Currently it is not possible to directly upload LFS files to external object stores. Theoretically we can support this as git-lfs documents [here](https://github.com/git-lfs/git-lfs/blob/main/docs/api/basic-transfers.md#verification). I believe we can build the headers for the `upload` action and then add a new `verify` action to the `/batch` `upload_actions` method. In the verify action we can send a callback to our servers to confirm the file was uploaded and then create a background job to link it to the project. This should help offload some processing which will likely resolve issues like https://gitlab.com/gitlab-org/gitlab/-/issues/371908+ We need to first investigate how to implement so I'm creating this as a ~spike We should also document how the upload flow currently works.