renderBlockKit

Translate the bot-ui BotNode IR to Slack Block Kit, degrading within Slack's per-element budgets (SLACK_LIMITS).

Overview

renderBlockKit translates the BotNode IR into Block Kit blocks; renderSlackMessage additionally extracts a top-level <Message accent> into the accent color for an attachment. The adapter calls these for you on every thread.post — reach for them directly when testing components or building custom egress.

Signature

import { renderBlockKit, renderSlackMessage, SLACK_LIMITS } from "@copilotkit/bot-slack";

function renderBlockKit(ir: BotNode[]): KnownBlock[];

function renderSlackMessage(ir: BotNode[]): {
  blocks: KnownBlock[];
  accent?: string;
};

Component mapping

Component	Block Kit
`Message`	the message's `blocks` (or an accent attachment)
`Header`	`header`
`Section` / `Markdown`	`section` (mrkdwn)
`Fields`	`section.fields`
`Context`	`context`
`Actions`	`actions`
`Button`	`button` (`action_id` = minted opaque id)
`Select`	`static_select`
`Input`	`plain_text_input`
`Image`	`image`
`Divider`	`divider`
`Table`	native `table` block

Per-element budgets

Slack caps every element. The renderer degrades instead of failing: over-long text is truncated with an overflow marker, and the top-level block list is clamped to 50 with an overflow-signal context block appended when blocks had to be dropped. Sub-collections (fields, actions elements, context elements, select options, table rows/columns) are clamped to their caps without a marker — an 11th field or 26th button is dropped silently. Nothing ever exceeds a platform limit. The limits ship as SLACK_LIMITS:

Limit	Value	Element
`blocksPerMessage`	50	blocks per message
`sectionText`	3000	section body chars
`headerText`	150	header chars
`fieldsPerSection`	10	fields per section
`fieldText`	2000	field chars
`actionsElements`	25	controls per actions row
`contextElements`	10	elements per context block
`buttonText`	75	button label chars
`actionId`	255	`action_id` chars
`buttonValue`	2000	button value chars
`selectOptions`	100	options per select
`tableColumns`	20	columns per table
`tableRows`	100	rows per table
`cellText`	2000	table cell chars

Accent attachments

Block Kit has no native accent color, so a single top-level <Message accent="#27AE60"> is surfaced by renderSlackMessage as accent, and the adapter posts the blocks as an attachment with a colored left bar: attachments: [{ color, blocks }].

slack() — the adapter that calls this on every post
BotNode — the IR this consumes
renderToIR — producing the IR from JSX