flat/frontmatter

configs["flat/frontmatter"] is a compatibility alias for configs.frontmatter.

import jsonSchemaValidator from "eslint-plugin-json-schema-validator-2";

export default [...jsonSchemaValidator.configs["flat/frontmatter"]];

It registers the same parser setup as configs.base and attaches the json-schema-validator-2/frontmatter processor to Markdown, MDX, and MDC files.

It does not enable json-schema-validator-2/no-invalid by itself. Prefer configs.frontmatter for new Flat Config setups, then add the validation rule with the schema that matches your frontmatter data.