Default binpkg caching policy for all installed packages

Gentoo's binpkg mechanism stores precompiled packages in /var/cache/paludis and can be restored by loading a precompiled package after a system backup.

The restored binaries must match the current system's USE flag configuration; verification typically involves comparing the package's metadata with the current system's configuration using available tools, but the open issue is whether binpkg should be enabled by default for every installed package or only for selected categories, which determines recovery workflow.

Verification after restoration must ensure flag consistency, raising the following questions:

What criteria should govern the default activation of binpkg for all packages?

Should the default policy be changed to include all installed packages, or remain limited to specific categories?

How can verification be automated to ensure flag consistency after restoration?