rewrite $ref in top-level oneOf/anyOf branches during variant generation

preprocess_schemas.py

@@ -514,6 +514,12 @@ def _create_single_variant(
             variant, op, file_path, global_variant_requirements
         )
 
+    # Rewrite all external $refs in the variant schema to point to their
+    # corresponding request variants where applicable. This covers top-level
+    # oneOf/anyOf/allOf branches as well as array items.
+    rewrite_refs_to_variants(
+        variant, op, file_path, global_variant_requirements
+    )
     return variant
 
 
@@ -570,19 +576,28 @@ def normalize_metadata_schemas(schemas, target_dir):
 
 
 def extract_external_refs(schema, path):
-    """Finds all relative external file references in the schema properties."""
+    """Finds all relative external file references in the schema."""
     refs = []
-    props = schema.get("properties", {})
-    if not isinstance(props, dict):
-        return refs
 
-    for name, data in props.items():
+    def _scan(name, data):
         for node in iter_nodes(data):
             if isinstance(node, dict) and "$ref" in node:
                 ref = node["$ref"]
                 if "#" not in ref:
                     abs_path = str((path.parent / ref).resolve())
                     refs.append((name, abs_path))
+
+    props = schema.get("properties", {})
+    if isinstance(props, dict):
+        for name, data in props.items():
+            _scan(name, data)
+
+    # Also scan top-level composition keywords (oneOf, anyOf, allOf, items)
+    for key in ["oneOf", "anyOf", "allOf"]:
+        if key in schema:
+            _scan(key, schema[key])
+    if "items" in schema:
+        _scan("items", schema["items"])
     return refs
 
 
@@ -599,23 +614,28 @@ def propagate_needs_transitive(variant_needs, schema_refs, schemas):
                 continue
 
             for op in list(variant_needs[path]):
-                for prop_name, child_path in refs:
+                for ref_name, child_path in refs:
                     if child_path not in schemas:
                         continue
 
-                    # Only propagate if the property isn't 'omit'ted for this op
-                    data = (
-                        schemas[path].get("properties", {}).get(prop_name, {})
-                    )
-                    include, _ = eval_prop_inclusion(
-                        prop_name, data, op, schemas[path].get("required", [])
-                    )
-
-                    if include:
-                        target_set = variant_needs.setdefault(child_path, set())
-                        if op not in target_set:
-                            target_set.add(op)
-                            changed = True
+                    # For property refs, check if the property is included for this op.
+                    # For non-property refs (oneOf, anyOf, allOf, items), always propagate.
+                    props = schemas[path].get("properties", {})
+                    if ref_name in props:
+                        data = props[ref_name]
+                        include, _ = eval_prop_inclusion(
+                            ref_name,
+                            data,
+                            op,
+                            schemas[path].get("required", []),
+                        )
+                        if not include:
+                            continue
+
+                    target_set = variant_needs.setdefault(child_path, set())
+                    if op not in target_set:
+                        target_set.add(op)
+                        changed = True
 
 
 # --- Main Flow ---

src/ucp_sdk/models/schemas/shopping/cart_create_request.py

@@ -20,7 +20,7 @@
 
 from pydantic import BaseModel, ConfigDict
 
-from .checkout import Checkout as Checkout_1
+from .checkout_create_request import CheckoutCreateRequest
 from .types import (
     attribution_create_request,
     buyer_create_request,
@@ -56,7 +56,7 @@ class CartCreateRequest(BaseModel):
     """
 
 
-class Checkout(Checkout_1):
+class Checkout(CheckoutCreateRequest):
     """
     Checkout extended with cart capability. Adds cart_id to create_checkout for cart-to-checkout conversion.
     """

src/ucp_sdk/models/schemas/shopping/cart_update_request.py

@@ -20,7 +20,7 @@
 
 from pydantic import BaseModel, ConfigDict
 
-from .checkout import Checkout as Checkout_1
+from .checkout_update_request import CheckoutUpdateRequest
 from .types import (
     attribution_update_request,
     buyer_update_request,
@@ -60,7 +60,7 @@ class CartUpdateRequest(BaseModel):
     """
 
 
-class Checkout(Checkout_1):
+class Checkout(CheckoutUpdateRequest):
     """
     Checkout extended with cart capability. Adds cart_id to create_checkout for cart-to-checkout conversion.
     """

src/ucp_sdk/models/schemas/shopping/types/error_code_create_request.py

@@ -0,0 +1,48 @@
+# Copyright 2026 UCP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# generated by datamodel-codegen
+# pylint: disable=all
+# pyformat: disable
+
+from __future__ import annotations
+
+from typing import Annotated
+
+from pydantic import Field
+from typing_extensions import TypeAliasType
+
+ErrorCodeCreateRequest = TypeAliasType(
+    "ErrorCodeCreateRequest",
+    Annotated[
+        str,
+        Field(
+            ...,
+            examples=[
+                "not_found",
+                "out_of_stock",
+                "item_unavailable",
+                "address_undeliverable",
+                "payment_failed",
+                "eligibility_invalid",
+                "identity_required",
+                "insufficient_scope",
+            ],
+            title="Error Code Create Request",
+        ),
+    ],
+)
+"""
+Error code identifying the type of error. Standard errors are defined in specification (see examples), and have standardized semantics; freeform codes are permitted.
+"""

src/ucp_sdk/models/schemas/shopping/types/error_code_update_request.py

@@ -0,0 +1,48 @@
+# Copyright 2026 UCP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# generated by datamodel-codegen
+# pylint: disable=all
+# pyformat: disable
+
+from __future__ import annotations
+
+from typing import Annotated
+
+from pydantic import Field
+from typing_extensions import TypeAliasType
+
+ErrorCodeUpdateRequest = TypeAliasType(
+    "ErrorCodeUpdateRequest",
+    Annotated[
+        str,
+        Field(
+            ...,
+            examples=[
+                "not_found",
+                "out_of_stock",
+                "item_unavailable",
+                "address_undeliverable",
+                "payment_failed",
+                "eligibility_invalid",
+                "identity_required",
+                "insufficient_scope",
+            ],
+            title="Error Code Update Request",
+        ),
+    ],
+)
+"""
+Error code identifying the type of error. Standard errors are defined in specification (see examples), and have standardized semantics; freeform codes are permitted.
+"""

src/ucp_sdk/models/schemas/shopping/types/fulfillment_destination_create_request.py

@@ -23,13 +23,16 @@
 from pydantic import Field
 from typing_extensions import TypeAliasType
 
-from . import retail_location, shipping_destination
+from . import (
+    retail_location_create_request,
+    shipping_destination_create_request,
+)
 
 FulfillmentDestinationCreateRequest = TypeAliasType(
     "FulfillmentDestinationCreateRequest",
     Annotated[
-        shipping_destination.ShippingDestination
-        | retail_location.RetailLocation,
+        shipping_destination_create_request.ShippingDestinationCreateRequest
+        | retail_location_create_request.RetailLocationCreateRequest,
         Field(..., title="Fulfillment Destination Create Request"),
     ],
 )

src/ucp_sdk/models/schemas/shopping/types/fulfillment_destination_update_request.py

@@ -23,13 +23,16 @@
 from pydantic import Field
 from typing_extensions import TypeAliasType
 
-from . import retail_location, shipping_destination
+from . import (
+    retail_location_update_request,
+    shipping_destination_update_request,
+)
 
 FulfillmentDestinationUpdateRequest = TypeAliasType(
     "FulfillmentDestinationUpdateRequest",
     Annotated[
-        shipping_destination.ShippingDestination
-        | retail_location.RetailLocation,
+        shipping_destination_update_request.ShippingDestinationUpdateRequest
+        | retail_location_update_request.RetailLocationUpdateRequest,
         Field(..., title="Fulfillment Destination Update Request"),
     ],
 )

src/ucp_sdk/models/schemas/shopping/types/info_code_create_request.py

@@ -0,0 +1,44 @@
+# Copyright 2026 UCP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# generated by datamodel-codegen
+# pylint: disable=all
+# pyformat: disable
+
+from __future__ import annotations
+
+from typing import Annotated
+
+from pydantic import Field
+from typing_extensions import TypeAliasType
+
+InfoCodeCreateRequest = TypeAliasType(
+    "InfoCodeCreateRequest",
+    Annotated[
+        str,
+        Field(
+            ...,
+            examples=[
+                "identity_optional",
+                "signal",
+                "free_shipping",
+                "not_found",
+            ],
+            title="Info Code Create Request",
+        ),
+    ],
+)
+"""
+Info code identifying the type of informational message. Standard codes are defined in capability specs (see examples), and have standardized semantics; freeform codes are permitted.
+"""

src/ucp_sdk/models/schemas/shopping/types/info_code_update_request.py

@@ -0,0 +1,44 @@
+# Copyright 2026 UCP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# generated by datamodel-codegen
+# pylint: disable=all
+# pyformat: disable
+
+from __future__ import annotations
+
+from typing import Annotated
+
+from pydantic import Field
+from typing_extensions import TypeAliasType
+
+InfoCodeUpdateRequest = TypeAliasType(
+    "InfoCodeUpdateRequest",
+    Annotated[
+        str,
+        Field(
+            ...,
+            examples=[
+                "identity_optional",
+                "signal",
+                "free_shipping",
+                "not_found",
+            ],
+            title="Info Code Update Request",
+        ),
+    ],
+)
+"""
+Info code identifying the type of informational message. Standard codes are defined in capability specs (see examples), and have standardized semantics; freeform codes are permitted.
+"""

src/ucp_sdk/models/schemas/shopping/types/message_create_request.py

@@ -23,14 +23,18 @@
 from pydantic import Field
 from typing_extensions import TypeAliasType
 
-from . import message_error, message_info, message_warning
+from . import (
+    message_error_create_request,
+    message_info_create_request,
+    message_warning_create_request,
+)
 
 MessageCreateRequest = TypeAliasType(
     "MessageCreateRequest",
     Annotated[
-        message_error.MessageError
-        | message_warning.MessageWarning
-        | message_info.MessageInfo,
+        message_error_create_request.MessageErrorCreateRequest
+        | message_warning_create_request.MessageWarningCreateRequest
+        | message_info_create_request.MessageInfoCreateRequest,
         Field(..., title="Message Create Request"),
     ],
 )