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tag

tag

sandwichcake tag <ref> <new-ref> copies a manifest to another tag — the fast way to promote, rename or mirror an image or slice.

What happens

Two paths depending on the destination:

  • Same repository — a registry-side tag write only. No blobs are read or transferred at all; this is effectively free and instant.
  • Different repository — the manifest (or index) is re-pushed to the destination repo. Blobs that exist in the source repo are cross-repo mounted where the registry supports it; anything that can’t be mounted is uploaded.

Either way the command prints tagged <src> -> <dst> on success. Both images and multi-arch indexes are handled; digest refs (repo@sha256:…) work as the source.

Examples

Promote a slice to a release tag (same repo, instant):

$ sandwichcake tag reg/ai/weights:qwen3-8b-rc1 :v1
tagged reg/ai/weights:qwen3-8b-rc1 -> reg/ai/weights:v1

Mirror a slice into a different repo (mounts layers server-side):

sandwichcake tag reg/ai/weights:qwen3-8b reg/prod/weights:qwen3-8b

Retag by digest for an exact pin:

sandwichcake tag reg/app@sha256:8de0… reg/app:stable

Notes

  • Metadata artifacts (referrers) are not copied — tag copies only the manifest/index itself.
  • Cross-repo copy uses the same chunked, resumable upload machinery as pack/compose for blobs that can’t be mounted.
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