identity for files and directories

[teamdandelion]

We'd like SourceCred to be able to track cred at the file level. It would be great to be able to ask "who has cred in this file" or "who has cred in this directory".

We may expect to have nodes of type FILE, and of type DIRECTORY, and then add CONTAINS edges that point from directories to files or directories. (And the repository will have a CONTAINS edge to the root directory). However, it's not clear how to implement this.

An intuitive-but-wrong approach is to identify files and directories by their path relative to root. However, suppose I create the file "foo", and then rename that file to "bar", and then create a new file called "foo". In which case a file-path-identity system will incorrectly think that "foo_0" and "foo_1" are the same file.