Hook scripts used hardcoded "\n" for newline characters when constructing file content. Replace with os.linesep and newline="" I/O to explicitly respect the OS newline convention.

Hook changes

All five file-writing hooks (export-functions, export-skills-directory, export-module-tree, fix-readme, fix-doc-sync) updated with the same pattern:

# Before
content = "\n".join(lines) + "\n"
existing = output_file.read_text(encoding="utf-8")
output_file.write_text(content, encoding="utf-8")

# After
content = os.linesep.join(lines) + os.linesep
with open(output_file, encoding="utf-8", newline="") as f:
    existing = f.read()
output_file.write_text(content, encoding="utf-8", newline="")

newline="" is required on both read and write to prevent Python's text mode from double-translating \r\n on Windows. read_text(newline=...) requires Python 3.13, so reads use open() instead (project minimum is 3.10).

For fix-readme.py, Jinja2 renders with \n internally, so conversion happens once after template.render(). For fix-doc-sync.py, _build_replacement() uses os.linesep and all file I/O uses newline="".

Agent skill update

Added a "Newline endings" section to the usethis-prek-hook-bespoke-create skill (v1.1 → v1.2) documenting the os.linesep + newline="" pattern for future hook authoring.