zsh_history_today.rb

# Because screw invalid sequences....
clean       = -> s { s.encode!('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '') }
DateHistory = Struct.new(:date, :command)
dt          = DateTime.now
today       = DateTime.new(dt.year, dt.month, dt.day, 0, 0, 0)..DateTime.new(dt.year, dt.month, dt.day, 23, 59, 59)

zsh_history.reverse.reduce([]) { |a, l|
  line = clean[l]
  data = /: (?<date>\d+):\d\;(?<command>.+)$/.match(line) { |m| 
    DateHistory.new(m[1], m[2]) if m[:date] && today.include?(Time.at(m[:date].to_i).to_date)
  }
  a << data if data
  a
}