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Biome is a linter for JavaScript, TypeScript, JSX, TSX, JSON, JSONC, and CSS. CodeRabbit runs Biome version 2.5.8.

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Files

Biome will run on files with the following extensions:
  • .js
  • .mjs
  • .cjs
  • .jsx
  • .ts
  • .mts
  • .cts
  • .tsx
  • .vue
  • .astro
  • .svelte
  • .json
  • .jsonc
  • .css

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Configuration

Biome is enabled by default. Enable or disable it with .coderabbit.yaml or the CodeRabbit web UI:
.coderabbit.yaml
Biome supports the following config files:
  • biome.json
  • biome.jsonc
  • .biome.json
  • .biome.jsonc
Dot-prefixed config files are supported only at the repository root. In nested directories, CodeRabbit looks for biome.json and biome.jsonc and applies the nearest config to each supported changed file. At the repository root, CodeRabbit recognizes all four filenames. In nested directories, CodeRabbit recognizes only biome.json and biome.jsonc and uses the nearest applicable configuration. CodeRabbit uses profile-based defaults if no config file is found. It also uses those defaults when a repository config has JSON or JSONC parse errors, is not a JSON object, declares a different Biome schema version, or uses a package-based extends value.

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Profile behavior

When CodeRabbit generates the Biome configuration:
  • Chill uses a focused set of correctness, suspicious-code, security, and performance rules.
  • Assertive adds broader correctness, suspicious-code, style, accessibility, and complexity rules. CSS linting is enabled only in Assertive mode.

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Security policy and restrictions

Biome runs inside the CodeRabbit sandbox. CodeRabbit does not load JavaScript-based Biome plugins, custom Node.js hooks, or package-based extends values that resolve through node_modules.

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When we skip Biome

CodeRabbit will skip running Biome when:
  • Biome is already running in GitHub Actions, GitLab CI, CircleCI, or Azure Pipelines.
  • Biome rejects the repository configuration during execution, including for unknown keys, nested root configurations, or unresolved configuration.

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Notes

  • Files in node_modules/ directories are automatically excluded.
  • Repository configurations that do not match the installed Biome schema version are replaced with CodeRabbit’s generated profile configuration for the run.