Auto-join buyers into a course's community

Set the default batch

Open a course → settings → Default community → pick one of your batches. (Or set it up the other way: open the batch and link it back to the course.) That single field wires up the auto-join — no separate flow.

What happens on each purchase

• Buyer completes checkout — storefront grants the course entitlement.
• An entitlement.course-granted event fires across the in-app store layer.
• The community store listens, looks up the course's defaultBatchId, and adds the buyer's userId to memberIds if they're not already in.
• The post-purchase 'What's next' page surfaces a 'Join the discussion' card pointing straight into the batch.
• Belt-and-braces: the next-step page also runs the same idempotent join, so a guest who skipped post-purchase still ends up in the community when they next visit.

Why this matters for retention

Course completion rates are dragged down by 'I'll join the community later' — which almost always means 'never'. Auto-join removes the second sale: every buyer is in the room with the other students from the moment they pay, which means the first lesson question, the first 'hi I'm new' post, the first instructor reply all happen in one place instead of being spread across email threads.