Svelte
A SvelteKit 3 prerelease series launched alongside a wave of stable improvements across the ecosystem.
Real-time queries got a dedicated transport. Kit 2.63.1 and the 3.0.0-next builds switched query.live to use Server-Sent Events instead of polling, giving live query instances a lower-overhead push channel.1 The 3.0.0-next.1 release also reinstated $app/environment as an alias for $app/env so dependencies that import the old path continue to work.2
Commands can now receive files directly. Kit 2.64.0 added support for File objects in command arguments, and fixed a bug where server components were bundled even when SSR was disabled for a route.3
Adapter builds migrated to rolldown. The Vercel, Node, and static adapters each published 0-next prereleases targeting SvelteKit 3. The Vercel adapter switched edge function bundling from rollup to rolldown and raised the build target to es2022.4 The Node adapter and static adapter now require SvelteKit 3, and the enhanced-img and package tools bumped their Node floor to Node 22.5
TypeScript 6.0 landed in SvelteKit. Kit 2.56.0 added TypeScript 6.0 support alongside field.as(type, value) for pre-populated form defaults and hydratable transport for richer query result types.6
Explicit environment variable handling tightened. Several Kit releases fixed Vite import timing, ensured version is defined when reading from $app/env with explicit env vars, and added a graceful warning when $app/environment is used alongside the new explicit mode.
Async reactivity and effect cleanup continued in Svelte 5. Version 5.56.3 made destroyed effects silently ignore errors rather than surface them, and corrected BigInt typing in $state.snapshot() return values.7 Earlier 5.55.x releases addressed stale derived resolution, {#await} batch handling, and SSR context reapplication.
The June 2026 blog post highlighted the new query.live(...) function for accessing real-time server data, while the May post noted Svelte's inclusion in the ThoughtWorks Technology Radar and the experimental arrival of community plugins in the Svelte CLI.89