Use PolarRequestValidationError for billing address validation

Replace custom InvoiceBillingAddressUpdateError with standard
PolarRequestValidationError for better consistency with the codebase.

Author: claude

clients/packages/ui/src/components/atoms/CountryPicker.tsx

@@ -41,7 +41,12 @@ const CountryPicker = ({
 }) => {
   const countryMap = getCountryList(allowedCountries as TCountryCode[])
   return (
-    <Select onValueChange={onChange} value={value} autoComplete={autoComplete} disabled={disabled}>
+    <Select
+      onValueChange={onChange}
+      value={value}
+      autoComplete={autoComplete}
+      disabled={disabled}
+    >
       <SelectTrigger className={className} disabled={disabled}>
         <SelectValue
           placeholder="Country"

server/polar/customer_portal/endpoints/order.py

@@ -12,7 +12,6 @@
 from polar.openapi import APITag
 from polar.order.schemas import OrderID
 from polar.order.service import (
-    InvoiceBillingAddressUpdateError,
     MissingInvoiceBillingDetails,
     NotPaidOrder,
     PaymentAlreadyInProgress,
@@ -114,13 +113,7 @@ async def get(
     "/{id}",
     summary="Update Order",
     response_model=CustomerOrder,
-    responses={
-        404: OrderNotFound,
-        422: {
-            "description": "Cannot update billing address country/state after order is paid.",
-            "model": InvoiceBillingAddressUpdateError.schema(),
-        },
-    },
+    responses={404: OrderNotFound},
 )
 async def update(
     id: OrderID,

server/polar/order/endpoints.py

@@ -26,11 +26,7 @@
 from . import auth, sorting
 from .schemas import Order as OrderSchema
 from .schemas import OrderID, OrderInvoice, OrderNotFound, OrderUpdate
-from .service import (
-    InvoiceBillingAddressUpdateError,
-    MissingInvoiceBillingDetails,
-    NotPaidOrder,
-)
+from .service import MissingInvoiceBillingDetails, NotPaidOrder
 from .service import order as order_service
 
 router = APIRouter(prefix="/orders", tags=["orders", APITag.public, APITag.mcp])
@@ -177,13 +173,7 @@ async def get(
     "/{id}",
     summary="Update Order",
     response_model=OrderSchema,
-    responses={
-        404: OrderNotFound,
-        422: {
-            "description": "Cannot update billing address country/state after order is paid.",
-            "model": InvoiceBillingAddressUpdateError.schema(),
-        },
-    },
+    responses={404: OrderNotFound},
 )
 async def update(
     id: OrderID,

server/polar/order/service.py

@@ -28,7 +28,7 @@
 from polar.event.service import event as event_service
 from polar.event.system import OrderPaidMetadata, SystemEvent, build_system_event
 from polar.eventstream.service import publish as eventstream_publish
-from polar.exceptions import PolarError
+from polar.exceptions import PolarError, PolarRequestValidationError
 from polar.file.s3 import S3_SERVICES
 from polar.held_balance.service import held_balance as held_balance_service
 from polar.integrations.stripe.service import stripe as stripe_service
@@ -223,16 +223,6 @@ def __init__(self, subscription: Subscription) -> None:
         super().__init__(message)
 
 
-class InvoiceBillingAddressUpdateError(OrderError):
-    def __init__(self, order: Order) -> None:
-        self.order = order
-        message = (
-            "Cannot update billing address country or state after order is paid, "
-            "as VAT was calculated based on the original address."
-        )
-        super().__init__(message, 422)
-
-
 def _is_empty_customer_address(customer_address: dict[str, Any] | None) -> bool:
     return customer_address is None or customer_address["country"] is None
 
@@ -355,14 +345,35 @@ async def update(
             new_address = order_update.billing_address
             existing_address = order.billing_address
 
-            # Check if country or state is being changed
-            new_country = new_address.country if new_address else None
+            new_country = str(new_address.country) if new_address else None
             new_state = new_address.state if new_address else None
-            existing_country = existing_address.get("country") if existing_address else None
-            existing_state = existing_address.get("state") if existing_address else None
-
-            if new_country != existing_country or new_state != existing_state:
-                raise InvoiceBillingAddressUpdateError(order)
+            existing_country = (
+                str(existing_address.country) if existing_address else None
+            )
+            existing_state = existing_address.state if existing_address else None
+
+            if new_country != existing_country:
+                raise PolarRequestValidationError(
+                    [
+                        {
+                            "type": "value_error",
+                            "loc": ("body", "billing_address", "country"),
+                            "msg": "Cannot change country after order is paid.",
+                            "input": new_country,
+                        }
+                    ]
+                )
+            if new_state != existing_state:
+                raise PolarRequestValidationError(
+                    [
+                        {
+                            "type": "value_error",
+                            "loc": ("body", "billing_address", "state"),
+                            "msg": "Cannot change state after order is paid.",
+                            "input": new_state,
+                        }
+                    ]
+                )
 
         repository = OrderRepository.from_session(session)
         order = await repository.update(