🐛 Reformatting doesn't work in an IntelliJ project with multiple modules

[donalmurtagh]

IDE and version

IntelliJ 2025.1.2 (Ultimate Edition)

Extension version

1.7.2

Biome version

2.0.0

Operating system

• Windows
• macOS
• Linux

Description

When I try to reformat a file via the hotkey ⌥⇧⌘+L, the Biome formatter options are ignored. Instead, the options configured in Editor | Code Style | JavaScript are used.

It seems the root cause is that the Biome language service is never active for the files that it should support: .vue, .js, etc.

Steps to reproduce

1. Setup an IntelliJ project with biome-web-module and java-module as separate modules as per the reproduction repository
2. Install the Biome IntelliJ plugin if necessary
3. In the Biome IntelliJ settings, enable Biome and "Enable LSP-based code formatting"
4. Notice that the Biome language service does not run when biome-web-module/src/script.js is opened, so reformatting with Biome doesn't work
5. Remove the java-module module from the project
6. Re-open biome-web-module/src/script.js and you should see that the Biome language service is now running, so reformatting with Biome does work

Expected behavior

When an eligible file (JavaScript, TypeScript, etc.) in any module with a biome config file is opened, the Biome language service should run, thus enabling reformatting with Biome.

The number of modules in the project shouldn't make any difference to the behaviour.

Does this issue occur when using the CLI directly?

Not sure / Not applicable

Link to a minimal reproduction

https://github.com/donalmurtagh/multi-module-project/

[github-actions]

Hello @donalmurtagh, please provide a minimal reproduction. You can use one of the following options:

• Provide a link to our playground, if it's applicable.
• Provide a link to GitHub repository. To easily create a reproduction, you can use our interactive CLI via npm create @biomejs/biome-reproduction

Issues marked with S-Needs repro will be closed if they have no activity within 3 days.

[donalmurtagh]

After a lot of trial and error, I figured out the cause of the problem and a way to workaround it.

In an IntelliJ project with multiple modules (e.g. one for the frontend app and another for the backend app) the Biome formatting may not work because the Biome language service is inactive for the frontend module. IntelliJ displays the list of active language services for the current file in the "Language Services" indicator in the status bar. This indicator shows {} when the current file does not have any active language services.

I worked around this problem by removing all modules except the frontend module, checking that the Biome language service is now active for the frontend module, then restoring the other modules.

I don't know how the Biome plugin currently decides which module in a multi-module project the language service should be activated for, but it should be any module with a biome.json or biome.jsonc file.

[siketyan]

@donalmurtagh Could you please create a reproduction repository with multiple modules inside a project?

[donalmurtagh]

@donalmurtagh Could you please create a reproduction repository with multiple modules inside a project?

https://github.com/donalmurtagh/multi-module-project/

[siketyan]

@donalmurtagh Could you include the project structure (the .idea folder) in the repository? It should help to reproduce your setup precisely.

[donalmurtagh]

@siketyan I've added the .idea dir and .iml files to Git, but it might be quicker for you to ignore my repo and just create an IntelliJ project with these properties

• project has 2 modules
• one module is eligible for Biome formatting, i.e. has Biome listed as a dependency in package.json and a Biome config file in the root directory
• the other module is not eligible for Biome formatting