The REACT_APP_DEFINITION_URL / REACT_APP_DEFINITION_FILE variables documented here have no effect / are not used within the codebase.
Local steps to reproduce:
$ REACT_APP_DEFINITION_URL=https://raw.githubusercontent.com/readmeio/oas-examples/refs/heads/main/3.1/yaml/train-travel.yaml npm run build:app
$ docker build . -f Dockerfile.unprivileged -t swaggerapi/swagger-editor:latest-unprivileged
$ docker run -d -p 8080:8080 swaggerapi/swagger-editor:latest-unprivileged
Then, visit http://localhost:8080 (clear the cache + app storage for the domain).
Observe that the AsyncAPI260StreetlightsYAML specification is always loaded - no matter the REACT_APP_DEFINITION_URL value.