[privatenumber]

Summary

• A bot now receives the content of Block Kit messages that apps and workflows post, instead of only their notification fallback
• When an app mentions the bot from a section block, the handler gets the request it was invoked for
• When the bot reads thread history, messages from alerting and deploy apps include the details shown in Slack
• Messages typed in a Slack client are unchanged

Problem

A Slack message can carry both text and blocks. When it carries blocks, Slack renders the blocks and uses text only as "a fallback string to display in notifications" (chat.postMessage). Apps and workflows rely on that: the fallback is often a one-line summary, and the content people read is in the blocks.

The adapter builds message.text and message.formatted from text. From the message's own blocks it reads only tables. Text in section, header, and context blocks never reaches the bot, so the bot works from the notification summary while people in the channel see the full message.

This affects a bot in two ways.

An app mentions the bot. An internal tool asks the bot to act:

{
  "type": "app_mention",
  "text": "New request",
  "blocks": [
    { "type": "section", "text": { "type": "mrkdwn", "text": "<@U_BOT> please check the deploy" } }
  ]
}

1. Slack fires app_mention for the token in the section block, even though text has none.
2. The adapter reads the mention from the block and reports isMention: true.
3. It builds the body from text, so message.text is New request.
4. onNewMention runs without the request it was invoked for, and the bot can only ask what to do.

The bot reads an app's message in history. A deploy app posts text: "Deployment failed" with the error, project, and links in section blocks. A user replies in the thread and asks the bot what went wrong. fetchMessages, fetchChannelMessages, and fetchMessage parse messages the same way, so the bot's view of the alert is Deployment failed, without the details the user is looking at.

Changes

When a message has no rich_text blocks, text from its layout blocks becomes the body, in block order:

• section text and fields, header text, and context text elements
• mrkdwn objects keep their markup and mentions, which resolve to display names like the rest of the body
• plain_text objects render literally, so * and _ stay characters

The same message now gives message.text = @Test Bot please check the deploy.

These rules keep existing behavior:

• Typed messages keep text. A Slack client sends rich_text blocks that text mirrors, so a message with any rich_text block keeps the text body. #1002 covers composer lists in that path.

• Blocks without text keep text. When the layout blocks carry no text, as in a message with only buttons or images, text stays the body.

• Table placement is unchanged. Tables from the message's blocks keep their position around the body.

• Mention detection is unchanged. Only the message content changes.

• packages/adapter-slack/src/index.ts: layoutBlockContent, rendered through the existing attachment-content path

• packages/adapter-slack/src/index.test.ts: a layout message parsed by both parse paths, a webhook mention in a section block, and a buttons-only message that keeps its fallback

• packages/adapter-slack/sample-messages.md: a captured section mention payload, anonymized

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