Python: Improve AG-UI tool call argument protocol conformance

[White-Mouse]

Summary

• make AG-UI TOOL_CALL_ARGS handling check the event toolCallId against the active tool call
• ignore argument fragments that do not belong to the active tool call instead of attaching them to another call
• clear active tool-call state only when the matching TOOL_CALL_END arrives
• add converter and client regression coverage for mismatched argument events

Details

This is a robustness and AG-UI protocol conformance fix. TOOL_CALL_ARGS events carry a tool-call identifier, and the client-side converter should keep streamed argument fragments bound to that identifier while it builds FunctionCallContent.

With this change, malformed or out-of-order argument fragments no longer get attached to the currently active tool call when their toolCallId points at a different call.

Validation

From python/:

• uv run --group dev pytest -q --disable-warnings packages/ag-ui/tests/ag_ui/test_event_converters.py::TestAGUIEventConverter::test_tool_call_args_must_match_current_tool_call_id packages/ag-ui/tests/ag_ui/test_ag_ui_client.py::TestAGUIChatClient::test_tool_call_args_id_mismatch_does_not_execute_current_client_tool
• uv run --group dev pytest -q --disable-warnings packages/ag-ui/tests/ag_ui/test_event_converters.py packages/ag-ui/tests/ag_ui/test_ag_ui_client.py
• uv run --group dev pytest -q --disable-warnings packages/ag-ui/tests/ag_ui
• uv run --group dev python -m py_compile packages/ag-ui/agent_framework_ag_ui/_event_converters.py packages/ag-ui/tests/ag_ui/test_event_converters.py packages/ag-ui/tests/ag_ui/test_ag_ui_client.py
• uv run --group dev ruff check packages/ag-ui/agent_framework_ag_ui/_event_converters.py packages/ag-ui/tests/ag_ui/test_event_converters.py packages/ag-ui/tests/ag_ui/test_ag_ui_client.py
• git diff --check

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds safeguards to prevent TOOL_CALL_ARGS events from being incorrectly associated with the “current” tool call when IDs mismatch, with regression tests covering the expected behavior.

Changes:

• Ignore TOOL_CALL_ARGS when toolCallId doesn’t match the active tool call ID (and log a warning).
• Update tool-call end handling to conditionally clear current tool state based on matching IDs.
• Add tests to ensure mismatched IDs don’t rebind arguments or execute the wrong client tool.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
python/packages/ag-ui/agent_framework_ag_ui/_event_converters.py	Adds toolCallId mismatch checks for TOOL_CALL_ARGS and conditional state reset on TOOL_CALL_END.
python/packages/ag-ui/tests/ag_ui/test_event_converters.py	Adds regression test ensuring mismatched TOOL_CALL_ARGS don’t attach to the wrong tool call.
python/packages/ag-ui/tests/ag_ui/test_ag_ui_client.py	Adds client-level regression test ensuring mismatched args don’t cause execution of the current tool.