SpiceDB is an open source, Google Zanzibar-inspired, database system for creating and managing security-critical application permissions.

SpiceDB

I'm open to any definition that would solve the problem
but if I define it like this
```definition user {}

definition folder {}

definition file {
    relation parent: folder
    relation viewer: user

    permission view = viewer
}```
I don't see a way to define a permission for the folder that would depend of its files

and if I define it like this
```definition user {}

definition folder {
    relation contents: file

    permission view = contents->view
}

definition file {
    relation viewer: user

    permission view = viewer
}```

the `view` permission for a folder will be granted when any file is viewable (while I want that all of them are)