Assign a plan to one or more stores for the current month. For each store it closes any active/expired store plans without an issued next-invoice, opens a new active store plan. It also creates or updates the CompanyPlan pointer for each affected account and fires a planChanged billing webhook. Billing side effect: the plan amount is applied to next month's invoice.

Auth

• Bearer partner / account token. plan_id must be assigned to the caller's plan-assignment company (company_plans for planAssignmentCompanyId); every store_ids[] must belong to the caller's hierarchy (an ownership check).

Rate limit

• No rate limit.

Body

Behaviour

• 200 — { data: { status: 'success', message } }.
• 422 — plan not assigned to caller, or a store_id invalid / out of scope.