Change Plan

Switch between Team and Business plans on an existing subscription.

Replaces the base plan subscription item in Stripe and removes any seat add-ons (extra_seats resets to 0 — re-add after switching if needed).

Pre-flight checks (409 with structured body):

• org_disconnect_required: target plan allows fewer org connections than are currently connected. Disconnect excess orgs first, then retry.
• member_eviction_required: target plan’s included seats are fewer than the current member count. Supply member_ids_to_evict (exactly the overflow count) to proceed atomically.