fix(responses): type aliasing not supported for pydantic code generation and discrimintated unions

docs/_static/llama-stack-spec.yaml

@@ -6589,39 +6589,118 @@ components:
       additionalProperties: false
       title: OpenAIResponsesTool
     OpenAIResponsesToolChoice:
+      oneOf:
+        - $ref: '#/components/schemas/ToolChoiceOptions'
+        - $ref: '#/components/schemas/ToolChoiceTypes'
+        - oneOf:
+            - $ref: '#/components/schemas/ToolChoiceAllowed'
+            - $ref: '#/components/schemas/ToolChoiceFunction'
+            - $ref: '#/components/schemas/ToolChoiceMcp'
+            - $ref: '#/components/schemas/ToolChoiceCustom'
+          discriminator:
+            propertyName: type
+            mapping:
+              allowed_tools: '#/components/schemas/ToolChoiceAllowed'
+              function: '#/components/schemas/ToolChoiceFunction'
+              mcp: '#/components/schemas/ToolChoiceMcp'
+              custom: '#/components/schemas/ToolChoiceCustom'
+    ToolChoiceAllowed:
       type: object
-      title: OpenAIResponsesToolChoice
-      description: >-
-        Type alias.
+      properties:
+        mode:
+          type: string
+          enum:
+            - auto
+            - required
+        tools:
+          type: array
+          items:
+            type: object
+            additionalProperties:
+              type: object
+              title: object
+              description: >-
+                The base class of the class hierarchy.
 
-        Type aliases are created through the type statement::
+                When called, it accepts no arguments and returns a new featureless
 
-            type Alias = int
-
-        In this example, Alias and int will be treated equivalently by static
-
-        type checkers.
-
-
-        At runtime, Alias is an instance of TypeAliasType. The __name__
-
-        attribute holds the name of the type alias. The value of the type alias
-
-        is stored in the __value__ attribute. It is evaluated lazily, so the
-
-        value is computed only if the attribute is accessed.
-
-
-        Type aliases can also be generic::
-
-            type ListOrSet[T] = list[T] | set[T]
-
-        In this case, the type parameters of the alias are stored in the
-
-        __type_params__ attribute.
-
-
-        See PEP 695 for more information.
+                instance that has no instance attributes and cannot be given any.
+        type:
+          type: string
+          const: allowed_tools
+          default: allowed_tools
+      additionalProperties: false
+      required:
+        - mode
+        - tools
+        - type
+      title: ToolChoiceAllowed
+    ToolChoiceCustom:
+      type: object
+      properties:
+        name:
+          type: string
+        type:
+          type: string
+          const: custom
+          default: custom
+      additionalProperties: false
+      required:
+        - name
+        - type
+      title: ToolChoiceCustom
+    ToolChoiceFunction:
+      type: object
+      properties:
+        name:
+          type: string
+        type:
+          type: string
+          const: function
+          default: function
+      additionalProperties: false
+      required:
+        - name
+        - type
+      title: ToolChoiceFunction
+    ToolChoiceMcp:
+      type: object
+      properties:
+        server_label:
+          type: string
+        type:
+          type: string
+          const: mcp
+          default: mcp
+        name:
+          type: string
+      additionalProperties: false
+      required:
+        - server_label
+        - type
+      title: ToolChoiceMcp
+    ToolChoiceOptions:
+      type: string
+      enum:
+        - none
+        - auto
+        - required
+    ToolChoiceTypes:
+      type: object
+      properties:
+        type:
+          type: string
+          enum:
+            - file_search
+            - web_search_preview
+            - computer_use_preview
+            - web_search_preview_2025_03_11
+            - image_generation
+            - code_interpreter
+      additionalProperties: false
+      required:
+        - type
+      title: ToolChoiceTypes
     OpenAIResponseContentPart:
       oneOf:
         - $ref: '#/components/schemas/OpenAIResponseContentPartOutputText'