Fix BodyPartReader.read() returning bytearray instead of bytes

[terminalchai]

Fixes #12404

Problem

\BodyPartReader.read()\ internally accumulates data into a \�ytearray\ but returned it directly, violating the documented return type of \�ytes.

Both code paths were affected:

\\python

decode=False path

return data # bytearray, not bytes

decode=True path

return decoded_data # bytearray, not bytes
\\

This causes a silent type contract violation. Downstream code doing \isinstance(result, bytes)\ would fail, and attempting to JSON-serialize the result raises \TypeError.

Fix

Wrap both return values in \�ytes():

\\python
return bytes(data)
return bytes(decoded_data)
\\

Tests

Added two regression tests in \ ests/test_multipart.py:

• \ est_read_returns_bytes_not_bytearray\ — decode=False path
• \ est_read_decode_returns_bytes_not_bytearray\ — decode=True path

Changelog

Added \CHANGES/12404.bugfix.rst.

[codspeed-hq]

Merging this PR will not alter performance

✅ 67 untouched benchmarks
⏩ 4 skipped benchmarks¹

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_{Comparing terminalchai:fix/multipart-read-returns-bytes (3dda5cb) with master (1842c3e)²}

Footnotes

1. 4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on master (573313e) during the generation of this report, so 1842c3e was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩