Loaded virtual module is unable to access parent react context

[Neo-Ciber94]

Describe the bug

I'm not fully sure if this is a bug or is how it works.

I have a react tree with a context on top:

function ServerEntry({ App }: { App: ComponentType }) {
  const theme = "dark";

  return (
    <ThemeContext.Provider value={theme}>
      <Root>
        <App />
      </Root>
      <script
        id="theme"
        dangerouslySetInnerHTML={{
          __html: `window.initialTheme = ${JSON.stringify(theme)}`,
        }}
      />
    </ThemeContext.Provider>
  );
}

The App is an export from a virtual module:

export async function handleRequest(
  _req: http.IncomingMessage,
  res: http.ServerResponse
) {
  const viteServer = getViteServer();
  const { default: Component } = await viteServer.ssrLoadModule("virtual:app");
  const { pipe } = renderToPipeableStream(<ServerEntry App={Component} />, { ... })
}

But when I try to access the context, I get an error because is reset to null:

import { createContext, useContext } from "react";

export type Theme = "dark" | "light";
export const ThemeContext = createContext<Theme | null>(null);
export function useTheme() {
  const theme = useContext(ThemeContext);
  if (!theme) {
    throw new Error('"ThemeContext" was not available');
  }
  return theme;
}

Reproduction

https://github.com/Neo-Ciber94/vite-ssr-react-context-issue

Steps to reproduce

yarn install and yarn dev

System Info

System:
    OS: Windows 11 10.0.22631
    CPU: (8) x64 Intel(R) Core(TM) i5-8300H CPU @ 2.30GHz
    Memory: 3.74 GB / 15.88 GB
  Binaries:
    Node: 20.14.0 - D:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - D:\Program Files\nodejs\yarn.CMD
    npm: 10.7.0 - D:\Program Files\nodejs\npm.CMD
    pnpm: 9.3.0 - D:\Program Files\nodejs\pnpm.CMD
    bun: 1.1.10 - ~\.bun\bin\bun.EXE
  Browsers:
    Edge: Chromium (126.0.2592.56)
    Internet Explorer: 11.0.22621.3527
  npmPackages:
    @vitejs/plugin-react: ^4.3.1 => 4.3.1
    vite: ^5.3.1 => 5.3.1

Used Package Manager

yarn

Logs

Error: "ThemeContext" was not available
at Module.useTheme (.../src/context.tsx:10:11)
at App (virtual:app:8:39)

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. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[hi-ogawa]

This is an expected behavior. It's important to note that you have src/context.tsx imported from two worlds, namely inside and outside of vite ssr module graph:

• (outside) vite.config.ts -> entry.server.tsx -> context.tsx
• (inside) ssrLoadModule("virtual:app") -> context.tsx

You might need to rework architecture so that entry.server.tsx only lives in vite ssr module graph via ssrLoadModule("/src/entry.server").

[Neo-Ciber94]

That explains the behaviour, it felt like the component imported was separated from my app.

Thank you very much @hi-ogawa for the explanation and providing a fix.