the snapshot.storage.k8s.io CRDs — VolumeSnapshot, VolumeSnapshotContent, VolumeSnapshotClass (v1, GA);
the snapshot-controller Deployment (into kube-system, the upstream default) that reconciles those objects against any CSI driver's CreateSnapshot/DeleteSnapshot.

Neither k3s nor the Longhorn chart ships this. It is a prerequisite for:

VolumeSnapshotClass (driver.longhorn.io) — see ../longhorn/volumesnapshotclass.yaml (applied by platform-config).
CDI snapshot smart-clone — the CDI StorageProfiles set cloneStrategy: snapshot (see ../kubevirt/cdi-storageprofiles.yaml); CDI clones VM disks by taking a CSI VolumeSnapshot instead of a slow host-assisted byte copy.
Clearing the CDIDefaultStorageClassDegraded alert — a default virtualization StorageClass must support both smart-clone and ReadWriteMany.

Wiring

Pass: platform (controllers). Registers the CRDs.
The VolumeSnapshotClass CR that consumes the CRDs lives in the platform-config pass (dependsOn: platform), per the controllers/configs split.
The CDI StorageProfiles live one pass further out, in platform-config-cdi (dependsOn: platform-config) — storageprofiles.cdi.kubevirt.io is created by cdi-operator only after it reconciles the CDI CR, so they cannot share a pass with it. See clusters/base/platform-config-cdi.yaml.

Version

Pinned to v8.2.0 (Renovate-maintained). The v8.x line aligned to Kubernetes 1.31 at v8.1.0; this cluster is now k3s v1.36.4, so the pin should be re-checked for 1.36 (a newer external-snapshotter line may be the version-matched choice) — do not treat v8.2.0 as verified against 1.36 yet. The snapshot-controller image is re-pinned to the same tag via the kustomization images transformer (the upstream setup manifest lags on the image tag).