Read current state of another, non-changed, file at each commit?

[ngbrown]

When either of two files changes, I need to run a process on both files and update both of them for that commit.

I have a script that is working that is using git filter-branch --tree-filter. I didn't write it in git filter-rep initially, because I thought it couldn't handle this scenario. But maybe it can. Can I use git restore to get the current state of a file that didn't change in the current commit using the commit original_id?

[newren]

See the contrib/filter-repo-demos/lint-history example, particularly the lint_with_real_filenames() function and cat_file_process variable. It uses the cat_file_process to read blobs from the git history by blob id. You could also pass it <commit_id>:<relative/file/path> instead of <blob_id> just as well.