Slack Block Kit Patterns (SBK-001)

Use this skill when generating Slack interactive messages (buttons, modals) or structured notifications that must be consistent and easy for handlers/workflows to interpret.

When to Use

• •HITL approval requests and decision confirmations (buttons)
• •Status updates (replace/update the original message)
• •Notifications and error responses (ephemeral vs in-channel)
• •Modals for collecting structured input (reason, change request, etc.)

Instructions

1. •

   Use a consistent block structure

   • •Prefer: header → section (reason/details) → section.fields (metadata) → actions → context.
   • •Keep text short; put details in fields/context.
2. •

   Encode workflow context deterministically

   • •Use button value for the primary identifier (e.g., workflowId).
   • •Use block_id as a stable grouping key (e.g., approval_<workflowId>).
   • •Keep action_id stable and versionless (contracts used by handlers).
   • •Example reference: packages/core/src/wcs/approval-signal.ts (APPROVAL_ACTION_IDS, createApprovalBlocks).
3. •

   Choose the right response mechanism

   • •For interactive callbacks, respond within 3 seconds.
   • •Prefer: acknowledge callback ({ ok: true }) and let the workflow update the message asynchronously.
   • •If you must respond immediately, use an ephemeral response describing next steps.
4. •

   Use predictable status updates

   • •Update the original message with a terminal result (approved/rejected/error).
   • •Include a timestamp + source in a context block for auditability.
5. •

   Keep templates JSON-serializable

   • •Blocks are plain objects only; avoid runtime-only types/classes.
   • •Use mrkdwn for formatted fields, plain_text for headers/buttons.

References

• •references/slack-block-kit-patterns.md
• •packages/core/src/wcs/approval-signal.ts
• •packages/apps/console/server/integrations/http/slack-interactive-handler.ts