Exercise 2: Why version Is Just a Number — Possible Solution
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WHY A PLAIN NUMBER, NOT THE ITEMS ARRAY
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If ItemsContext held the actual item data, every feature that needs
items - alerts, search, recipes - would either have to read from that
one shared copy (forcing them to share the exact same shape and
filtering logic) or the Context would need to somehow hold several
different views of the same underlying data at once. Neither is what
this app actually needs. What every feature genuinely needs is just to
know "something changed, go refetch your own view" - and a plain
incrementing number is enough to express that: each consumer's own
useEffect depends on version, so any change to it triggers a refetch,
regardless of what the new value actually is.

WHAT THIS CONTEXT IS AND ISN'T RESPONSIBLE FOR
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It is responsible for coordination - broadcasting "a mutation just
happened" to anything that cares. It is explicitly not responsible for
storage or caching - it never holds item data itself, and every hook
(useExpiryAlerts, the search hook, RecipeSuggestions) still owns its
own fetch call to its own Express route, gets back exactly the shape it
needs, and manages its own loading state independently.

WHY THIS WORKS AS AN ANSWER
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It correctly explains why a single number is sufficient to express "a
change happened" without needing to represent what changed, and it
correctly draws the line between what this Context does (signal
coordination) and what it deliberately avoids doing (owning or caching
actual data), rather than describing version as an arbitrary
implementation detail.