Clear and concise description of the problem

As a developer using Vite, I want to be able to override rollupOptions.manualChunks without losing the default behaviors from Vite, so that I don't have to reimplement the wonderful things Vite does for me

Suggested solution

Two solutions come to mind:

• Exposing the default rollupOptions.manualChunks implementation so that my function can call it
• Special-casing the rollupOptions.manualChunks option and "merging" it with the Vite default (ie, call myChunks ?? viteChunks since the function should already return undefined to use rollup defaults)

Honestly I think either would work nicely!

Alternative

No response

Additional context

No response

Validations

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