http-client-python doesn't emit code with discriminator

[howieleung]

Hello folks,
Got an issue to use python emitter from tsp for discriminator. Could someone help?

I have this in typespec.

@discriminated(#{ envelope: "none", discriminatorPropertyName: "type" })
union Tool {
  function: FunctionTool,
  file_search: FileSearchTool,
}

@summary("Function")
model FunctionTool {
  /** The type of the function tool. Always `function`. */
  @extension("x-stainless-const", true)
  type: "function" = "function";

  /** The name of the function to call. */
  name: string;

  description?: string | null;
  parameters: Record<unknown> | null;
  strict: boolean | null;
}

model FileSearchTool {
  /** The type of the file search tool. Always `file_search`. */
  @extension("x-stainless-const", true)
  type: "file_search" = "file_search";

  /** The IDs of the vector stores to search. */
  vector_store_ids: string[];

  /** The maximum number of results to return. This number should be between 1 and 50 inclusive. */
  max_num_results?: integer;

  /** Ranking options for search. */
  ranking_options?: RankingOptions;

  filters?: Filters | null;
}

generate

Tool = Union["_models.FunctionTool", "_models.FileSearchTool"]

class FunctionTool(_Model):

    type: Literal["function"] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """The type of the function tool. Always ``function``. Required. Default value is \"function\"."""
    name: str = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """The name of the function to call. Required."""
    description: Optional[str] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    parameters: dict[str, Any] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """Required."""
    strict: bool = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """Required."""

    @overload
    def __init__(
        self,
        *,
        name: str,
        parameters: dict[str, Any],
        strict: bool,
        description: Optional[str] = None,
    ) -> None: ...

    @overload
    def __init__(self, mapping: Mapping[str, Any]) -> None:
        """
        :param mapping: raw JSON to initialize the model.
        :type mapping: Mapping[str, Any]
        """

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        super().__init__(*args, **kwargs)
        self.type: Literal["function"] = "function"

class FileSearchTool(_Model):
    """File search.

    :ivar type: The type of the file search tool. Always ``file_search``. Required. Default value
     is "file_search".
    :vartype type: str
    :ivar vector_store_ids: The IDs of the vector stores to search. Required.
    :vartype vector_store_ids: list[str]
    :ivar max_num_results: The maximum number of results to return. This number should be between 1
     and 50 inclusive.
    :vartype max_num_results: int
    :ivar ranking_options: Ranking options for search.
    :vartype ranking_options: ~openai.models.RankingOptions
    :ivar filters: Is either a ComparisonFilter type or a CompoundFilter type.
    :vartype filters: ~openai.models.ComparisonFilter or ~openai.models.CompoundFilter
    """

    type: Literal["file_search"] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """The type of the file search tool. Always ``file_search``. Required. Default value is
     \"file_search\"."""
    vector_store_ids: list[str] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """The IDs of the vector stores to search. Required."""
    max_num_results: Optional[int] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """The maximum number of results to return. This number should be between 1 and 50 inclusive."""
    ranking_options: Optional["_models.RankingOptions"] = rest_field(
        visibility=["read", "create", "update", "delete", "query"]
    )
    """Ranking options for search."""
    filters: Optional["_types.Filters"] = rest_field(visibility=["read", "create", "update", "delete", "query"])
    """Is either a ComparisonFilter type or a CompoundFilter type."""

    @overload
    def __init__(
        self,
        *,
        vector_store_ids: list[str],
        max_num_results: Optional[int] = None,
        ranking_options: Optional["_models.RankingOptions"] = None,
        filters: Optional["_types.Filters"] = None,
    ) -> None: ...

    @overload
    def __init__(self, mapping: Mapping[str, Any]) -> None:
        """
        :param mapping: raw JSON to initialize the model.
        :type mapping: Mapping[str, Any]
        """

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        super().__init__(*args, **kwargs)
        self.type: Literal["file_search"] = "file_search"

The generated code doesn't indicate type is the discriminator.

I have this in tspconfig.yaml:

  "@typespec/http-client-python":
    emitter-output-dir: "{output-dir}/clients/python"