แหล่งความจริงเพียงหนึ่งเดียว

A single source of truth means every piece of state lives in exactly one spot. Everything else reads from it, never copies it.

If two Composables each hold their own copy of the same value, they can drift apart. One updates, the other shows stale data. 😬

Hoisting naturally gives you a single owner. The parent holds the value; children only receive it, so there is nothing to fall out of sync.

Children should always read from the hoisted value, not from a private copy. When the source changes, every reader updates together.

Need a filtered or formatted version? Derive it from the source instead of storing a second copy that can go stale.

When a derived value is expensive, wrap it in derivedStateOf so it recomputes only when its inputs truly change.

Want two fields editing the same data? Point both at the same hoisted state. They share one truth and stay perfectly in sync.

A common bug is copying a parameter into local state inside an effect. Now you have a mirror that silently goes out of date.

If a child needs to change shared data, lift the state to a common parent instead of duplicating it. One owner, many readers.

A single source makes bugs obvious: there is only one place a value can be wrong, so you know exactly where to look. ✅

State should be owned once and shared by reference. Duplicate state is the root of most sync bugs in Compose.

Why is keeping a single source of truth important?

Keep each fact in one place, read or derive from it, and never mirror it. One source of truth means no drift. 🚀