Set ToolCallPartDelta.tool_call_id when known from previous delta (#1694)

Author: DouweM

pydantic_ai_slim/pydantic_ai/_parts_manager.py

@@ -14,7 +14,7 @@
 from __future__ import annotations as _annotations
 
 from collections.abc import Hashable
-from dataclasses import dataclass, field
+from dataclasses import dataclass, field, replace
 from typing import Any, Union
 
 from pydantic_ai.exceptions import UnexpectedModelBehavior
@@ -198,6 +198,8 @@ def handle_tool_call_delta(
                     return PartStartEvent(index=part_index, part=updated_part)
                 else:
                     # We updated an existing part, so emit a PartDeltaEvent
+                    if updated_part.tool_call_id and not delta.tool_call_id:
+                        delta = replace(delta, tool_call_id=updated_part.tool_call_id)
                     return PartDeltaEvent(index=part_index, delta=delta)
 
     def handle_tool_call_part(

tests/test_parts_manager.py

@@ -104,7 +104,7 @@ def test_handle_tool_call_deltas():
         PartDeltaEvent(
             index=0,
             delta=ToolCallPartDelta(
-                tool_name_delta='1', args_delta=None, tool_call_id=None, part_delta_kind='tool_call'
+                tool_name_delta='1', args_delta=None, tool_call_id=IsStr(), part_delta_kind='tool_call'
             ),
             event_kind='part_delta',
         )
@@ -118,7 +118,7 @@ def test_handle_tool_call_deltas():
         PartDeltaEvent(
             index=0,
             delta=ToolCallPartDelta(
-                tool_name_delta=None, args_delta='"value1"}', tool_call_id=None, part_delta_kind='tool_call'
+                tool_name_delta=None, args_delta='"value1"}', tool_call_id=IsStr(), part_delta_kind='tool_call'
             ),
             event_kind='part_delta',
         )
@@ -196,7 +196,7 @@ def test_handle_tool_call_part():
         PartDeltaEvent(
             index=0,
             delta=ToolCallPartDelta(
-                tool_name_delta=None, args_delta='"value1"}', tool_call_id=None, part_delta_kind='tool_call'
+                tool_name_delta=None, args_delta='"value1"}', tool_call_id=IsStr(), part_delta_kind='tool_call'
             ),
             event_kind='part_delta',
         )