fix: chat api in explore page reject blank conversation id (#29500)

api/controllers/console/explore/completion.py

@@ -2,7 +2,7 @@ import logging
 from typing import Any, Literal
 from uuid import UUID
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 from werkzeug.exceptions import InternalServerError, NotFound
 
 import services
@@ -52,10 +52,24 @@ class ChatMessagePayload(BaseModel):
     inputs: dict[str, Any]
     query: str
     files: list[dict[str, Any]] | None = None
-    conversation_id: UUID | None = None
+    conversation_id: str | None = None
-    parent_message_id: UUID | None = None
+    parent_message_id: str | None = None
     retriever_from: str = Field(default="explore_app")
 
+    @field_validator("conversation_id", "parent_message_id", mode="before")
+    @classmethod
+    def normalize_uuid(cls, value: str | UUID | None) -> str | None:
+        """
+        Accept blank IDs and validate UUID format when provided.
+        """
+        if not value:
+            return None
+
+        try:
+            return helper.uuid_value(value)
+        except ValueError as exc:
+            raise ValueError("must be a valid UUID") from exc
+
 
 register_schema_models(console_ns, CompletionMessagePayload, ChatMessagePayload)