The frontend of marimo communicates with the backend through an OpenAPI specification, which can be found in packages/openapi/api.yaml.
marimo development openapiTo modify the schema, add the type under _generate_server_api_schema in commands.py and run
marimo development openapi > packages/openapi/api.yamlpipx install openapi-spec-validator
marimo development openapi | openapi-spec-validator -make fe-codegenYou will then need to reinstall the package in /frontend:
cd frontend
pnpm update @marimo-team/marimo-api