slack-events

Typed Slack events, dispatch, and bot reply helpers.

pip install slack-events
pip install 'slack-events[fastapi,client]'

The Python import is slack_events. The base package depends only on typing-extensions; pydantic, fastapi, and client extras enable validation, HTTP routing, and the Slack SDK client respectively.

Responding with Block Kit

Thread.post, Message.reply, SlashCommand.respond, Action.respond, and string returns from SlackBot command handlers accept standard Markdown. They send a markdown block and top-level text containing the same content for notifications and screen readers. Slack performs the Markdown conversion. post_stream uses Slack's native Markdown streaming protocol; its post-and-edit fallback sends blocks on both the initial post and every update.

await message.reply("## Results\n**Done.** See [the report](https://example.com).")

Use explicit blocks= for interactive layouts, structured rich_text, or legacy Slack mrkdwn. In this case text is your accessible fallback and should contain all necessary information. Explicit blocks are passed through unchanged; [] is an intentional opt-out. Raw dictionary returns and the low-level dispatcher also remain caller-controlled.

message_payload(text, blocks=...) exposes the same policy to response layers that call Slack directly. Generated Markdown is capped at Slack's cumulative 12,000-character limit, with a visible truncation notice. Applications can use truncate_markdown to reserve room for a link to the full response. Callers supplying their own blocks are responsible for block limits and content.

Slack's references:

• Markdown blocks for LLM output
• Rich text for structured user-authored content
• Fallback text and accessibility
• Streaming finalization

In mo, finalized replies replace the complete message with Markdown blocks after stopping a native stream. Blocks passed to chat.stopStream would be appended to the streamed content, so that method is not used to replace the answer.