Alert: Slack notification when new rows appear in a question result (with per-row template interpolation)

Feature request: Slack alert when new rows appear in a question result

What problem does this solve?
Currently, Metabase alerts only notify when an aggregate metric crosses a threshold. There's no way to get notified — with actual row data — when a new row appears in a question's result set. This makes it hard to use Metabase for operational monitoring use cases (e.g. "alert me in Slack when a new high-priority ticket is created").

What I'm requesting
A new alert type: "When new rows appear". When triggered, it should:

  • Compare each scheduled run against the previous result set (snapshot-based diffing)
  • Send a Slack notification only for genuinely new rows (not re-send existing ones)
  • Support two delivery modes:
    • Per-row: one Slack message per new row
    • Digest: one Slack message summarising all new rows
  • Allow a custom message template using {{column_name}} placeholders, so the Slack notification can say something like: "New booking: {{customer_name}} on {{date}} for {{amount}}"
  • Skip sending on the first run (baseline snapshot only), to avoid a flood of messages on setup

Why this would be valuable
This bridges the gap between Metabase and operational Slack workflows without needing a separate tool like Zapier or a custom pipeline. It turns any saved question into a lightweight real-time feed for a team.

I've actually built this already - PR #74498: https://github.com/metabase/metabase/pull/74498 — happy to discuss the approach or iterate on feedback.

Would love to know if this is on the roadmap or if there's a workaround I'm missing. Thanks!