Official marketplace plugins are now distributed via Google Cloud Storage (downloads.claude.ai) with ZIP-based atomic updates and SHA-based cache validation, providing faster and more reliable plugin installation compared to the previous git-only approach. Falls back to git if GCS is unavailable.
Evidence
GCS plugin distribution (search for "downloads.claude.ai", "Official marketplace GCS")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.