Both max and min characters would be nice!
And "min" characters
This would have to be done in fields/types/text/TextType.js in the validateInput function: https://github.com/keystonejs/keystone/blob/22076e6c2be4df15c0693deb30244f013a52c8ae/fields/types/text/TextType.js#L19-L23
There is a bit more information of what the API for this could look like here: https://github.com/keystonejs/keystone/issues/126#issuecomment-33288991
This looks like it's already been merged and probably should be marked as complete, yeah?
@Kevin Brown Very much so, good catch, thanks!