Keys en Flutter ayudan al framework a identificar y preservar correctamente los widgets entre reconstrucciones — particularmente importante para widgets con estado en listas que se reordenan, agregan o eliminan. Comprender cuándo se necesitan las keys previene errores sutiles y confusos.
Por qué es importante
During rebuilds, Flutter MATCHES new widgets to existing elements/state by POSITION and
TYPE. Usually this works fine. But when widgets of the SAME TYPE are reordered/added/
removed in a list, position-matching gets confused → state attaches to the WRONG widget.
→ KEYS give widgets a stable IDENTITY so Flutter matches them correctly across changes.
