Nutrition scope

Choice: Track calories, protein, carbs and fat. Do not ask about allergies. Do not estimate other nutrients from a photo. Show sugar, fibre, salt and saturated fat only for a barcode product, as printed on its label: FEAT-0003.

Why:

• A photo cannot see allergens, sugar or salt. Showing them would break what the app stands for: mark what it does not know.
• Asking about allergies implies the app keeps people safe. Its data cannot do that, and a mistake could hurt someone.
• Demand is low: of 1,600 rival reviews, about 4 mention allergies, 9 sugar, 5 sodium and 18 fiber (rival-reviews).
• Reviews already complain that rivals invent these numbers and give bogus health scores.

Rejected:

• Allergy question, profile or warnings: unsafe, since OpenFoodFacts data is crowd-sourced and a missing allergen reads as "safe".
• Health scores, grades, and warnings about preservatives or additives: a different product, with dedicated rivals, and the rules behind them are opinions.
• Targets or daily totals for extra nutrients: photo meals have no values, so the totals would be wrong.
• Vitamins and minerals: most labels omit them.

Revisit: Extra tracking if paying users ask for a nutrient more often than for anything else. Never allergens.