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Engineering · April 9, 2026 · 9 min read
Why we chose Slack as the primary surface for our agent
In-app notifications vs Slack DMs vs email. Why founders actually open Slack. The 5 Block Kit patterns we ended up using.
Founders don't sit in our app all day. They sit in Slack. So we put the agent there.
Five Block Kit patterns we settled on: (1) intake card with multiple-choice questions, (2) candidate-ranking card for assigner, (3) adaptive follow-up with snooze buttons, (4) blocker card with one suggested next step, (5) EOD digest as a single rich post.
The hardest part is not rendering — it's rate limits + idempotency. We learned to defer the right things, batch the rest, and never send the same notification twice even if the producer fires twice.