.ts })
    }
  })
})

The signature is checked, the url_verification challenge is answered, and the acknowledgement goes out inside Slack's three second deadline before your handler runs. A slow handler therefore cannot cause a duplicate delivery.

What will cost you an hour

• Bold is one asterisk. *bold*, not **bold**. Two are literal.
• @here is written <!here>. A @here copied from Discord sits there as dead text and notifies nobody, without an error.
• Slack answers 200 even when it failed. The reason is in the body as { ok: false, error: 'missing_scope' }. The module throws on that, so a missing scope cannot pass for success.
• An edit drops the blocks when only text is sent, but keeps the attachments. Two opposite rules in one method. The module sends the blocks again for you.
• An upload has no message timestamp. The file becomes the message, so it can be deleted but never edited, and delete uses files.delete rather than chat.delete.
• Uploading needs the bot in the channel. chat:write.public covers messages but not files, so /invite it once.
• Slack sends you your own messages. Every message in the channel produces an event, including the one your app just posted. Yours carry bot_id, and answering without checking builds a loop.

Read more

• chat.postMessage
• chat.update
• Uploading files
• Events API
• Block Kit builder