Get a lightweight billing summary for the authenticated partner for the given period: headline totals plus a flat per-account cost breakdown and active store count. This is the same base payload the dashboard endpoint enriches.

Auth: Partner — authentication; under the partner/billing route group. getAuthPartner resolves scope; returns 403 if the user is not associated with a partner. Always the caller's own partner tree — no path target.

Rate limit: No rate limit.

Request

• Query: year (integer, optional) — 2000–2100; defaults to current year.
• Query: month (integer, optional) — 1–12; defaults to current month.

Response — { data. } envelope.

• total_billed (number) — period sum of client_amount line items for the partner.
• period (string) — YYYY-MM.
• billing_model (string|null) — e.g. plan-based / usage-based.
• contract_model (string|null) — model-a / model-b.
• active_stores (integer) — total active stores across the partner's accounts.
• accounts (array) — per-account summary rows: account_id (int), account_name (string), plan_name (string|null), store_count (int), cost (number), overage (number), status (string: within_limits / overage / halted).

Errors: 422 on validation failure.