feat: harden public OpenAI API contracts

backend/services/openai_realtime/events.py

@@ -6,6 +6,9 @@ from dataclasses import dataclass
 from typing import Any
 from uuid import uuid4
 
+from pydantic import ValidationError
+from services.openai_realtime.schemas import REALTIME_CLIENT_EVENT_ADAPTER
+
 
 SUPPORTED_CLIENT_EVENTS = {
     "session.update",
@@ -51,7 +54,21 @@ def require_event(message: object) -> dict[str, Any]:
             param="type",
             event_id=str(message.get("event_id") or "") or None,
         )
-    return message
+    try:
+        validated = REALTIME_CLIENT_EVENT_ADAPTER.validate_python(message)
+    except ValidationError as exc:
+        first = exc.errors(include_url=False)[0]
+        location = list(first.get("loc") or [])
+        if location and location[0] == event_type:
+            location.pop(0)
+        param = ".".join(str(part) for part in location) or None
+        raise RealtimeEventError(
+            str(first.get("msg") or "Event does not match the schema"),
+            code="invalid_event",
+            param=param,
+            event_id=str(message.get("event_id") or "") or None,
+        ) from exc
+    return validated.model_dump(exclude_none=True)
 
 
 def assistant_id_from_model(model: object) -> str: