Slack Webhook Message

Posts one message to the channel associated with a Slack incoming webhook.

Before running, create or select a Slack app with incoming webhooks enabled and add the complete webhook URL as the graph-scoped secret SLACK_WEBHOOK_URL. Webhook URLs are credentials: never paste one into the graph, export, notes, or logs. Edit Message to send, review the destination channel, and run once.

This graph performs an externally visible write. Every successful execution posts a new Slack message. Re-running after an ambiguous timeout can duplicate the message, and incoming webhooks cannot delete messages they posted. The request has a 20-second timeout and a 64 KB response cap. Slack normally returns plain-text ok; errors may use other HTTP statuses and text bodies.

Expected outputs are provider status, provider_response, and a text response. Slack service terms and workspace policies apply. No live webhook request was made while authoring or validating this example.