Svelte 5: runes and a new mental model

Svelte 5 is not a cosmetic major. It rewires the framework's core programming model while trying to preserve the directness that made Svelte attractive in the first place.

The center of gravity is runes: a new way to express reactivity explicitly and consistently across components and extracted logic. The release also promises smaller, faster, more reliable apps while staying largely backwards-compatible with Svelte 4 for most teams.

That combination is the real accomplishment. Svelte 5 gives the framework a stronger long-term model without turning migration into a punitive rewrite exercise.