Vite 8: deprecated config options cause build warnings

[Divkix]

Description

After upgrading to vinext 0.0.30 with Vite 8.0.0, the build produces warnings about deprecated config options:

Warning: Invalid input options (1 issue found)
- For the "treeshake.preset". Invalid key: Expected never but received "preset".

Warning: Invalid output options (1 issue found)
- For the "experimentalMinChunkSize". Invalid key: Expected never but received "experimentalMinChunkSize".

Exact Location

The deprecated options are defined in packages/vinext/src/index.ts:

Line 493-496 - experimentalMinChunkSize:

const clientOutputConfig = {
  manualChunks: clientManualChunks,
  experimentalMinChunkSize: 10_000,  // REMOVED in Vite 8 (Rolldown)
};

Line 523-526 - treeshake.preset:

const clientTreeshakeConfig = {
  preset: "recommended" as const,   // INVALID in Vite 8 (Rolldown)
  moduleSideEffects: "no-external" as const,
};

These configs are applied in multiple places:

• Lines 1235, 1243 (multi-env builds)
• Lines 1447-1448, 1466-1467 (Pages Router)
• packages/vinext/src/cli.ts lines 390-391 (CLI builds)

Root Cause

Vite 8 uses Rolldown instead of Rollup. These options are Rollup-specific:

1. experimentalMinChunkSize - This was a Rollup feature, removed in Vite 8/Rolldown. Rolldown handles chunk merging differently.

2. treeshake.preset - This was a Rollup treeshake option. In Vite 8 with Rolldown, treeshake configuration should use build.rolldownOptions.treeshake instead.

Suggested Fix

Based on Vite 8 migration docs, the fix options are:

1. Remove entirely - Vite 8/Rolldown has better default treeshaking
2. Use Vite 8 config - Move treeshake config to build.rolldownOptions.treeshake
3. Conditional application - Only apply these options when building with Vite 7

Example fix for treeshake:

// Instead of treeshake.preset, use:
build: {
  rolldownOptions: {
    treeshake: {
      moduleSideEffects: "no-external",
    },
  },
}

For experimentalMinChunkSize - this feature may need to be reimplemented differently or removed if Rolldown handles it automatically.

Impact

• Build still works (Vite 8 silently ignores invalid keys)
• Some optimizations may not be applied
• Produces warning noise in CI/CD

Environment

• vinext: 0.0.30
• vite: 8.0.0
• @cloudflare/vite-plugin: 1.28.0