Pre-commit convention: hooks that modify files must return exit code 1 so pre-commit knows to re-stage and re-run. Our three export hooks (export-functions, export-module-tree, export-skills-directory) always returned 0 after writing.

• Export hooks: Compare generated content against existing file before writing. Write only on diff. Return 1 if modified, 0 if unchanged.
• Refactor export-skills-directory.py: Extract _collect_skills() helper to stay within ruff's PLR0912 branch limit after adding the comparison logic.
• Skill docs: Update usethis-prek-hook-bespoke-create skill to document this exit code convention for future hook authors.

Core pattern applied to each hook:

try:
    existing = output_file.read_text(encoding="utf-8")
except FileNotFoundError:
    existing = None

modified = content != existing
if modified:
    output_file.parent.mkdir(parents=True, exist_ok=True)
    output_file.write_text(content, encoding="utf-8")

return 1 if modified else 0