In _prepare_inputs_and_namespace the return annotation uses tuple[type[math] | _ArrayNamespace, tuple]; callers may rely on concrete tuple element types. Verify downstream usage expects a bare tuple and not specific shapes, and that isinstance checks on the first element work across both math and ArrayNamespace.

The function array_namespace now returns using PEP 604 unions; ensure all internal consumers and any exported typing stubs are updated to match _ArrayNamespace | _ArrayNamespaceWithLinAlg to avoid mypy/pyright mismatches.

file_digest docstring and logic reference Python 3.11 API while targeting 3.10; confirm behavior matches hashlib.file_digest for edge cases (empty files, non-seekable streams) and that digest callable typing covers constructors without args.