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Biome is a linter for JavaScript, TypeScript, JSX, TSX, JSON, JSONC, and CSS. CodeRabbit runs Biome v2.5.14.

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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

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boolean
default:true
Enable Biome
.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, targets a Biome schema version newer than the installed Biome version, or uses a package-based extends value. For nested configurations, CodeRabbit accepts root: false or extends: "//" with root omitted. It uses profile-based defaults when neither condition is met, when an extends array contains "//", or when the root config cannot be used.

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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, security, performance, style, accessibility, and complexity rules. CSS linting is enabled only in Assertive mode.
In both profiles, CodeRabbit requests only error-level diagnostics from Biome (--diagnostic-level=error), so rules configured at warning level do not produce review findings.

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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 reports a configuration or plugin-loading error during execution, including unknown keys, nested root configurations, or unresolved configuration. CodeRabbit skips the affected files.
  • The changed file is a Biome configuration file. CodeRabbit uses configuration files for discovery but does not lint them.

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Notes

  • Files in node_modules/ directories are automatically excluded.
  • Repository configurations that target a Biome schema version newer than the installed Biome version are replaced with CodeRabbit’s generated profile configuration for the run.