fix: handle null response.output in parse_response

[nightcityblade]

Summary

Handle responses where response.output is null when parsing response snapshots, avoiding a TypeError during response.completed handling.

Changes

• Iterate over response.output or [] in parse_response()
• Add a targeted regression test covering a Response with null output

Testing

• uv run pytest tests/lib/responses/test_responses.py -q
• uv run pyright src/openai/lib/_parsing/_responses.py tests/lib/responses/test_responses.py

Fixes #3325

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve accumulated stream output when final output is null

When streaming, the API can send response.completed with event.response.output as null after earlier response.output_item.* and delta events have populated the snapshot. ResponseStreamState.accumulate_event() stores _completed_response from parse_response(event.response), and get_final_response() returns that object, so this fallback turns those completed streams into a parsed response with empty output/output_text, discarding the already accumulated content instead of parsing the snapshot.

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[nightcityblade]

Thanks for catching this. I updated the stream accumulator so that when the terminal response.completed payload has output: null, it preserves the accumulated snapshot output while keeping the final response metadata. I also added a regression test covering streamed output deltas followed by a completed event with null output.

Tests run:

• uv run pytest tests/lib/responses/test_responses.py -q
• uv run ruff check src/openai/lib/streaming/responses/_responses.py tests/lib/responses/test_responses.py
• uv run ruff format --check src/openai/lib/streaming/responses/_responses.py tests/lib/responses/test_responses.py

[marcuswood-oai]

Thank you for the contribution! The null-output parsing and stream recovery fix has landed in #3345, so I am closing this PR as superseded. We appreciate your help!