init commit

app/models/message.py

@@ -0,0 +1,50 @@
+"""Message schema for LLM conversation history."""
+
+from typing import Any, Literal
+
+from pydantic import BaseModel, Field
+
+from app.models.tool_call import ToolCall
+
+
+class Message(BaseModel):
+    """A single message in the conversation history.
+
+    Follows the OpenAI chat completions message format with support for
+    system, user, assistant, and tool roles.
+    """
+
+    role: Literal["system", "user", "assistant", "tool"] = Field(
+        description="Role of the message sender"
+    )
+    content: str | None = Field(default=None, description="Text content of the message")
+    tool_calls: list[ToolCall] | None = Field(
+        default=None, description="Tool calls made by the assistant"
+    )
+    tool_call_id: str | None = Field(
+        default=None, description="ID of the tool call this message responds to (role=tool)"
+    )
+    name: str | None = Field(
+        default=None, description="Name of the tool that produced this message (role=tool)"
+    )
+
+    def to_api_dict(self) -> dict[str, Any]:
+        """Serialize to a dict suitable for the OpenAI-compatible API.
+
+        Strips None-valued fields to keep the payload clean.
+        """
+        data: dict[str, Any] = {"role": self.role}
+
+        if self.content is not None:
+            data["content"] = self.content
+
+        if self.tool_calls is not None:
+            data["tool_calls"] = [tc.model_dump() for tc in self.tool_calls]
+
+        if self.tool_call_id is not None:
+            data["tool_call_id"] = self.tool_call_id
+
+        if self.name is not None:
+            data["name"] = self.name
+
+        return data