Fix invoice preview SDK schema

docs/COMPATIBILITY.md

@@ -103,7 +103,7 @@ Base path: `/v1`
 | Subscriptions           | `POST /v1/subscriptions`, `GET /v1/subscriptions`, `GET /v1/subscriptions/{id}`, `POST /v1/subscriptions/{id}`, `DELETE /v1/subscriptions/{id}`, `GET/DELETE /v1/subscriptions/{id}/discount`                     | Partial          | Create/list/retrieve subscriptions through the local checkout-completion state path. Update supports item replacement, metadata merge, single coupon or promotion-code discount application, `test_clock`, and `cancel_at_period_end`. List supports arbitrary metadata equality filters such as `metadata[billtap_fixture_ref]`. Delete performs immediate sandbox cancellation. Test-clock and scenario clock advances can activate due trials, renew active periods with bounded discount math, fail configured renewals from subscription or customer metadata, and cancel period-end subscriptions in the local billing graph. |
 | Subscription schedules  | `POST /v1/subscription_schedules`, `GET /v1/subscription_schedules`, `GET /v1/subscription_schedules/{id}`, `POST /v1/subscription_schedules/{id}`, `POST /v1/subscription_schedules/{id}/cancel`, `POST /v1/subscription_schedules/{id}/release` | Partial | Local schedule evidence for one due phase on an existing subscription. Test-clock advance applies a due phase by replacing subscription items and emits `customer.subscription.updated`; complex multi-phase billing, proration, invoices, and schedule lifecycle parity are not modeled. |
 | Subscription items      | `POST /v1/subscription_items`, `DELETE /v1/subscription_items/{id}`                                                                                                 | Partial          | Add or remove local subscription items for integration smoke paths. Billing proration and invoice recalculation are not modeled.                                                                                                                                                                                                                                                                                                                                        |
-| Invoices                | `GET /v1/invoices`, `GET /v1/invoices/{id}`, `POST /v1/invoices/{id}/pay`, `POST /v1/invoices/create_preview`, `GET/POST /v1/invoices/upcoming`                     | Partial          | List/retrieve invoices created by checkout. `pay` retries open local invoices with deterministic sandbox `payment_method` or `source` aliases, mutating invoice, subscription, payment-intent, timeline, and webhook evidence. Preview endpoints calculate a Stripe-shaped subscription-update proration line from current period bounds, old/new price totals, `subscription_details[items]`, `subscription_details[proration_date]`, `subscription_details[proration_behavior]`, and `subscription_details[billing_cycle_anchor]`. A bounded single-discount subset updates `subtotal`, `total`, and `total_discount_amounts`; taxes, pending invoice items, and full invoice collection lifecycle are outside the modeled subset. |
+| Invoices                | `GET /v1/invoices`, `GET /v1/invoices/{id}`, `POST /v1/invoices/{id}/pay`, `POST /v1/invoices/create_preview`, `GET/POST /v1/invoices/upcoming`                     | Partial          | List/retrieve invoices created by checkout. `pay` retries open local invoices with deterministic sandbox `payment_method` or `source` aliases, mutating invoice, subscription, payment-intent, timeline, and webhook evidence. Preview endpoints calculate a Stripe-shaped subscription-update proration line from current period bounds, old/new price totals, `subscription_details[items]`, `subscription_details[proration_date]`, `subscription_details[proration_behavior]`, and `subscription_details[billing_cycle_anchor]`. Invoice and preview responses include the common Stripe Invoice default fields expected by generated SDK models, including status transitions, automatic tax state, tax totals, payment settings, and array-shaped `discounts`. A bounded single-discount subset updates `subtotal`, `total`, and `total_discount_amounts`; taxes, pending invoice items, and full invoice collection lifecycle are outside the modeled subset. |
 | Payment intents         | `POST /v1/payment_intents`, `GET /v1/payment_intents`, `GET /v1/payment_intents/{id}`, `POST /v1/payment_intents/{id}/confirm`, `POST /v1/payment_intents/{id}/capture`, `POST /v1/payment_intents/{id}/cancel` | Partial          | Create/list/retrieve and mutate local payment intents. `confirm` supports deterministic sandbox PaymentMethod aliases such as `pm_card_visa`, `pm_card_visa_chargeDeclined`, `pm_card_threeDSecure2Required`, `requires_action`, and local bank-transfer processing. Manual capture moves through `requires_capture` before `capture` succeeds. Direct one-time intents emit `payment_intent.created` and a terminal event when confirmed. Deferred per-intent outcomes and customer defaults are supported; `requires_action` can return either `use_stripe_sdk` or local `redirect_to_url` next-action payloads. |
 | Setup intents           | `POST /v1/setup_intents`, `GET /v1/setup_intents`, `GET /v1/setup_intents/{id}`, `POST /v1/setup_intents/{id}/confirm`, `POST /v1/setup_intents/{id}/cancel`        | Partial          | Create/list/retrieve and mutate local setup intents with deterministic success, decline, and authentication-required aliases. Mandates, bank-account verification, and full SCA behavior are not modeled.                                                                                                                                                                                                                                                               |
 | Payment methods         | `GET /v1/payment_methods?customer={id}&type=card`, `GET /v1/customers/{id}/payment_methods?type=card`                                                              | Partial          | Returns deterministic sandbox card PaymentMethod projections for known customers, including SDK-friendly `billing_details`, `card.checks`, `country`, `fingerprint`, `funding`, `networks`, `three_d_secure_usage`, `metadata`, and `redaction` fields. Query validation covers `type`, `allow_redisplay`, `limit`, and unknown parameters; non-card valid types return an empty local list. Customer fixtures can opt into empty or explicit payment-method lists for no-card and multi-card local scenarios. Create, attach, detach, and general update are not supported.                        |