Why does Vitest Browser mode start two Vite servers

[maxpatiiuk]

Hi. I noticed that Vitest browser mode starts two Vite dev servers
The second server is started here:

vitest/packages/vitest/src/node/project.ts

Lines 507 to 510 in b526896

	const browser = await createBrowserServer(
	this,
	this.vite.config.configFile,
	[

I'm curious as to what is the reason why two servers are created rather than have one Vite server.
Is it because browser mode requires changing Vite configuration, and by the time Vitest knows that the config enables browser mode, it is too late to modify the config?

As a plugin developer, what should I be aware of and how should I handle this? Thanks.

[hi-ogawa]

Here is the rational and also the plan to be changed #6912

For plugin authors, I'd expect there no issue unless it relies on something global hack globalThis.__myPluginState. Currently each Vite server is loading a config file separately and thus plugins are instantiated separately, so it shouldn't break Vite/rollup plugin conventions.

[maxpatiiuk]

Thank you for the information!
I am happy to hear this would change in the future. I don't have errors with current setup but it is a bit surprising and has performance overhead