Permanently delete a specific commit/stash from Git

Question

I have an automated process that creates a temporary commit and stash, does some stuff, and then pops the stash and reverts the commit.

After doing this a few times, the automated git gc complains that there is too much stuff for it to clean up, so I'd like this process to tidy up after itself.

I don't however want to completely wipe out any other orphaned commits or stashes that might be in the repository, so git prune and git gc --prune=now will be more destructive than I want.

Is there a way to specifically delete one commit or stash that is no longer accessible?

Answer 1

Try first to git config --global gc."refs/stash".reflogExpireUnreachable now in order to configure the removal of reflog entries, limited to stash, older than this time and are not reachable from the current tip.

Then a git reflog expire would not be too destructive (as opposed to a git gc --prune=now)

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For the rest, you can rely on git maintenance, (introduced with Git 2.29, Q4 2020).
Since Git 2.31, Q1 2021, it knows how to schedule packing refs cleanup.

See this article by Brooke Kuhlmann for illustration.