[deanrie]

Checklist

• I have read both the CONTRIBUTING.md and Contributor License Agreement documents.
• I have created an issue or feature request and received approval from xAI maintainers. (two small defects found by reading files.py; no issue filed)
• I have tested my changes locally and they pass all CI checks.
• I have added necessary documentation or updated existing documentation. (CHANGELOG)

Description

Two defects in the files.upload progress path, same for the sync and async clients.

1. _invoke_progress used except TypeError to detect arity. It called progress(uploaded, total) and, on TypeError, retried with progress(chunk_size). That except also catches a TypeError raised inside the user's callback, so the callback was called a second time with one argument and the user saw progress() missing 1 required positional argument: 'total' instead of their own error. The docstring's own example triggers it:

def progress(uploaded, total):
    print(f"Uploaded {uploaded}/{total} bytes ({100*uploaded/total:.1f}%)")

With a non-seekable stream total is None, 100*uploaded/total raises TypeError, and the SDK reports the wrong failure. Arity is now read once from inspect.signature; a callable that cannot be inspected gets the documented two-argument form; exceptions from the callback propagate unchanged. tqdm-style objects with .update are handled as before.

2. _chunk_file_from_fileobj reported the file's full length as total. It seeked to the end and used that offset, ignoring the current position. A file object that has been read past a header (common when the caller inspects magic bytes first) got a total the upload could never reach: (uploaded, total) == (10, 16) for 10 uploaded bytes. Now total = end - current_position, the bytes that will actually be sent.

Tests

tests/sync/files_test.py:

• one-argument plain function receives chunk sizes summing to the payload;
• a two-argument callback that raises TypeError on total=None surfaces its own message (unsupported operand ... NoneType), not the arity one;
• a BytesIO read past a header reports (len(payload), len(payload)) on the last call.

The last two fail on main. uv run pytest tests/sync/files_test.py tests/aio/files_test.py: 74 passed. ruff check, ruff format --check, pyright clean on the touched files.