`@vitejs/plugin-rsc` build fails on Vite 8.0.8 with Deno 2.7

Related plugins

• plugin-react

• plugin-react-swc

• plugin-rsc

Describe the bug

Environment

• Vite: 7.x → 8.0.8 (regression)
• @vitejs/plugin-rsc: 0.5.23
• Runtime: Deno 2.7

The build fails only during vite build (dev mode works fine) with the following error:

[plugin rsc:virtual:vite-rsc/assets-manifest]
AssertionError: The expression evaluated to a falsy value:

  assert(this.environment.mode === "dev")

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:

  assert(this.environment.mode === "dev")

Root Cause

Vite 8 switched to Rolldown (Rust-based bundler) and introduced changes to the Environment API and virtual module handling. This exposed two issues in @vitejs/plugin-rsc:

1. Virtual modules prefixed with virtual:vite-rsc/ are not properly recognized by Rolldown unless they are explicitly prefixed with the standard \0 (null byte) convention.
2. The assets-manifest virtual plugin still reaches the strict assert(this.environment.mode === "dev") during production builds, even though the plugin contains logic to treat it as external: true in build mode.

Required Workarounds

To make builds succeed on Vite 8 + Deno 2.7, we currently need these two patches (placed early in the plugins array, before rsc()):

Patch 1: virtual-rsc-scheme-fix.ts (fixes virtual module resolution - in dev and build)

import type { Plugin } from 'vite';

export function virtualRscSchemeFix(): Plugin {
  return {
    name: 'virtual-rsc-scheme-fix',
    enforce: 'pre' as const,

    resolveId(id: string) {
      if (id.startsWith('virtual:vite-rsc/')) {
        return '\0' + id;   // Standard virtual module prefix for Rolldown/Vite
      }
    },
  };
}

Patch 2: fix-rsc-assets-manifest-build.ts (forces correct build behavior)

import { Plugin } from 'vite';

export function fixRscAssetsManifestBuild(): Plugin {
  return {
    name: 'fix-rsc-assets-manifest-build',
    enforce: 'pre' as const,

    resolveId(source) {
      if (source === 'virtual:vite-rsc/assets-manifest') {
        if (this.environment?.mode === 'build') {
          return { id: source, external: true };
        }
      }
    },
  };
}

Plugin order is very sensitive — moving these patches earlier in the array (or changing the order of other plugins) can make the build succeed or fail.

Additional Context

• Uses a full multi-environment setup (rsc, ssr, client) with @deno/vite-plugin.
• Worked reliably on Vite 7.
• The combination of Rolldown’s stricter virtual module handling + Deno’s npm compatibility layer appears to trigger the issue more easily.

Reproduction

gleez/deno-rsc-starter

Steps to reproduce

No response

System Info

Vite: 7.x → 8.0.8 (regression)
@vitejs/plugin-rsc: 0.5.23
Runtime: Deno 2.7

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start with @vitejs/plugin-rsc's virtual:vite-rsc/assets-manifest handling and the Vite 8/Rolldown Environment API, then reproduce the failure with gleez/deno-rsc-starter. Compare the Vite 7 and Vite 8 build paths; done means vite build succeeds on Vite 8.0.8 with Deno 2.7 without the external workaround plugins.