The local days_in_month table in _increment_date() listed July as
having 30 days instead of 31, diverging from the correct table in
_days_in_month(). This made July 31 unreachable when incrementing
the day field in settings mode.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSucp94GA31sshe5AjvSzQ