How to run biome migrate on configuration files included via extends?

[marcin-it3-wskz]

Hello,

I have a question about the intended workflow for the biome migrate command when using a split configuration with extends.

Problem Description:
My setup involves a root biome.json that extends other JSON biome-configuration files containing the bulk of the rules.

After upgrading to a new version of Biome, the configuration in my extended file (biome-common.json) is no longer compatible. However, when I run npx biome migrate --write, the command seems to only process the root biome.json and does not apply any migrations to the files specified in the extends array.

Expected Behavior:
I would expect biome migrate to parse the extends field in the root biome.json and apply the necessary migrations to the biome-common.json file as well, updating its schema and rule structure.

Actual Behavior:
The biome-common.json file is left untouched. No migrations are applied to it, and it remains incompatible with the new Biome version.

My Question:
Is there a way to make biome migrate aware of these extended configuration files?

[agammann]

In Biome 2.5.15, migrate processes the selected config file; it does not recursively rewrite files named in extends. Run it once per extended file, for example:

npx @biomejs/biome migrate --write --config-path=biome-common.json

I tested this with a root biome.json extending biome-common.json that used the old organizeImports.enabled setting. Migrating the root left the extended file unchanged; the command above migrated that file to assist.actions.source.organizeImports and added root: false. Review the resulting config diff, then run your normal Biome check. See the CLI reference.