fix: make FunctionParameters and LogitBias OpenAI-compatible

Use Pydantic's RootModel to accept bare JSON Schema dicts instead of
requiring a non-standard RootModel wrapper field. This makes m serve
compatible with standard OpenAI clients.

BREAKING CHANGE: FunctionParameters(RootModel={...}) is now FunctionParameters({...})

Signed-off-by: Mark Sturdevant <mark.sturdevant@ibm.com>
Assisted-by: IBM Bob

Author: markstur

cli/serve/models.py

@@ -1,6 +1,6 @@
 from typing import Any, Literal
 
-from pydantic import BaseModel, Field, model_validator
+from pydantic import BaseModel, Field
 
 from mellea.helpers.openai_compatible_helpers import CompletionUsage
 
@@ -13,9 +13,14 @@ class ChatMessage(BaseModel):
     function_call: dict[str, Any] | None = None  # For function/tool messages
 
 
-class FunctionParameters(BaseModel):
-    # Accept any structure for function parameters
-    RootModel: dict[str, Any]
+class FunctionParameters(RootModel[dict[str, Any]]):
+    """OpenAI-compatible function parameters as a bare JSON Schema object.
+
+    Accepts a standard JSON Schema dict directly without wrapping.
+    Example: {"type": "object", "properties": {...}, "required": [...]}
+    """
+
+    root: dict[str, Any]
 
 
 class FunctionDefinition(BaseModel):
@@ -73,8 +78,10 @@ class StreamOptions(BaseModel):
     """
 
 
-class LogitBias(BaseModel):
-    RootModel: dict[str, float]
+class LogitBias(RootModel[dict[str, float]]):
+    """OpenAI-compatible logit bias as a bare dict mapping token IDs to bias values."""
+
+    root: dict[str, float]
 
 
 class ChatCompletionRequest(BaseModel):

test/cli/test_serve.py

@@ -462,7 +462,7 @@ async def test_tool_params_passed_to_model_options(self, mock_module):
                     function=FunctionDefinition(
                         name="test_func",
                         description="A test function",
-                        parameters=FunctionParameters(RootModel={"type": "object"}),
+                        parameters=FunctionParameters({"type": "object"}),
                     ),
                 )
             ],
@@ -471,7 +471,7 @@ async def test_tool_params_passed_to_model_options(self, mock_module):
                 FunctionDefinition(
                     name="legacy_func",
                     description="A legacy function",
-                    parameters=FunctionParameters(RootModel={"type": "object"}),
+                    parameters=FunctionParameters({"type": "object"}),
                 )
             ],
             function_call="auto",