adapter-biome

Runs Biome via the CLI and generates a biome.json config file.

Package: @retemper/lodestar-adapter-biome

Managed file: biome.json

Config Options

Option	Type	Description
rules	Record<string, BiomeRuleSeverity>	Rule overrides -- keys are group/rule (e.g., "style/noNonNullAssertion")
ignore	string[]	Glob patterns to ignore
extends	string	Path to existing biome.json to extend
bin	string	Binary name or path (default: "biome")

BiomeRuleSeverity is 'error' | 'warn' | 'info' | 'off'.

Example

import { biomeAdapter } from '@retemper/lodestar-adapter-biome';

biomeAdapter({
  rules: {
    'style/noNonNullAssertion': 'error',
    'suspicious/noExplicitAny': 'warn',
  },
  ignore: ['dist/**', 'node_modules/**'],
  extends: './biome-base.json',
});

Temporary Config File

During check, the biome adapter does not use the project's biome.json directly. Instead it:

1. Writes a temporary config file (.lodestar-biome-tmp.json) derived from the lodestar config.
2. Runs biome lint --reporter=json with the temporary config.
3. Parses the JSON diagnostics into lodestar Violation objects.
4. Cleans up the temporary file after the run completes.

This approach avoids conflicts with an existing biome.json and ensures the lodestar config is always the source of truth during checks.

How verifySetup Works

1. Checks that biome.json exists in rootDir.
2. Reads the file content and compares it against the config that lodestar would generate.
3. Returns a missing violation if the file does not exist.
4. Returns a drift violation (with a diff of expected vs actual) if the content does not match.
5. Returns no violations if biome.json matches.

Running lodestar check --fix regenerates biome.json to resolve setup violations.