As of version 1.6.0, Hatta checks page existence by looking directly into the repository, so it can no longer access files that haven't been added and commited.
It is possible to commit into Mercurial repository using memctx without having to touch the files in the working directory. Hatta currently (as of 1.6.0) does that.
As of version 1.6.0, Hatta reads data from the repository, not from the working directory. Changes won't be visible until commited.