sveltejs/kit

`manualChunks` is not working on `2.17.2`

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#13,496 opened on Feb 23, 2025

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bughelp wanted

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Description

Describe the bug

Recently I updated @sveltejs/kit from 2.16.1 to 2.17.2 on a website that used manualChunks to reduce the number of generated chunks and group code by concern.

The result is the following build:

Image

Note that named chunks are on the server and hashed chunks on the client.

Reproduction

Run pnpm build and see the generated client chunks on .svelte-kit/output/client/_app/immutable/chunks

https://stackblitz.com/edit/sveltejs-kit-template-default-gbsyrknf?description=The%20default%20SvelteKit%20template,%20generated%20with%20create-svelte&file=package.json,vite.config.js&title=SvelteKit%20Default%20Template

Logs

System Info

Does not matter

Severity

annoyance

Additional Information

No response

Contributor guide

Research direction
Investigate the `vite.config.js` file in the provided reproduction. The issue is that `manualChunks` defined in the Vite config are not applied to client chunks; instead, named chunks end up on the server. Compare the behavior between SvelteKit versions 2.16.1 and 2.17.2. Look for recent commits or changes in SvelteKit's build process that may have affected chunking logic. Check the output in `.svelte kit/output/client/ app/immutable/chunks` to confirm the lack of manual chunk grouping.
Tech stack
javascriptsvelte
Domain
frontendbuild system
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
SvelteKit basicsVite config understanding
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30