[OpenAI] Fix tool_choice=required streaming when output has trailing extra data

[maylikenoother]

Problem:

When using tool_choice="required", OpenAIServingChat.extract_tool_call_required_streaming parses the partial stream as JSON. If the model emits a valid JSON tool-call array and then continues with trailing tokens (e.g. "\nDONE"), parsing can hit a JSON "Extra data" case and stop/behave incorrectly.

Fix:

• Parse required-tool streaming output using partial_json_loads(..., Allow.ALL) so we can safely parse the first JSON value while tolerating trailing extra data.
• Continue to treat incomplete JSON as "not enough tokens yet" (no behavior change there).

Tests:

• Add regression test: test_streaming_output_valid_with_trailing_extra_data (tests/tool_use/test_tool_choice_required.py)

[gemini-code-assist]

Code Review

This pull request addresses an issue in streaming mode with tool_choice="required" where trailing data after a valid JSON tool call would cause a parsing error. The fix correctly uses a partial JSON parser that tolerates extra data. The changes are logical and a regression test is included. I've provided two suggestions to improve the code: one to make the new test case more robust by adding specific assertions, and another to simplify exception handling by combining redundant except blocks.

[chaunceyjiang]

Thanks~

[maylikenoother]

Thanks~

@chaunceyjiang
All the failed checks – are they going to be fixed from your end?