Read the person's daily calorie and macro targets and unit system before planning meals or judging a day, unless already read in this conversation. Each period applies from startsOn until the next; values null means no targets from that day, so judge a past day by its own period. Targets are always kilocalories and grams. units (metric, imperial for US customary, or uk; null when unknown) is how to talk to the person about portions and weights; meal items still use each food's own units. Diet, allergies, likes and dislikes are not saved: use what the person says in the conversation, treat stated allergies as constraints, and never infer allergy safety from missing product data.