[Bug]: lit-html is loaded twice

[jpzwarte]

Describe the bug

As of Storybook 9 (using rc.0 atm), i've noticed the following console error:

lit-html.ts:226 Multiple versions of Lit loaded. Loading multiple versions is not recommended. See https://lit.dev/msg/multiple-versions for more information.

I traced this to lit-html being loaded twice: once by storybook itself, and once because we use Lit for our web components.

@shilman Perhaps consider not bundling lit-html with Storybook and instead make it a peerDependency?

Reproduction link

http://localhost:6006/?path=/story/actions-button--basic

Reproduction steps

lit-html only outputs the warning when in dev mode, so i can't link to our production storybook.

System

Storybook Environment Info:

  System:
    OS: macOS 15.5
    CPU: (16) arm64 Apple M4 Max
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.15.1 - /opt/homebrew/bin/node
    Yarn: 4.8.1 - /opt/homebrew/bin/yarn <----- active
    npm: 10.9.2 - /opt/homebrew/bin/npm
  Browsers:
    Chrome: 136.0.7103.114
    Safari: 18.5
  npmPackages:
    @storybook/addon-a11y: ^9.0.0-rc.0 => 9.0.0-rc.0 
    @storybook/addon-docs: ^9.0.0-rc.0 => 9.0.0-rc.0 
    @storybook/web-components-vite: ^9.0.0-rc.0 => 9.0.0-rc.0 
    chromatic: ^11.28.2 => 11.28.2 
    storybook: ^9.0.0-rc.0 => 9.0.0-rc.0

Additional context

No response

[greptile-apps]

** Disclaimer** This information might be inaccurate, due to it being generated automatically
This issue can be resolved by making lit-html a peer dependency in Storybook's web-components framework package. Changes needed: 1. In code/frameworks/web-components-vite/package.json, move lit-html from dependencies to peerDependencies 2. Update the version range to match Lit's recommended version: "lit-html": "^2.0.0" 3. Add lit-html to peerDependenciesMeta as optional: json "peerDependenciesMeta": { "lit-html": { "optional": true } } This will allow projects to use their own version of lit-html without conflicts with Storybook's bundled version.

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[shilman]

AFAIK there have been no changes to the framework in SB9, so this is likely an existing an issue. Have you tried yarn dedupe as a workaround?