`slack://`¶

Slack producer (incoming-webhook OR chat.postMessage) + polling consumer (conversations.history). Stdlib HTTP — no Slack SDK dependency.

URI shape¶

slack://#<channel>?token=xoxb-…                            # Web API producer + consumer
slack://?webhookUrl=https://hooks.slack.com/services/…      # incoming-webhook producer

The leading # is canonical Slack form and is stripped at parse time. Channel can also be passed as ?channel=… (channel name or channel ID — IDs are auto-detected by their C/G/D prefix).

Parameters¶

Common¶

Param	Type	Default	Description
`channel`	string	from URI	Target channel name (or channel ID for consumer).
`token`	string	—	Slack bot/user token (`xoxb-…` / `xoxp-…`). Required for Web API producer + any consumer.

Consumer¶

Param	Type	Default	Description
`conversationType`	enum	`PUBLIC_CHANNEL`	`conversations.list` type filter (`PUBLIC_CHANNEL` / `PRIVATE_CHANNEL` / `MPIM` / `IM`).
`maxResults`	integer	`10`	Cap on messages dispatched per poll.
`naturalOrder`	boolean	`false`	Emit oldest-first (Slack API returns newest-first).
`sendEmptyMessageWhenIdle`	boolean	`false`	Emit a heartbeat Exchange when poll yields zero messages.
`serverUrl`	string	`https://slack.com`	Slack API base URL (overridable for tests).

Producer¶

Param	Type	Default	Description
`webhookUrl`	string	—	Incoming-webhook URL. Mutually exclusive with `token` posting.
`iconEmoji`	string	—	`icon_emoji` for the posted message (e.g. `:robot_face:`).
`iconUrl`	string	—	`icon_url` for the posted message.
`username`	string	—	`username` (display-name override) for the posted message.

Polling scheduler¶

delay (default 60s), initialDelay (1s), useFixedDelay, repeatCount, greedy, pollInterval (legacy alias for delay).

Headers (Helix-only)¶

Header	Direction	Notes
`HelixSlackChannel`	Both	Per-message channel override (producer); written by consumer on each emitted message.
`HelixSlackTimestamp`	Written by consumer + producer	The Slack `ts` field. Written by the producer with the value returned from `chat.postMessage`.
`HelixSlackUser`	Written by consumer	The Slack user ID who sent the message.
`HelixSlackEventType`	Written by consumer	Event type (`message`/`empty`/…).
`HelixSlackBlocks`	Read by producer	Block Kit `[]any` (or `[]map[string]any`) passed straight through into the `blocks` field.
`HelixSlackThreadTS`	Read by producer	Sets `thread_ts` for thread replies.

YAML examples¶

workflows:
  # 1. Webhook producer — fire-and-forget alerts to an incoming-webhook URL.
  - id: slack-webhook-alert
    description: Post to a Slack incoming-webhook on every direct:// message.
    trigger:
      uri: direct://alert
    steps:
      - to: slack://?webhookUrl=https://hooks.slack.com/services/XXX/YYY/ZZZ&username=helix-alerts&iconEmoji=:rocket:

  # 2. Token-based producer — post to a channel by name.
  - id: slack-channel-post
    description: Post via chat.postMessage using a bot token.
    trigger:
      uri: direct://ops-message
    steps:
      - to: slack://#ops?token=xoxb-…&username=Helix&iconEmoji=:robot_face:

  # 3. Block Kit producer — rich message via HelixSlackBlocks header.
  - id: slack-blocks
    description: Send a Block Kit message.
    trigger:
      uri: direct://rich-message
    steps:
      - set-header:
          name: HelixSlackBlocks
          starlang: |
            [
              {type: "section", text: {type: "mrkdwn", text: "*Status:* :large_green_circle: All good"}},
              {type: "context", elements: [{type: "mrkdwn", text: "_via Helix_"}]}
            ]
      - to: slack://#ops?token=xoxb-…

  # 4. Polling consumer — emit each new message in a channel.
  - id: slack-consume
    description: Poll #incoming for new messages, oldest-first.
    trigger:
      uri: slack://#incoming?token=xoxb-…&conversationType=PUBLIC_CHANNEL&maxResults=20&naturalOrder=true&delay=10s
    steps:
      - log:
          message: "[${headers.HelixSlackTimestamp}] ${headers.HelixSlackUser}: ${body}"

  # 5. Thread reply.
  - id: slack-thread-reply
    description: Reply in a thread.
    trigger:
      uri: direct://reply
    steps:
      - set-header:
          name: HelixSlackThreadTS
          starlang: headers["original_ts"]
      - to: slack://#alerts?token=xoxb-…

slack://¶