Log a packaged food by its barcode

Microwave on the counter, frozen-meal box in your hand, two minutes until you eat. You scan the barcode instead of typing the name. The agent pulls the product, fills the macros from the shared catalog, and logs it to lunch.

What the agent needs to hear

Behind your sentence, the agent works backwards to three pieces: the barcode (scanned via your phone camera or read aloud as digits), the quantity (default: the package’s stated serving — usually one serving; override with « half the package », « two servings », « 200 g »), and the meal slot (default: time-of-day infers it).

The agent looks up the barcode in the shared catalog and shows the matched product, its macros, and the quantity on a preview card before saving. The digits carry the identity, and the catalog carries the rest. If you’re scanning at an odd hour, name the slot: « log this as lunch even though it’s 4 pm » lands cleanly.

Quantity and what the package says

Products in the catalog carry a stated serving size — « 1 nugget », « 30 g », « 1 bar ». The default log uses one serving’s worth, with macros scaled from the catalog values.

You override in plain language. « Two servings » doubles it; « 150 g » switches to a weight basis; « half the package » reads « servings per container » and halves it. « The whole package » carries cleanly without you doing the multiplication.

Time of day infers the meal slot — noon goes to lunch, 9 pm to dinner. Numbers override defaults, and units stick.

When the barcode isn’t found

Most well-known brands are in the shared catalog. When the agent doesn’t find a match, it asks once: « no product matched that barcode — want to create a custom food and log it together? »

You provide the macros from the package label — protein, carbs, fat, calories, serving size — and the agent saves the food and logs the entry in the same step. The next time the same barcode is scanned, the product is already there. One person’s miss becomes everyone’s hit.

When the agent gets it wrong

Scans aren’t infallible. Three failure modes show up. The wrong product matched — different brand, outer carton — and the preview shows a food you don’t recognize: « no, that’s a different chicken nugget, search by name instead ».

The serving math is off — one serving logged when you ate three: « three servings, not one ». The package’s printed weight doesn’t match the scale — box says 200 g, you weighed 180: « scale it down, actual weight was 180 g ».

The preview card is the chokepoint. Talk to it the way you’d correct a friend who misheard.

What makes barcode logging worth using

Three things decide whether scanning beats typing:

• the product is a packaged item with a real barcode (homemade meals and weighed-ingredient cooking don’t need this path; barcode lookup is for box-and-bag foods)
• the quantity you log matches what you actually ate (the default serving is convenient but inflates the log when you ate less)
• a mismatched scan gets corrected, not accepted (a similar product silently substituted corrupts the macros until you fix it; the preview card is where you catch it)

Used on the right foods, barcode logging shrinks a packaged meal to a two-second interaction without sacrificing macro fidelity.