date-and-timezone.txt
Here is my date handling: <paste>

Audit it against the rules that matter:
- Store in UTC. Convert only when displaying to a person.
- Never build a date from string slicing.
- "Today" depends on who is asking — where does my code assume mine?
- Watch for daylight saving: a day is not always 24 hours, and some
  local times happen twice or not at all.

Point at each line that breaks a rule and show me the fix.

Test with a user in a different hemisphere and a date near the end of the month. That combination surfaces almost every timezone bug you have.