- a client on an old tablet or laptop in your kitchen, (sitting on the fridge and also holding a recipe book),
- and a server serving a web page with shopping check list, automatically updated, to a mobile app.
Every time you run out of something (eggs, sugar, tea, …), you add this thing to the list of ‘missing’ goods (lookup/predictive input make adding easier). When you go shopping, whatever you added is in the shopping list, when you buy, you cross out the entry.
A background knowledge module knows how to measure different things (sugar in kg or packets, eggs are counted, etc.), and suggests default amounts to buy. If you have to buy too often, the amount is automatically increased.