01 · Source
Read-only fetch
The GitHub App reads repository contents to create and update a mirror. It does not need write access to source repositories.
Data model
A mirror made of ordinary Git.
slerim keeps the repository’s objects and refs in a form developers can inspect with the tools they already use.
Four parts, one portable history
The design keeps recovery understandable and avoids a proprietary export format.
02 · Objects
Git history
Commits, trees, and blobs are stored as Git objects. Incremental fetches add objects that were not already present.
03 · References
Dated branch tips
Snapshot refs keep branch tips reachable after a force-push or branch deletion, preserving a route back to earlier commits.
04 · Proof
Integrity check
A rebuilt copy can be checked with git fsck --full to detect missing or corrupt objects.
Storage
Only new history needs uploading
Git packs group objects for transfer. When a repository has no new objects, a backup run can finish without uploading another pack.
Portability
Restore without a special reader
A Git bundle can be cloned and inspected with ordinary Git. The mirror stays useful even if the original hosting account is unavailable.