Svelte 5.56.9

Svelte 5.56.9 — released August 12, 2026. This is a patch release focused on the compiler and the AST printer. No new features, no breaking changes: four targeted fixes that tighten output correctness and quiet the edge cases reported by the community.

Overview

Svelte 5.56.9 addresses regressions and output-quality issues surfaced in the 5.56 line. The changes concentrate on the svelte/compiler printer — the code path responsible for serializing the AST back to source — and on the runtime's handling of controlled each blocks during batching.

Fixes in This Release

• Controlled each fast path — the fast path for controlled each blocks is now skipped while another batch is pending, preventing inconsistent intermediate renders (#18625).
• Whitespace handling in the printer — improved whitespace preservation inside the AST printer, so compiled output matches author intent more closely (#18638).
• Duplicate comments in attributes — comments inside attributes are no longer duplicated when the AST is printed (#18636).
• CSS comments preserved — the printer now preserves CSS comments in the AST output instead of dropping them (#18637).

Deprecations and Removals

None. Svelte 5.56.9 introduces no deprecations and removes no public APIs.

How to Upgrade

Upgrade via your package manager of choice. For npm users:

npm install -D [email protected]

Contributions from the community continue to drive the 5.56 maintenance line; the fixes above were authored and reviewed by the Svelte maintainers with input from issue reporters. As always, thank you to everyone who filed reproductions.