extensible OpenAPI validator?

[David....@apiture.com]

We currently use swagger-cli https://github.com/BigstickCarpet/swagger-cli to validate OpenAPI documents in our build process (i.e. as a pre-build hook in Git)

but it is not extensible (I don't think) by adding custom local validation rules based on internal standards. 

https://github.com/swagger-api/validator-badge runs primarily as a web app/service and does not have a cli callable from a build (i.e. that can run on a local file.)

sway and swagger-lint are limited and also not extensible via plugins.

Are there other tools which provide similar validation and are easily extensible via a rules plugin mechanism?