File key & uniqueness

Hello Figma community :wave:

While working on a new plugin intended to the community, I stepped upon the issue that fileKey is only available to private plugins.

How are we suppose to uniquely identify files in thirdparty systems (eg. my database)?

I decided to store a custom id plugin property on figma.root but I cannot guarantee its uniqueness when a file is duplicated. Moreover, having access to it would mean providing an easy URL from my product to the Figma file my user works on.

Any solution/alternative to this issue?

Thanks & happy hacking/coding