From d8d3e2268d2c812ae41231258a2c5f6dcf3b524e Mon Sep 17 00:00:00 2001
From: Julian Sommer <115516918+juliansommer@users.noreply.github.com>
Date: Thu, 3 Sep 2026 15:38:23 +1000
Subject: [PATCH] feat: partition EBS metadata keys by owning account (#989)

---
 cmd/spinifex/cmd/admin.go                     |   5 +-
 cmd/spinifex/cmd/admin_ochre.go               |  17 +-
 cmd/spinifex/cmd/admin_ochre_test.go          |   7 +-
 .../register_imported_ami_snapshot_test.go    |   5 +-
 spinifex/admin/images_promote.go              |  64 ++-
 spinifex/admin/images_promote_test.go         |  69 ++++
 spinifex/admin/images_remove.go               |  76 +---
 spinifex/admin/images_remove_test.go          |  10 +-
 spinifex/admin/orphan_volumes.go              |   2 +-
 spinifex/admin/orphan_volumes_test.go         |   2 +-
 spinifex/daemon/daemon_handlers_test.go       |   7 +-
 spinifex/daemon/daemon_handlers_volume.go     |  12 +-
 spinifex/daemon/daemon_test.go                |  35 +-
 spinifex/daemon/ownership.go                  |   9 -
 spinifex/daemon/ownership_test.go             |  75 ----
 spinifex/daemon/vm_adapters.go                |   2 +-
 spinifex/ebsmetadata/metadata.go              |  73 +++-
 spinifex/ebsmetadata/metadata_test.go         |  58 ++-
 spinifex/ebsmetadata/snapshot_store_test.go   | 215 ++++++++++
 spinifex/ebsmetadata/store.go                 | 152 ++++++-
 spinifex/ebsmetadata/store_test.go            | 185 ++++++---
 .../ec2/image/ami_source_volume_test.go       |  82 +++-
 .../ec2/image/provider_snapshot_test.go       |   6 +-
 spinifex/handlers/ec2/image/service_impl.go   |  91 +++--
 .../handlers/ec2/image/service_impl_test.go   | 154 ++++---
 .../ec2/instance/provider_root_volume_test.go |   6 +-
 .../delete_snapshot_pagination_test.go        |   2 +-
 .../ec2/snapshot/describe_fanout_test.go      |  11 +-
 .../handlers/ec2/snapshot/record_tags_test.go |   6 +-
 .../handlers/ec2/snapshot/service_impl.go     | 308 ++++++--------
 .../ec2/snapshot/service_impl_test.go         | 107 +++--
 .../ec2/snapshot/snapshot_partition_test.go   | 345 ++++++++++++++++
 .../volume/config_route_invariants_test.go    |  12 +-
 .../describe_volumes_provider_bench_test.go   |  12 +-
 ...describe_volumes_provider_fastpath_test.go |  28 +-
 .../handlers/ec2/volume/force_detach_test.go  |  22 +-
 .../get_volume_metadata_provider_test.go      |  14 +-
 .../ec2/volume/lifecycle_invariants_test.go   |  10 +-
 .../volume/provider_snapshot_source_test.go   |  24 +-
 .../handlers/ec2/volume/record_tags_test.go   |  12 +-
 spinifex/handlers/ec2/volume/service_impl.go  | 193 ++++-----
 .../volume/service_impl_encryption_test.go    |   6 +-
 .../handlers/ec2/volume/service_impl_test.go  | 378 +++++++++---------
 .../handlers/ec2/volume/testhelpers_test.go   |   5 +
 .../handlers/ec2/volume/volume_leak_reaper.go |  20 +-
 .../ec2/volume/volume_leak_reaper_test.go     |   4 +-
 .../ec2/volume/volume_partition_test.go       | 150 +++++++
 .../services/viperblockd/list_volumes_test.go |   2 +-
 .../testutil/recordingstore/recordingstore.go |  86 ++++
 spinifex/vm/instance_type_resolver.go         |   2 +-
 spinifex/vm/lifecycle.go                      |   2 +-
 spinifex/vm/manager_deps_test.go              |   7 +-
 spinifex/vm/vm.go                             |   4 +-
 spinifex/vm/volume_state_account_test.go      | 148 +++++++
 spinifex/vm/volumes.go                        |   6 +-
 tests/integration/image_test.go               |   4 +-
 56 files changed, 2314 insertions(+), 1035 deletions(-)
 delete mode 100644 spinifex/daemon/ownership_test.go
 create mode 100644 spinifex/ebsmetadata/snapshot_store_test.go
 create mode 100644 spinifex/handlers/ec2/snapshot/snapshot_partition_test.go
 create mode 100644 spinifex/handlers/ec2/volume/volume_partition_test.go
 create mode 100644 spinifex/testutil/recordingstore/recordingstore.go
 create mode 100644 spinifex/vm/volume_state_account_test.go

diff --git a/cmd/spinifex/cmd/admin.go b/cmd/spinifex/cmd/admin.go
index bd34dbe2a..b1218204f 100644
--- a/cmd/spinifex/cmd/admin.go
+++ b/cmd/spinifex/cmd/admin.go
@@ -35,7 +35,6 @@ import (
 	"github.com/mulgadc/spinifex/spinifex/ebsprovider"
 	"github.com/mulgadc/spinifex/spinifex/formation"
 	"github.com/mulgadc/spinifex/spinifex/gpu"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	handlers_ec2_vpc "github.com/mulgadc/spinifex/spinifex/handlers/ec2/vpc"
 	handlers_iam "github.com/mulgadc/spinifex/spinifex/handlers/iam"
 	"github.com/mulgadc/spinifex/spinifex/hostdns"
@@ -733,7 +732,7 @@ func runimagesImportCmd(cmd *cobra.Command, args []string) {
 // DescribeSnapshots call cannot resolve it. The volume ID matches ami.ImageID:
 // admin.ImportImage creates the volume under the AMI's own ID.
 func registerImportedAMISnapshot(store objectstore.ObjectStore, bucket string, ami ebsmetadata.AMI, az string, encrypted bool) error {
-	cfg := &handlers_ec2_snapshot.SnapshotConfig{
+	cfg := ebsmetadata.Snapshot{
 		SnapshotID:       ami.SnapshotID,
 		VolumeID:         ami.ImageID,
 		VolumeSize:       safecast.Uint64ToInt64(ami.VolumeSizeGiB),
@@ -745,7 +744,7 @@ func registerImportedAMISnapshot(store objectstore.ObjectStore, bucket string, a
 		OwnerID:          utils.GlobalAccountID,
 		AvailabilityZone: az,
 	}
-	if err := handlers_ec2_snapshot.WriteSnapshotConfig(store, bucket, ami.SnapshotID, cfg); err != nil {
+	if err := ebsmetadata.NewStore(store, bucket).PutSnapshot(context.Background(), cfg); err != nil {
 		return fmt.Errorf("register snapshot metadata: %w", err)
 	}
 	return nil
diff --git a/cmd/spinifex/cmd/admin_ochre.go b/cmd/spinifex/cmd/admin_ochre.go
index d1de126d1..2424dd293 100644
--- a/cmd/spinifex/cmd/admin_ochre.go
+++ b/cmd/spinifex/cmd/admin_ochre.go
@@ -20,10 +20,10 @@ import (
 	"github.com/mulgadc/bluebottle/pkg/safecast"
 	"github.com/mulgadc/spinifex/spinifex/admin"
 	"github.com/mulgadc/spinifex/spinifex/config"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
 	"github.com/mulgadc/spinifex/spinifex/ebsprovider"
 	gateway_bedrock "github.com/mulgadc/spinifex/spinifex/gateway/bedrock"
 	"github.com/mulgadc/spinifex/spinifex/gateway/bedrock/hfhub"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
 	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/nats-io/nats.go"
@@ -633,7 +633,7 @@ func buildWeightsImage(srcDir, imagePath string, contentBytes int64) error {
 // metadata.json sitting alongside them, so without this the endpoint launcher
 // cannot see the snapshot at all and fails with InvalidSnapshot.NotFound.
 func registerWeightsSnapshot(store objectstore.ObjectStore, bucket, snapshotID, volumeID string, volumeSize uint64, az string, encrypted bool) error {
-	cfg := &handlers_ec2_snapshot.SnapshotConfig{
+	cfg := ebsmetadata.Snapshot{
 		SnapshotID: snapshotID,
 		VolumeID:   volumeID,
 		// GiB, not bytes: CreateVolume compares this against a requested Size
@@ -647,7 +647,7 @@ func registerWeightsSnapshot(store objectstore.ObjectStore, bucket, snapshotID,
 		OwnerID:          utils.GlobalAccountID,
 		AvailabilityZone: az,
 	}
-	if err := handlers_ec2_snapshot.WriteSnapshotConfig(store, bucket, snapshotID, cfg); err != nil {
+	if err := ebsmetadata.NewStore(store, bucket).PutSnapshot(context.Background(), cfg); err != nil {
 		return fmt.Errorf("register snapshot metadata: %w", err)
 	}
 	return nil
@@ -805,13 +805,14 @@ func materializeWeightsVolume(ctx context.Context, provider ebsprovider.EBSProvi
 }
 
 // newWeightsSnapshotChecker is the real weightsSnapshotChecker: it reads the
-// EC2 control plane's metadata.json for snapshotID from the node's
-// predastore bucket -- the same record registerWeightsSnapshot writes at
-// stage time -- and treats a missing object as gone. Any other read failure
-// is a real error, not a signal to guess the snapshot's existence.
+// EC2 control plane's snapshot document for snapshotID under the global
+// account -- the same record registerWeightsSnapshot writes at stage time --
+// and treats a missing object as gone. Any other read failure is a real
+// error, not a signal to guess the snapshot's existence.
 func newWeightsSnapshotChecker(store objectstore.ObjectStore, bucket string) weightsSnapshotChecker {
+	metadata := ebsmetadata.NewStore(store, bucket)
 	return func(ctx context.Context, snapshotID string) (bool, error) {
-		if _, err := handlers_ec2_snapshot.ReadSnapshotConfig(ctx, store, bucket, snapshotID); err != nil {
+		if _, err := metadata.GetSnapshot(ctx, utils.GlobalAccountID, snapshotID); err != nil {
 			if objectstore.IsNoSuchKeyError(err) {
 				return false, nil
 			}
diff --git a/cmd/spinifex/cmd/admin_ochre_test.go b/cmd/spinifex/cmd/admin_ochre_test.go
index f1ef4b818..04fb28e1f 100644
--- a/cmd/spinifex/cmd/admin_ochre_test.go
+++ b/cmd/spinifex/cmd/admin_ochre_test.go
@@ -15,10 +15,11 @@ import (
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/config"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
 	gateway_bedrock "github.com/mulgadc/spinifex/spinifex/gateway/bedrock"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
 	"github.com/mulgadc/spinifex/spinifex/testutil"
+	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/nats-io/nats.go"
 	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/assert"
@@ -1094,7 +1095,7 @@ func TestRegisterWeightsSnapshot_WritesEC2ReadableMetadata(t *testing.T) {
 	require.NoError(t, registerWeightsSnapshot(store, bucket,
 		"snap-vol-abc", "vol-abc", 12*bytesPerGiB, "ap-southeast-2a", true))
 
-	cfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, bucket, "snap-vol-abc")
+	cfg, err := ebsmetadata.NewStore(store, bucket).GetSnapshot(context.Background(), utils.GlobalAccountID, "snap-vol-abc")
 	require.NoError(t, err)
 	assert.Equal(t, "snap-vol-abc", cfg.SnapshotID)
 	assert.Equal(t, "vol-abc", cfg.VolumeID)
@@ -1111,7 +1112,7 @@ func TestRegisterWeightsSnapshot_UnencryptedVolume(t *testing.T) {
 	require.NoError(t, registerWeightsSnapshot(store, "predastore",
 		"snap-vol-plain", "vol-plain", bytesPerGiB, "ap-southeast-2a", false))
 
-	cfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, "predastore", "snap-vol-plain")
+	cfg, err := ebsmetadata.NewStore(store, "predastore").GetSnapshot(context.Background(), utils.GlobalAccountID, "snap-vol-plain")
 	require.NoError(t, err)
 	assert.False(t, cfg.Encrypted)
 }
diff --git a/cmd/spinifex/cmd/register_imported_ami_snapshot_test.go b/cmd/spinifex/cmd/register_imported_ami_snapshot_test.go
index cc7f60804..91a4e3131 100644
--- a/cmd/spinifex/cmd/register_imported_ami_snapshot_test.go
+++ b/cmd/spinifex/cmd/register_imported_ami_snapshot_test.go
@@ -5,7 +5,6 @@ import (
 	"testing"
 
 	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
 	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/stretchr/testify/assert"
@@ -29,7 +28,7 @@ func TestRegisterImportedAMISnapshot_WritesEC2ReadableMetadata(t *testing.T) {
 
 	require.NoError(t, registerImportedAMISnapshot(store, bucket, ami, "ap-southeast-2a", true))
 
-	cfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, bucket, "snap-ami-import01")
+	cfg, err := ebsmetadata.NewStore(store, bucket).GetSnapshot(context.Background(), utils.GlobalAccountID, "snap-ami-import01")
 	require.NoError(t, err)
 	assert.Equal(t, "snap-ami-import01", cfg.SnapshotID)
 	assert.Equal(t, "ami-import01", cfg.VolumeID, "the import path creates the volume under the AMI's own ID")
@@ -50,7 +49,7 @@ func TestRegisterImportedAMISnapshot_UnencryptedVolume(t *testing.T) {
 
 	require.NoError(t, registerImportedAMISnapshot(store, "predastore", ami, "ap-southeast-2a", false))
 
-	cfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, "predastore", "snap-ami-plain01")
+	cfg, err := ebsmetadata.NewStore(store, "predastore").GetSnapshot(context.Background(), utils.GlobalAccountID, "snap-ami-plain01")
 	require.NoError(t, err)
 	assert.False(t, cfg.Encrypted)
 }
diff --git a/spinifex/admin/images_promote.go b/spinifex/admin/images_promote.go
index 3ada9f239..8b8ccfcdd 100644
--- a/spinifex/admin/images_promote.go
+++ b/spinifex/admin/images_promote.go
@@ -32,13 +32,15 @@ type PromoteImageResult struct {
 }
 
 // PromoteSystemImage promotes an account-owned AMI to a system image by
-// rewriting its ImageOwnerAlias to SystemOwnerAlias. After the call the AMI
-// is immediately visible to all accounts via DescribeImages.
+// rewriting its ImageOwnerAlias to SystemOwnerAlias and re-keying its snapshot
+// document under the global account. After the call the AMI is immediately
+// visible to all accounts via DescribeImages.
 //
 // Guards:
 //   - ImageID must have "ami-" prefix
 //   - config.json must exist and parse cleanly
 //   - AMI must currently be account-owned; already-system AMIs are rejected
+//   - the snapshot document must be readable, so it can be re-keyed
 func PromoteSystemImage(store objectstore.ObjectStore, bucket string, opts PromoteImageOpts) (*PromoteImageResult, error) {
 	if !strings.HasPrefix(opts.ImageID, "ami-") {
 		return nil, errors.New(awserrors.ErrorInvalidAMIIDMalformed)
@@ -62,17 +64,69 @@ func PromoteSystemImage(store objectstore.ObjectStore, bucket string, opts Promo
 	}
 
 	prev := meta.ImageOwnerAlias
-	meta.ImageOwnerAlias = SystemOwnerAlias
+	metaStore := ebsmetadata.NewStore(store, bucket)
 
-	if err := ebsmetadata.NewStore(store, bucket).PutAMI(context.Background(), meta); err != nil {
+	// The snapshot document has to move before the alias is rewritten: readers
+	// derive its account from the alias, so a system alias over a tenant-keyed
+	// snapshot resolves to nothing.
+	snap, moveSnapshot, err := readPromotedSnapshot(metaStore, prev, meta.SnapshotID)
+	switch {
+	case err == nil:
+		// ok
+	case errors.Is(err, ebsmetadata.ErrCorruptDocument):
+		return nil, fmt.Errorf("%s references snapshot %s, whose document is corrupt and cannot be re-keyed; promotion not allowed",
+			opts.ImageID, meta.SnapshotID)
+	default:
+		slog.Error("PromoteSystemImage: read snapshot document", "imageId", opts.ImageID, "snapshotId", meta.SnapshotID, "err", err)
+		return nil, errors.New(awserrors.ErrorServerInternal)
+	}
+	if moveSnapshot {
+		snap.OwnerID = utils.GlobalAccountID
+		if err := metaStore.PutSnapshot(context.Background(), snap); err != nil {
+			slog.Error("PromoteSystemImage: write snapshot document under the global account",
+				"imageId", opts.ImageID, "snapshotId", meta.SnapshotID, "err", err)
+			return nil, errors.New(awserrors.ErrorServerInternal)
+		}
+	}
+
+	meta.ImageOwnerAlias = SystemOwnerAlias
+	if err := metaStore.PutAMI(context.Background(), meta); err != nil {
 		slog.Error("PromoteSystemImage: write AMI document", "imageId", opts.ImageID, "err", err)
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 
-	slog.Info("PromoteSystemImage completed", "imageId", opts.ImageID, "previousOwner", prev, "newOwner", SystemOwnerAlias)
+	// Last, so every intermediate state resolves: until the alias is rewritten
+	// readers look under prev, and afterwards under the global account.
+	if moveSnapshot {
+		if err := metaStore.DeleteSnapshot(context.Background(), prev, meta.SnapshotID); err != nil {
+			slog.Error("PromoteSystemImage: delete the superseded snapshot document; the promoting account can still delete its blocks",
+				"imageId", opts.ImageID, "snapshotId", meta.SnapshotID, "previousOwner", prev, "err", err)
+		}
+	}
+
+	slog.Info("PromoteSystemImage completed", "imageId", opts.ImageID, "previousOwner", prev,
+		"newOwner", SystemOwnerAlias, "snapshotMoved", moveSnapshot)
 	return &PromoteImageResult{PreviousOwner: prev}, nil
 }
 
+// readPromotedSnapshot reads the document an AMI's snapshot is keyed under
+// before promotion. A bundled image has no snapshot of its own, which is not an
+// error: it already resolves under the global account by falling back.
+func readPromotedSnapshot(store *ebsmetadata.Store, owner, snapshotID string) (ebsmetadata.Snapshot, bool, error) {
+	if snapshotID == "" {
+		return ebsmetadata.Snapshot{}, false, nil
+	}
+	snap, err := store.GetSnapshot(context.Background(), owner, snapshotID)
+	switch {
+	case err == nil:
+		return snap, true, nil
+	case objectstore.IsNoSuchKeyError(err):
+		return ebsmetadata.Snapshot{}, false, nil
+	default:
+		return ebsmetadata.Snapshot{}, false, err
+	}
+}
+
 // GetAMIMetadata reads and returns the control-plane document for the given
 // image ID. Returns ErrorInvalidAMIIDNotFound for missing or corrupt documents.
 func GetAMIMetadata(store objectstore.ObjectStore, bucket, imageID string) (ebsmetadata.AMI, error) {
diff --git a/spinifex/admin/images_promote_test.go b/spinifex/admin/images_promote_test.go
index 626e98b7d..72f9347af 100644
--- a/spinifex/admin/images_promote_test.go
+++ b/spinifex/admin/images_promote_test.go
@@ -1,10 +1,15 @@
 package admin
 
 import (
+	"bytes"
 	"testing"
 
+	"github.com/aws/aws-sdk-go/aws"
+	awss3 "github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
+	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -27,6 +32,70 @@ func TestPromoteSystemImage_HappyPath(t *testing.T) {
 	assert.Equal(t, "snap-user-001", meta.SnapshotID)
 }
 
+// A promoted AMI's readers derive the snapshot account from the alias, so the
+// document has to end up under the global account or every launch of it falls
+// back to the image ID and the provider refuses the clone.
+func TestPromoteSystemImage_MovesSnapshotToGlobalAccount(t *testing.T) {
+	store := objectstore.NewMemoryObjectStore()
+	const id = "ami-user-snap"
+	const snapID = "snap-user-snap"
+	putAMI(t, store, id, "my-app", testRemoveAccountID, snapID)
+	putSnapMetadata(t, store, snapID, "vol-source-001")
+
+	_, err := PromoteSystemImage(store, testRemoveBucket, PromoteImageOpts{ImageID: id})
+	require.NoError(t, err)
+
+	metaStore := ebsmetadata.NewStore(store, testRemoveBucket)
+	moved, err := metaStore.GetSnapshot(t.Context(), utils.GlobalAccountID, snapID)
+	require.NoError(t, err)
+	assert.Equal(t, utils.GlobalAccountID, moved.OwnerID)
+	assert.Equal(t, "vol-source-001", moved.VolumeID)
+
+	_, err = metaStore.GetSnapshot(t.Context(), testRemoveAccountID, snapID)
+	require.Error(t, err)
+	assert.True(t, objectstore.IsNoSuchKeyError(err), "the superseded document must not survive: %v", err)
+}
+
+// A bundled image has no snapshot document; promotion still succeeds and the
+// AMI keeps resolving through the fallback.
+func TestPromoteSystemImage_NoSnapshotDocument_Promotes(t *testing.T) {
+	store := objectstore.NewMemoryObjectStore()
+	const id = "ami-user-nosnap"
+	putAMI(t, store, id, "bundled", testRemoveAccountID, "snap-absent")
+
+	_, err := PromoteSystemImage(store, testRemoveBucket, PromoteImageOpts{ImageID: id})
+	require.NoError(t, err)
+
+	meta, err := readAMI(store, testRemoveBucket, id)
+	require.NoError(t, err)
+	assert.Equal(t, SystemOwnerAlias, meta.ImageOwnerAlias)
+}
+
+// Refusing beats promoting an AMI whose snapshot cannot be re-keyed, which
+// would leave the alias pointing at a document no reader can find.
+func TestPromoteSystemImage_CorruptSnapshotDocument_Refused(t *testing.T) {
+	store := objectstore.NewMemoryObjectStore()
+	const id = "ami-user-corruptsnap"
+	const snapID = "snap-corrupt-001"
+	putAMI(t, store, id, "my-app", testRemoveAccountID, snapID)
+	key, err := ebsmetadata.SnapshotKey(testRemoveAccountID, snapID)
+	require.NoError(t, err)
+	_, err = store.PutObject(t.Context(), &awss3.PutObjectInput{
+		Bucket: aws.String(testRemoveBucket),
+		Key:    aws.String(key),
+		Body:   bytes.NewReader([]byte("{not valid json")),
+	})
+	require.NoError(t, err)
+
+	_, err = PromoteSystemImage(store, testRemoveBucket, PromoteImageOpts{ImageID: id})
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "corrupt")
+
+	meta, err := readAMI(store, testRemoveBucket, id)
+	require.NoError(t, err)
+	assert.Equal(t, testRemoveAccountID, meta.ImageOwnerAlias, "the alias must not move without its snapshot")
+}
+
 func TestPromoteSystemImage_AlreadySystem_Refused(t *testing.T) {
 	store := objectstore.NewMemoryObjectStore()
 	const id = "ami-sys-001"
diff --git a/spinifex/admin/images_remove.go b/spinifex/admin/images_remove.go
index ea44b1f7c..6dda7536c 100644
--- a/spinifex/admin/images_remove.go
+++ b/spinifex/admin/images_remove.go
@@ -12,7 +12,6 @@ import (
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
 	"github.com/mulgadc/spinifex/spinifex/utils"
 )
@@ -128,35 +127,25 @@ func PreviewRemoveSystemImage(store objectstore.ObjectStore, bucket, imageID str
 func FindAMIDependents(store objectstore.ObjectStore, bucket, imageID string) (Dependents, error) {
 	var deps Dependents
 
-	prefixes, err := listCommonPrefixes(store, bucket)
-	if err != nil {
-		return Dependents{}, fmt.Errorf("list bucket prefixes: %w", err)
-	}
-
 	// Pass 1: collect derived snaps (CopyImage of this AMI writes a snap whose
-	// VolumeID points back at the source AMI ID).
+	// VolumeID points back at the source AMI ID). Whole-cluster: a copy made by
+	// any account still pins this AMI's blocks. Strict: this answer gates
+	// deleting those blocks, and a document that failed to read is not evidence
+	// that no copy depends on them.
+	snapDocs, err := ebsmetadata.NewStore(store, bucket).ListAllSnapshotsStrict(context.Background())
+	if err != nil {
+		return Dependents{}, fmt.Errorf("list ebsmetadata snapshots: %w", err)
+	}
 	derived := map[string]bool{}
-	for _, p := range prefixes {
-		if !strings.HasPrefix(p, "snap-") {
+	for _, cfg := range snapDocs {
+		// Skip the viperblock-internal snap for this AMI — it has no document
+		// (it was written by viperblock.CreateSnapshot, not the EC2 service).
+		if cfg.SnapshotID == SnapPrefix(imageID) {
 			continue
 		}
-		snapID := strings.TrimSuffix(p, "/")
-		// Skip the viperblock-internal snap prefix for this AMI — it has no
-		// metadata.json (it was written by viperblock.CreateSnapshot, not by
-		// the EC2 snapshot service).
-		if snapID == SnapPrefix(imageID) {
-			continue
-		}
-		cfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, bucket, snapID)
-		if err != nil {
-			if objectstore.IsNoSuchKeyError(err) || errors.Is(err, handlers_ec2_snapshot.ErrCorruptSnapshotMetadata) {
-				continue
-			}
-			return Dependents{}, fmt.Errorf("read snapshot %s: %w", snapID, err)
-		}
 		if cfg.VolumeID == imageID {
-			derived[snapID] = true
-			deps.Snapshots = append(deps.Snapshots, snapID)
+			derived[cfg.SnapshotID] = true
+			deps.Snapshots = append(deps.Snapshots, cfg.SnapshotID)
 		}
 	}
 
@@ -170,8 +159,9 @@ func FindAMIDependents(store objectstore.ObjectStore, bucket, imageID string) (D
 	// Pass 2: volumes whose SnapshotID matches. The ebsmetadata documents are
 	// the whole fleet — a volume with blocks but no document does not exist as
 	// far as the control plane is concerned — and they carry SnapshotID
-	// already, so no second read per volume is needed.
-	volDocs, err := ebsmetadata.NewStore(store, bucket).ListVolumes(context.Background())
+	// already, so no second read per volume is needed. Strict for the same
+	// reason as pass 1.
+	volDocs, err := ebsmetadata.NewStore(store, bucket).ListAllVolumesStrict(context.Background())
 	if err != nil {
 		return Dependents{}, fmt.Errorf("list ebsmetadata volumes: %w", err)
 	}
@@ -296,38 +286,6 @@ func readAMI(store objectstore.ObjectStore, bucket, imageID string) (ebsmetadata
 	return ebsmetadata.NewStore(store, bucket).GetAMI(context.Background(), imageID)
 }
 
-// listCommonPrefixes returns the top-level "directory" prefixes in the bucket
-// (e.g. "ami-xxx/", "vol-yyy/", "snap-zzz/"), exhausting any pagination.
-func listCommonPrefixes(store objectstore.ObjectStore, bucket string) ([]string, error) {
-	seen := map[string]bool{}
-	var token *string
-	for {
-		out, err := store.ListObjectsV2(context.Background(), &s3.ListObjectsV2Input{
-			Bucket:            aws.String(bucket),
-			Delimiter:         aws.String("/"),
-			ContinuationToken: token,
-		})
-		if err != nil {
-			return nil, err
-		}
-		for _, cp := range out.CommonPrefixes {
-			if cp.Prefix == nil {
-				continue
-			}
-			seen[*cp.Prefix] = true
-		}
-		if !aws.BoolValue(out.IsTruncated) {
-			break
-		}
-		token = out.NextContinuationToken
-	}
-	prefixes := make([]string, 0, len(seen))
-	for p := range seen {
-		prefixes = append(prefixes, p)
-	}
-	return prefixes, nil
-}
-
 // sumPrefix returns (object count, total bytes) for every object under prefix.
 // Used by the preview to surface what an operator is about to delete.
 func sumPrefix(store objectstore.ObjectStore, bucket, prefix string) (int, int64, error) {
diff --git a/spinifex/admin/images_remove_test.go b/spinifex/admin/images_remove_test.go
index ffb9df7c1..4236f8436 100644
--- a/spinifex/admin/images_remove_test.go
+++ b/spinifex/admin/images_remove_test.go
@@ -9,7 +9,6 @@ import (
 	awss3 "github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -80,13 +79,13 @@ func putSnapBlocks(t *testing.T, store *objectstore.MemoryObjectStore, snapID st
 // VolumeID back at an admin-imported AMI's ID.
 func putSnapMetadata(t *testing.T, store *objectstore.MemoryObjectStore, snapID, volumeID string) {
 	t.Helper()
-	cfg := &handlers_ec2_snapshot.SnapshotConfig{
+	require.NoError(t, ebsmetadata.NewStore(store, testRemoveBucket).PutSnapshot(t.Context(), ebsmetadata.Snapshot{
 		SnapshotID: snapID,
 		VolumeID:   volumeID,
 		VolumeSize: 8,
 		State:      "completed",
-	}
-	require.NoError(t, handlers_ec2_snapshot.WriteSnapshotConfig(store, testRemoveBucket, snapID, cfg))
+		OwnerID:    testRemoveAccountID,
+	}))
 }
 
 // putVolume registers a volume document carrying the given SnapshotID.
@@ -94,6 +93,7 @@ func putVolume(t *testing.T, store *objectstore.MemoryObjectStore, volID, snapsh
 	t.Helper()
 	require.NoError(t, ebsmetadata.NewStore(store, testRemoveBucket).PutVolume(t.Context(), ebsmetadata.Volume{
 		VolumeID:    volID,
+		TenantID:    testRemoveAccountID,
 		SnapshotID:  snapshotID,
 		CapacityGiB: 8,
 	}))
@@ -268,7 +268,7 @@ func TestRemoveSystemImage_Force_OverridesDependents(t *testing.T) {
 	metadata := ebsmetadata.NewStore(store, testRemoveBucket)
 	_, err = metadata.GetAMI(t.Context(), id)
 	require.Error(t, err)
-	_, err = metadata.GetVolume(t.Context(), "vol-orphan")
+	_, err = metadata.GetVolume(t.Context(), testRemoveAccountID, "vol-orphan")
 	require.NoError(t, err)
 }
 
diff --git a/spinifex/admin/orphan_volumes.go b/spinifex/admin/orphan_volumes.go
index e524953a5..d903e832e 100644
--- a/spinifex/admin/orphan_volumes.go
+++ b/spinifex/admin/orphan_volumes.go
@@ -51,7 +51,7 @@ func FindOrphanVolumes(ctx context.Context, provider ebsprovider.EBSProvider, me
 	// Strict listing on purpose: a document this cannot decode must abort the
 	// scan, never be treated as absent. Reporting a volume as orphaned because
 	// its document was unreadable would point an operator at live data.
-	documented, err := metadata.ListVolumesStrict(ctx)
+	documented, err := metadata.ListAllVolumesStrict(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("orphan scan: list control-plane volumes: %w", err)
 	}
diff --git a/spinifex/admin/orphan_volumes_test.go b/spinifex/admin/orphan_volumes_test.go
index b43c63791..54e857fb8 100644
--- a/spinifex/admin/orphan_volumes_test.go
+++ b/spinifex/admin/orphan_volumes_test.go
@@ -44,7 +44,7 @@ func documentVolume(t *testing.T, metadata *ebsmetadata.Store, volumeID string)
 // so a test can plant one the store cannot decode.
 func putRawVolumeDocument(t *testing.T, store objectstore.ObjectStore, volumeID string, body []byte) {
 	t.Helper()
-	key, err := ebsmetadata.VolumeKey(volumeID)
+	key, err := ebsmetadata.VolumeKey("123456789012", volumeID)
 	require.NoError(t, err)
 	_, err = store.PutObject(t.Context(), &s3.PutObjectInput{
 		Bucket: aws.String(orphanTestBucket),
diff --git a/spinifex/daemon/daemon_handlers_test.go b/spinifex/daemon/daemon_handlers_test.go
index bd3917a13..888bb3620 100644
--- a/spinifex/daemon/daemon_handlers_test.go
+++ b/spinifex/daemon/daemon_handlers_test.go
@@ -97,6 +97,11 @@ func wireTestEBSProvider(daemon *Daemon, store objectstore.ObjectStore) {
 // here rather than writing storage state the control plane never reads.
 func seedVolumeDocument(t *testing.T, store objectstore.ObjectStore, volume ebsmetadata.Volume) {
 	t.Helper()
+	// The owning account is a key segment, so a fixture that does not care
+	// which account owns it still has to have one.
+	if volume.TenantID == "" {
+		volume.TenantID = testAccountID
+	}
 	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutVolume(t.Context(), volume))
 }
 
@@ -2658,7 +2663,7 @@ func TestHandleEC2ModifyVolume_Success(t *testing.T) {
 		Size:     aws.Int64(20),
 	}
 	reqData, _ := json.Marshal(input)
-	reply, err := daemon.natsConn.Request("ec2.ModifyVolume", reqData, 5*time.Second)
+	reply, err := natsRequest(daemon.natsConn, "ec2.ModifyVolume", reqData, 5*time.Second)
 	require.NoError(t, err)
 
 	var output ec2.ModifyVolumeOutput
diff --git a/spinifex/daemon/daemon_handlers_volume.go b/spinifex/daemon/daemon_handlers_volume.go
index d403af10c..c401cf7b0 100644
--- a/spinifex/daemon/daemon_handlers_volume.go
+++ b/spinifex/daemon/daemon_handlers_volume.go
@@ -40,14 +40,20 @@ func (d *Daemon) handleAttachVolume(ctx context.Context, msg *nats.Msg, command
 		return respondErrorOutcome(d.node, msg, awserrors.ErrorIncorrectInstanceState)
 	}
 
-	volMeta, err := d.volumeService.GetVolumeMetadata(volumeID)
+	// The caller's account is a key segment, so it is needed before the read
+	// rather than after it.
+	callerAccountID := utils.AccountIDFromMsg(msg)
+
+	volMeta, err := d.volumeService.GetVolumeMetadata(callerAccountID, volumeID)
 	if err != nil {
 		slog.ErrorContext(ctx, "AttachVolume: failed to get volume metadata", "volumeId", volumeID, "err", err)
 		return respondErrorOutcome(d.node, msg, awserrors.ErrorInvalidVolumeNotFound)
 	}
 
-	callerAccountID := utils.AccountIDFromMsg(msg)
-	if !volumeVisibleTo(volMeta.TenantID, callerAccountID) {
+	// The read was keyed on the caller's account, so the document is theirs by
+	// construction and an empty caller never got this far. The comparison stays
+	// as an assertion.
+	if volMeta.TenantID != callerAccountID {
 		slog.WarnContext(ctx, "AttachVolume: account does not own volume",
 			"volumeId", volumeID,
 			"callerAccount", callerAccountID,
diff --git a/spinifex/daemon/daemon_test.go b/spinifex/daemon/daemon_test.go
index 65fe88a22..f4159e942 100644
--- a/spinifex/daemon/daemon_test.go
+++ b/spinifex/daemon/daemon_test.go
@@ -1595,7 +1595,7 @@ func TestInstanceCleanerAdapter_DeleteVolumes_BootVolumeDeletedAfterAttachmentCl
 	err = cleaner.DeleteVolumes(instance)
 	require.NoError(t, err, "the still-attached boot volume must be deleted, not rejected as VolumeInUse")
 
-	_, err = daemon.volumeService.GetVolumeMetadata(volumeID)
+	_, err = daemon.volumeService.GetVolumeMetadata(testAccountID, volumeID)
 	require.Error(t, err, "the volume must actually be deleted")
 	assert.Contains(t, err.Error(), awserrors.ErrorInvalidVolumeNotFound)
 }
@@ -1633,7 +1633,7 @@ func TestInstanceCleanerAdapter_DeleteVolumes_NonDoTBootVolumeDetachedNotDeleted
 	err := cleaner.DeleteVolumes(instance)
 	require.NoError(t, err)
 
-	meta, err := daemon.volumeService.GetVolumeMetadata(volumeID)
+	meta, err := daemon.volumeService.GetVolumeMetadata(testAccountID, volumeID)
 	require.NoError(t, err, "a DeleteOnTermination=false volume must survive terminate")
 	assert.Equal(t, "available", meta.State)
 	assert.Empty(t, meta.AttachedInstance, "terminate must still detach it")
@@ -1673,7 +1673,7 @@ func TestInstanceCleanerAdapter_DeleteVolumes_NonBootNonDoTVolumeDetachedNotDele
 	err := cleaner.DeleteVolumes(instance)
 	require.NoError(t, err)
 
-	meta, err := daemon.volumeService.GetVolumeMetadata(volumeID)
+	meta, err := daemon.volumeService.GetVolumeMetadata(testAccountID, volumeID)
 	require.NoError(t, err, "a DeleteOnTermination=false volume must survive terminate")
 	assert.Equal(t, "available", meta.State)
 	assert.Empty(t, meta.AttachedInstance, "terminate must still detach it")
@@ -1743,7 +1743,7 @@ func TestTerminatedTeardownReaper_SelfHealsFailedVolumeTeardown(t *testing.T) {
 	_, err = reaper.Sweep(context.Background())
 	require.NoError(t, err)
 
-	_, err = daemon.volumeService.GetVolumeMetadata(volumeID)
+	_, err = daemon.volumeService.GetVolumeMetadata(testAccountID, volumeID)
 	require.Error(t, err, "the retried delete must actually remove the volume")
 	assert.Contains(t, err.Error(), awserrors.ErrorInvalidVolumeNotFound)
 
@@ -1804,7 +1804,7 @@ func TestTerminatedTeardownReaper_SelfHealsFailedVolumeDetach(t *testing.T) {
 	_, err := reaper.Sweep(context.Background())
 	require.NoError(t, err)
 
-	meta, err := daemon.volumeService.GetVolumeMetadata(volumeID)
+	meta, err := daemon.volumeService.GetVolumeMetadata(testAccountID, volumeID)
 	require.NoError(t, err, "the volume must survive: DeleteOnTermination=false")
 	assert.Equal(t, "available", meta.State)
 	assert.Empty(t, meta.AttachedInstance, "the retry must clear the stale attachment")
@@ -1862,7 +1862,7 @@ func TestStuckTerminateReaper_DetachesNonDoTVolumeWithoutUnmount(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 1, reaped, "the wedged terminate must be force-completed")
 
-	meta, err := daemon.volumeService.GetVolumeMetadata(volumeID)
+	meta, err := daemon.volumeService.GetVolumeMetadata(testAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, "available", meta.State,
 		"the force-complete path must still detach a non-Boot DeleteOnTermination=false volume")
@@ -3396,15 +3396,21 @@ func TestVolumeMounterAdapter_UnmountOne_RequestFailure(t *testing.T) {
 
 // recordingVolState records UpdateVolumeState calls so the bulk-unmount test can
 // assert which volumes transitioned to available.
+// accounts is recorded separately because the account is a key segment of the
+// document, not a label: an unmount that writes under anything but the
+// instance's own account leaves the volume stuck in-use, and the adapter only
+// logs the error.
 type recordingVolState struct {
-	mu    sync.Mutex
-	calls []string
+	mu       sync.Mutex
+	calls    []string
+	accounts []string
 }
 
-func (r *recordingVolState) UpdateVolumeState(volumeID, state, instanceID, attachmentDevice string) error {
+func (r *recordingVolState) UpdateVolumeState(accountID, volumeID, state, instanceID, attachmentDevice string) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	r.calls = append(r.calls, volumeID+":"+state)
+	r.accounts = append(r.accounts, accountID)
 	return nil
 }
 
@@ -3414,6 +3420,12 @@ func (r *recordingVolState) snapshot() []string {
 	return append([]string(nil), r.calls...)
 }
 
+func (r *recordingVolState) accountsSnapshot() []string {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return append([]string(nil), r.accounts...)
+}
+
 var _ vm.VolumeStateUpdater = (*recordingVolState)(nil)
 
 // TestVolumeMounterAdapter_Unmount_SealFailureSkipsAvailable verifies the
@@ -3482,7 +3494,8 @@ func TestVolumeMounterAdapter_Unmount_NotFoundFlipsToAvailable(t *testing.T) {
 	defer sub.Unsubscribe()
 
 	inst := &vm.VM{
-		ID: "i-unmount-retry",
+		ID:        "i-unmount-retry",
+		AccountID: "000000000042",
 		EBSRequests: types.EBSRequests{
 			Requests: []types.EBSRequest{
 				{Name: "vol-boot-retry", Boot: true, EFI: false},
@@ -3497,6 +3510,8 @@ func TestVolumeMounterAdapter_Unmount_NotFoundFlipsToAvailable(t *testing.T) {
 		"a NotFound response (already-completed seal) must still flip a non-boot data volume to available")
 	assert.NotContains(t, calls, "vol-boot-retry:available",
 		"a boot volume must stay attached even when the seal retry reports NotFound")
+	assert.Equal(t, []string{"000000000042"}, volState.accountsSnapshot(),
+		"the state write must be keyed on the instance's own account, not its ID")
 }
 
 // TestUnmountResponseError covers the shared seal-result parser used by both the
diff --git a/spinifex/daemon/ownership.go b/spinifex/daemon/ownership.go
index 9714e105c..f50e9f54a 100644
--- a/spinifex/daemon/ownership.go
+++ b/spinifex/daemon/ownership.go
@@ -31,12 +31,3 @@ func checkInstanceOwnership(nodeID string, msg *nats.Msg, instanceID, ownerAccou
 	}
 	return true
 }
-
-// volumeVisibleTo reports whether callerAccountID may access a volume.
-// Empty tenantID is root-only to prevent untenanted volumes from leaking.
-func volumeVisibleTo(tenantID, callerAccountID string) bool {
-	if tenantID == "" {
-		return callerAccountID == utils.GlobalAccountID
-	}
-	return callerAccountID == tenantID
-}
diff --git a/spinifex/daemon/ownership_test.go b/spinifex/daemon/ownership_test.go
deleted file mode 100644
index 6a1f2d764..000000000
--- a/spinifex/daemon/ownership_test.go
+++ /dev/null
@@ -1,75 +0,0 @@
-package daemon
-
-import (
-	"testing"
-
-	"github.com/mulgadc/spinifex/spinifex/utils"
-)
-
-func TestVolumeVisibleTo(t *testing.T) {
-	tests := []struct {
-		name            string
-		tenantID        string
-		callerAccountID string
-		expected        bool
-	}{
-		{
-			name:            "same tenant",
-			tenantID:        "123456789012",
-			callerAccountID: "123456789012",
-			expected:        true,
-		},
-		{
-			name:            "different tenant denied",
-			tenantID:        "123456789012",
-			callerAccountID: "999999999999",
-			expected:        false,
-		},
-		{
-			name:            "untenanted volume visible to root",
-			tenantID:        "",
-			callerAccountID: utils.GlobalAccountID,
-			expected:        true,
-		},
-		{
-			name:            "untenanted volume hidden from non-root tenant",
-			tenantID:        "",
-			callerAccountID: "123456789012",
-			expected:        false,
-		},
-		{
-			name:            "untenanted volume denied to empty caller",
-			tenantID:        "",
-			callerAccountID: "",
-			expected:        false,
-		},
-		{
-			name:            "tenant volume denied to empty caller",
-			tenantID:        "123456789012",
-			callerAccountID: "",
-			expected:        false,
-		},
-		{
-			name:            "root cannot impersonate tenant volume",
-			tenantID:        "123456789012",
-			callerAccountID: utils.GlobalAccountID,
-			expected:        false,
-		},
-		{
-			name:            "root accessing root-owned volume",
-			tenantID:        utils.GlobalAccountID,
-			callerAccountID: utils.GlobalAccountID,
-			expected:        true,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			got := volumeVisibleTo(tt.tenantID, tt.callerAccountID)
-			if got != tt.expected {
-				t.Errorf("volumeVisibleTo(%q, %q) = %v, want %v",
-					tt.tenantID, tt.callerAccountID, got, tt.expected)
-			}
-		})
-	}
-}
diff --git a/spinifex/daemon/vm_adapters.go b/spinifex/daemon/vm_adapters.go
index 837e00608..26d49e983 100644
--- a/spinifex/daemon/vm_adapters.go
+++ b/spinifex/daemon/vm_adapters.go
@@ -258,7 +258,7 @@ func (a *volumeMounterAdapter) Unmount(ctx context.Context, instance *vm.VM) err
 		// Boot too. Only DetachVolume and terminate release a boot volume; flipping
 		// it available here while the instance restarts splits the state record.
 		if sealed && !ebsRequest.EFI && !ebsRequest.Boot && a.volState != nil {
-			if err := a.volState.UpdateVolumeState(ebsRequest.Name, "available", "", ""); err != nil {
+			if err := a.volState.UpdateVolumeState(instance.AccountID, ebsRequest.Name, "available", "", ""); err != nil {
 				slog.Error("Failed to update volume state to available after unmount",
 					"volumeId", ebsRequest.Name, "err", err)
 			}
diff --git a/spinifex/ebsmetadata/metadata.go b/spinifex/ebsmetadata/metadata.go
index 60faf23dc..4560164fe 100644
--- a/spinifex/ebsmetadata/metadata.go
+++ b/spinifex/ebsmetadata/metadata.go
@@ -8,9 +8,14 @@ import (
 	"fmt"
 	"strings"
 	"time"
+
+	"github.com/mulgadc/spinifex/spinifex/utils"
 )
 
-const SchemaVersion uint16 = 1
+// SchemaVersion is the document's field generation, and moves independently of
+// the key layout's v2 prefix. They start aligned on a fresh install and are not
+// promised to stay so: adding a field bumps this without re-keying anything.
+const SchemaVersion uint16 = 2
 
 // ErrCorruptDocument wraps decode and schema-version failures so callers can
 // tell a document that exists but cannot be read from one that is absent. The
@@ -61,6 +66,25 @@ type VolumeModification struct {
 	EndTime            time.Time `json:"end_time,omitzero"`
 }
 
+// Snapshot is the control-plane record used for EC2 snapshot operations. It
+// deliberately excludes viperblock's own half of the snapshot prefix — the
+// block checkpoint and config.json — which stays at the bucket root.
+type Snapshot struct {
+	SchemaVersion    uint16            `json:"schema_version"`
+	SnapshotID       string            `json:"snapshot_id"`
+	VolumeID         string            `json:"volume_id"`
+	VolumeSize       int64             `json:"volume_size"`
+	State            string            `json:"state"`
+	Progress         string            `json:"progress"`
+	StartTime        time.Time         `json:"start_time"`
+	Description      string            `json:"description"`
+	Encrypted        bool              `json:"encrypted"`
+	OwnerID          string            `json:"owner_id"`
+	AvailabilityZone string            `json:"availability_zone"`
+	Tags             map[string]string `json:"tags,omitempty"`
+	ProviderHandle   string            `json:"provider_handle,omitempty"`
+}
+
 // AMI is the control-plane record used for EC2 image operations.
 type AMI struct {
 	SchemaVersion   uint16            `json:"schema_version"`
@@ -82,14 +106,39 @@ type AMI struct {
 	State           string            `json:"state,omitempty"`
 }
 
-func VolumeKey(volumeID string) (string, error) { return key("volumes", volumeID) }
-func AMIKey(imageID string) (string, error)     { return key("amis", imageID) }
+// VolumeKey keys a volume document under its owning account, so a listing of
+// one account's prefix cannot reach another account's document. accountID comes
+// from the document's own TenantID, never from the caller.
+func VolumeKey(accountID, volumeID string) (string, error) {
+	return partitionedKey("volumes", accountID, volumeID)
+}
 
+// SnapshotKey keys a snapshot document under its owning account, taken from the
+// document's own OwnerID rather than from the caller.
+func SnapshotKey(accountID, snapshotID string) (string, error) {
+	return partitionedKey("snapshots", accountID, snapshotID)
+}
+
+// AMIKey is unpartitioned: an AMI's owner is an alias rather than an account,
+// and system images are visible to every account.
+func AMIKey(imageID string) (string, error) { return key("amis", imageID) }
+
+// partitionedKey refuses an owning account that is not an account ID, so an
+// untenanted document cannot be written, cannot exist, and never has to be
+// read. A transposed (id, account) pair fails here too.
+func partitionedKey(kind, accountID, id string) (string, error) {
+	if !utils.IsAccountID(accountID) {
+		return "", fmt.Errorf("invalid EBS metadata account ID %q", accountID)
+	}
+	return key(kind+"/"+accountID, id)
+}
+
+// key rejects an ID that would escape or rename its own path segment.
 func key(kind, id string) (string, error) {
 	if id == "" || id == "." || id == ".." || strings.ContainsAny(id, "/\\") {
 		return "", fmt.Errorf("invalid EBS metadata ID %q", id)
 	}
-	return "spinifex/ebsmetadata/v1/" + kind + "/" + id + ".json", nil
+	return "spinifex/ebsmetadata/v2/" + kind + "/" + id + ".json", nil
 }
 
 func MarshalVolume(volume Volume) ([]byte, error) {
@@ -108,6 +157,22 @@ func UnmarshalVolume(data []byte) (Volume, error) {
 	return volume, nil
 }
 
+func MarshalSnapshot(snapshot Snapshot) ([]byte, error) {
+	snapshot.SchemaVersion = SchemaVersion
+	return json.Marshal(snapshot)
+}
+
+func UnmarshalSnapshot(data []byte) (Snapshot, error) {
+	var snapshot Snapshot
+	if err := json.Unmarshal(data, &snapshot); err != nil {
+		return Snapshot{}, fmt.Errorf("%w: %w", ErrCorruptDocument, err)
+	}
+	if snapshot.SchemaVersion != SchemaVersion {
+		return Snapshot{}, fmt.Errorf("%w: unsupported snapshot metadata schema version %d", ErrCorruptDocument, snapshot.SchemaVersion)
+	}
+	return snapshot, nil
+}
+
 func MarshalAMI(ami AMI) ([]byte, error) {
 	ami.SchemaVersion = SchemaVersion
 	return json.Marshal(ami)
diff --git a/spinifex/ebsmetadata/metadata_test.go b/spinifex/ebsmetadata/metadata_test.go
index d2191ccb1..584639051 100644
--- a/spinifex/ebsmetadata/metadata_test.go
+++ b/spinifex/ebsmetadata/metadata_test.go
@@ -4,13 +4,14 @@ import (
 	"testing"
 	"time"
 
+	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestVolumeMetadataRoundTripOwnsItsSchema(t *testing.T) {
 	want := Volume{
-		VolumeID: "vol-1", TenantID: "acct-1", CapacityGiB: 20,
+		VolumeID: "vol-1", TenantID: "000000000001", CapacityGiB: 20,
 		State: "available", CreatedAt: time.Date(2026, 8, 5, 0, 0, 0, 0, time.UTC),
 		ProviderHandle: "opaque-provider-handle", Tags: map[string]string{"env": "test"},
 	}
@@ -30,7 +31,7 @@ func TestVolumeMetadataRoundTripOwnsItsSchema(t *testing.T) {
 // survive a marshal/unmarshal round-trip.
 func TestVolumeRoundTripsEncryptedAndModification(t *testing.T) {
 	want := Volume{
-		VolumeID: "vol-1", TenantID: "acct-1", CapacityGiB: 20,
+		VolumeID: "vol-1", TenantID: "000000000001", CapacityGiB: 20,
 		State: "available", Encrypted: true,
 		Modification: &VolumeModification{
 			ModificationState: "completed", Progress: 100,
@@ -57,10 +58,59 @@ func TestMetadataRejectsUnknownSchemaVersion(t *testing.T) {
 
 func TestMetadataKeysRejectPathTraversal(t *testing.T) {
 	for _, id := range []string{"", "..", "../escape", "a/b", "a\\b"} {
-		_, err := VolumeKey(id)
+		_, err := VolumeKey("000000000001", id)
 		require.Error(t, err, "ID %q must not escape metadata prefix", id)
+
+		_, err = SnapshotKey("000000000001", id)
+		require.Error(t, err, "ID %q must not escape metadata prefix", id)
+
+		_, err = VolumeKey(id, "vol-1")
+		require.Error(t, err, "account %q must not escape metadata prefix", id)
 	}
 	key, err := AMIKey("ami-1")
 	require.NoError(t, err)
-	assert.Equal(t, "spinifex/ebsmetadata/v1/amis/ami-1.json", key)
+	assert.Equal(t, "spinifex/ebsmetadata/v2/amis/ami-1.json", key)
+}
+
+// An untenanted document cannot be written, so it cannot exist, so nothing
+// needs to read one.
+func TestPartitionedKeysRejectNonAccountOwner(t *testing.T) {
+	for _, accountID := range []string{"", "acct-1", "12345678901", "1234567890123", "00000000000a", "system"} {
+		_, err := VolumeKey(accountID, "vol-1")
+		require.Error(t, err, "account %q is not an account ID", accountID)
+
+		_, err = SnapshotKey(accountID, "snap-1")
+		require.Error(t, err, "account %q is not an account ID", accountID)
+	}
+
+	// A transposed (id, account) pair: a vol- string is not twelve digits.
+	_, err := VolumeKey("vol-1", "000000000001")
+	require.Error(t, err)
+
+	// The system account is an ordinary account and partitions like any other.
+	key, err := VolumeKey(utils.GlobalAccountID, "vol-1")
+	require.NoError(t, err)
+	assert.Equal(t, "spinifex/ebsmetadata/v2/volumes/000000000000/vol-1.json", key)
+}
+
+func TestSnapshotKeyPartitionsByOwningAccount(t *testing.T) {
+	key, err := SnapshotKey("000000000001", "snap-1")
+	require.NoError(t, err)
+	assert.Equal(t, "spinifex/ebsmetadata/v2/snapshots/000000000001/snap-1.json", key)
+
+	other, err := SnapshotKey("000000000002", "snap-1")
+	require.NoError(t, err)
+	assert.NotEqual(t, key, other, "the same snapshot ID under two accounts must be two keys")
+}
+
+// The owning account is a key segment, which is what lets a listing of one
+// account's prefix answer without reading another account's documents.
+func TestVolumeKeyPartitionsByOwningAccount(t *testing.T) {
+	key, err := VolumeKey("000000000001", "vol-1")
+	require.NoError(t, err)
+	assert.Equal(t, "spinifex/ebsmetadata/v2/volumes/000000000001/vol-1.json", key)
+
+	other, err := VolumeKey("000000000002", "vol-1")
+	require.NoError(t, err)
+	assert.NotEqual(t, key, other, "the same volume ID under two accounts must be two keys")
 }
diff --git a/spinifex/ebsmetadata/snapshot_store_test.go b/spinifex/ebsmetadata/snapshot_store_test.go
new file mode 100644
index 000000000..553b0cda7
--- /dev/null
+++ b/spinifex/ebsmetadata/snapshot_store_test.go
@@ -0,0 +1,215 @@
+package ebsmetadata_test
+
+import (
+	"context"
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/s3"
+	. "github.com/mulgadc/spinifex/spinifex/ebsmetadata"
+	"github.com/mulgadc/spinifex/spinifex/objectstore"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	accountA = "000000000001"
+	accountB = "000000000002"
+)
+
+func TestStoreRoundTripsSnapshot(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+
+	snapshot := Snapshot{SnapshotID: "snap-1", VolumeID: "vol-1", OwnerID: accountA,
+		VolumeSize: 8, State: "completed", ProviderHandle: "opaque"}
+	require.NoError(t, store.PutSnapshot(ctx, snapshot))
+
+	got, err := store.GetSnapshot(ctx, accountA, "snap-1")
+	require.NoError(t, err)
+	assert.Equal(t, snapshot.VolumeID, got.VolumeID)
+	assert.Equal(t, snapshot.ProviderHandle, got.ProviderHandle)
+	assert.Equal(t, SchemaVersion, got.SchemaVersion)
+
+	require.NoError(t, store.DeleteSnapshot(ctx, accountA, "snap-1"))
+	_, err = store.GetSnapshot(ctx, accountA, "snap-1")
+	assert.True(t, objectstore.IsNoSuchKeyError(err))
+}
+
+// PutSnapshot takes the key segment from the document's own OwnerID, so an
+// untenanted snapshot has nowhere to be written and cannot exist.
+func TestPutSnapshot_RefusesUntenantedDocument(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	err := store.PutSnapshot(context.Background(), Snapshot{SnapshotID: "snap-1", VolumeID: "vol-1"})
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "invalid EBS metadata account ID")
+}
+
+// A snapshot outside the caller's prefix is absent, not denied: the key is the
+// ownership check.
+func TestGetSnapshot_OtherAccountIsNotFound(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	require.NoError(t, store.PutSnapshot(ctx, Snapshot{SnapshotID: "snap-1", VolumeID: "vol-1", OwnerID: accountA}))
+
+	_, err := store.GetSnapshot(ctx, accountB, "snap-1")
+	assert.True(t, objectstore.IsNoSuchKeyError(err))
+}
+
+func TestListSnapshots_ScopedToOneAccount(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	for _, snapshot := range []Snapshot{
+		{SnapshotID: "snap-a1", OwnerID: accountA},
+		{SnapshotID: "snap-a2", OwnerID: accountA},
+		{SnapshotID: "snap-b1", OwnerID: accountB},
+	} {
+		require.NoError(t, store.PutSnapshot(ctx, snapshot))
+	}
+
+	got, err := store.ListSnapshots(ctx, accountA)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"snap-a1", "snap-a2"}, snapshotIDs(got))
+
+	got, err = store.ListSnapshots(ctx, accountB)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"snap-b1"}, snapshotIDs(got))
+}
+
+// The two verbs must partition and list the same way: a key builder that wrote
+// one shape and listed another would show up here and nowhere else.
+func TestListAllSnapshots_IsTheUnionOfEveryAccount(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	for _, snapshot := range []Snapshot{
+		{SnapshotID: "snap-a1", OwnerID: accountA},
+		{SnapshotID: "snap-b1", OwnerID: accountB},
+		{SnapshotID: "snap-b2", OwnerID: accountB},
+	} {
+		require.NoError(t, store.PutSnapshot(ctx, snapshot))
+	}
+
+	all, err := store.ListAllSnapshots(ctx)
+	require.NoError(t, err)
+
+	var union []Snapshot
+	for _, account := range []string{accountA, accountB} {
+		scoped, err := store.ListSnapshots(ctx, account)
+		require.NoError(t, err)
+		union = append(union, scoped...)
+	}
+	assert.Equal(t, snapshotIDs(all), snapshotIDs(union))
+}
+
+// An empty account must not widen a listing to every account's documents.
+func TestListSnapshots_RefusesANonAccountPrefix(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	require.NoError(t, store.PutSnapshot(ctx, Snapshot{SnapshotID: "snap-a1", OwnerID: accountA}))
+
+	for _, account := range []string{"", "not-an-account", "snap-a1"} {
+		_, err := store.ListSnapshots(ctx, account)
+		require.Error(t, err, "account %q must not list", account)
+		_, err = store.ListSnapshotsStrict(ctx, account)
+		require.Error(t, err, "account %q must not list strictly", account)
+	}
+}
+
+func TestListSnapshots_SkipsCorruptButStrictDoesNot(t *testing.T) {
+	objects := objectstore.NewMemoryObjectStore()
+	store := NewStore(objects, "control-plane")
+	ctx := context.Background()
+	require.NoError(t, store.PutSnapshot(ctx, Snapshot{SnapshotID: "snap-a1", OwnerID: accountA}))
+
+	key, err := SnapshotKey(accountA, "snap-corrupt")
+	require.NoError(t, err)
+	_, err = objects.PutObject(ctx, &s3.PutObjectInput{
+		Bucket: aws.String("control-plane"), Key: aws.String(key),
+		Body: strings.NewReader("{not json"),
+	})
+	require.NoError(t, err)
+
+	tolerant, err := store.ListSnapshots(ctx, accountA)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"snap-a1"}, snapshotIDs(tolerant))
+
+	_, err = store.ListSnapshotsStrict(ctx, accountA)
+	require.ErrorIs(t, err, ErrCorruptDocument)
+}
+
+// A snapshot document written by an older schema is corrupt, not absent: the
+// two deserve different answers.
+func TestUnmarshalSnapshot_RejectsUnknownSchemaVersion(t *testing.T) {
+	data, err := MarshalSnapshot(Snapshot{SnapshotID: "snap-1", OwnerID: accountA})
+	require.NoError(t, err)
+	stale := strings.Replace(string(data), `"schema_version":2`, `"schema_version":1`, 1)
+	require.NotEqual(t, string(data), stale)
+
+	_, err = UnmarshalSnapshot([]byte(stale))
+	require.ErrorIs(t, err, ErrCorruptDocument)
+}
+
+// A malformed account reaches the key builder only through a Spinifex bug, so
+// it stays a plain error rather than a not-found the caller would report as a
+// missing snapshot.
+func TestSnapshotVerbs_RefuseAMalformedAccount(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+
+	_, err := store.GetSnapshot(ctx, "not-an-account", "snap-1")
+	require.Error(t, err)
+	assert.False(t, objectstore.IsNoSuchKeyError(err))
+
+	require.Error(t, store.DeleteSnapshot(ctx, "", "snap-1"))
+}
+
+func TestListAllSnapshotsStrict_FailsOnACorruptDocument(t *testing.T) {
+	objects := objectstore.NewMemoryObjectStore()
+	store := NewStore(objects, "control-plane")
+	ctx := context.Background()
+	require.NoError(t, store.PutSnapshot(ctx, Snapshot{SnapshotID: "snap-a1", OwnerID: accountA}))
+
+	key, err := SnapshotKey(accountB, "snap-corrupt")
+	require.NoError(t, err)
+	_, err = objects.PutObject(ctx, &s3.PutObjectInput{
+		Bucket: aws.String("control-plane"), Key: aws.String(key),
+		Body: strings.NewReader("{not json"),
+	})
+	require.NoError(t, err)
+
+	tolerant, err := store.ListAllSnapshots(ctx)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"snap-a1"}, snapshotIDs(tolerant))
+
+	_, err = store.ListAllSnapshotsStrict(ctx)
+	require.ErrorIs(t, err, ErrCorruptDocument)
+}
+
+// An unconfigured store must say so rather than answer "no snapshots", which a
+// caller would act on as authoritative absence.
+func TestSnapshotListings_RefuseAnUnconfiguredStore(t *testing.T) {
+	store := NewStore(nil, "control-plane")
+	ctx := context.Background()
+
+	for name, list := range map[string]func() ([]Snapshot, error){
+		"ListSnapshots":          func() ([]Snapshot, error) { return store.ListSnapshots(ctx, accountA) },
+		"ListSnapshotsStrict":    func() ([]Snapshot, error) { return store.ListSnapshotsStrict(ctx, accountA) },
+		"ListAllSnapshots":       func() ([]Snapshot, error) { return store.ListAllSnapshots(ctx) },
+		"ListAllSnapshotsStrict": func() ([]Snapshot, error) { return store.ListAllSnapshotsStrict(ctx) },
+	} {
+		_, err := list()
+		require.Error(t, err, name)
+		assert.Contains(t, err.Error(), "not configured", name)
+	}
+}
+
+func snapshotIDs(snapshots []Snapshot) []string {
+	ids := make([]string, 0, len(snapshots))
+	for _, snapshot := range snapshots {
+		ids = append(ids, snapshot.SnapshotID)
+	}
+	sort.Strings(ids)
+	return ids
+}
diff --git a/spinifex/ebsmetadata/store.go b/spinifex/ebsmetadata/store.go
index 1c4daa8bd..ef65f3441 100644
--- a/spinifex/ebsmetadata/store.go
+++ b/spinifex/ebsmetadata/store.go
@@ -13,6 +13,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
+	"github.com/mulgadc/spinifex/spinifex/utils"
 )
 
 // Store persists Spinifex-owned metadata documents in the existing object
@@ -26,8 +27,11 @@ func NewStore(objects objectstore.ObjectStore, bucket string) *Store {
 	return &Store{objects: objects, bucket: bucket}
 }
 
+// PutVolume takes no account: the key segment is the document's own TenantID.
+// An account passed alongside a document that already carries one is how the
+// two come to disagree.
 func (s *Store) PutVolume(ctx context.Context, volume Volume) error {
-	key, err := VolumeKey(volume.VolumeID)
+	key, err := VolumeKey(volume.TenantID, volume.VolumeID)
 	if err != nil {
 		return err
 	}
@@ -40,8 +44,8 @@ func (s *Store) PutVolume(ctx context.Context, volume Volume) error {
 
 // GetVolume returns the volume's ebsmetadata document. A volume with no
 // document does not exist as far as the control plane is concerned.
-func (s *Store) GetVolume(ctx context.Context, volumeID string) (Volume, error) {
-	key, err := VolumeKey(volumeID)
+func (s *Store) GetVolume(ctx context.Context, accountID, volumeID string) (Volume, error) {
+	key, err := VolumeKey(accountID, volumeID)
 	if err != nil {
 		return Volume{}, err
 	}
@@ -52,8 +56,8 @@ func (s *Store) GetVolume(ctx context.Context, volumeID string) (Volume, error)
 	return UnmarshalVolume(data)
 }
 
-func (s *Store) DeleteVolume(ctx context.Context, volumeID string) error {
-	key, err := VolumeKey(volumeID)
+func (s *Store) DeleteVolume(ctx context.Context, accountID, volumeID string) error {
+	key, err := VolumeKey(accountID, volumeID)
 	if err != nil {
 		return err
 	}
@@ -61,28 +65,137 @@ func (s *Store) DeleteVolume(ctx context.Context, volumeID string) error {
 	return err
 }
 
-// ListVolumes returns every ebsmetadata volume document, skipping any it
-// cannot read or decode. One unreadable document must not make every volume in
-// the cluster invisible, so the tolerance is deliberate and each skip is logged.
-func (s *Store) ListVolumes(ctx context.Context) ([]Volume, error) {
-	if s == nil || s.objects == nil {
-		return nil, errors.New("metadata store is not configured")
-	}
-	return s.listVolumeDocuments(ctx, true)
+// ListVolumes returns one account's volume documents, skipping any it cannot
+// read or decode. The prefix is the isolation: no other account's document is
+// read, so none has to be filtered out afterwards. One unreadable document must
+// not make every volume invisible, so the tolerance is deliberate and logged.
+func (s *Store) ListVolumes(ctx context.Context, accountID string) ([]Volume, error) {
+	return s.listVolumeDocuments(ctx, accountID, true)
 }
 
 // ListVolumesStrict is ListVolumes without the tolerance. It is for callers
 // whose answer would be wrong rather than merely partial: a volume that failed
 // to read is not evidence that no volume holds the resource being checked.
-func (s *Store) ListVolumesStrict(ctx context.Context) ([]Volume, error) {
+func (s *Store) ListVolumesStrict(ctx context.Context, accountID string) ([]Volume, error) {
+	return s.listVolumeDocuments(ctx, accountID, false)
+}
+
+// ListAllVolumes lists across every account. Whole-cluster by intent: the name
+// is deliberately not ListVolumes so no caller gets this reach by leaving a
+// call site untouched.
+func (s *Store) ListAllVolumes(ctx context.Context) ([]Volume, error) {
 	if s == nil || s.objects == nil {
 		return nil, errors.New("metadata store is not configured")
 	}
-	return s.listVolumeDocuments(ctx, false)
+	return listDocuments(ctx, s, volumePrefix, "volume", UnmarshalVolume, true)
 }
 
-func (s *Store) listVolumeDocuments(ctx context.Context, skipCorrupt bool) ([]Volume, error) {
-	return listDocuments(ctx, s, volumePrefix, "volume", UnmarshalVolume, skipCorrupt)
+// ListAllVolumesStrict is ListAllVolumes without the tolerance.
+func (s *Store) ListAllVolumesStrict(ctx context.Context) ([]Volume, error) {
+	if s == nil || s.objects == nil {
+		return nil, errors.New("metadata store is not configured")
+	}
+	return listDocuments(ctx, s, volumePrefix, "volume", UnmarshalVolume, false)
+}
+
+func (s *Store) listVolumeDocuments(ctx context.Context, accountID string, skipCorrupt bool) ([]Volume, error) {
+	if s == nil || s.objects == nil {
+		return nil, errors.New("metadata store is not configured")
+	}
+	prefix, err := accountPrefix(volumePrefix, accountID)
+	if err != nil {
+		return nil, err
+	}
+	return listDocuments(ctx, s, prefix, "volume", UnmarshalVolume, skipCorrupt)
+}
+
+// PutSnapshot takes no account: like PutVolume, the key segment is the
+// document's own OwnerID.
+func (s *Store) PutSnapshot(ctx context.Context, snapshot Snapshot) error {
+	key, err := SnapshotKey(snapshot.OwnerID, snapshot.SnapshotID)
+	if err != nil {
+		return err
+	}
+	data, err := MarshalSnapshot(snapshot)
+	if err != nil {
+		return fmt.Errorf("marshal snapshot metadata: %w", err)
+	}
+	return s.put(ctx, key, data)
+}
+
+// GetSnapshot returns the snapshot's ebsmetadata document. A snapshot outside
+// accountID's prefix is not found rather than denied: the key is the ownership
+// check.
+func (s *Store) GetSnapshot(ctx context.Context, accountID, snapshotID string) (Snapshot, error) {
+	key, err := SnapshotKey(accountID, snapshotID)
+	if err != nil {
+		return Snapshot{}, err
+	}
+	data, err := s.get(ctx, key)
+	if err != nil {
+		return Snapshot{}, err
+	}
+	return UnmarshalSnapshot(data)
+}
+
+func (s *Store) DeleteSnapshot(ctx context.Context, accountID, snapshotID string) error {
+	key, err := SnapshotKey(accountID, snapshotID)
+	if err != nil {
+		return err
+	}
+	_, err = s.objects.DeleteObject(ctx, &s3.DeleteObjectInput{Bucket: aws.String(s.bucket), Key: aws.String(key)})
+	return err
+}
+
+// ListSnapshots returns one account's snapshot documents, skipping any it
+// cannot read or decode. The prefix is the isolation: no other account's
+// document is read, so none has to be filtered out afterwards.
+func (s *Store) ListSnapshots(ctx context.Context, accountID string) ([]Snapshot, error) {
+	return s.listSnapshotDocuments(ctx, accountID, true)
+}
+
+// ListSnapshotsStrict is ListSnapshots without the tolerance, for callers whose
+// answer would be wrong rather than merely partial.
+func (s *Store) ListSnapshotsStrict(ctx context.Context, accountID string) ([]Snapshot, error) {
+	return s.listSnapshotDocuments(ctx, accountID, false)
+}
+
+// ListAllSnapshots lists across every account. Whole-cluster by intent: the
+// name is deliberately not ListSnapshots so no caller gets this reach by
+// leaving a call site untouched.
+func (s *Store) ListAllSnapshots(ctx context.Context) ([]Snapshot, error) {
+	if s == nil || s.objects == nil {
+		return nil, errors.New("metadata store is not configured")
+	}
+	return listDocuments(ctx, s, snapshotPrefix, "snapshot", UnmarshalSnapshot, true)
+}
+
+// ListAllSnapshotsStrict is ListAllSnapshots without the tolerance.
+func (s *Store) ListAllSnapshotsStrict(ctx context.Context) ([]Snapshot, error) {
+	if s == nil || s.objects == nil {
+		return nil, errors.New("metadata store is not configured")
+	}
+	return listDocuments(ctx, s, snapshotPrefix, "snapshot", UnmarshalSnapshot, false)
+}
+
+func (s *Store) listSnapshotDocuments(ctx context.Context, accountID string, skipCorrupt bool) ([]Snapshot, error) {
+	if s == nil || s.objects == nil {
+		return nil, errors.New("metadata store is not configured")
+	}
+	prefix, err := accountPrefix(snapshotPrefix, accountID)
+	if err != nil {
+		return nil, err
+	}
+	return listDocuments(ctx, s, prefix, "snapshot", UnmarshalSnapshot, skipCorrupt)
+}
+
+// accountPrefix rejects the same accounts the key builders do, so a listing
+// cannot widen to the whole tree by being handed an empty account.
+func accountPrefix(kindPrefix, accountID string) (string, error) {
+	if !utils.IsAccountID(accountID) {
+		return "", fmt.Errorf("invalid EBS metadata account ID %q", accountID)
+	}
+	return kindPrefix + accountID + "/", nil
 }
 
 // ListAMIs returns every AMI document, skipping any it cannot decode. One
@@ -111,8 +224,9 @@ func (s *Store) listAMIDocuments(ctx context.Context, skipCorrupt bool) ([]AMI,
 
 // Prefixes the metadata documents live under, one per document kind.
 const (
-	volumePrefix = "spinifex/ebsmetadata/v1/volumes/"
-	amiPrefix    = "spinifex/ebsmetadata/v1/amis/"
+	volumePrefix   = "spinifex/ebsmetadata/v2/volumes/"
+	snapshotPrefix = "spinifex/ebsmetadata/v2/snapshots/"
+	amiPrefix      = "spinifex/ebsmetadata/v2/amis/"
 )
 
 // listFetchConcurrency bounds the object fetches a single listing may have in
diff --git a/spinifex/ebsmetadata/store_test.go b/spinifex/ebsmetadata/store_test.go
index 43f01ff6c..6d7859eb9 100644
--- a/spinifex/ebsmetadata/store_test.go
+++ b/spinifex/ebsmetadata/store_test.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sort"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -22,9 +23,9 @@ func TestStoreRoundTripsVolumeAndAMI(t *testing.T) {
 	objects := objectstore.NewMemoryObjectStore()
 	store := NewStore(objects, "control-plane")
 
-	volume := Volume{VolumeID: "vol-1", TenantID: "acct-1", CapacityGiB: 10, State: "available", ProviderHandle: "opaque"}
+	volume := Volume{VolumeID: "vol-1", TenantID: "000000000001", CapacityGiB: 10, State: "available", ProviderHandle: "opaque"}
 	require.NoError(t, store.PutVolume(context.Background(), volume))
-	gotVolume, err := store.GetVolume(context.Background(), volume.VolumeID)
+	gotVolume, err := store.GetVolume(context.Background(), volume.TenantID, volume.VolumeID)
 	require.NoError(t, err)
 	assert.Equal(t, volume.VolumeID, gotVolume.VolumeID)
 	assert.Equal(t, volume.ProviderHandle, gotVolume.ProviderHandle)
@@ -38,31 +39,31 @@ func TestStoreRoundTripsVolumeAndAMI(t *testing.T) {
 	assert.Equal(t, ami.SnapshotID, gotAMI.SnapshotID)
 	assert.Equal(t, SchemaVersion, gotAMI.SchemaVersion)
 
-	require.NoError(t, store.DeleteVolume(context.Background(), volume.VolumeID))
+	require.NoError(t, store.DeleteVolume(context.Background(), volume.TenantID, volume.VolumeID))
 	require.NoError(t, store.DeleteAMI(context.Background(), ami.ImageID))
 }
 
 func TestListVolumes_Empty(t *testing.T) {
 	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
-	volumes, err := store.ListVolumes(context.Background())
+	volumes, err := store.ListVolumes(context.Background(), "000000000001")
 	require.NoError(t, err)
 	assert.Empty(t, volumes)
 }
 
-func TestListVolumes_ReturnsAllStoredVolumes(t *testing.T) {
+func TestListAllVolumes_ReturnsEveryAccountsVolumes(t *testing.T) {
 	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
 	ctx := context.Background()
 
 	want := []Volume{
-		{VolumeID: "vol-1", TenantID: "acct-1", CapacityGiB: 8, State: "available"},
-		{VolumeID: "vol-2", TenantID: "acct-2", CapacityGiB: 16, State: "in-use"},
-		{VolumeID: "vol-3", TenantID: "acct-1", CapacityGiB: 32, State: "available"},
+		{VolumeID: "vol-1", TenantID: "000000000001", CapacityGiB: 8, State: "available"},
+		{VolumeID: "vol-2", TenantID: "000000000002", CapacityGiB: 16, State: "in-use"},
+		{VolumeID: "vol-3", TenantID: "000000000001", CapacityGiB: 32, State: "available"},
 	}
 	for _, v := range want {
 		require.NoError(t, store.PutVolume(ctx, v))
 	}
 
-	got, err := store.ListVolumes(ctx)
+	got, err := store.ListAllVolumes(ctx)
 	require.NoError(t, err)
 	require.Len(t, got, len(want))
 
@@ -83,9 +84,9 @@ func corruptVolumeStore(t *testing.T) (*Store, context.Context) {
 	store := NewStore(objects, "control-plane")
 	ctx := context.Background()
 
-	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-good", CapacityGiB: 1}))
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-good", TenantID: "000000000001", CapacityGiB: 1}))
 
-	key, err := VolumeKey("vol-corrupt")
+	key, err := VolumeKey("000000000001", "vol-corrupt")
 	require.NoError(t, err)
 	_, err = objects.PutObject(ctx, &s3.PutObjectInput{
 		Bucket: aws.String("control-plane"), Key: aws.String(key), Body: bytes.NewReader([]byte("not json")),
@@ -100,7 +101,7 @@ func corruptVolumeStore(t *testing.T) (*Store, context.Context) {
 func TestListVolumes_SkipsCorruptObject(t *testing.T) {
 	store, ctx := corruptVolumeStore(t)
 
-	volumes, err := store.ListVolumes(ctx)
+	volumes, err := store.ListVolumes(ctx, "000000000001")
 	require.NoError(t, err)
 	require.Len(t, volumes, 1, "the readable volume must still be listed")
 	assert.Equal(t, "vol-good", volumes[0].VolumeID)
@@ -111,7 +112,7 @@ func TestListVolumes_SkipsCorruptObject(t *testing.T) {
 func TestListVolumesStrict_CorruptObjectReturnsError(t *testing.T) {
 	store, ctx := corruptVolumeStore(t)
 
-	_, err := store.ListVolumesStrict(ctx)
+	_, err := store.ListVolumesStrict(ctx, "000000000001")
 	require.Error(t, err)
 }
 
@@ -123,20 +124,20 @@ func TestListVolumes_SkipsUnreadableObject(t *testing.T) {
 	store := NewStore(objects, "control-plane")
 	ctx := context.Background()
 
-	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-good", CapacityGiB: 1}))
-	key, err := VolumeKey("vol-unreadable")
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-good", TenantID: "000000000001", CapacityGiB: 1}))
+	key, err := VolumeKey("000000000001", "vol-unreadable")
 	require.NoError(t, err)
-	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-unreadable", CapacityGiB: 1}))
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-unreadable", TenantID: "000000000001", CapacityGiB: 1}))
 
 	failing := &getFailsStore{ObjectStore: objects, failKey: key}
 	broken := NewStore(failing, "control-plane")
 
-	volumes, err := broken.ListVolumes(ctx)
+	volumes, err := broken.ListVolumes(ctx, "000000000001")
 	require.NoError(t, err, "an unreadable document must not fail the whole listing")
 	require.Len(t, volumes, 1)
 	assert.Equal(t, "vol-good", volumes[0].VolumeID)
 
-	_, err = broken.ListVolumesStrict(ctx)
+	_, err = broken.ListVolumesStrict(ctx, "000000000001")
 	require.Error(t, err, "the strict listing must still report the failure")
 }
 
@@ -159,13 +160,107 @@ func (s *getFailsStore) GetObject(ctx context.Context, in *s3.GetObjectInput) (*
 // Store method: a zero-value *Store (no ObjectStore wired up) must error
 // instead of panicking on a nil dereference.
 func TestListVolumes_NotConfigured(t *testing.T) {
-	var store *Store
-	_, err := store.ListVolumes(context.Background())
-	require.Error(t, err)
+	ctx := context.Background()
+	for _, store := range []*Store{nil, {}} {
+		for name, list := range map[string]func() ([]Volume, error){
+			"ListVolumes":          func() ([]Volume, error) { return store.ListVolumes(ctx, "000000000001") },
+			"ListVolumesStrict":    func() ([]Volume, error) { return store.ListVolumesStrict(ctx, "000000000001") },
+			"ListAllVolumes":       func() ([]Volume, error) { return store.ListAllVolumes(ctx) },
+			"ListAllVolumesStrict": func() ([]Volume, error) { return store.ListAllVolumesStrict(ctx) },
+		} {
+			_, err := list()
+			require.Error(t, err, name)
+		}
+	}
+}
 
-	empty := &Store{}
-	_, err = empty.ListVolumes(context.Background())
-	require.Error(t, err)
+// The account prefix is the isolation, so a listing must return one account's
+// documents without reading another's.
+func TestListVolumes_ScopedToOneAccount(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	for _, volume := range []Volume{
+		{VolumeID: "vol-a1", TenantID: "000000000001"},
+		{VolumeID: "vol-a2", TenantID: "000000000001"},
+		{VolumeID: "vol-b1", TenantID: "000000000002"},
+	} {
+		require.NoError(t, store.PutVolume(ctx, volume))
+	}
+
+	got, err := store.ListVolumes(ctx, "000000000001")
+	require.NoError(t, err)
+	assert.Equal(t, []string{"vol-a1", "vol-a2"}, volumeIDs(got))
+
+	got, err = store.ListVolumes(ctx, "000000000002")
+	require.NoError(t, err)
+	assert.Equal(t, []string{"vol-b1"}, volumeIDs(got))
+}
+
+// The two verbs must partition and list the same way: a key builder that wrote
+// one shape and listed another would show up here and nowhere else.
+func TestListAllVolumes_IsTheUnionOfEveryAccount(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	for _, volume := range []Volume{
+		{VolumeID: "vol-a1", TenantID: "000000000001"},
+		{VolumeID: "vol-b1", TenantID: "000000000002"},
+		{VolumeID: "vol-b2", TenantID: "000000000002"},
+	} {
+		require.NoError(t, store.PutVolume(ctx, volume))
+	}
+
+	all, err := store.ListAllVolumes(ctx)
+	require.NoError(t, err)
+
+	var union []Volume
+	for _, account := range []string{"000000000001", "000000000002"} {
+		scoped, err := store.ListVolumes(ctx, account)
+		require.NoError(t, err)
+		union = append(union, scoped...)
+	}
+	assert.Equal(t, volumeIDs(all), volumeIDs(union))
+}
+
+// An empty account must not widen a listing to every account's documents.
+func TestListVolumes_RefusesANonAccountPrefix(t *testing.T) {
+	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
+	ctx := context.Background()
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-a1", TenantID: "000000000001"}))
+
+	for _, account := range []string{"", "not-an-account", "vol-a1"} {
+		_, err := store.ListVolumes(ctx, account)
+		require.Error(t, err, "account %q must not list", account)
+		_, err = store.ListVolumesStrict(ctx, account)
+		require.Error(t, err, "account %q must not list strictly", account)
+	}
+}
+
+// The whole-cluster verbs keep the tolerant/strict split the scoped ones have.
+func TestListAllVolumesStrict_FailsOnACorruptDocument(t *testing.T) {
+	objects := objectstore.NewMemoryObjectStore()
+	store := NewStore(objects, "control-plane")
+	ctx := context.Background()
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-a1", TenantID: "000000000001"}))
+
+	key, err := VolumeKey("000000000002", "vol-corrupt")
+	require.NoError(t, err)
+	writeRaw(t, objects, key, []byte("{not json"))
+
+	tolerant, err := store.ListAllVolumes(ctx)
+	require.NoError(t, err)
+	assert.Equal(t, []string{"vol-a1"}, volumeIDs(tolerant))
+
+	_, err = store.ListAllVolumesStrict(ctx)
+	require.ErrorIs(t, err, ErrCorruptDocument)
+}
+
+func volumeIDs(volumes []Volume) []string {
+	ids := make([]string, 0, len(volumes))
+	for _, volume := range volumes {
+		ids = append(ids, volume.VolumeID)
+	}
+	sort.Strings(ids)
+	return ids
 }
 
 // TestListAMIs_Empty mirrors TestListVolumes_Empty: an AMI-less store lists
@@ -177,7 +272,7 @@ func TestListAMIs_Empty(t *testing.T) {
 	assert.Empty(t, amis)
 }
 
-// TestListAMIs_ReturnsAllStoredAMIs mirrors TestListVolumes_ReturnsAllStoredVolumes.
+// TestListAMIs_ReturnsAllStoredAMIs mirrors TestListAllVolumes_ReturnsEveryAccountsVolumes.
 func TestListAMIs_ReturnsAllStoredAMIs(t *testing.T) {
 	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
 	ctx := context.Background()
@@ -220,7 +315,7 @@ func TestListAMIs_NotConfigured(t *testing.T) {
 // concerned, reported as the object store's not-found rather than a zero value.
 func TestGetVolume_MissingDocumentIsNotFound(t *testing.T) {
 	store := NewStore(objectstore.NewMemoryObjectStore(), "control-plane")
-	_, err := store.GetVolume(context.Background(), "vol-missing")
+	_, err := store.GetVolume(context.Background(), "000000000001", "vol-missing")
 	require.Error(t, err)
 	assert.True(t, objectstore.IsNoSuchKeyError(err))
 }
@@ -241,14 +336,14 @@ func TestGet_CorruptDocumentIsDistinguishable(t *testing.T) {
 	store := NewStore(objects, "control-plane")
 	ctx := context.Background()
 
-	volKey, err := VolumeKey("vol-corrupt")
+	volKey, err := VolumeKey("000000000001", "vol-corrupt")
 	require.NoError(t, err)
 	writeRaw(t, objects, volKey, []byte("{not json"))
 	amiKey, err := AMIKey("ami-corrupt")
 	require.NoError(t, err)
 	writeRaw(t, objects, amiKey, []byte("{not json"))
 
-	_, err = store.GetVolume(ctx, "vol-corrupt")
+	_, err = store.GetVolume(ctx, "000000000001", "vol-corrupt")
 	require.ErrorIs(t, err, ErrCorruptDocument)
 	assert.False(t, objectstore.IsNoSuchKeyError(err), "corrupt must not read as absent")
 
@@ -302,7 +397,7 @@ func TestListVolumes_FetchesDocumentsConcurrently(t *testing.T) {
 	const delay = 20 * time.Millisecond
 	for i := range documents {
 		require.NoError(t, store.PutVolume(ctx, Volume{
-			VolumeID: fmt.Sprintf("vol-%02d", i), TenantID: "acct-1", CapacityGiB: 1,
+			VolumeID: fmt.Sprintf("vol-%02d", i), TenantID: "000000000001", CapacityGiB: 1,
 		}))
 	}
 
@@ -310,7 +405,7 @@ func TestListVolumes_FetchesDocumentsConcurrently(t *testing.T) {
 	measured := NewStore(slow, "control-plane")
 
 	start := time.Now()
-	volumes, err := measured.ListVolumes(ctx)
+	volumes, err := measured.ListVolumes(ctx, "000000000001")
 	elapsed := time.Since(start)
 
 	require.NoError(t, err)
@@ -338,8 +433,8 @@ func TestListVolumes_ConcurrentFetchPreservesListingOrder(t *testing.T) {
 	keys := make([]string, 0, documents)
 	for i := range documents {
 		id := fmt.Sprintf("vol-%02d", i)
-		require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: id, TenantID: "acct-1", CapacityGiB: 1}))
-		key, err := VolumeKey(id)
+		require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: id, TenantID: "000000000001", CapacityGiB: 1}))
+		key, err := VolumeKey("000000000001", id)
 		require.NoError(t, err)
 		want = append(want, id)
 		keys = append(keys, key)
@@ -347,7 +442,7 @@ func TestListVolumes_ConcurrentFetchPreservesListingOrder(t *testing.T) {
 
 	fixed := NewStore(&fixedOrderStore{ObjectStore: objects, keys: keys}, "control-plane")
 	for range 5 {
-		volumes, err := fixed.ListVolumes(ctx)
+		volumes, err := fixed.ListVolumes(ctx, "000000000001")
 		require.NoError(t, err)
 		got := make([]string, 0, len(volumes))
 		for _, v := range volumes {
@@ -429,15 +524,15 @@ func TestListVolumes_BoundsOneSlowDocument(t *testing.T) {
 	store := NewStore(objects, "control-plane")
 	ctx := context.Background()
 
-	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-good", CapacityGiB: 1}))
-	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-slow", CapacityGiB: 1}))
-	key, err := VolumeKey("vol-slow")
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-good", TenantID: "000000000001", CapacityGiB: 1}))
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-slow", TenantID: "000000000001", CapacityGiB: 1}))
+	key, err := VolumeKey("000000000001", "vol-slow")
 	require.NoError(t, err)
 
 	hanging := NewStore(&hangingGetStore{ObjectStore: objects, hangKey: key}, "control-plane")
 
 	start := time.Now()
-	volumes, err := hanging.ListVolumes(ctx)
+	volumes, err := hanging.ListVolumes(ctx, "000000000001")
 	elapsed := time.Since(start)
 
 	require.NoError(t, err, "one slow document must not fail the whole listing")
@@ -445,7 +540,7 @@ func TestListVolumes_BoundsOneSlowDocument(t *testing.T) {
 	assert.Equal(t, "vol-good", volumes[0].VolumeID)
 	assert.Less(t, elapsed, time.Second, "the listing must not wait on the slow document indefinitely")
 
-	_, err = hanging.ListVolumesStrict(ctx)
+	_, err = hanging.ListVolumesStrict(ctx, "000000000001")
 	require.Error(t, err, "the strict listing must still report the document it could not read")
 }
 
@@ -462,8 +557,8 @@ func TestListVolumesFollowsEveryPage(t *testing.T) {
 	keys := make([]string, 0, documents)
 	for i := range documents {
 		id := fmt.Sprintf("vol-%02d", i)
-		require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: id, TenantID: "acct-1", CapacityGiB: 1}))
-		key, err := VolumeKey(id)
+		require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: id, TenantID: "000000000001", CapacityGiB: 1}))
+		key, err := VolumeKey("000000000001", id)
 		require.NoError(t, err)
 		want = append(want, id)
 		keys = append(keys, key)
@@ -478,7 +573,7 @@ func TestListVolumesFollowsEveryPage(t *testing.T) {
 			if strict {
 				list = paged.ListVolumesStrict
 			}
-			volumes, err := list(ctx)
+			volumes, err := list(ctx, "000000000001")
 			require.NoError(t, err)
 
 			got := make([]string, 0, len(volumes))
@@ -498,17 +593,17 @@ func TestListVolumesRefusesTruncationItCannotFollow(t *testing.T) {
 	store := NewStore(objects, "control-plane")
 	ctx := context.Background()
 
-	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-1", TenantID: "acct-1", CapacityGiB: 1}))
-	key, err := VolumeKey("vol-1")
+	require.NoError(t, store.PutVolume(ctx, Volume{VolumeID: "vol-1", TenantID: "000000000001", CapacityGiB: 1}))
+	key, err := VolumeKey("000000000001", "vol-1")
 	require.NoError(t, err)
 
 	broken := NewStore(&truncatedNoTokenStore{ObjectStore: objects, keys: []string{key}}, "control-plane")
 
-	_, err = broken.ListVolumes(ctx)
+	_, err = broken.ListVolumes(ctx, "000000000001")
 	require.Error(t, err)
 	assert.Contains(t, err.Error(), "continuation token")
 
-	_, err = broken.ListVolumesStrict(ctx)
+	_, err = broken.ListVolumesStrict(ctx, "000000000001")
 	require.Error(t, err)
 }
 
diff --git a/spinifex/handlers/ec2/image/ami_source_volume_test.go b/spinifex/handlers/ec2/image/ami_source_volume_test.go
index 35086c495..b90b536a6 100644
--- a/spinifex/handlers/ec2/image/ami_source_volume_test.go
+++ b/spinifex/handlers/ec2/image/ami_source_volume_test.go
@@ -8,29 +8,32 @@ import (
 
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
-	"github.com/mulgadc/spinifex/spinifex/objectstore"
+	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 // putSourceVolumeAMI registers an AMI document plus, when volumeID is set, the
-// snapshot metadata recording which volume the snapshot was taken from.
-func putSourceVolumeAMI(t *testing.T, svc *ImageServiceImpl, store *objectstore.MemoryObjectStore, ami ebsmetadata.AMI, volumeID string) {
+// snapshot document recording which volume the snapshot was taken from. The
+// document is keyed under the account the AMI's owner alias derives to, which
+// is what GetAMISourceVolumeID has to reproduce to find it.
+func putSourceVolumeAMI(t *testing.T, svc *ImageServiceImpl, ami ebsmetadata.AMI, volumeID string) {
 	t.Helper()
 	require.NoError(t, svc.MetadataStore().PutAMI(context.Background(), ami))
 	if volumeID == "" {
 		return
 	}
-	require.NoError(t, handlers_ec2_snapshot.WriteSnapshotConfig(store, testBucket, ami.SnapshotID,
-		&handlers_ec2_snapshot.SnapshotConfig{SnapshotID: ami.SnapshotID, VolumeID: volumeID}))
+	owner, _ := snapshotAccountForAMI(ami)
+	require.NoError(t, svc.MetadataStore().PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+		SnapshotID: ami.SnapshotID, VolumeID: volumeID, OwnerID: owner,
+	}))
 }
 
 // TestGetAMISourceVolumeID_ReadsSnapshotMetadata locks the normal case: the
-// source volume comes from the snapshot's own metadata.json.
+// source volume comes from the snapshot's own document.
 func TestGetAMISourceVolumeID_ReadsSnapshotMetadata(t *testing.T) {
-	svc, store := setupProviderImageService(t)
-	putSourceVolumeAMI(t, svc, store, ebsmetadata.AMI{
+	svc, _ := setupProviderImageService(t)
+	putSourceVolumeAMI(t, svc, ebsmetadata.AMI{
 		ImageID: "ami-src01", SnapshotID: "snap-src01", ImageOwnerAlias: testAccountID,
 	}, "vol-origin")
 
@@ -42,8 +45,8 @@ func TestGetAMISourceVolumeID_ReadsSnapshotMetadata(t *testing.T) {
 // TestGetAMISourceVolumeID_BundledSystemAMI locks the fallback for bundled
 // system AMIs, whose snapshot is named after the AMI and carries no metadata.json.
 func TestGetAMISourceVolumeID_BundledSystemAMI(t *testing.T) {
-	svc, store := setupProviderImageService(t)
-	putSourceVolumeAMI(t, svc, store, ebsmetadata.AMI{
+	svc, _ := setupProviderImageService(t)
+	putSourceVolumeAMI(t, svc, ebsmetadata.AMI{
 		ImageID: "ami-sys01", SnapshotID: "snap-ami-sys01", ImageOwnerAlias: "system",
 	}, "")
 
@@ -57,8 +60,8 @@ func TestGetAMISourceVolumeID_BundledSystemAMI(t *testing.T) {
 // document, so a caller relying on it (e.g. a stale catalog import predating
 // this fix) must be able to spot it in the logs rather than launch silently.
 func TestGetAMISourceVolumeID_BundledSystemAMI_LogsFallbackWarning(t *testing.T) {
-	svc, store := setupProviderImageService(t)
-	putSourceVolumeAMI(t, svc, store, ebsmetadata.AMI{
+	svc, _ := setupProviderImageService(t)
+	putSourceVolumeAMI(t, svc, ebsmetadata.AMI{
 		ImageID: "ami-sys02", SnapshotID: "snap-ami-sys02", ImageOwnerAlias: "system",
 	}, "")
 
@@ -76,11 +79,49 @@ func TestGetAMISourceVolumeID_BundledSystemAMI_LogsFallbackWarning(t *testing.T)
 	assert.Contains(t, logs, "ami-sys02")
 }
 
+// TestGetAMISourceVolumeID_ImportedSystemAMI locks that a system AMI whose
+// snapshot document exists under the global account resolves through it rather
+// than taking the bundled fallback. The bundled path logs a warn; a wrongly
+// derived account here would silently return an image ID where a volume ID
+// belongs, and the launch would clone the wrong blocks.
+func TestGetAMISourceVolumeID_ImportedSystemAMI(t *testing.T) {
+	svc, _ := setupProviderImageService(t)
+	require.NoError(t, svc.MetadataStore().PutAMI(context.Background(), ebsmetadata.AMI{
+		ImageID: "ami-sysimp01", SnapshotID: "snap-sysimp01", ImageOwnerAlias: "system",
+	}))
+	// The owner is spelled out rather than derived, reproducing what
+	// registerImportedAMISnapshot writes. Deriving it here would let the
+	// fixture follow the read path and pin nothing.
+	require.NoError(t, svc.MetadataStore().PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+		SnapshotID: "snap-sysimp01", VolumeID: "vol-imported", OwnerID: utils.GlobalAccountID,
+	}))
+
+	got, err := svc.GetAMISourceVolumeID(context.Background(), "ami-sysimp01")
+	require.NoError(t, err)
+	assert.Equal(t, "vol-imported", got, "an imported system AMI must resolve its recorded source volume, not fall back")
+}
+
+// TestGetAMISourceVolumeID_EmptyOwnerAliasDoesNotFallBack locks that an AMI with
+// no owner alias is treated as corrupt rather than as a system image. Deriving
+// it to the global account and letting the bundled fallback fire would return
+// the image ID where a volume ID belongs, and the launch would clone holes.
+func TestGetAMISourceVolumeID_EmptyOwnerAliasDoesNotFallBack(t *testing.T) {
+	svc, _ := setupProviderImageService(t)
+	putSourceVolumeAMI(t, svc, ebsmetadata.AMI{
+		ImageID: "ami-noalias", SnapshotID: "snap-noalias", ImageOwnerAlias: "",
+	}, "")
+
+	got, err := svc.GetAMISourceVolumeID(context.Background(), "ami-noalias")
+	require.Error(t, err)
+	assert.Empty(t, got, "a corrupt AMI must not resolve to its own image ID")
+	assert.Equal(t, awserrors.ErrorInvalidSnapshotNotFound, err.Error())
+}
+
 // TestGetAMISourceVolumeID_AccountAMIMissingSnapshotMetadata locks that the
 // bundled fallback does not apply to account-owned AMIs.
 func TestGetAMISourceVolumeID_AccountAMIMissingSnapshotMetadata(t *testing.T) {
-	svc, store := setupProviderImageService(t)
-	putSourceVolumeAMI(t, svc, store, ebsmetadata.AMI{
+	svc, _ := setupProviderImageService(t)
+	putSourceVolumeAMI(t, svc, ebsmetadata.AMI{
 		ImageID: "ami-acct01", SnapshotID: "snap-acct01", ImageOwnerAlias: testAccountID,
 	}, "")
 
@@ -92,8 +133,8 @@ func TestGetAMISourceVolumeID_AccountAMIMissingSnapshotMetadata(t *testing.T) {
 // TestGetAMISourceVolumeID_AMIWithoutSnapshot locks that an AMI carrying no
 // snapshot reference is reported as not found rather than resolving to "".
 func TestGetAMISourceVolumeID_AMIWithoutSnapshot(t *testing.T) {
-	svc, store := setupProviderImageService(t)
-	putSourceVolumeAMI(t, svc, store, ebsmetadata.AMI{
+	svc, _ := setupProviderImageService(t)
+	putSourceVolumeAMI(t, svc, ebsmetadata.AMI{
 		ImageID: "ami-nosnap", ImageOwnerAlias: testAccountID,
 	}, "")
 
@@ -114,12 +155,13 @@ func TestGetAMISourceVolumeID_UnknownAMI(t *testing.T) {
 // TestGetAMISourceVolumeID_EmptySnapshotSourceVolume locks that corrupt
 // snapshot metadata naming no source volume fails instead of returning "".
 func TestGetAMISourceVolumeID_EmptySnapshotSourceVolume(t *testing.T) {
-	svc, store := setupProviderImageService(t)
+	svc, _ := setupProviderImageService(t)
 	require.NoError(t, svc.MetadataStore().PutAMI(context.Background(), ebsmetadata.AMI{
 		ImageID: "ami-empty", SnapshotID: "snap-empty", ImageOwnerAlias: testAccountID,
 	}))
-	require.NoError(t, handlers_ec2_snapshot.WriteSnapshotConfig(store, testBucket, "snap-empty",
-		&handlers_ec2_snapshot.SnapshotConfig{SnapshotID: "snap-empty"}))
+	require.NoError(t, svc.MetadataStore().PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+		SnapshotID: "snap-empty", OwnerID: testAccountID,
+	}))
 
 	_, err := svc.GetAMISourceVolumeID(context.Background(), "ami-empty")
 	require.Error(t, err)
diff --git a/spinifex/handlers/ec2/image/provider_snapshot_test.go b/spinifex/handlers/ec2/image/provider_snapshot_test.go
index 07b53274f..ea382c1f9 100644
--- a/spinifex/handlers/ec2/image/provider_snapshot_test.go
+++ b/spinifex/handlers/ec2/image/provider_snapshot_test.go
@@ -77,7 +77,7 @@ func TestGetVolumeMetadata_Provider_ResolvesProviderCreatedVolume(t *testing.T)
 	svc, _, provider := setupProviderSnapshotImageService(t)
 	doc := seedProviderVolume(t, svc, provider, "vol-provider001", 10)
 
-	meta, err := svc.getVolumeMetadata(context.Background(), doc.VolumeID)
+	meta, err := svc.getVolumeMetadata(context.Background(), testAccountID, doc.VolumeID)
 	require.NoError(t, err, "a provider-created volume with no config.json must resolve")
 	assert.Equal(t, doc.VolumeID, meta.VolumeID)
 	assert.Equal(t, testAccountID, meta.TenantID)
@@ -91,7 +91,7 @@ func TestGetVolumeMetadata_Provider_ResolvesProviderCreatedVolume(t *testing.T)
 func TestGetVolumeMetadata_Provider_UnknownVolumeIsNotFound(t *testing.T) {
 	svc, _, _ := setupProviderSnapshotImageService(t)
 
-	_, err := svc.getVolumeMetadata(context.Background(), "vol-does-not-exist")
+	_, err := svc.getVolumeMetadata(context.Background(), testAccountID, "vol-does-not-exist")
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 }
@@ -104,7 +104,7 @@ func TestSnapshotStoppedVolume_Provider_CreatesThroughProvider(t *testing.T) {
 	svc, _, provider := setupProviderSnapshotImageService(t)
 	doc := seedProviderVolume(t, svc, provider, "vol-stopped001", 8)
 
-	err := svc.snapshotStoppedVolume(doc.VolumeID, "snap-stopped001")
+	err := svc.snapshotStoppedVolume(doc.VolumeID, "snap-stopped001", testAccountID)
 	require.NoError(t, err, "the provider path must not fall through to the embedded engine against the closed Predastore port")
 
 	// CreateSnapshot is idempotent on (SnapshotID, VolumeID): re-issuing it
diff --git a/spinifex/handlers/ec2/image/service_impl.go b/spinifex/handlers/ec2/image/service_impl.go
index 2fcc2ddbb..30fc2c90e 100644
--- a/spinifex/handlers/ec2/image/service_impl.go
+++ b/spinifex/handlers/ec2/image/service_impl.go
@@ -372,14 +372,14 @@ func (s *ImageServiceImpl) CreateImageFromInstance(params CreateImageParams, acc
 	if params.IsRunning {
 		snapshotErr = s.snapshotRunningVolume(params.RootVolumeID, snapshotID, accountID)
 	} else {
-		snapshotErr = s.snapshotStoppedVolume(params.RootVolumeID, snapshotID)
+		snapshotErr = s.snapshotStoppedVolume(params.RootVolumeID, snapshotID, accountID)
 	}
 	if snapshotErr != nil {
 		return nil, snapshotErr
 	}
 
 	// Step 2: Read source volume config for size
-	volMeta, err := s.getVolumeMetadata(context.Background(), params.RootVolumeID)
+	volMeta, err := s.getVolumeMetadata(context.Background(), accountID, params.RootVolumeID)
 	if err != nil {
 		slog.Error("CreateImageFromInstance: failed to read volume metadata", "volumeId", params.RootVolumeID, "err", err)
 		return nil, errors.New(awserrors.ErrorServerInternal)
@@ -449,7 +449,7 @@ func (s *ImageServiceImpl) snapshotRunningVolume(volumeID, snapshotID, accountID
 		return errors.New(awserrors.ErrorServerInternal)
 	}
 
-	volMeta, err := s.getVolumeMetadata(context.Background(), volumeID)
+	volMeta, err := s.getVolumeMetadata(context.Background(), accountID, volumeID)
 	if err != nil {
 		slog.Error("snapshotRunningVolume: failed to read volume metadata", "volumeId", volumeID, "err", err)
 		return errors.New(awserrors.ErrorServerInternal)
@@ -472,12 +472,12 @@ func (s *ImageServiceImpl) snapshotRunningVolume(volumeID, snapshotID, accountID
 // volume is stopped/detached, so nothing is buffered on a serving node.
 // viperblockd's handleCreateSnapshot prefers a live mounted engine over opening
 // a second one, so it handles the mounted case itself.
-func (s *ImageServiceImpl) snapshotStoppedVolume(volumeID, snapshotID string) error {
+func (s *ImageServiceImpl) snapshotStoppedVolume(volumeID, snapshotID, accountID string) error {
 	if s.config == nil {
 		return errors.New(awserrors.ErrorServerInternal)
 	}
 
-	volMeta, err := s.getVolumeMetadata(context.Background(), volumeID)
+	volMeta, err := s.getVolumeMetadata(context.Background(), accountID, volumeID)
 	if err != nil {
 		slog.Error("snapshotStoppedVolume: failed to read volume metadata", "volumeId", volumeID, "err", err)
 		return errors.New(awserrors.ErrorServerInternal)
@@ -506,8 +506,8 @@ func (s *ImageServiceImpl) createSnapshot(ctx context.Context, volMeta ebsmetada
 
 // getVolumeMetadata reads a volume's control-plane document, remapping a
 // missing document to InvalidVolume.NotFound.
-func (s *ImageServiceImpl) getVolumeMetadata(ctx context.Context, volumeID string) (ebsmetadata.Volume, error) {
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+func (s *ImageServiceImpl) getVolumeMetadata(ctx context.Context, accountID, volumeID string) (ebsmetadata.Volume, error) {
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		if objectstore.IsNoSuchKeyError(err) {
 			return ebsmetadata.Volume{}, errors.New(awserrors.ErrorInvalidVolumeNotFound)
@@ -539,9 +539,21 @@ func (s *ImageServiceImpl) GetAMIConfig(ctx context.Context, imageID string) (eb
 	return s.metadata.GetAMI(ctx, imageID)
 }
 
+// snapshotAccountForAMI derives the account an AMI's snapshot document is keyed
+// under: an account-ID alias keys under itself, a system alias under the global
+// account. derived reports which, so the bundled-AMI fallback below cannot
+// drift from this predicate. An empty alias is a corrupt document rather than a
+// system image, so it derives nothing and the fallback cannot answer for it.
+func snapshotAccountForAMI(meta ebsmetadata.AMI) (accountID string, derived bool) {
+	if utils.IsAccountID(meta.ImageOwnerAlias) {
+		return meta.ImageOwnerAlias, false
+	}
+	return utils.GlobalAccountID, meta.ImageOwnerAlias != ""
+}
+
 // GetAMISourceVolumeID returns the volume whose blocks imageID's snapshot
-// references, read from the snapshot's metadata.json. Bundled system AMIs have
-// no standalone snapshot metadata; their snapshot is named after the AMI.
+// references, read from the snapshot's document. Bundled system AMIs have no
+// standalone snapshot metadata; their snapshot is named after the AMI.
 func (s *ImageServiceImpl) GetAMISourceVolumeID(ctx context.Context, imageID string) (string, error) {
 	meta, err := s.GetAMIConfig(ctx, imageID)
 	if err != nil {
@@ -555,14 +567,19 @@ func (s *ImageServiceImpl) GetAMISourceVolumeID(ctx context.Context, imageID str
 		return "", errors.New(awserrors.ErrorInvalidAMIIDNotFound)
 	}
 
-	snapCfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(ctx, s.store, s.bucketName, meta.SnapshotID)
+	// The snapshot is keyed under its own owner, which for a system AMI is the
+	// global account rather than the alias and rather than the caller. Falling
+	// back on the caller's miss would silently return an image ID where a
+	// volume ID belongs for an imported system AMI.
+	snapAccount, derived := snapshotAccountForAMI(meta)
+	snapCfg, err := s.metadata.GetSnapshot(ctx, snapAccount, meta.SnapshotID)
 	if err != nil {
-		if objectstore.IsNoSuchKeyError(err) && meta.ImageOwnerAlias != "" && !utils.IsAccountID(meta.ImageOwnerAlias) {
+		if objectstore.IsNoSuchKeyError(err) && derived {
 			slog.WarnContext(ctx, "GetAMISourceVolumeID: system AMI has no snapshot metadata document, falling back to imageID as volume ID",
 				"imageId", imageID, "snapshotId", meta.SnapshotID, "imageOwnerAlias", meta.ImageOwnerAlias)
 			return imageID, nil
 		}
-		if objectstore.IsNoSuchKeyError(err) || errors.Is(err, handlers_ec2_snapshot.ErrCorruptSnapshotMetadata) {
+		if objectstore.IsNoSuchKeyError(err) || errors.Is(err, ebsmetadata.ErrCorruptDocument) {
 			return "", errors.New(awserrors.ErrorInvalidSnapshotNotFound)
 		}
 		slog.ErrorContext(ctx, "GetAMISourceVolumeID: failed to read snapshot metadata",
@@ -696,9 +713,10 @@ func (s *ImageServiceImpl) loadAMIForMutation(ctx context.Context, imageID, acco
 	return meta, nil
 }
 
-// putSnapshotMetadata stores snapshot metadata in S3 using the canonical SnapshotConfig type.
+// putSnapshotMetadata stores the snapshot's control-plane document under the
+// account that owns it.
 func (s *ImageServiceImpl) putSnapshotMetadata(ctx context.Context, snapshotID, volumeID string, volumeSizeGiB uint64, accountID string) error {
-	cfg := handlers_ec2_snapshot.SnapshotConfig{
+	return s.metadata.PutSnapshot(ctx, ebsmetadata.Snapshot{
 		SnapshotID: snapshotID,
 		VolumeID:   volumeID,
 		VolumeSize: safecast.Uint64ToInt64(volumeSizeGiB),
@@ -706,8 +724,7 @@ func (s *ImageServiceImpl) putSnapshotMetadata(ctx context.Context, snapshotID,
 		Progress:   "100%",
 		StartTime:  time.Now(),
 		OwnerID:    accountID,
-	}
-	return handlers_ec2_snapshot.WriteSnapshotConfig(s.store, s.bucketName, snapshotID, &cfg)
+	})
 }
 
 // CopyImage clones an AMI same-region, metadata-only: the new snapshot shares the
@@ -742,17 +759,20 @@ func (s *ImageServiceImpl) CopyImage(ctx context.Context, input *ec2.CopyImageIn
 	if srcMeta.SnapshotID == "" {
 		return nil, errors.New(awserrors.ErrorInvalidAMIIDNotFound)
 	}
-	srcSnap, err := handlers_ec2_snapshot.ReadSnapshotConfig(ctx, s.store, s.bucketName, srcMeta.SnapshotID)
+	// Read the source snapshot under its own owner, not the caller's: a system
+	// AMI's snapshot is keyed under the global account.
+	srcSnapAccount, srcSnapDerived := snapshotAccountForAMI(srcMeta)
+	srcSnap, err := s.metadata.GetSnapshot(ctx, srcSnapAccount, srcMeta.SnapshotID)
 	if err != nil {
-		// Bundled system AMIs have no standalone snap-xxx/metadata.json; synthesize
-		// a minimal snap view using VolumeID = sourceImageID so CopyImage succeeds.
-		if objectstore.IsNoSuchKeyError(err) && srcMeta.ImageOwnerAlias != "" && !utils.IsAccountID(srcMeta.ImageOwnerAlias) {
-			srcSnap = &handlers_ec2_snapshot.SnapshotConfig{
+		// Bundled system AMIs have no standalone snapshot document; synthesize a
+		// minimal view using VolumeID = sourceImageID so CopyImage succeeds.
+		if objectstore.IsNoSuchKeyError(err) && srcSnapDerived {
+			srcSnap = ebsmetadata.Snapshot{
 				SnapshotID: srcMeta.SnapshotID,
 				VolumeID:   sourceImageID,
 				VolumeSize: safecast.Uint64ToInt64(srcMeta.VolumeSizeGiB),
 			}
-		} else if objectstore.IsNoSuchKeyError(err) || errors.Is(err, handlers_ec2_snapshot.ErrCorruptSnapshotMetadata) {
+		} else if objectstore.IsNoSuchKeyError(err) || errors.Is(err, ebsmetadata.ErrCorruptDocument) {
 			return nil, errors.New(awserrors.ErrorInvalidAMIIDNotFound)
 		} else {
 			slog.ErrorContext(ctx, "CopyImage: failed to read source snapshot metadata",
@@ -816,11 +836,7 @@ func (s *ImageServiceImpl) CopyImage(ctx context.Context, input *ec2.CopyImageIn
 		slog.ErrorContext(ctx, "CopyImage: failed to write AMI config",
 			"amiId", newImageID, "orphanSnapshotId", newSnapshotID, "err", err)
 		// Best-effort rollback of the orphaned snapshot metadata.
-		snapKey := handlers_ec2_snapshot.GetSnapshotKey(newSnapshotID)
-		if _, delErr := s.store.DeleteObject(ctx, &s3.DeleteObjectInput{
-			Bucket: aws.String(s.bucketName),
-			Key:    aws.String(snapKey),
-		}); delErr != nil {
+		if delErr := s.metadata.DeleteSnapshot(ctx, accountID, newSnapshotID); delErr != nil {
 			slog.ErrorContext(ctx, "CopyImage: failed to roll back orphaned snapshot metadata",
 				"snapshotId", newSnapshotID, "err", delErr)
 		}
@@ -937,6 +953,13 @@ func (s *ImageServiceImpl) RegisterImage(ctx context.Context, input *ec2.Registe
 		return nil, errors.New(awserrors.ErrorMissingParameter)
 	}
 
+	// The snapshot is read under the caller's account, so an untenanted caller
+	// has no prefix to read from. Refuse at the boundary rather than in the key
+	// builder, where the rejection would surface as an internal error.
+	if accountID == "" {
+		return nil, errors.New(awserrors.ErrorAuthFailure)
+	}
+
 	name := *input.Name
 
 	rootBDM := pickRootSnapshotBDM(input.BlockDeviceMappings, input.RootDeviceName)
@@ -945,23 +968,19 @@ func (s *ImageServiceImpl) RegisterImage(ctx context.Context, input *ec2.Registe
 	}
 	snapshotID := *rootBDM.Ebs.SnapshotId
 
-	snapCfg, err := handlers_ec2_snapshot.ReadSnapshotConfig(ctx, s.store, s.bucketName, snapshotID)
+	// The snapshot arrives through a caller-supplied BlockDeviceMapping, not
+	// through an AMI, so there is no owner alias to derive from: it is read
+	// under the caller's own account and the key is the ownership check.
+	snapCfg, err := s.metadata.GetSnapshot(ctx, accountID, snapshotID)
 	if err != nil {
 		// Corrupt snapshot is surfaced as NotFound, same as CopyImage.
-		if objectstore.IsNoSuchKeyError(err) || errors.Is(err, handlers_ec2_snapshot.ErrCorruptSnapshotMetadata) {
+		if objectstore.IsNoSuchKeyError(err) || errors.Is(err, ebsmetadata.ErrCorruptDocument) {
 			return nil, errors.New(awserrors.ErrorInvalidSnapshotNotFound)
 		}
 		slog.ErrorContext(ctx, "RegisterImage: failed to read snapshot metadata", "snapshotId", snapshotID, "err", err)
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 
-	// Only the snapshot owner (or any caller for system snapshots) can register.
-	if utils.IsAccountID(snapCfg.OwnerID) && snapCfg.OwnerID != accountID {
-		slog.WarnContext(ctx, "RegisterImage: rejected cross-account snapshot",
-			"snapshotId", snapshotID, "snapshotOwner", snapCfg.OwnerID, "accountId", accountID)
-		return nil, errors.New(awserrors.ErrorUnauthorizedOperation)
-	}
-
 	snapSizeGiB := uint64(0)
 	if snapCfg.VolumeSize > 0 {
 		snapSizeGiB = uint64(snapCfg.VolumeSize)
diff --git a/spinifex/handlers/ec2/image/service_impl_test.go b/spinifex/handlers/ec2/image/service_impl_test.go
index 3f640db53..2643e6984 100644
--- a/spinifex/handlers/ec2/image/service_impl_test.go
+++ b/spinifex/handlers/ec2/image/service_impl_test.go
@@ -2,7 +2,6 @@ package handlers_ec2_image
 
 import (
 	"context"
-	"encoding/json"
 	"io"
 	"log/slog"
 	"net/http"
@@ -17,8 +16,9 @@ import (
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/config"
 	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
+	"github.com/mulgadc/spinifex/spinifex/testutil/recordingstore"
+	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -64,6 +64,11 @@ func amiDocumentKey(t *testing.T, imageID string) string {
 // putVolumeDocument writes a volume's control-plane document.
 func putVolumeDocument(t *testing.T, store *objectstore.MemoryObjectStore, volume ebsmetadata.Volume) {
 	t.Helper()
+	// The owning account is a key segment, so a fixture that does not care
+	// which account owns it still has to have one.
+	if volume.TenantID == "" {
+		volume.TenantID = testAccountID
+	}
 	require.NoError(t, ebsmetadata.NewStore(store, testBucket).PutVolume(context.Background(), volume))
 }
 
@@ -275,7 +280,7 @@ func TestGetVolumeMetadata(t *testing.T) {
 
 	createTestVolumeConfig(t, store, "vol-abc123", 20)
 
-	meta, err := svc.getVolumeMetadata(context.Background(), "vol-abc123")
+	meta, err := svc.getVolumeMetadata(context.Background(), testAccountID, "vol-abc123")
 	require.NoError(t, err)
 	assert.Equal(t, uint64(20), meta.CapacityGiB)
 }
@@ -283,7 +288,7 @@ func TestGetVolumeMetadata(t *testing.T) {
 func TestGetVolumeMetadata_NotFound(t *testing.T) {
 	svc, _ := setupTestImageService(t)
 
-	_, err := svc.getVolumeMetadata(context.Background(), "vol-nonexistent")
+	_, err := svc.getVolumeMetadata(context.Background(), testAccountID, "vol-nonexistent")
 	require.Error(t, err)
 }
 
@@ -314,16 +319,8 @@ func TestPutSnapshotMetadata(t *testing.T) {
 	err := svc.putSnapshotMetadata(context.Background(), "snap-abc123", "vol-xyz789", 10, testAccountID)
 	require.NoError(t, err)
 
-	// Verify the metadata was written correctly
-	result, err := store.GetObject(context.Background(), &awss3.GetObjectInput{
-		Bucket: aws.String(testBucket),
-		Key:    aws.String("snap-abc123/metadata.json"),
-	})
-	require.NoError(t, err)
-	defer result.Body.Close()
-
-	var cfg handlers_ec2_snapshot.SnapshotConfig
-	err = json.NewDecoder(result.Body).Decode(&cfg)
+	// The document must land under the owning account's prefix.
+	cfg, err := ebsmetadata.NewStore(store, testBucket).GetSnapshot(context.Background(), testAccountID, "snap-abc123")
 	require.NoError(t, err)
 	assert.Equal(t, "snap-abc123", cfg.SnapshotID)
 	assert.Equal(t, "vol-xyz789", cfg.VolumeID)
@@ -590,10 +587,7 @@ func TestDeregisterImage_DoesNotTouchSnapshot(t *testing.T) {
 	require.NoError(t, err)
 
 	// Snapshot metadata still present
-	_, snapErr := store.GetObject(context.Background(), &awss3.GetObjectInput{
-		Bucket: aws.String(testBucket),
-		Key:    aws.String(snapID + "/metadata.json"),
-	})
+	_, snapErr := ebsmetadata.NewStore(store, testBucket).GetSnapshot(context.Background(), testAccountID, snapID)
 	require.NoError(t, snapErr)
 }
 
@@ -835,7 +829,7 @@ func TestGetAMIConfig_InvalidJSON(t *testing.T) {
 func TestGetVolumeMetadata_InvalidJSON(t *testing.T) {
 	svc, store := setupTestImageService(t)
 
-	key, err := ebsmetadata.VolumeKey("vol-badjson")
+	key, err := ebsmetadata.VolumeKey(testAccountID, "vol-badjson")
 	require.NoError(t, err)
 	_, err = store.PutObject(context.Background(), &awss3.PutObjectInput{
 		Bucket: aws.String(testBucket),
@@ -844,7 +838,7 @@ func TestGetVolumeMetadata_InvalidJSON(t *testing.T) {
 	})
 	require.NoError(t, err)
 
-	_, err = svc.getVolumeMetadata(context.Background(), "vol-badjson")
+	_, err = svc.getVolumeMetadata(context.Background(), testAccountID, "vol-badjson")
 	assert.Error(t, err)
 }
 
@@ -1146,28 +1140,32 @@ func TestDescribeImages_FilterNoFilters(t *testing.T) {
 
 // --- RegisterImage tests ---
 
-// putTestSnapshotConfig writes a SnapshotConfig at {snapshotID}/metadata.json,
+// putTestSnapshotConfig writes a snapshot document under its owning account,
 // matching the layout that the snapshot service uses.
 func putTestSnapshotConfig(t *testing.T, store *objectstore.MemoryObjectStore, snapshotID string, sizeGiB int64, ownerID string) {
 	t.Helper()
-	cfg := handlers_ec2_snapshot.SnapshotConfig{
+	putTestSnapshotDoc(t, store, ebsmetadata.Snapshot{
 		SnapshotID: snapshotID,
 		VolumeID:   "vol-source-" + snapshotID,
 		VolumeSize: sizeGiB,
 		State:      "completed",
 		Progress:   "100%",
 		OwnerID:    ownerID,
-	}
-	data, err := json.Marshal(cfg)
-	require.NoError(t, err)
-
-	_, err = store.PutObject(context.Background(), &awss3.PutObjectInput{
-		Bucket:      aws.String(testBucket),
-		Key:         aws.String(snapshotID + "/metadata.json"),
-		Body:        strings.NewReader(string(data)),
-		ContentType: aws.String("application/json"),
 	})
+}
+
+// putTestSnapshotDoc writes one snapshot document through the metadata store.
+func putTestSnapshotDoc(t *testing.T, store *objectstore.MemoryObjectStore, snapshot ebsmetadata.Snapshot) {
+	t.Helper()
+	require.NoError(t, ebsmetadata.NewStore(store, testBucket).PutSnapshot(context.Background(), snapshot))
+}
+
+// readTestSnapshotDoc reads a snapshot document from the account that owns it.
+func readTestSnapshotDoc(t *testing.T, store *objectstore.MemoryObjectStore, accountID, snapshotID string) ebsmetadata.Snapshot {
+	t.Helper()
+	snapshot, err := ebsmetadata.NewStore(store, testBucket).GetSnapshot(context.Background(), accountID, snapshotID)
 	require.NoError(t, err)
+	return snapshot
 }
 
 func validRegisterImageServiceInput(snapshotID string) *ec2.RegisterImageInput {
@@ -1230,6 +1228,8 @@ func TestRegisterImage_SnapshotNotFound(t *testing.T) {
 	assert.Equal(t, awserrors.ErrorInvalidSnapshotNotFound, err.Error())
 }
 
+// A snapshot outside the caller's prefix is not found rather than refused, so
+// the endpoint does not confirm another account's snapshot IDs.
 func TestRegisterImage_CrossAccountSnapshot(t *testing.T) {
 	svc, store := setupTestImageService(t)
 
@@ -1237,23 +1237,37 @@ func TestRegisterImage_CrossAccountSnapshot(t *testing.T) {
 
 	_, err := svc.RegisterImage(context.Background(), validRegisterImageServiceInput("snap-other01"), testAccountID)
 	require.Error(t, err)
-	assert.Equal(t, awserrors.ErrorUnauthorizedOperation, err.Error())
+	assert.Equal(t, awserrors.ErrorInvalidSnapshotNotFound, err.Error())
 }
 
-func TestRegisterImage_SystemSnapshotAllowed(t *testing.T) {
+// An untenanted caller is refused at the boundary. Asserting that nothing was
+// read is what stops the guard being deleted later as redundant with the key
+// builder, whose rejection is an internal error rather than an AuthFailure.
+func TestRegisterImage_EmptyCallerAccountIsRefusedAtTheBoundary(t *testing.T) {
+	objects := recordingstore.New()
+	svc := NewImageServiceImplWithStore(objects, testBucket)
+
+	_, err := svc.RegisterImage(context.Background(), validRegisterImageServiceInput("snap-guard01"), "")
+	require.Error(t, err)
+	assert.Equal(t, awserrors.ErrorAuthFailure, err.Error())
+	assert.Empty(t, objects.Gets(), "the guard must fire before any read")
+	assert.Empty(t, objects.ListPrefixes(), "the guard must fire before any listing")
+}
+
+// The system account is an ordinary account: it registers against its own
+// snapshot with no special path.
+func TestRegisterImage_SystemAccountSnapshot(t *testing.T) {
 	svc, store := setupTestImageService(t)
 
-	// System-owned snapshot (non-account-ID owner) is launchable by anyone,
-	// matching how system AMIs work.
-	putTestSnapshotConfig(t, store, "snap-sys01", 8, "spinifex")
+	putTestSnapshotConfig(t, store, "snap-sys01", 8, utils.GlobalAccountID)
 
-	out, err := svc.RegisterImage(context.Background(), validRegisterImageServiceInput("snap-sys01"), testAccountID)
+	out, err := svc.RegisterImage(context.Background(), validRegisterImageServiceInput("snap-sys01"), utils.GlobalAccountID)
 	require.NoError(t, err)
 	require.NotNil(t, out.ImageId)
 
 	meta, err := svc.GetAMIConfig(context.Background(), *out.ImageId)
 	require.NoError(t, err)
-	assert.Equal(t, testAccountID, meta.ImageOwnerAlias)
+	assert.Equal(t, utils.GlobalAccountID, meta.ImageOwnerAlias)
 }
 
 func TestRegisterImage_ArchitectureAndVirtualizationDefaults(t *testing.T) {
@@ -1518,12 +1532,14 @@ func readAMIConfigBytes(t *testing.T, store *objectstore.MemoryObjectStore, imag
 	return data
 }
 
-// readSnapshotConfigBytes returns the raw bytes of {snapshotID}/metadata.json.
-func readSnapshotConfigBytes(t *testing.T, store *objectstore.MemoryObjectStore, snapshotID string) []byte {
+// readSnapshotConfigBytes returns the raw bytes of the snapshot's document.
+func readSnapshotConfigBytes(t *testing.T, store *objectstore.MemoryObjectStore, accountID, snapshotID string) []byte {
 	t.Helper()
+	key, err := ebsmetadata.SnapshotKey(accountID, snapshotID)
+	require.NoError(t, err)
 	result, err := store.GetObject(context.Background(), &awss3.GetObjectInput{
 		Bucket: aws.String(testBucket),
-		Key:    aws.String(snapshotID + "/metadata.json"),
+		Key:    aws.String(key),
 	})
 	require.NoError(t, err)
 	defer result.Body.Close()
@@ -1563,23 +1579,17 @@ func putTestAMIConfigWithSnapshot(t *testing.T, store *objectstore.MemoryObjectS
 // end-to-end.
 func seedCopyableAMI(t *testing.T, store *objectstore.MemoryObjectStore, imageID, name, owner, snapshotID, volumeID string, sizeGiB int64) {
 	t.Helper()
-	cfg := handlers_ec2_snapshot.SnapshotConfig{
+	// A system AMI's owner is an alias rather than an account, and its snapshot
+	// is keyed under the global account. Mirror the service's derivation.
+	snapOwner, _ := snapshotAccountForAMI(ebsmetadata.AMI{ImageOwnerAlias: owner})
+	putTestSnapshotDoc(t, store, ebsmetadata.Snapshot{
 		SnapshotID: snapshotID,
 		VolumeID:   volumeID,
 		VolumeSize: sizeGiB,
 		State:      "completed",
 		Progress:   "100%",
-		OwnerID:    owner,
-	}
-	data, err := json.Marshal(cfg)
-	require.NoError(t, err)
-	_, err = store.PutObject(context.Background(), &awss3.PutObjectInput{
-		Bucket:      aws.String(testBucket),
-		Key:         aws.String(snapshotID + "/metadata.json"),
-		Body:        strings.NewReader(string(data)),
-		ContentType: aws.String("application/json"),
+		OwnerID:    snapOwner,
 	})
-	require.NoError(t, err)
 
 	putTestAMIConfigWithSnapshot(t, store, imageID, name, owner, snapshotID, ebsmetadata.AMI{
 		VolumeSizeGiB: uint64(sizeGiB),
@@ -1603,7 +1613,7 @@ func TestCopyImage_HappyPath(t *testing.T) {
 	// Capture the source config bytes before the copy so we can prove the
 	// source wasn't mutated (not just that name still resolves).
 	srcBefore := readAMIConfigBytes(t, store, "ami-src001")
-	srcSnapBefore := readSnapshotConfigBytes(t, store, "snap-src001")
+	srcSnapBefore := readSnapshotConfigBytes(t, store, testAccountID, "snap-src001")
 
 	out, err := svc.CopyImage(context.Background(), validCopyImageServiceInput("ami-src001", "copy-of-source"), testAccountID)
 	require.NoError(t, err)
@@ -1625,7 +1635,7 @@ func TestCopyImage_HappyPath(t *testing.T) {
 	// Source AMI config and source snapshot metadata must be byte-identical.
 	assert.Equal(t, srcBefore, readAMIConfigBytes(t, store, "ami-src001"),
 		"source AMI config was mutated by CopyImage")
-	assert.Equal(t, srcSnapBefore, readSnapshotConfigBytes(t, store, "snap-src001"),
+	assert.Equal(t, srcSnapBefore, readSnapshotConfigBytes(t, store, testAccountID, "snap-src001"),
 		"source snapshot metadata was mutated by CopyImage")
 }
 
@@ -1633,19 +1643,10 @@ func TestCopyImage_InheritsSourceFields(t *testing.T) {
 	svc, store := setupTestImageService(t)
 
 	// Seed snapshot for the source AMI.
-	_, err := store.PutObject(context.Background(), &awss3.PutObjectInput{
-		Bucket: aws.String(testBucket),
-		Key:    aws.String("snap-arm001/metadata.json"),
-		Body: strings.NewReader(func() string {
-			b, _ := json.Marshal(handlers_ec2_snapshot.SnapshotConfig{
-				SnapshotID: "snap-arm001", VolumeID: "vol-arm", VolumeSize: 32,
-				State: "completed", Progress: "100%", OwnerID: testAccountID,
-			})
-			return string(b)
-		}()),
-		ContentType: aws.String("application/json"),
+	putTestSnapshotDoc(t, store, ebsmetadata.Snapshot{
+		SnapshotID: "snap-arm001", VolumeID: "vol-arm", VolumeSize: 32,
+		State: "completed", Progress: "100%", OwnerID: testAccountID,
 	})
-	require.NoError(t, err)
 
 	// Source AMI with non-default fields that must propagate.
 	putTestAMIConfigWithSnapshot(t, store, "ami-arm001", "arm-source", testAccountID, "snap-arm001", ebsmetadata.AMI{
@@ -1678,8 +1679,7 @@ func TestCopyImage_NewSnapshotSharesSourceVolumeID(t *testing.T) {
 
 	seedCopyableAMI(t, store, "ami-shareblocks", "shareblocks", testAccountID, "snap-orig", "vol-shared", 16)
 
-	srcSnap, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, testBucket, "snap-orig")
-	require.NoError(t, err)
+	srcSnap := readTestSnapshotDoc(t, store, testAccountID, "snap-orig")
 
 	out, err := svc.CopyImage(context.Background(), validCopyImageServiceInput("ami-shareblocks", "shared-copy"), testAccountID)
 	require.NoError(t, err)
@@ -1688,8 +1688,7 @@ func TestCopyImage_NewSnapshotSharesSourceVolumeID(t *testing.T) {
 	require.NoError(t, err)
 	require.NotEqual(t, "snap-orig", newMeta.SnapshotID)
 
-	newSnap, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, testBucket, newMeta.SnapshotID)
-	require.NoError(t, err)
+	newSnap := readTestSnapshotDoc(t, store, testAccountID, newMeta.SnapshotID)
 	// Compare against the source snapshot, not hard-coded literals — proves
 	// the new snap truly inherits the source's VolumeID rather than happening
 	// to match a test fixture value.
@@ -1745,8 +1744,7 @@ func TestCopyImage_BundledSystemAMINoStandaloneSnap(t *testing.T) {
 	// snap-ami-bundled01 viperblock reference.
 	require.NotEqual(t, "snap-ami-bundled01", newMeta.SnapshotID,
 		"copy must mint a new user-owned snap id, not borrow the source's")
-	newSnap, err := handlers_ec2_snapshot.ReadSnapshotConfig(context.Background(), store, testBucket, newMeta.SnapshotID)
-	require.NoError(t, err)
+	newSnap := readTestSnapshotDoc(t, store, testAccountID, newMeta.SnapshotID)
 	assert.Equal(t, "ami-bundled01", newSnap.VolumeID,
 		"bundled fallback must point the new snap at the source AMI's prefix")
 	assert.Equal(t, int64(8), newSnap.VolumeSize)
@@ -1759,7 +1757,7 @@ func TestCopyImage_CrossAccountHidesExistence(t *testing.T) {
 	seedCopyableAMI(t, store, "ami-other001", "other-acct", "000000000002", "snap-other001", "vol-other", 8)
 
 	srcBefore := readAMIConfigBytes(t, store, "ami-other001")
-	srcSnapBefore := readSnapshotConfigBytes(t, store, "snap-other001")
+	srcSnapBefore := readSnapshotConfigBytes(t, store, "000000000002", "snap-other001")
 
 	_, err := svc.CopyImage(context.Background(), validCopyImageServiceInput("ami-other001", "stolen-copy"), testAccountID)
 	require.Error(t, err)
@@ -1768,7 +1766,7 @@ func TestCopyImage_CrossAccountHidesExistence(t *testing.T) {
 	// Rejection must not touch the source AMI config or its snapshot metadata.
 	assert.Equal(t, srcBefore, readAMIConfigBytes(t, store, "ami-other001"),
 		"source AMI config altered after rejected cross-account copy")
-	assert.Equal(t, srcSnapBefore, readSnapshotConfigBytes(t, store, "snap-other001"),
+	assert.Equal(t, srcSnapBefore, readSnapshotConfigBytes(t, store, "000000000002", "snap-other001"),
 		"source snapshot metadata altered after rejected cross-account copy")
 }
 
@@ -2400,7 +2398,7 @@ func TestSnapshotStoppedVolume_VolumeConfigMissing(t *testing.T) {
 		store:      store,
 		bucketName: testBucket,
 	}
-	err := svc.snapshotStoppedVolume("vol-missing", "snap-s1")
+	err := svc.snapshotStoppedVolume("vol-missing", "snap-s1", testAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
 }
@@ -2425,7 +2423,7 @@ func TestSnapshotStoppedVolume_BackendInitFails(t *testing.T) {
 	}
 	createTestVolumeConfig(t, store, "vol-stopped1", 10)
 
-	err := svc.snapshotStoppedVolume("vol-stopped1", "snap-s2")
+	err := svc.snapshotStoppedVolume("vol-stopped1", "snap-s2", testAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
 }
@@ -2527,7 +2525,7 @@ func TestSnapshotStoppedVolume_EncryptionKeyLoadError(t *testing.T) {
 	}
 	createTestVolumeConfig(t, store, "vol-stopped-enckey", 10)
 
-	err := svc.snapshotStoppedVolume("vol-stopped-enckey", "snap-stop-enckey")
+	err := svc.snapshotStoppedVolume("vol-stopped-enckey", "snap-stop-enckey", testAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
 }
@@ -2552,7 +2550,7 @@ func TestSnapshotStoppedVolume_LoadStateFails(t *testing.T) {
 	}
 	createTestVolumeConfig(t, store, "vol-stopped-lsf", 10)
 
-	err := svc.snapshotStoppedVolume("vol-stopped-lsf", "snap-stop-lsf")
+	err := svc.snapshotStoppedVolume("vol-stopped-lsf", "snap-stop-lsf", testAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
 }
diff --git a/spinifex/handlers/ec2/instance/provider_root_volume_test.go b/spinifex/handlers/ec2/instance/provider_root_volume_test.go
index fc9690d85..687821061 100644
--- a/spinifex/handlers/ec2/instance/provider_root_volume_test.go
+++ b/spinifex/handlers/ec2/instance/provider_root_volume_test.go
@@ -120,7 +120,7 @@ func TestPrepareRootVolume_Provider_WritesMetadataDocument(t *testing.T) {
 		"vol-root", testRootVolumeBytes, 0, instance, true)
 	require.NoError(t, err)
 
-	doc, err := ebsmetadata.NewStore(store, testRootBucket).GetVolume(context.Background(), "vol-root")
+	doc, err := ebsmetadata.NewStore(store, testRootBucket).GetVolume(context.Background(), testRootAccount, "vol-root")
 	require.NoError(t, err, "the root volume must have an ebsmetadata document")
 
 	assert.Equal(t, "vol-root", doc.VolumeID)
@@ -154,7 +154,7 @@ func TestPrepareRootVolume_Provider_HonoursRequestedIOPS(t *testing.T) {
 		"vol-root", testRootVolumeBytes, 5000, &vm.VM{AccountID: testRootAccount}, true)
 	require.NoError(t, err)
 
-	doc, err := ebsmetadata.NewStore(store, testRootBucket).GetVolume(context.Background(), "vol-root")
+	doc, err := ebsmetadata.NewStore(store, testRootBucket).GetVolume(context.Background(), testRootAccount, "vol-root")
 	require.NoError(t, err)
 	assert.Equal(t, 5000, doc.IOPS)
 }
@@ -184,7 +184,7 @@ func TestPrepareRootVolume_Provider_RollbackOnMetadataWriteFailure(t *testing.T)
 	seedProviderSnapshot(t, provider, "vol-origin", "snap-source")
 	store := &failingPutObjectStore{
 		ObjectStore: objectstore.NewMemoryObjectStore(),
-		failPrefix:  "spinifex/ebsmetadata/v1/volumes/",
+		failPrefix:  "spinifex/ebsmetadata/v2/volumes/",
 	}
 	svc := providerRootVolumeService(t, provider, rootVolumeAMILoader(), store)
 
diff --git a/spinifex/handlers/ec2/snapshot/delete_snapshot_pagination_test.go b/spinifex/handlers/ec2/snapshot/delete_snapshot_pagination_test.go
index cd53831c7..39a9f6867 100644
--- a/spinifex/handlers/ec2/snapshot/delete_snapshot_pagination_test.go
+++ b/spinifex/handlers/ec2/snapshot/delete_snapshot_pagination_test.go
@@ -45,7 +45,7 @@ func TestDeleteSnapshot_RemovesEveryObjectAcrossMultiplePages(t *testing.T) {
 	})
 	require.NoError(t, err)
 	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutVolume(context.Background(), ebsmetadata.Volume{
-		VolumeID: "vol-1", CapacityGiB: 10, AvailabilityZone: "us-east-1a",
+		VolumeID: "vol-1", TenantID: testAccountID, CapacityGiB: 10, AvailabilityZone: "us-east-1a",
 	}))
 
 	snap, err := svc.CreateSnapshot(context.Background(), &ec2.CreateSnapshotInput{
diff --git a/spinifex/handlers/ec2/snapshot/describe_fanout_test.go b/spinifex/handlers/ec2/snapshot/describe_fanout_test.go
index 141469985..ddb841123 100644
--- a/spinifex/handlers/ec2/snapshot/describe_fanout_test.go
+++ b/spinifex/handlers/ec2/snapshot/describe_fanout_test.go
@@ -10,6 +10,7 @@ import (
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/config"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
 	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/objectstore"
 	"github.com/stretchr/testify/assert"
@@ -55,13 +56,13 @@ func seedSnapshots(t *testing.T, store objectstore.ObjectStore, n int) *handlers
 	t.Helper()
 	cfg := &config.Config{Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
 	svc := handlers_ec2_snapshot.NewSnapshotServiceImplWithStore(cfg, store, nil)
+	metadata := ebsmetadata.NewStore(store, "test-bucket")
 	for i := range n {
 		id := "snap-fanout" + string(rune('a'+i%26)) + string(rune('a'+i/26))
-		require.NoError(t, handlers_ec2_snapshot.WriteSnapshotConfig(store, "test-bucket", id,
-			&handlers_ec2_snapshot.SnapshotConfig{
-				SnapshotID: id, VolumeID: "vol-fanout", State: "completed",
-				OwnerID: fanoutAccountID, StartTime: time.Now(),
-			}))
+		require.NoError(t, metadata.PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+			SnapshotID: id, VolumeID: "vol-fanout", State: "completed",
+			OwnerID: fanoutAccountID, StartTime: time.Now(),
+		}))
 	}
 	return svc
 }
diff --git a/spinifex/handlers/ec2/snapshot/record_tags_test.go b/spinifex/handlers/ec2/snapshot/record_tags_test.go
index e398ff25f..b2ae711e9 100644
--- a/spinifex/handlers/ec2/snapshot/record_tags_test.go
+++ b/spinifex/handlers/ec2/snapshot/record_tags_test.go
@@ -22,7 +22,7 @@ func TestSnapshotRecordTagsMirror(t *testing.T) {
 		},
 	}, testAccountID))
 
-	cfg, err := svc.getSnapshotConfig(context.Background(), snapID)
+	cfg, err := svc.getSnapshotConfig(context.Background(), testAccountID, snapID)
 	require.NoError(t, err)
 	assert.Equal(t, "yes", cfg.Tags["keep"])
 	assert.Equal(t, "v", cfg.Tags["drop"])
@@ -36,7 +36,7 @@ func TestSnapshotRecordTagsMirror(t *testing.T) {
 		},
 	}, testAccountID))
 
-	cfg, err = svc.getSnapshotConfig(context.Background(), snapID)
+	cfg, err = svc.getSnapshotConfig(context.Background(), testAccountID, snapID)
 	require.NoError(t, err)
 	assert.Equal(t, "yes", cfg.Tags["keep"])
 	_, ok := cfg.Tags["drop"]
@@ -53,7 +53,7 @@ func TestSnapshotRecordTagsMirror_CrossTenantNoMutation(t *testing.T) {
 		Tags:      []*ec2.Tag{{Key: aws.String("evil"), Value: aws.String("1")}},
 	}, "999999999999"))
 
-	cfg, err := svc.getSnapshotConfig(context.Background(), snapID)
+	cfg, err := svc.getSnapshotConfig(context.Background(), testAccountID, snapID)
 	require.NoError(t, err)
 	assert.Equal(t, map[string]string{"orig": "1"}, cfg.Tags)
 }
diff --git a/spinifex/handlers/ec2/snapshot/service_impl.go b/spinifex/handlers/ec2/snapshot/service_impl.go
index 766ceccab..bebe86f6b 100644
--- a/spinifex/handlers/ec2/snapshot/service_impl.go
+++ b/spinifex/handlers/ec2/snapshot/service_impl.go
@@ -1,7 +1,6 @@
 package handlers_ec2_snapshot
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
@@ -71,22 +70,6 @@ func (s *SnapshotServiceImpl) MetadataStore() *ebsmetadata.Store {
 	return s.metadata
 }
 
-// SnapshotConfig represents snapshot metadata stored in S3.
-type SnapshotConfig struct {
-	SnapshotID       string            `json:"snapshot_id"`
-	VolumeID         string            `json:"volume_id"`
-	VolumeSize       int64             `json:"volume_size"`
-	State            string            `json:"state"`
-	Progress         string            `json:"progress"`
-	StartTime        time.Time         `json:"start_time"`
-	Description      string            `json:"description"`
-	Encrypted        bool              `json:"encrypted"`
-	OwnerID          string            `json:"owner_id"`
-	AvailabilityZone string            `json:"availability_zone"`
-	Tags             map[string]string `json:"tags"`
-	ProviderHandle   string            `json:"provider_handle,omitempty"`
-}
-
 // NewSnapshotServiceImplWithNATS creates a snapshot service with JetStream KV for volume-snapshot tracking.
 func NewSnapshotServiceImplWithNATS(ctx context.Context, cfg *config.Config, natsConn *nats.Conn) (*SnapshotServiceImpl, jetstream.KeyValue, error) {
 	store := objectstore.NewS3ObjectStoreFromConfig(
@@ -135,73 +118,21 @@ func NewSnapshotServiceImplWithStore(cfg *config.Config, store objectstore.Objec
 	return svc
 }
 
-// GetSnapshotKey uses metadata.json to avoid colliding with viperblock's
-// config.json (which stores SnapshotState: block map, source volume, etc).
-func GetSnapshotKey(snapshotID string) string {
-	return fmt.Sprintf("%s/metadata.json", snapshotID)
-}
-
-// ErrCorruptSnapshotMetadata lets callers distinguish a missing snapshot from
-// one whose metadata.json can't be parsed.
-var ErrCorruptSnapshotMetadata = errors.New("corrupt snapshot metadata")
-
-// ReadSnapshotConfig reads {snapshotID}/metadata.json. Object-store errors are
-// returned unchanged; callers map NoSuchKey to their preferred AWS error.
-// Decode failures wrap ErrCorruptSnapshotMetadata. ctx carries the caller's
-// deadline: a describe that has already given up must not keep the object
-// store busy on its behalf.
-func ReadSnapshotConfig(ctx context.Context, store objectstore.ObjectStore, bucket, snapshotID string) (*SnapshotConfig, error) {
-	key := GetSnapshotKey(snapshotID)
-	result, err := store.GetObject(ctx, &s3.GetObjectInput{
-		Bucket: aws.String(bucket),
-		Key:    aws.String(key),
-	})
-	if err != nil {
-		return nil, err
-	}
-	defer result.Body.Close()
-
-	var cfg SnapshotConfig
-	if err := json.NewDecoder(result.Body).Decode(&cfg); err != nil {
-		return nil, fmt.Errorf("%w: %w", ErrCorruptSnapshotMetadata, err)
-	}
-	return &cfg, nil
-}
-
-// WriteSnapshotConfig writes the SnapshotConfig to {snapshotID}/metadata.json.
-func WriteSnapshotConfig(store objectstore.ObjectStore, bucket, snapshotID string, cfg *SnapshotConfig) error {
-	data, err := json.Marshal(cfg)
-	if err != nil {
-		return err
-	}
-	_, err = store.PutObject(context.Background(), &s3.PutObjectInput{
-		Bucket:      aws.String(bucket),
-		Key:         aws.String(GetSnapshotKey(snapshotID)),
-		Body:        bytes.NewReader(data),
-		ContentType: aws.String("application/json"),
-	})
-	return err
-}
-
-// getSnapshotConfig translates NoSuchKey to InvalidSnapshot.NotFound.
-func (s *SnapshotServiceImpl) getSnapshotConfig(ctx context.Context, snapshotID string) (*SnapshotConfig, error) {
-	cfg, err := ReadSnapshotConfig(ctx, s.store, s.config.Predastore.Bucket, snapshotID)
+// getSnapshotConfig reads the caller's own snapshot document. A snapshot
+// outside the caller's prefix is absent, so ownership needs no second check.
+func (s *SnapshotServiceImpl) getSnapshotConfig(ctx context.Context, accountID, snapshotID string) (ebsmetadata.Snapshot, error) {
+	cfg, err := s.metadata.GetSnapshot(ctx, accountID, snapshotID)
 	if err != nil {
 		if objectstore.IsNoSuchKeyError(err) {
-			return nil, errors.New(awserrors.ErrorInvalidSnapshotNotFound)
+			return ebsmetadata.Snapshot{}, errors.New(awserrors.ErrorInvalidSnapshotNotFound)
 		}
-		return nil, err
+		return ebsmetadata.Snapshot{}, err
 	}
 	return cfg, nil
 }
 
-// putSnapshotConfig stores snapshot config to S3.
-func (s *SnapshotServiceImpl) putSnapshotConfig(snapshotID string, cfg *SnapshotConfig) error {
-	return WriteSnapshotConfig(s.store, s.config.Predastore.Bucket, snapshotID, cfg)
-}
-
-// snapshotConfigToEC2 converts a SnapshotConfig to an EC2 Snapshot response object.
-func snapshotConfigToEC2(cfg *SnapshotConfig) *ec2.Snapshot {
+// snapshotConfigToEC2 converts a snapshot document to an EC2 response object.
+func snapshotConfigToEC2(cfg ebsmetadata.Snapshot) *ec2.Snapshot {
 	snapshot := &ec2.Snapshot{
 		SnapshotId:  aws.String(cfg.SnapshotID),
 		VolumeId:    aws.String(cfg.VolumeID),
@@ -225,6 +156,13 @@ func (s *SnapshotServiceImpl) CreateSnapshot(ctx context.Context, input *ec2.Cre
 		return nil, errors.New(awserrors.ErrorInvalidParameterValue)
 	}
 
+	// The caller's account is a key segment, so an untenanted caller has no
+	// prefix to read or write under. Refuse at the boundary rather than in the
+	// key builder, where the rejection would surface as an internal error.
+	if accountID == "" {
+		return nil, errors.New(awserrors.ErrorAuthFailure)
+	}
+
 	volumeID := *input.VolumeId
 
 	slog.InfoContext(ctx, "CreateSnapshot request", "volumeId", volumeID)
@@ -235,11 +173,10 @@ func (s *SnapshotServiceImpl) CreateSnapshot(ctx context.Context, input *ec2.Cre
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 
-	// A volume predating tenancy records no owner. Refusing it would strand
-	// every pre-tenancy volume as unsnapshottable, so an absent TenantID stays
-	// open to any caller; a recorded one must match.
-	volume, err := s.metadata.GetVolume(ctx, volumeID)
-	if err != nil || (accountID != "" && volume.TenantID != "" && volume.TenantID != accountID) {
+	// The read is already scoped to the caller's prefix, so a returned document
+	// is the caller's by construction. The comparison stays as an assertion.
+	volume, err := s.metadata.GetVolume(ctx, accountID, volumeID)
+	if err != nil || volume.TenantID != accountID {
 		return nil, errors.New(awserrors.ErrorInvalidVolumeNotFound)
 	}
 	if volume.CapacityGiB == 0 {
@@ -261,7 +198,7 @@ func (s *SnapshotServiceImpl) CreateSnapshot(ctx context.Context, input *ec2.Cre
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 	now := time.Now()
-	snapshotCfg := &SnapshotConfig{
+	snapshotCfg := ebsmetadata.Snapshot{
 		SnapshotID: snapshotID, VolumeID: volumeID,
 		VolumeSize: safecast.Uint64ToInt64(volume.CapacityGiB),
 		State:      string(created.State), Progress: "100%", StartTime: now,
@@ -284,7 +221,7 @@ func (s *SnapshotServiceImpl) CreateSnapshot(ctx context.Context, input *ec2.Cre
 		_ = s.provider.DeleteSnapshot(ctx, ebsprovider.DeleteSnapshotRequest{Versioned: ebsprovider.NewVersioned(), SnapshotID: snapshotID, Handle: created.Handle})
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
-	if err := s.putSnapshotConfig(snapshotID, snapshotCfg); err != nil {
+	if err := s.metadata.PutSnapshot(ctx, snapshotCfg); err != nil {
 		slog.ErrorContext(ctx, "CreateSnapshot failed to write config", "snapshotId", snapshotID, "err", err)
 		_ = s.removeSnapshotRefForCleanup(ctx, volumeID, snapshotID)
 		_ = s.provider.DeleteSnapshot(ctx, ebsprovider.DeleteSnapshotRequest{Versioned: ebsprovider.NewVersioned(), SnapshotID: snapshotID, Handle: created.Handle})
@@ -508,70 +445,42 @@ func (s *SnapshotServiceImpl) describeSnapshots(ctx context.Context, input *ec2.
 		return nil, errors.New(awserrors.ErrorInvalidParameterValue)
 	}
 
-	_, commonPrefixes, err := objectstore.ListAll(ctx, s.store, &s3.ListObjectsV2Input{
-		Bucket:    aws.String(s.config.Predastore.Bucket),
-		Prefix:    aws.String("snap-"),
-		Delimiter: aws.String("/"),
-	})
-	if err != nil {
-		slog.ErrorContext(ctx, "DescribeSnapshots failed to list objects", "err", err)
-		return nil, errors.New(awserrors.ErrorServerInternal)
-	}
-
-	// Extract snapshot-id filter values for early prefix skipping to avoid
-	// unnecessary S3 GetObject calls on non-matching snapshots.
-	var snapshotIDFilterValues []string
-	if parsedFilters != nil {
-		snapshotIDFilterValues = parsedFilters["snapshot-id"]
-	}
-
-	var wanted []string
-	for _, prefix := range commonPrefixes {
-		if prefix == nil || prefix.Prefix == nil {
-			continue
+	// The caller's prefix is the isolation and the whole answer: no other
+	// account's document is read, so none has to be filtered out afterwards.
+	// Named ids are matched against this listing rather than fetched directly —
+	// the listing already costs what the account owns.
+	//
+	// OwnerIds names either the caller, which the prefix already is, or another
+	// account, whose snapshots cannot be under it — so that case is empty without
+	// a read, and the tail below still reports a named id as not found.
+	var configs []ebsmetadata.Snapshot
+	if ownerIDsIncludeCaller(input.OwnerIds, accountID) {
+		if strict {
+			configs, err = s.metadata.ListSnapshotsStrict(ctx, accountID)
+		} else {
+			configs, err = s.metadata.ListSnapshots(ctx, accountID)
 		}
-
-		snapshotID := strings.TrimSuffix(*prefix.Prefix, "/")
-
-		if len(snapshotIDFilter) > 0 && !snapshotIDFilter[snapshotID] {
-			continue
-		}
-
-		// Early skip: if snapshot-id filter is set, check the prefix against
-		// filter values before fetching config from S3.
-		if len(snapshotIDFilterValues) > 0 {
-			if !filterutil.MatchesAny(snapshotIDFilterValues, snapshotID) {
-				continue
+		if err != nil {
+			slog.ErrorContext(ctx, "DescribeSnapshots failed to list snapshot documents", "accountID", accountID, "err", err)
+			if strict {
+				return nil, fmt.Errorf("describe snapshots for %s: %w", accountID, err)
 			}
+			return nil, errors.New(awserrors.ErrorServerInternal)
 		}
-
-		wanted = append(wanted, snapshotID)
 	}
 
-	configs, readErrs := s.readSnapshotConfigs(ctx, wanted)
-
-	// Every read fails once the caller's deadline passes, and reporting that as
-	// an empty list would read as "this account has no snapshots".
+	// Every read fails once the caller's deadline passes, and a tolerant listing
+	// reports that as an empty list, which reads as "this account has no
+	// snapshots".
 	if err := ctx.Err(); err != nil {
 		slog.WarnContext(ctx, "DescribeSnapshots gave up reading metadata",
-			"requested", len(wanted), "read", len(configs), "err", err)
+			"read", len(configs), "err", err)
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 
 	var snapshots []*ec2.Snapshot
-	for _, snapshotID := range wanted {
-		cfg, ok := configs[snapshotID]
-		if !ok {
-			slog.WarnContext(ctx, "DescribeSnapshots failed to get config",
-				"snapshotId", snapshotID, "err", readErrs[snapshotID])
-			if strict {
-				return nil, fmt.Errorf("describe snapshot %s metadata: %w", snapshotID, readErrs[snapshotID])
-			}
-			continue
-		}
-
-		// Filter by account: only return snapshots owned by the caller
-		if accountID != "" && cfg.OwnerID != "" && cfg.OwnerID != accountID {
+	for _, cfg := range configs {
+		if len(snapshotIDFilter) > 0 && !snapshotIDFilter[cfg.SnapshotID] {
 			continue
 		}
 
@@ -605,48 +514,29 @@ func (s *SnapshotServiceImpl) describeSnapshots(ctx context.Context, input *ec2.
 	}, nil
 }
 
-// describeSnapshotFanout bounds how many metadata reads a single describe has
-// in flight. A describe used to read every snapshot's metadata.json one after
-// the other, so its latency was the sum of them all and a single slow object
-// made the whole listing miss its caller's deadline. The bound keeps a large
-// account from turning one describe into a burst against the object store.
-const describeSnapshotFanout = 16
-
-// readSnapshotConfigs fetches metadata for each snapshot concurrently. It
-// returns what it could read plus the error for each one it could not, so the
-// caller decides whether an unreadable snapshot is fatal or simply skipped.
-func (s *SnapshotServiceImpl) readSnapshotConfigs(
-	ctx context.Context, ids []string,
-) (map[string]*SnapshotConfig, map[string]error) {
-	configs := make(map[string]*SnapshotConfig, len(ids))
-	readErrs := make(map[string]error)
-	if len(ids) == 0 {
-		return configs, readErrs
+// ownerIDsIncludeCaller reports whether an OwnerIds request parameter selects
+// the account whose prefix is being listed. "self" and the caller's own account
+// ID both name that prefix; any other value names an account the caller's
+// prefix cannot contain.
+func ownerIDsIncludeCaller(ownerIDs []*string, accountID string) bool {
+	if len(ownerIDs) == 0 {
+		return true
 	}
 
-	var mu sync.Mutex
-	sem := make(chan struct{}, describeSnapshotFanout)
-	var wg sync.WaitGroup
-	for _, id := range ids {
-		sem <- struct{}{}
-		wg.Go(func() {
-			defer func() { <-sem }()
-			cfg, err := s.getSnapshotConfig(ctx, id)
-			mu.Lock()
-			defer mu.Unlock()
-			if err != nil {
-				readErrs[id] = err
-				return
-			}
-			configs[id] = cfg
-		})
+	for _, owner := range ownerIDs {
+		if owner == nil {
+			continue
+		}
+		if *owner == "self" || *owner == accountID {
+			return true
+		}
 	}
-	wg.Wait()
-	return configs, readErrs
+
+	return false
 }
 
-// snapshotMatchesFilters checks whether a SnapshotConfig satisfies all parsed filters.
-func snapshotMatchesFilters(cfg *SnapshotConfig, filters map[string][]string) bool {
+// snapshotMatchesFilters checks whether a snapshot document satisfies all parsed filters.
+func snapshotMatchesFilters(cfg ebsmetadata.Snapshot, filters map[string][]string) bool {
 	for name, values := range filters {
 		if strings.HasPrefix(name, "tag:") {
 			continue
@@ -680,9 +570,14 @@ func snapshotMatchesFilters(cfg *SnapshotConfig, filters map[string][]string) bo
 // snapshot. A clone records its source in its ebsmetadata document; missing one
 // here would let a delete strip the chunks a live clone still reads.
 func (s *SnapshotServiceImpl) snapshotInUseByVolumes(ctx context.Context, snapshotID string) (bool, error) {
+	// Whole-cluster, and not scoping this to the snapshot's own account is the
+	// point: launching from a system AMI writes a root volume owned by the
+	// launching tenant whose SnapshotID is the system snapshot, so a clone
+	// routinely lives outside the snapshot owner's prefix.
+	//
 	// Strict: a volume that failed to read is not evidence that no clone reads
 	// the snapshot's chunks, and this answer gates deleting them.
-	volumes, err := s.metadata.ListVolumesStrict(ctx)
+	volumes, err := s.metadata.ListAllVolumesStrict(ctx)
 	if err != nil {
 		return false, fmt.Errorf("snapshotInUseByVolumes: failed to list volumes: %w", err)
 	}
@@ -700,18 +595,25 @@ func (s *SnapshotServiceImpl) DeleteSnapshot(ctx context.Context, input *ec2.Del
 		return nil, errors.New(awserrors.ErrorInvalidParameterValue)
 	}
 
+	// An untenanted caller has no prefix to delete under; refuse here rather
+	// than in the key builder.
+	if accountID == "" {
+		return nil, errors.New(awserrors.ErrorAuthFailure)
+	}
+
 	snapshotID := *input.SnapshotId
 
 	slog.InfoContext(ctx, "DeleteSnapshot request", "snapshotId", snapshotID, "accountID", accountID)
 
-	cfg, err := s.getSnapshotConfig(ctx, snapshotID)
+	cfg, err := s.getSnapshotConfig(ctx, accountID, snapshotID)
 	if err != nil {
 		slog.ErrorContext(ctx, "DeleteSnapshot snapshot not found", "snapshotId", snapshotID, "err", err)
 		return nil, err
 	}
 
-	// Verify ownership: caller must own the snapshot
-	if accountID != "" && cfg.OwnerID != "" && cfg.OwnerID != accountID {
+	// The read was scoped to the caller's prefix, so the document is theirs by
+	// construction. The comparison stays as an assertion.
+	if cfg.OwnerID != accountID {
 		slog.WarnContext(ctx, "DeleteSnapshot: account does not own snapshot", "snapshotId", snapshotID, "accountID", accountID, "ownerID", cfg.OwnerID)
 		return nil, errors.New(awserrors.ErrorUnauthorizedOperation)
 	}
@@ -743,6 +645,10 @@ func (s *SnapshotServiceImpl) DeleteSnapshot(ctx context.Context, input *ec2.Del
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 
+	// A key the sweep could not delete has to keep the document alive. The
+	// listing no longer enumerates snap- prefixes, so deleting the document over
+	// surviving chunks strands them where nothing can see or reclaim them.
+	var sweepErr error
 	for _, obj := range objects {
 		if obj == nil || obj.Key == nil {
 			continue
@@ -752,9 +658,24 @@ func (s *SnapshotServiceImpl) DeleteSnapshot(ctx context.Context, input *ec2.Del
 			Key:    obj.Key,
 		})
 		if err != nil {
-			slog.WarnContext(ctx, "DeleteSnapshot failed to delete object", "key", *obj.Key, "err", err)
+			slog.ErrorContext(ctx, "DeleteSnapshot failed to delete object", "key", *obj.Key, "err", err)
+			sweepErr = errors.Join(sweepErr, err)
 		}
 	}
+	if sweepErr != nil {
+		slog.ErrorContext(ctx, "DeleteSnapshot leaving the document in place after an incomplete sweep",
+			"snapshotId", snapshotID, "err", sweepErr)
+		return nil, errors.New(awserrors.ErrorServerInternal)
+	}
+
+	// The document no longer sits inside the swept prefix, so it has to go
+	// explicitly, and last: a crash with it still present leaves a snapshot that
+	// DescribeSnapshots shows and DeleteSnapshot can retry, rather than chunks
+	// nothing enumerates.
+	if err := s.metadata.DeleteSnapshot(ctx, accountID, snapshotID); err != nil {
+		slog.ErrorContext(ctx, "DeleteSnapshot failed to delete metadata document", "snapshotId", snapshotID, "err", err)
+		return nil, errors.New(awserrors.ErrorServerInternal)
+	}
 
 	// Remove from KV after S3 cleanup. Failure is logged but not fatal —
 	// a phantom entry safely blocks volume deletion rather than allowing it.
@@ -776,17 +697,24 @@ func (s *SnapshotServiceImpl) CopySnapshot(ctx context.Context, input *ec2.CopyS
 		return nil, errors.New(awserrors.ErrorInvalidParameterValue)
 	}
 
+	// The copy is written under the caller's account, so an untenanted caller
+	// has nowhere to put it; refuse here rather than in the key builder.
+	if accountID == "" {
+		return nil, errors.New(awserrors.ErrorAuthFailure)
+	}
+
 	sourceSnapshotID := *input.SourceSnapshotId
 
 	slog.InfoContext(ctx, "CopySnapshot request", "sourceSnapshotId", sourceSnapshotID, "accountID", accountID)
 
-	sourceCfg, err := s.getSnapshotConfig(ctx, sourceSnapshotID)
+	sourceCfg, err := s.getSnapshotConfig(ctx, accountID, sourceSnapshotID)
 	if err != nil {
 		slog.ErrorContext(ctx, "CopySnapshot source snapshot not found", "snapshotId", sourceSnapshotID, "err", err)
 		return nil, err
 	}
 
-	if accountID != "" && sourceCfg.OwnerID != "" && sourceCfg.OwnerID != accountID {
+	// Assertion: the read was already scoped to the caller's prefix.
+	if sourceCfg.OwnerID != accountID {
 		slog.WarnContext(ctx, "CopySnapshot: account does not own source snapshot", "snapshotId", sourceSnapshotID, "accountID", accountID, "ownerID", sourceCfg.OwnerID)
 		return nil, errors.New(awserrors.ErrorUnauthorizedOperation)
 	}
@@ -812,7 +740,7 @@ func (s *SnapshotServiceImpl) CopySnapshot(ctx context.Context, input *ec2.CopyS
 	}
 
 	now := time.Now()
-	snapshotCfg := &SnapshotConfig{
+	snapshotCfg := ebsmetadata.Snapshot{
 		SnapshotID: newSnapshotID, VolumeID: sourceCfg.VolumeID,
 		VolumeSize: sourceCfg.VolumeSize,
 		State:      string(copied.State), Progress: "100%", StartTime: now,
@@ -836,7 +764,7 @@ func (s *SnapshotServiceImpl) CopySnapshot(ctx context.Context, input *ec2.CopyS
 		_ = s.provider.DeleteSnapshot(ctx, ebsprovider.DeleteSnapshotRequest{Versioned: ebsprovider.NewVersioned(), SnapshotID: newSnapshotID, Handle: copied.Handle})
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
-	if err := s.putSnapshotConfig(newSnapshotID, snapshotCfg); err != nil {
+	if err := s.metadata.PutSnapshot(ctx, snapshotCfg); err != nil {
 		_ = s.removeSnapshotRefForCleanup(ctx, sourceCfg.VolumeID, newSnapshotID)
 		_ = s.provider.DeleteSnapshot(ctx, ebsprovider.DeleteSnapshotRequest{Versioned: ebsprovider.NewVersioned(), SnapshotID: newSnapshotID, Handle: copied.Handle})
 		return nil, errors.New(awserrors.ErrorServerInternal)
@@ -1011,30 +939,26 @@ func (s *SnapshotServiceImpl) RemoveRecordTags(input *ec2.DeleteTagsInput, accou
 	return s.mirrorSnapshotTags(input.Resources, accountID, utils.RemoveTagsMut(input))
 }
 
-// mirrorSnapshotTags read-modify-writes SnapshotConfig.Tags for each snap- id.
-// metadata.json lives at a global ID-keyed path, so the mutation is gated on
-// the caller owning the snapshot (OwnerID match); mismatch or absence no-ops.
+// mirrorSnapshotTags read-modify-writes the snapshot document's Tags for each
+// snap- id. The document is read under the caller's own prefix, so a snapshot
+// they do not own is simply absent and no-ops.
 func (s *SnapshotServiceImpl) mirrorSnapshotTags(resources []*string, accountID string, mut func(map[string]string)) error {
 	for _, res := range resources {
 		if res == nil || !strings.HasPrefix(*res, "snap-") {
 			continue
 		}
-		cfg, err := ReadSnapshotConfig(context.Background(), s.store, s.config.Predastore.Bucket, *res)
+		cfg, err := s.metadata.GetSnapshot(context.Background(), accountID, *res)
 		if err != nil {
 			if objectstore.IsNoSuchKeyError(err) {
 				continue
 			}
 			return err
 		}
-		if cfg.OwnerID != accountID {
-			slog.Debug("mirrorSnapshotTags: skipping snapshot not owned by caller", "snapshotId", *res)
-			continue
-		}
 		if cfg.Tags == nil {
 			cfg.Tags = map[string]string{}
 		}
 		mut(cfg.Tags)
-		if err := s.putSnapshotConfig(*res, cfg); err != nil {
+		if err := s.metadata.PutSnapshot(context.Background(), cfg); err != nil {
 			return err
 		}
 	}
diff --git a/spinifex/handlers/ec2/snapshot/service_impl_test.go b/spinifex/handlers/ec2/snapshot/service_impl_test.go
index 86d8d151b..5b5921000 100644
--- a/spinifex/handlers/ec2/snapshot/service_impl_test.go
+++ b/spinifex/handlers/ec2/snapshot/service_impl_test.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"path"
 	"strings"
 	"testing"
 
@@ -44,10 +45,18 @@ func setupTestSnapshotService(t *testing.T) (*SnapshotServiceImpl, *objectstore.
 // createTestVolume seeds a volume on both sides: the provider holds the blocks
 // a snapshot copies, the document is what the control plane resolves.
 func createTestVolume(t *testing.T, svc *SnapshotServiceImpl, store *objectstore.MemoryObjectStore, volumeID string, sizeGiB int) {
+	t.Helper()
+	createTestVolumeForAccount(t, svc, store, volumeID, sizeGiB, testAccountID)
+}
+
+// createTestVolumeForAccount is createTestVolume for a volume owned by an
+// account other than the default one.
+func createTestVolumeForAccount(t *testing.T, svc *SnapshotServiceImpl, store *objectstore.MemoryObjectStore, volumeID string, sizeGiB int, accountID string) {
 	t.Helper()
 	seedProviderVolume(t, svc, volumeID, sizeGiB)
 	seedVolumeDocument(t, store, ebsmetadata.Volume{
 		VolumeID:         volumeID,
+		TenantID:         accountID,
 		CapacityGiB:      uint64(sizeGiB),
 		AvailabilityZone: "us-east-1a",
 	})
@@ -56,9 +65,24 @@ func createTestVolume(t *testing.T, svc *SnapshotServiceImpl, store *objectstore
 // seedVolumeDocument writes the control-plane document for a volume.
 func seedVolumeDocument(t *testing.T, store objectstore.ObjectStore, volume ebsmetadata.Volume) {
 	t.Helper()
+	// The owning account is a key segment, so a fixture that does not care
+	// which account owns it still has to have one.
+	if volume.TenantID == "" {
+		volume.TenantID = testAccountID
+	}
 	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutVolume(context.Background(), volume))
 }
 
+// seedSnapshotDocument writes the control-plane document for a snapshot,
+// keyed under its own OwnerID.
+func seedSnapshotDocument(t *testing.T, store objectstore.ObjectStore, snapshot ebsmetadata.Snapshot) {
+	t.Helper()
+	if snapshot.OwnerID == "" {
+		snapshot.OwnerID = testAccountID
+	}
+	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutSnapshot(context.Background(), snapshot))
+}
+
 // seedProviderVolume gives the service's provider a volume to snapshot. A
 // control-plane document alone is not a volume: the provider owns the blocks,
 // and CreateSnapshot fails against one it has never allocated.
@@ -232,9 +256,11 @@ func TestDescribeSnapshots(t *testing.T) {
 
 func TestDescribeSnapshotsStrict_RejectsPartialMetadataResults(t *testing.T) {
 	svc, store := setupTestSnapshotService(t)
-	_, err := store.PutObject(t.Context(), &s3.PutObjectInput{
+	key, err := ebsmetadata.SnapshotKey(testAccountID, "snap-corrupt")
+	require.NoError(t, err)
+	_, err = store.PutObject(t.Context(), &s3.PutObjectInput{
 		Bucket: aws.String("test-bucket"),
-		Key:    aws.String(GetSnapshotKey("snap-corrupt")),
+		Key:    aws.String(key),
 		Body:   strings.NewReader("not-json"),
 	})
 	require.NoError(t, err)
@@ -248,7 +274,7 @@ func TestDescribeSnapshotsStrict_RejectsPartialMetadataResults(t *testing.T) {
 	// absence, so its internal lookup surfaces the metadata failure.
 	_, err = svc.DescribeSnapshotsStrict(t.Context(), &ec2.DescribeSnapshotsInput{}, testAccountID)
 	require.Error(t, err)
-	assert.ErrorIs(t, err, ErrCorruptSnapshotMetadata)
+	assert.ErrorIs(t, err, ebsmetadata.ErrCorruptDocument)
 }
 
 // TestDescribeSnapshots_ByID tests listing specific snapshots by ID.
@@ -310,22 +336,21 @@ func TestDescribeSnapshots_Empty(t *testing.T) {
 }
 
 // TestDescribeSnapshots_ImportedAMISnapshotVisible locks that a snapshot
-// registered directly via WriteSnapshotConfig -- the way a provider-backed
-// AMI import registers its snapshot, without ever calling CreateSnapshot --
-// is still listed. Before that registration exists, ListObjectsV2 finds the
-// provider-written "snap-.../" prefix but getSnapshotConfig 404s on it, and
-// DescribeSnapshots silently skips it.
+// whose document is written directly -- the way a provider-backed AMI import
+// registers its snapshot, without ever calling CreateSnapshot -- is still
+// listed. Without that document the snapshot is not in the account's prefix
+// and DescribeSnapshots cannot see it at all.
 func TestDescribeSnapshots_ImportedAMISnapshotVisible(t *testing.T) {
 	svc, store := setupTestSnapshotService(t)
 
-	require.NoError(t, WriteSnapshotConfig(store, "test-bucket", "snap-ami-import01", &SnapshotConfig{
+	seedSnapshotDocument(t, store, ebsmetadata.Snapshot{
 		SnapshotID: "snap-ami-import01",
 		VolumeID:   "ami-import01",
 		VolumeSize: 8,
 		State:      "completed",
 		Progress:   "100%",
 		OwnerID:    testAccountID,
-	}))
+	})
 
 	result, err := svc.DescribeSnapshots(context.Background(), &ec2.DescribeSnapshotsInput{}, testAccountID)
 	require.NoError(t, err)
@@ -339,6 +364,7 @@ func TestDescribeSnapshots_AccountScoping(t *testing.T) {
 	svc, store := setupTestSnapshotService(t)
 
 	createTestVolume(t, svc, store, "vol-1", 50)
+	createTestVolumeForAccount(t, svc, store, "vol-2", 50, otherAccountID)
 
 	// Account A creates a snapshot
 	snapA, err := svc.CreateSnapshot(context.Background(), &ec2.CreateSnapshotInput{
@@ -346,9 +372,9 @@ func TestDescribeSnapshots_AccountScoping(t *testing.T) {
 	}, testAccountID)
 	require.NoError(t, err)
 
-	// Account B creates a snapshot
+	// Account B creates a snapshot of its own volume
 	snapB, err := svc.CreateSnapshot(context.Background(), &ec2.CreateSnapshotInput{
-		VolumeId: aws.String("vol-1"),
+		VolumeId: aws.String("vol-2"),
 	}, otherAccountID)
 	require.NoError(t, err)
 
@@ -403,7 +429,9 @@ func TestDeleteSnapshot(t *testing.T) {
 	assert.Empty(t, result.Snapshots)
 }
 
-// TestDeleteSnapshot_WrongAccount tests that account B cannot delete account A's snapshot.
+// TestDeleteSnapshot_WrongAccount tests that account B cannot delete account
+// A's snapshot. It is not found rather than refused: the caller's prefix is
+// the read, so the endpoint never confirms another account's snapshot IDs.
 func TestDeleteSnapshot_WrongAccount(t *testing.T) {
 	svc, store := setupTestSnapshotService(t)
 
@@ -418,7 +446,7 @@ func TestDeleteSnapshot_WrongAccount(t *testing.T) {
 		SnapshotId: snap.SnapshotId,
 	}, otherAccountID)
 	require.Error(t, err)
-	assert.Contains(t, err.Error(), awserrors.ErrorUnauthorizedOperation)
+	assert.Contains(t, err.Error(), awserrors.ErrorInvalidSnapshotNotFound)
 
 	// Verify snapshot still exists
 	result, err := svc.DescribeSnapshots(context.Background(), &ec2.DescribeSnapshotsInput{
@@ -524,12 +552,13 @@ func TestCopySnapshot_WrongAccount(t *testing.T) {
 	require.NoError(t, err)
 	require.Len(t, result.Snapshots, 1)
 
-	// Account B tries to copy account A's snapshot — should fail
+	// Account B tries to copy account A's snapshot — not found, not refused:
+	// the source is read under the caller's own prefix.
 	_, err = svc.CopySnapshot(context.Background(), &ec2.CopySnapshotInput{
 		SourceSnapshotId: result.Snapshots[0].SnapshotId,
 	}, otherAccountID)
 	require.Error(t, err)
-	assert.Contains(t, err.Error(), awserrors.ErrorUnauthorizedOperation)
+	assert.Contains(t, err.Error(), awserrors.ErrorInvalidSnapshotNotFound)
 }
 
 // TestCopySnapshot_NotFound tests copying a non-existent snapshot.
@@ -750,20 +779,15 @@ func TestCreateSnapshot_CrossAccountVolumeRejected(t *testing.T) {
 	assert.Equal(t, testAccountID, *result.OwnerId)
 }
 
-// TestCreateSnapshot_PrePhase4VolumeAllowed tests that volumes without TenantID (pre-phase4) are allowed.
-func TestCreateSnapshot_PrePhase4VolumeAllowed(t *testing.T) {
-	svc, store := setupTestSnapshotService(t)
+// A volume with no owning account cannot be keyed, so the untenanted volume
+// any caller used to be able to snapshot is not a state the store can hold.
+func TestCreateSnapshot_UntenantedVolumeIsUnwritable(t *testing.T) {
+	_, store := setupTestSnapshotService(t)
 
-	// Create a volume with no TenantID (pre-phase4)
-	volumeID := "vol-legacy"
-	createTestVolume(t, svc, store, volumeID, 50)
-
-	// Any account can snapshot — backward compatibility
-	result, err := svc.CreateSnapshot(context.Background(), &ec2.CreateSnapshotInput{
-		VolumeId: aws.String(volumeID),
-	}, otherAccountID)
-	require.NoError(t, err)
-	assert.Equal(t, otherAccountID, *result.OwnerId)
+	err := ebsmetadata.NewStore(store, "test-bucket").PutVolume(context.Background(), ebsmetadata.Volume{
+		VolumeID: "vol-untenanted", CapacityGiB: 50, AvailabilityZone: "us-east-1a",
+	})
+	require.Error(t, err)
 }
 
 // --- DescribeSnapshots filter tests ---
@@ -998,7 +1022,7 @@ func TestCreateDeleteSnapshot_UsesInjectedProvider(t *testing.T) {
 	snapshot, err := svc.CreateSnapshot(context.Background(), &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-provider")}, testAccountID)
 	require.NoError(t, err)
 	require.NotNil(t, snapshot)
-	cfgStored, err := svc.getSnapshotConfig(context.Background(), aws.StringValue(snapshot.SnapshotId))
+	cfgStored, err := svc.getSnapshotConfig(context.Background(), testAccountID, aws.StringValue(snapshot.SnapshotId))
 	require.NoError(t, err)
 	assert.Equal(t, "memory://snapshot/"+aws.StringValue(snapshot.SnapshotId), cfgStored.ProviderHandle)
 	_, err = svc.DeleteSnapshot(context.Background(), &ec2.DeleteSnapshotInput{SnapshotId: snapshot.SnapshotId}, testAccountID)
@@ -1041,23 +1065,28 @@ func TestDeleteSnapshot_Provider_BlockedByCloneRecordedInMetadata(t *testing.T)
 	assert.EqualError(t, err, awserrors.ErrorInvalidSnapshotInUse)
 
 	// Once the clone is gone the snapshot is deletable again.
-	require.NoError(t, svc.metadata.DeleteVolume(ctx, "vol-clone"))
+	require.NoError(t, svc.metadata.DeleteVolume(ctx, testAccountID, "vol-clone"))
 	_, err = svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: aws.String(snapshotID)}, testAccountID)
 	require.NoError(t, err)
 }
 
-// snapshotMetadataFailingObjectStore fails PutObject for any snapshot
-// metadata.json write and records the last such key, so a test can recover
-// the randomly generated snapshot ID CreateSnapshot attempted to persist.
+// snapshotMetadataFailingObjectStore fails PutObject for any snapshot document
+// write and records the last such key, so a test can recover the randomly
+// generated snapshot ID CreateSnapshot attempted to persist.
 type snapshotMetadataFailingObjectStore struct {
 	objectstore.ObjectStore
 
 	attemptedKey string
 }
 
+// snapshotDocumentPrefix is where the store keys snapshot documents. Spelled
+// out here so the fake matches only those writes, not the volume document
+// CreateSnapshot reads through on the way.
+const snapshotDocumentPrefix = "spinifex/ebsmetadata/v2/snapshots/"
+
 func (s *snapshotMetadataFailingObjectStore) PutObject(ctx context.Context, input *s3.PutObjectInput) (*s3.PutObjectOutput, error) {
 	key := aws.StringValue(input.Key)
-	if strings.HasSuffix(key, "/metadata.json") {
+	if strings.HasPrefix(key, snapshotDocumentPrefix) {
 		s.attemptedKey = key
 		return nil, errors.New("simulated metadata write failure")
 	}
@@ -1089,7 +1118,7 @@ func TestCreateSnapshot_Provider_RollbackOnMetadataWriteFailure(t *testing.T) {
 	require.EqualError(t, err, awserrors.ErrorServerInternal)
 	require.NotEmpty(t, store.attemptedKey, "the snapshot metadata write must have been attempted")
 
-	snapshotID := strings.TrimSuffix(store.attemptedKey, "/metadata.json")
+	snapshotID := strings.TrimSuffix(path.Base(store.attemptedKey), ".json")
 	_, err = provider.GetVolume(context.Background(), ebsprovider.GetVolumeRequest{Versioned: ebsprovider.NewVersioned(), VolumeID: "vol-rollback"})
 	require.NoError(t, err, "the source volume must be unaffected by the snapshot rollback")
 
@@ -1152,7 +1181,7 @@ func TestCopySnapshot_Provider_CreatesBackendSnapshot(t *testing.T) {
 	require.True(t, ok, "the copy must exist in the provider, not only in the control plane")
 	assert.Equal(t, "vol-copysrc", got.SourceVolumeID)
 
-	stored, err := svc.getSnapshotConfig(context.Background(), newID)
+	stored, err := svc.getSnapshotConfig(context.Background(), testAccountID, newID)
 	require.NoError(t, err)
 	assert.Equal(t, "vol-copysrc", stored.VolumeID)
 	assert.Equal(t, "copied", stored.Description)
@@ -1194,7 +1223,7 @@ func TestCopySnapshot_Provider_InheritsSourceDescription(t *testing.T) {
 
 	out, err := svc.CopySnapshot(ctx, &ec2.CopySnapshotInput{SourceSnapshotId: src.SnapshotId}, testAccountID)
 	require.NoError(t, err)
-	stored, err := svc.getSnapshotConfig(context.Background(), aws.StringValue(out.SnapshotId))
+	stored, err := svc.getSnapshotConfig(context.Background(), testAccountID, aws.StringValue(out.SnapshotId))
 	require.NoError(t, err)
 	assert.Equal(t, "original text", stored.Description)
 }
@@ -1229,7 +1258,7 @@ func TestCopySnapshot_Provider_ForeignSnapshotRefused(t *testing.T) {
 
 	_, err = svc.CopySnapshot(ctx, &ec2.CopySnapshotInput{SourceSnapshotId: src.SnapshotId}, "999988887777")
 	require.Error(t, err)
-	assert.Equal(t, awserrors.ErrorUnauthorizedOperation, err.Error())
+	assert.Equal(t, awserrors.ErrorInvalidSnapshotNotFound, err.Error())
 
 	_, ok := provider.Snapshot(aws.StringValue(src.SnapshotId))
 	require.True(t, ok, "the source must survive a refused copy")
diff --git a/spinifex/handlers/ec2/snapshot/snapshot_partition_test.go b/spinifex/handlers/ec2/snapshot/snapshot_partition_test.go
new file mode 100644
index 000000000..6985ca729
--- /dev/null
+++ b/spinifex/handlers/ec2/snapshot/snapshot_partition_test.go
@@ -0,0 +1,345 @@
+// These tests reach svc.metadata and reuse setupTestSnapshotService and
+// createTestVolume, all package-internal.
+//
+//test:in-package
+package handlers_ec2_snapshot
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/mulgadc/spinifex/spinifex/awserrors"
+	"github.com/mulgadc/spinifex/spinifex/config"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
+	"github.com/mulgadc/spinifex/spinifex/ebsprovider"
+	"github.com/mulgadc/spinifex/spinifex/objectstore"
+	"github.com/mulgadc/spinifex/spinifex/testutil/recordingstore"
+	"github.com/mulgadc/spinifex/spinifex/utils"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// The document no longer lives inside the prefix DeleteSnapshot sweeps, so it
+// has to be deleted explicitly. Miss that and DescribeSnapshots keeps returning
+// a snapshot whose chunks are gone.
+func TestDeleteSnapshot_LeavesNoDocument(t *testing.T) {
+	ctx := context.Background()
+	svc, store := setupTestSnapshotService(t)
+	createTestVolume(t, svc, store, "vol-del", 8)
+
+	snap, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-del")}, testAccountID)
+	require.NoError(t, err)
+
+	_, err = svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: snap.SnapshotId}, testAccountID)
+	require.NoError(t, err)
+
+	listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{}, testAccountID)
+	require.NoError(t, err)
+	assert.Empty(t, listed.Snapshots, "a deleted snapshot must leave no document behind")
+
+	_, err = svc.metadata.GetSnapshot(ctx, testAccountID, aws.StringValue(snap.SnapshotId))
+	require.Error(t, err)
+}
+
+// The system account partitions like any tenant: GlobalAccountID is a valid
+// account ID, so nothing on this path needs a special case. This fails if
+// IsAccountID is ever tightened in a way that rejects "000000000000".
+func TestSnapshot_SystemAccountIsAnOrdinaryAccount(t *testing.T) {
+	ctx := context.Background()
+	svc, store := setupTestSnapshotService(t)
+	createTestVolumeForAccount(t, svc, store, "vol-sys", 8, utils.GlobalAccountID)
+
+	snap, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-sys")}, utils.GlobalAccountID)
+	require.NoError(t, err)
+
+	listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{}, utils.GlobalAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.Snapshots, 1)
+	assert.Equal(t, aws.StringValue(snap.SnapshotId), aws.StringValue(listed.Snapshots[0].SnapshotId))
+
+	_, err = svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: snap.SnapshotId}, utils.GlobalAccountID)
+	require.NoError(t, err)
+}
+
+// A caller with no account cannot name a prefix, so the listing fails rather
+// than widening to every account's snapshots. The strict form reports the
+// underlying failure; the tolerant one maps it to an internal error.
+func TestDescribeSnapshots_RefusesACallerWithNoAccount(t *testing.T) {
+	ctx := context.Background()
+	svc, _ := setupTestSnapshotService(t)
+
+	_, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{}, "")
+	require.Error(t, err)
+
+	_, err = svc.DescribeSnapshotsStrict(ctx, &ec2.DescribeSnapshotsInput{}, "")
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "invalid EBS metadata account ID")
+}
+
+// A document that survives the delete leaves DescribeSnapshots returning a
+// snapshot whose chunks are gone, so the failure must surface rather than be
+// logged and swallowed.
+func TestDeleteSnapshot_DocumentDeleteFailureSurfaces(t *testing.T) {
+	ctx := context.Background()
+	objects := &deleteFailingStore{MemoryObjectStore: objectstore.NewMemoryObjectStore(),
+		failPrefix: "spinifex/ebsmetadata/v2/snapshots/"}
+	cfg := &config.Config{Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
+	svc := NewSnapshotServiceImplWithStore(cfg, objects, nil)
+	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
+	createTestVolume(t, svc, objects.MemoryObjectStore, "vol-delfail", 8)
+
+	snap, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-delfail")}, testAccountID)
+	require.NoError(t, err)
+
+	_, err = svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: snap.SnapshotId}, testAccountID)
+	require.Error(t, err)
+	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
+}
+
+// A chunk the sweep could not delete has to keep the document alive. The
+// listing no longer enumerates snap- prefixes, so deleting the document over
+// surviving chunks strands them where no API can see or reclaim them, and the
+// delete cannot be retried to finish.
+func TestDeleteSnapshot_ChunkSweepFailureRetainsDocument(t *testing.T) {
+	ctx := context.Background()
+	objects := &deleteFailingStore{MemoryObjectStore: objectstore.NewMemoryObjectStore()}
+	cfg := &config.Config{Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
+	svc := NewSnapshotServiceImplWithStore(cfg, objects, nil)
+	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
+	createTestVolume(t, svc, objects.MemoryObjectStore, "vol-sweepfail", 8)
+
+	snap, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-sweepfail")}, testAccountID)
+	require.NoError(t, err)
+	snapshotID := aws.StringValue(snap.SnapshotId)
+
+	// A block chunk under the swept prefix, which is viperblock's half of the
+	// snapshot and the thing the document must not outlive.
+	_, err = objects.PutObject(ctx, &s3.PutObjectInput{
+		Bucket: aws.String("test-bucket"), Key: aws.String(snapshotID + "/chunk-0"),
+		Body: strings.NewReader("blocks"),
+	})
+	require.NoError(t, err)
+	objects.failPrefix = snapshotID + "/"
+
+	_, err = svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: snap.SnapshotId}, testAccountID)
+	require.Error(t, err)
+	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
+
+	_, err = svc.metadata.GetSnapshot(ctx, testAccountID, snapshotID)
+	require.NoError(t, err, "an incomplete sweep must leave the document so the delete can be retried")
+
+	listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{}, testAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.Snapshots, 1, "the snapshot must stay visible while its chunks survive")
+	assert.Equal(t, snapshotID, aws.StringValue(listed.Snapshots[0].SnapshotId))
+}
+
+// deleteFailingStore fails DeleteObject for keys under failPrefix, leaving
+// every other operation intact. failPrefix is settable after construction so a
+// test can target a generated snapshot ID.
+type deleteFailingStore struct {
+	*objectstore.MemoryObjectStore
+
+	failPrefix string
+}
+
+func (s *deleteFailingStore) DeleteObject(ctx context.Context, input *s3.DeleteObjectInput) (*s3.DeleteObjectOutput, error) {
+	if strings.HasPrefix(aws.StringValue(input.Key), s.failPrefix) {
+		return nil, errors.New("simulated document delete failure")
+	}
+	return s.MemoryObjectStore.DeleteObject(ctx, input)
+}
+
+// Isolation must be enforced *by* the read, not by a filter after it. A
+// whole-tree listing plus a correct in-memory filter would return the same
+// snapshots, so this asserts the access pattern: the listing prefix is the
+// caller's own, and no key under another account's prefix is fetched.
+func TestDescribeSnapshots_TouchesNoOtherAccountsPrefix(t *testing.T) {
+	ctx := context.Background()
+	objects := recordingstore.New()
+	cfg := &config.Config{Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
+	svc := NewSnapshotServiceImplWithStore(cfg, objects, nil)
+	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
+
+	for _, snapshot := range []ebsmetadata.Snapshot{
+		{SnapshotID: "snap-mine1", VolumeID: "vol-1", OwnerID: testAccountID, State: "completed"},
+		{SnapshotID: "snap-theirs1", VolumeID: "vol-2", OwnerID: otherAccountID, State: "completed"},
+	} {
+		require.NoError(t, svc.metadata.PutSnapshot(ctx, snapshot))
+	}
+
+	objects.Reset()
+	listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{}, testAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.Snapshots, 1)
+	assert.Equal(t, "snap-mine1", aws.StringValue(listed.Snapshots[0].SnapshotId))
+
+	// Spelled out rather than derived: this is the layout claim itself.
+	assert.False(t, objects.TouchedPrefix("spinifex/ebsmetadata/v2/snapshots/"+otherAccountID+"/"),
+		"a describe must not read or list another account's prefix: %v %v", objects.ListPrefixes(), objects.Gets())
+}
+
+// OwnerIds used to be read by nobody: the account-teardown reaper set it and
+// the describe ignored it, so the parameter promised a scoping it never
+// applied. Under the account prefix the answer is structural.
+func TestDescribeSnapshots_HonoursOwnerIds(t *testing.T) {
+	ctx := context.Background()
+	svc, store := setupTestSnapshotService(t)
+	createTestVolume(t, svc, store, "vol-owner", 8)
+
+	snap, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-owner")}, testAccountID)
+	require.NoError(t, err)
+
+	for _, tc := range []struct {
+		name     string
+		ownerIDs []*string
+		want     int
+	}{
+		{name: "unset", want: 1},
+		{name: "self", ownerIDs: []*string{aws.String("self")}, want: 1},
+		{name: "own account ID", ownerIDs: []*string{aws.String(testAccountID)}, want: 1},
+		{name: "another account", ownerIDs: []*string{aws.String(otherAccountID)}},
+		{name: "another account and self", ownerIDs: []*string{aws.String(otherAccountID), aws.String("self")}, want: 1},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{OwnerIds: tc.ownerIDs}, testAccountID)
+			require.NoError(t, err)
+			require.Len(t, listed.Snapshots, tc.want)
+			if tc.want > 0 {
+				assert.Equal(t, aws.StringValue(snap.SnapshotId), aws.StringValue(listed.Snapshots[0].SnapshotId))
+			}
+		})
+	}
+
+	// Naming an id the owner filter excludes is the same answer as naming one
+	// that does not exist.
+	_, err = svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{
+		SnapshotIds: []*string{snap.SnapshotId},
+		OwnerIds:    []*string{aws.String(otherAccountID)},
+	}, testAccountID)
+	require.Error(t, err)
+	assert.Equal(t, awserrors.ErrorInvalidSnapshotNotFound, err.Error())
+}
+
+// An account the caller's prefix cannot contain is answered without a read at
+// all, rather than by listing and filtering afterwards.
+func TestDescribeSnapshots_ForeignOwnerIDReadsNothing(t *testing.T) {
+	ctx := context.Background()
+	objects := recordingstore.New()
+	cfg := &config.Config{Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
+	svc := NewSnapshotServiceImplWithStore(cfg, objects, nil)
+	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
+
+	require.NoError(t, svc.metadata.PutSnapshot(ctx,
+		ebsmetadata.Snapshot{SnapshotID: "snap-mine", VolumeID: "vol-1", OwnerID: testAccountID, State: "completed"}))
+
+	objects.Reset()
+	listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{
+		OwnerIds: []*string{aws.String(otherAccountID)},
+	}, testAccountID)
+	require.NoError(t, err)
+	assert.Empty(t, listed.Snapshots)
+
+	assert.Empty(t, objects.ListPrefixes(), "an owner the prefix cannot contain needs no listing")
+	assert.Empty(t, objects.Gets(), "an owner the prefix cannot contain needs no read")
+}
+
+// The dependency check must stay whole-cluster. Launching from a system AMI
+// writes a root volume owned by the launching tenant whose SnapshotID is the
+// system snapshot, so a clone routinely lives outside the snapshot owner's
+// prefix. Scope the check and the delete strips chunks a live tenant volume
+// still reads.
+func TestDeleteSnapshot_BlockedByACloneInAnotherAccount(t *testing.T) {
+	ctx := context.Background()
+	svc, store := setupTestSnapshotService(t)
+	createTestVolumeForAccount(t, svc, store, "vol-system", 8, utils.GlobalAccountID)
+
+	snap, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-system")}, utils.GlobalAccountID)
+	require.NoError(t, err)
+
+	seedVolumeDocument(t, store, ebsmetadata.Volume{
+		VolumeID:   "vol-tenant-root",
+		TenantID:   otherAccountID,
+		SnapshotID: aws.StringValue(snap.SnapshotId),
+	})
+
+	_, err = svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: snap.SnapshotId}, utils.GlobalAccountID)
+	require.Error(t, err)
+	assert.Equal(t, awserrors.ErrorInvalidSnapshotInUse, err.Error())
+}
+
+// The irreversible case. The teardown reaper lists with OwnerIds set to the
+// account being removed and deletes everything it gets back, so a listing that
+// reached past that account once destroyed every other account's snapshots.
+// This walks the reaper's exact shape rather than asserting the input again.
+func TestAccountTeardown_LeavesAnotherAccountsSnapshotsAlone(t *testing.T) {
+	ctx := context.Background()
+	svc, store := setupTestSnapshotService(t)
+	createTestVolumeForAccount(t, svc, store, "vol-doomed", 8, testAccountID)
+	createTestVolumeForAccount(t, svc, store, "vol-bystander", 8, otherAccountID)
+
+	doomed, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-doomed")}, testAccountID)
+	require.NoError(t, err)
+	bystander, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-bystander")}, otherAccountID)
+	require.NoError(t, err)
+
+	listed, err := svc.DescribeSnapshots(ctx, &ec2.DescribeSnapshotsInput{
+		OwnerIds: []*string{aws.String(testAccountID)},
+	}, testAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.Snapshots, 1)
+	assert.Equal(t, aws.StringValue(doomed.SnapshotId), aws.StringValue(listed.Snapshots[0].SnapshotId))
+
+	for _, snapshot := range listed.Snapshots {
+		_, err := svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: snapshot.SnapshotId}, testAccountID)
+		require.NoError(t, err)
+	}
+
+	survived, err := svc.metadata.GetSnapshot(ctx, otherAccountID, aws.StringValue(bystander.SnapshotId))
+	require.NoError(t, err, "tearing down one account must not delete another account's snapshot")
+	assert.Equal(t, otherAccountID, survived.OwnerID)
+}
+
+// An untenanted caller is refused at the boundary, with the client-facing
+// answer the boundary owns. Asserting that nothing was read is what stops the
+// guard being deleted later as redundant with the key builder, whose rejection
+// is an internal error rather than an AuthFailure.
+func TestSnapshot_EmptyCallerAccountIsRefusedAtTheBoundary(t *testing.T) {
+	ctx := context.Background()
+	objects := recordingstore.New()
+	cfg := &config.Config{Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
+	svc := NewSnapshotServiceImplWithStore(cfg, objects, nil)
+	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
+
+	for _, tc := range []struct {
+		name string
+		call func() error
+	}{
+		{name: "CreateSnapshot", call: func() error {
+			_, err := svc.CreateSnapshot(ctx, &ec2.CreateSnapshotInput{VolumeId: aws.String("vol-1")}, "")
+			return err
+		}},
+		{name: "DeleteSnapshot", call: func() error {
+			_, err := svc.DeleteSnapshot(ctx, &ec2.DeleteSnapshotInput{SnapshotId: aws.String("snap-1")}, "")
+			return err
+		}},
+		{name: "CopySnapshot", call: func() error {
+			_, err := svc.CopySnapshot(ctx, &ec2.CopySnapshotInput{SourceSnapshotId: aws.String("snap-1")}, "")
+			return err
+		}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			objects.Reset()
+			err := tc.call()
+			require.Error(t, err)
+			assert.Equal(t, awserrors.ErrorAuthFailure, err.Error())
+			assert.Empty(t, objects.Gets(), "the guard must fire before any read")
+			assert.Empty(t, objects.ListPrefixes(), "the guard must fire before any listing")
+		})
+	}
+}
diff --git a/spinifex/handlers/ec2/volume/config_route_invariants_test.go b/spinifex/handlers/ec2/volume/config_route_invariants_test.go
index 9da0a880a..6fd052674 100644
--- a/spinifex/handlers/ec2/volume/config_route_invariants_test.go
+++ b/spinifex/handlers/ec2/volume/config_route_invariants_test.go
@@ -26,13 +26,13 @@ func TestUpdateVolumeState_WritesDocumentNotConfig(t *testing.T) {
 	})
 	before := getStoredConfig(t, store, volumeID)
 
-	require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", "i-abc", "/dev/nbd0"))
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, volumeID, "in-use", "i-abc", "/dev/nbd0"))
 
 	after := getStoredConfig(t, store, volumeID)
 	assert.Equal(t, string(before), string(after),
 		"UpdateVolumeState must not write config.json; the live VB owns it")
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", meta.State)
 	assert.Equal(t, "i-abc", meta.AttachedInstance)
@@ -55,13 +55,13 @@ func TestUpdateVolumeState_EncryptedConfigUntouched(t *testing.T) {
 	})
 	before := getStoredConfig(t, store, volumeID)
 
-	require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", "i-enc", "/dev/nbd0"))
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, volumeID, "in-use", "i-enc", "/dev/nbd0"))
 
 	after := getStoredConfig(t, store, volumeID)
 	assert.Equal(t, string(before), string(after),
 		"UpdateVolumeState must not rewrite the sealed config.json (AES-GCM nonce reuse)")
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", meta.State)
 }
@@ -82,7 +82,7 @@ func TestGetVolumeMetadata_DocumentBeatsConfig(t *testing.T) {
 		State: "in-use", AttachedInstance: "i-overlay", DeviceName: "/dev/nbd0",
 	})
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", meta.State,
 		"the ebsmetadata document must override any State in config.json")
@@ -101,7 +101,7 @@ func TestGetVolumeMetadata_ConfigAloneIsNotAVolume(t *testing.T) {
 	volumeID := "vol-config-only"
 	seedProviderConfig(t, store, volumeID)
 
-	_, err := svc.GetVolumeMetadata(volumeID)
+	_, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.Error(t, err)
 	assert.Contains(t, err.Error(), "InvalidVolume.NotFound")
 }
diff --git a/spinifex/handlers/ec2/volume/describe_volumes_provider_bench_test.go b/spinifex/handlers/ec2/volume/describe_volumes_provider_bench_test.go
index d1eaddce5..6444cc1d7 100644
--- a/spinifex/handlers/ec2/volume/describe_volumes_provider_bench_test.go
+++ b/spinifex/handlers/ec2/volume/describe_volumes_provider_bench_test.go
@@ -50,14 +50,14 @@ func BenchmarkDescribeVolumes_Provider_SingleID(b *testing.B) {
 		b.Run(fmt.Sprintf("volumes=%d", n), func(b *testing.B) {
 			svc := newTestVolumeService("ap-southeast-2a")
 			svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
-			targetID := seedProviderVolumes(b, svc, n, "acct-bench")
+			targetID := seedProviderVolumes(b, svc, n, "000000000013")
 			ctx := context.Background()
 			input := &ec2.DescribeVolumesInput{VolumeIds: []*string{aws.String(targetID)}}
 
 			defer silenceLogs(b)()
 			b.ResetTimer()
 			for i := 0; i < b.N; i++ {
-				if _, err := svc.DescribeVolumes(ctx, input, "acct-bench"); err != nil {
+				if _, err := svc.DescribeVolumes(ctx, input, "000000000013"); err != nil {
 					b.Fatalf("DescribeVolumes: %v", err)
 				}
 			}
@@ -75,19 +75,19 @@ func BenchmarkDescribeVolumes_Provider_ListAndFilter(b *testing.B) {
 		b.Run(fmt.Sprintf("volumes=%d", n), func(b *testing.B) {
 			svc := newTestVolumeService("ap-southeast-2a")
 			svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
-			targetID := seedProviderVolumes(b, svc, n, "acct-bench")
+			targetID := seedProviderVolumes(b, svc, n, "000000000013")
 			ctx := context.Background()
 
 			defer silenceLogs(b)()
 			b.ResetTimer()
 			for i := 0; i < b.N; i++ {
-				metadata, err := svc.metadata.ListVolumes(ctx)
+				metadata, err := svc.metadata.ListAllVolumes(ctx)
 				if err != nil {
-					b.Fatalf("ListVolumes: %v", err)
+					b.Fatalf("ListAllVolumes: %v", err)
 				}
 				var found *ec2.Volume
 				for _, meta := range metadata {
-					if meta.TenantID != "acct-bench" || meta.VolumeID != targetID {
+					if meta.TenantID != "000000000013" || meta.VolumeID != targetID {
 						continue
 					}
 					found = metadataVolumeToEC2(meta)
diff --git a/spinifex/handlers/ec2/volume/describe_volumes_provider_fastpath_test.go b/spinifex/handlers/ec2/volume/describe_volumes_provider_fastpath_test.go
index 59cf64c54..7137672fc 100644
--- a/spinifex/handlers/ec2/volume/describe_volumes_provider_fastpath_test.go
+++ b/spinifex/handlers/ec2/volume/describe_volumes_provider_fastpath_test.go
@@ -21,10 +21,10 @@ func TestDescribeVolumes_Provider_FastPath_SingleID(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000001")
 	require.NoError(t, err)
 
-	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "000000000001")
 	require.NoError(t, err)
 	require.Len(t, out.Volumes, 1)
 	assert.Equal(t, aws.StringValue(vol.VolumeId), aws.StringValue(out.Volumes[0].VolumeId))
@@ -40,10 +40,10 @@ func TestDescribeVolumes_Provider_FastPath_CrossTenantIsNotFound(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	otherTenantVol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-2")
+	otherTenantVol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000002")
 	require.NoError(t, err)
 
-	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{otherTenantVol.VolumeId}}, "acct-1")
+	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{otherTenantVol.VolumeId}}, "000000000001")
 	require.Error(t, err)
 	assert.EqualError(t, err, awserrors.ErrorInvalidVolumeNotFound)
 	assert.Nil(t, out)
@@ -56,7 +56,7 @@ func TestDescribeVolumes_Provider_FastPath_UnknownIDIsNotFound(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{aws.String("vol-doesnotexist0")}}, "acct-1")
+	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{aws.String("vol-doesnotexist0")}}, "000000000001")
 	require.Error(t, err)
 	assert.EqualError(t, err, awserrors.ErrorInvalidVolumeNotFound)
 	assert.Nil(t, out)
@@ -70,14 +70,14 @@ func TestDescribeVolumes_Provider_FastPath_FiltersApply(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000001")
 	require.NoError(t, err)
 
 	t.Run("matching filter keeps the volume", func(t *testing.T) {
 		out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{
 			VolumeIds: []*string{vol.VolumeId},
 			Filters:   []*ec2.Filter{{Name: aws.String("size"), Values: []*string{aws.String("8")}}},
-		}, "acct-1")
+		}, "000000000001")
 		require.NoError(t, err)
 		require.Len(t, out.Volumes, 1)
 	})
@@ -86,7 +86,7 @@ func TestDescribeVolumes_Provider_FastPath_FiltersApply(t *testing.T) {
 		out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{
 			VolumeIds: []*string{vol.VolumeId},
 			Filters:   []*ec2.Filter{{Name: aws.String("size"), Values: []*string{aws.String("16")}}},
-		}, "acct-1")
+		}, "000000000001")
 		require.NoError(t, err)
 		assert.Empty(t, out.Volumes)
 	})
@@ -99,12 +99,12 @@ func TestDescribeVolumes_Provider_FastPath_MultipleIDs(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	volA, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	volA, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000001")
 	require.NoError(t, err)
-	volB, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(16), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	volB, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(16), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000001")
 	require.NoError(t, err)
 
-	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{volA.VolumeId, volB.VolumeId}}, "acct-1")
+	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{volA.VolumeId, volB.VolumeId}}, "000000000001")
 	require.NoError(t, err)
 	require.Len(t, out.Volumes, 2)
 
@@ -123,12 +123,12 @@ func TestDescribeVolumes_Provider_NoIDs_StillEnumerates(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	volA, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	volA, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000001")
 	require.NoError(t, err)
-	_, err = svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(16), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-2")
+	_, err = svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(16), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000002")
 	require.NoError(t, err)
 
-	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{}, "acct-1")
+	out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{}, "000000000001")
 	require.NoError(t, err)
 	require.Len(t, out.Volumes, 1)
 	assert.Equal(t, aws.StringValue(volA.VolumeId), aws.StringValue(out.Volumes[0].VolumeId))
diff --git a/spinifex/handlers/ec2/volume/force_detach_test.go b/spinifex/handlers/ec2/volume/force_detach_test.go
index e9491124f..c4510b5d1 100644
--- a/spinifex/handlers/ec2/volume/force_detach_test.go
+++ b/spinifex/handlers/ec2/volume/force_detach_test.go
@@ -29,7 +29,7 @@ func seedAttachedVolume(t *testing.T, svc *VolumeServiceImpl, volumeID, accountI
 		VolumeID: volumeID, TenantID: accountID, CapacityGiB: 1,
 		State: "available", AvailabilityZone: "ap-southeast-2a", VolumeType: "gp3",
 	}))
-	require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", instanceID, "/dev/sdf"))
+	require.NoError(t, svc.UpdateVolumeState(accountID, volumeID, "in-use", instanceID, "/dev/sdf"))
 }
 
 // This is the escape from the deadlock teardown exists to break: a volume
@@ -37,11 +37,11 @@ func seedAttachedVolume(t *testing.T, svc *VolumeServiceImpl, volumeID, accountI
 // the attachment is cleared without the guest's cooperation.
 func TestForceDetachVolumeClearsTheAttachment(t *testing.T) {
 	svc := newForceDetachService(t)
-	seedAttachedVolume(t, svc, "vol-forcedetach1", "acct-tenant", "i-stuck0000000000")
+	seedAttachedVolume(t, svc, "vol-forcedetach1", "000000000011", "i-stuck0000000000")
 
 	attachment, err := svc.ForceDetachVolume(context.Background(), &ec2.DetachVolumeInput{
 		VolumeId: aws.String("vol-forcedetach1"), Force: aws.Bool(true),
-	}, "acct-tenant")
+	}, "000000000011")
 	require.NoError(t, err)
 
 	// The previous instance is reported back: it is the only record of what
@@ -49,7 +49,7 @@ func TestForceDetachVolumeClearsTheAttachment(t *testing.T) {
 	assert.Equal(t, "i-stuck0000000000", aws.StringValue(attachment.InstanceId))
 	assert.Equal(t, "detached", aws.StringValue(attachment.State))
 
-	meta, err := svc.GetVolumeMetadata("vol-forcedetach1")
+	meta, err := svc.GetVolumeMetadata("000000000011", "vol-forcedetach1")
 	require.NoError(t, err)
 	assert.Equal(t, "available", meta.State)
 	assert.Empty(t, meta.AttachedInstance)
@@ -60,18 +60,18 @@ func TestForceDetachVolumeClearsTheAttachment(t *testing.T) {
 // guard; it may never reach a volume belonging to another tenant.
 func TestForceDetachVolumeRefusesAnotherAccountsVolume(t *testing.T) {
 	svc := newForceDetachService(t)
-	seedAttachedVolume(t, svc, "vol-forcedetach2", "acct-owner", "i-stuck0000000000")
+	seedAttachedVolume(t, svc, "vol-forcedetach2", "000000000014", "i-stuck0000000000")
 
 	_, err := svc.ForceDetachVolume(context.Background(), &ec2.DetachVolumeInput{
 		VolumeId: aws.String("vol-forcedetach2"),
-	}, "acct-intruder")
+	}, "000000000015")
 
 	require.Error(t, err)
 	// The same answer an absent volume gives, so this cannot be used to prove
 	// a volume id exists in someone else's account.
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 
-	meta, err := svc.GetVolumeMetadata("vol-forcedetach2")
+	meta, err := svc.GetVolumeMetadata("000000000014", "vol-forcedetach2")
 	require.NoError(t, err)
 	assert.Equal(t, "i-stuck0000000000", meta.AttachedInstance)
 }
@@ -80,7 +80,7 @@ func TestForceDetachVolumeRejectsBadInput(t *testing.T) {
 	svc := newForceDetachService(t)
 
 	for _, input := range []*ec2.DetachVolumeInput{nil, {}, {VolumeId: aws.String("")}} {
-		_, err := svc.ForceDetachVolume(context.Background(), input, "acct-tenant")
+		_, err := svc.ForceDetachVolume(context.Background(), input, "000000000011")
 		require.Error(t, err)
 		assert.Equal(t, awserrors.ErrorInvalidParameterValue, err.Error())
 	}
@@ -91,7 +91,7 @@ func TestForceDetachVolumeReportsAMissingVolume(t *testing.T) {
 
 	_, err := svc.ForceDetachVolume(context.Background(), &ec2.DetachVolumeInput{
 		VolumeId: aws.String("vol-doesnotexist"),
-	}, "acct-tenant")
+	}, "000000000011")
 
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
@@ -102,13 +102,13 @@ func TestForceDetachVolumeReportsAMissingVolume(t *testing.T) {
 func TestForceDetachVolumeOnAnUnattachedVolume(t *testing.T) {
 	svc := newForceDetachService(t)
 	require.NoError(t, svc.metadata.PutVolume(context.Background(), ebsmetadata.Volume{
-		VolumeID: "vol-forcedetach3", TenantID: "acct-tenant", CapacityGiB: 1,
+		VolumeID: "vol-forcedetach3", TenantID: "000000000011", CapacityGiB: 1,
 		State: "available", AvailabilityZone: "ap-southeast-2a", VolumeType: "gp3",
 	}))
 
 	attachment, err := svc.ForceDetachVolume(context.Background(), &ec2.DetachVolumeInput{
 		VolumeId: aws.String("vol-forcedetach3"),
-	}, "acct-tenant")
+	}, "000000000011")
 	require.NoError(t, err)
 
 	assert.Empty(t, aws.StringValue(attachment.InstanceId))
diff --git a/spinifex/handlers/ec2/volume/get_volume_metadata_provider_test.go b/spinifex/handlers/ec2/volume/get_volume_metadata_provider_test.go
index 92a571b81..c8052ca8e 100644
--- a/spinifex/handlers/ec2/volume/get_volume_metadata_provider_test.go
+++ b/spinifex/handlers/ec2/volume/get_volume_metadata_provider_test.go
@@ -29,7 +29,7 @@ func TestGetVolumeMetadata_Provider_ResolvesProviderCreatedVolume(t *testing.T)
 	volumeID := "vol-provider00001"
 	require.NoError(t, svc.metadata.PutVolume(context.Background(), ebsmetadata.Volume{
 		VolumeID:         volumeID,
-		TenantID:         "acct-provider",
+		TenantID:         "000000000012",
 		CapacityGiB:      8,
 		State:            "available",
 		CreatedAt:        time.Now(),
@@ -39,10 +39,10 @@ func TestGetVolumeMetadata_Provider_ResolvesProviderCreatedVolume(t *testing.T)
 		Encrypted:        true,
 	}))
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata("000000000012", volumeID)
 	require.NoError(t, err, "a provider-created volume must resolve without a legacy config.json")
 	assert.Equal(t, volumeID, meta.VolumeID)
-	assert.Equal(t, "acct-provider", meta.TenantID)
+	assert.Equal(t, "000000000012", meta.TenantID)
 	assert.Equal(t, "available", meta.State)
 	assert.Equal(t, "ap-southeast-2a", meta.AvailabilityZone)
 	assert.Equal(t, uint64(8), meta.CapacityGiB)
@@ -56,13 +56,13 @@ func TestGetVolumeMetadata_Provider_ReflectsAttachmentState(t *testing.T) {
 
 	volumeID := "vol-provider00002"
 	require.NoError(t, svc.metadata.PutVolume(context.Background(), ebsmetadata.Volume{
-		VolumeID: volumeID, TenantID: "acct-provider", CapacityGiB: 1,
+		VolumeID: volumeID, TenantID: "000000000012", CapacityGiB: 1,
 		State: "available", AvailabilityZone: "ap-southeast-2a", VolumeType: "gp3",
 	}))
 
-	require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", "i-0123456789abcdef0", "/dev/sdf"))
+	require.NoError(t, svc.UpdateVolumeState("000000000012", volumeID, "in-use", "i-0123456789abcdef0", "/dev/sdf"))
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata("000000000012", volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", meta.State)
 	assert.Equal(t, "i-0123456789abcdef0", meta.AttachedInstance)
@@ -72,7 +72,7 @@ func TestGetVolumeMetadata_Provider_ReflectsAttachmentState(t *testing.T) {
 func TestGetVolumeMetadata_Provider_UnknownVolumeIsNotFound(t *testing.T) {
 	svc := newProviderVolumeService(t)
 
-	_, err := svc.GetVolumeMetadata("vol-doesnotexist0")
+	_, err := svc.GetVolumeMetadata(testVolAccountID, "vol-doesnotexist0")
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 }
diff --git a/spinifex/handlers/ec2/volume/lifecycle_invariants_test.go b/spinifex/handlers/ec2/volume/lifecycle_invariants_test.go
index 5e612e93a..b868f14cd 100644
--- a/spinifex/handlers/ec2/volume/lifecycle_invariants_test.go
+++ b/spinifex/handlers/ec2/volume/lifecycle_invariants_test.go
@@ -61,7 +61,7 @@ func seedVolume(t *testing.T, svc *VolumeServiceImpl, volID, state, attachedInst
 // metadataKey is the object key the control-plane document for volumeID lives at.
 func metadataKey(t *testing.T, volumeID string) string {
 	t.Helper()
-	key, err := ebsmetadata.VolumeKey(volumeID)
+	key, err := ebsmetadata.VolumeKey(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	return key
 }
@@ -109,7 +109,7 @@ func TestVolumeTagMirror_WritesOnlyControlPlaneDocument(t *testing.T) {
 	seedVolumeDocument(t, memoryStore, ebsmetadata.Volume{
 		VolumeID: volumeID, TenantID: testVolAccountID, CapacityGiB: 10, State: "available",
 	})
-	require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", "i-live0000000000", "/dev/nbd0"))
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, volumeID, "in-use", "i-live0000000000", "/dev/nbd0"))
 	before := getStoredConfig(t, memoryStore, volumeID)
 	store := &recordingObjectStore{ObjectStore: memoryStore}
 	svc.store = store
@@ -191,7 +191,7 @@ func TestRLC5_VolumeGCMarksLeakedVolumeNeverDeletes(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 1, marked, "ADR-0005 §3: the GC must surface exactly the leaked volume")
 
-	leaked, err := svc.GetVolumeMetadata("vol-leaked0000000")
+	leaked, err := svc.GetVolumeMetadata(testVolAccountID, "vol-leaked0000000")
 	require.NoErrorf(t, err, "ADR-0005 §3: the GC must NOT delete the leaked volume — it carries data; it may only mark + alarm")
 	assert.NotEmpty(t, leaked.Tags[orphanTagKey],
 		"ADR-0005 §3: a leaked volume must be marked orphaned")
@@ -200,7 +200,7 @@ func TestRLC5_VolumeGCMarksLeakedVolumeNeverDeletes(t *testing.T) {
 
 	// A volume attached to an instance NOT in the leaked set must be untouched —
 	// node-local detection never false-marks another node's live-instance volume.
-	live, err := svc.GetVolumeMetadata("vol-live000000000")
+	live, err := svc.GetVolumeMetadata(testVolAccountID, "vol-live000000000")
 	require.NoError(t, err)
 	assert.Empty(t, live.Tags[orphanTagKey],
 		"a volume on a live instance must never be marked orphaned")
@@ -209,6 +209,6 @@ func TestRLC5_VolumeGCMarksLeakedVolumeNeverDeletes(t *testing.T) {
 	marked, err = reaper.Sweep(context.Background())
 	require.NoError(t, err)
 	assert.Equal(t, 0, marked, "an already-marked orphan must not be re-marked")
-	_, err = svc.GetVolumeMetadata("vol-leaked0000000")
+	_, err = svc.GetVolumeMetadata(testVolAccountID, "vol-leaked0000000")
 	require.NoError(t, err, "ADR-0005 §3: the volume must still exist after repeated sweeps")
 }
diff --git a/spinifex/handlers/ec2/volume/provider_snapshot_source_test.go b/spinifex/handlers/ec2/volume/provider_snapshot_source_test.go
index 07543f730..31700de33 100644
--- a/spinifex/handlers/ec2/volume/provider_snapshot_source_test.go
+++ b/spinifex/handlers/ec2/volume/provider_snapshot_source_test.go
@@ -2,14 +2,11 @@ package handlers_ec2_volume
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
-	"strings"
 	"testing"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/ec2"
-	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/spinifex/spinifex/config"
 	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
 	"github.com/mulgadc/spinifex/spinifex/ebsprovider"
@@ -52,14 +49,9 @@ func newSnapshotSourceProvider() *snapshotSourceProvider {
 // CreateVolume fails closed on a snapshot whose owner it cannot match.
 func writeSnapshotMetadata(t *testing.T, store objectstore.ObjectStore, snapshotID, sourceVolumeID, ownerID string, sizeGiB int64) {
 	t.Helper()
-	data, err := json.Marshal(snapshotMetadata{VolumeID: sourceVolumeID, VolumeSize: sizeGiB, OwnerID: ownerID})
-	require.NoError(t, err)
-	_, err = store.PutObject(context.Background(), &s3.PutObjectInput{
-		Bucket: aws.String("test-bucket"),
-		Key:    aws.String(snapshotID + "/metadata.json"),
-		Body:   strings.NewReader(string(data)),
-	})
-	require.NoError(t, err)
+	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+		SnapshotID: snapshotID, VolumeID: sourceVolumeID, VolumeSize: sizeGiB, OwnerID: ownerID,
+	}))
 }
 
 // TestCreateVolume_Provider_FromSnapshotSendsSourceVolumeID locks that a
@@ -72,11 +64,11 @@ func TestCreateVolume_Provider_FromSnapshotSendsSourceVolumeID(t *testing.T) {
 	provider := newSnapshotSourceProvider()
 	svc.SetEBSProvider(provider)
 
-	writeSnapshotMetadata(t, store, "snap-src", "vol-origin", "acct-1", 8)
+	writeSnapshotMetadata(t, store, "snap-src", "vol-origin", "000000000001", 8)
 
 	created, err := svc.CreateVolume(context.Background(), &ec2.CreateVolumeInput{
 		Size: aws.Int64(8), AvailabilityZone: aws.String(providerTestAZ), SnapshotId: aws.String("snap-src"),
-	}, "acct-1")
+	}, "000000000001")
 	require.NoError(t, err)
 	require.NotNil(t, created)
 
@@ -96,7 +88,7 @@ func TestCreateVolume_Provider_WithoutSnapshotSendsNoSource(t *testing.T) {
 
 	_, err := svc.CreateVolume(context.Background(), &ec2.CreateVolumeInput{
 		Size: aws.Int64(8), AvailabilityZone: aws.String(providerTestAZ),
-	}, "acct-1")
+	}, "000000000001")
 	require.NoError(t, err)
 
 	assert.Empty(t, provider.lastRequest.SourceSnapshotID)
@@ -150,7 +142,7 @@ func TestDescribeVolumes_Provider_SeesInstanceRootVolume(t *testing.T) {
 		sourceVolumeID: "vol-origin",
 	}, nil, nil, nil)
 
-	instance := &vm.VM{AccountID: "acct-1"}
+	instance := &vm.VM{AccountID: "000000000001"}
 	volumeInfos, err := instanceSvc.GenerateVolumes(context.Background(), &ec2.RunInstancesInput{
 		ImageId: aws.String("ami-1"),
 	}, instance)
@@ -161,7 +153,7 @@ func TestDescribeVolumes_Provider_SeesInstanceRootVolume(t *testing.T) {
 	volumeSvc := NewVolumeServiceImplWithStore(cfg, store, nil)
 	volumeSvc.SetEBSProvider(provider)
 
-	out, err := volumeSvc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "acct-1")
+	out, err := volumeSvc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "000000000001")
 	require.NoError(t, err)
 	require.Len(t, out.Volumes, 1, "the instance root volume must be visible to DescribeVolumes")
 
diff --git a/spinifex/handlers/ec2/volume/record_tags_test.go b/spinifex/handlers/ec2/volume/record_tags_test.go
index e7a66e92f..91676919d 100644
--- a/spinifex/handlers/ec2/volume/record_tags_test.go
+++ b/spinifex/handlers/ec2/volume/record_tags_test.go
@@ -27,7 +27,7 @@ func TestVolumeRecordTagsMirror(t *testing.T) {
 		},
 	}, testVolAccountID))
 
-	meta, err := svc.GetVolumeMetadata("vol-tagmirror0001")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-tagmirror0001")
 	require.NoError(t, err)
 	assert.Equal(t, "yes", meta.Tags["keep"])
 	assert.Equal(t, "v", meta.Tags["drop"])
@@ -41,7 +41,7 @@ func TestVolumeRecordTagsMirror(t *testing.T) {
 		},
 	}, testVolAccountID))
 
-	meta, err = svc.GetVolumeMetadata("vol-tagmirror0001")
+	meta, err = svc.GetVolumeMetadata(testVolAccountID, "vol-tagmirror0001")
 	require.NoError(t, err)
 	assert.Equal(t, "yes", meta.Tags["keep"])
 	_, ok := meta.Tags["drop"]
@@ -94,7 +94,7 @@ func TestApplyRecordTags_SurvivesStaleConfigRewrite(t *testing.T) {
 	})
 	require.NoError(t, err)
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, "retain", meta.Tags["sweep"])
 
@@ -126,7 +126,7 @@ func TestApplyRecordTags_MergesWithExistingTags(t *testing.T) {
 		Tags:      []*ec2.Tag{{Key: aws.String("added-later"), Value: aws.String("yes")}},
 	}, testVolAccountID))
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Equal(t, map[string]string{
 		"created-with": "volume",
@@ -151,7 +151,7 @@ func TestRemoveRecordTags_LastTagLeavesEmptySet(t *testing.T) {
 		Tags:      []*ec2.Tag{{Key: aws.String("legacy"), Value: aws.String("tag")}},
 	}, testVolAccountID))
 
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.Empty(t, meta.Tags, "the deleted tag must not come back from anywhere")
 }
@@ -167,7 +167,7 @@ func TestVolumeRecordTagsMirror_CrossTenantNoMutation(t *testing.T) {
 		Tags:      []*ec2.Tag{{Key: aws.String("evil"), Value: aws.String("1")}},
 	}, "999999999999"))
 
-	meta, err := svc.GetVolumeMetadata("vol-tenantguard01")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-tenantguard01")
 	require.NoError(t, err)
 	assert.Empty(t, meta.Tags)
 }
diff --git a/spinifex/handlers/ec2/volume/service_impl.go b/spinifex/handlers/ec2/volume/service_impl.go
index 818363cef..86e27d69b 100644
--- a/spinifex/handlers/ec2/volume/service_impl.go
+++ b/spinifex/handlers/ec2/volume/service_impl.go
@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io"
 	"log/slog"
 	"strings"
 	"sync"
@@ -15,7 +14,6 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/ec2"
-	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/mulgadc/bluebottle/pkg/safecast"
 	"github.com/mulgadc/spinifex/spinifex/awserrors"
 	"github.com/mulgadc/spinifex/spinifex/config"
@@ -120,6 +118,12 @@ func (s *VolumeServiceImpl) CreateVolume(ctx context.Context, input *ec2.CreateV
 		return nil, errors.New(awserrors.ErrorInvalidParameterValue)
 	}
 
+	// The owning account is a key segment, so an untenanted volume has nowhere
+	// to be written. Refuse at the boundary rather than in the key builder.
+	if accountID == "" {
+		return nil, errors.New(awserrors.ErrorAuthFailure)
+	}
+
 	// Validate volume type: only gp3 supported (or empty defaults to gp3)
 	if input.VolumeType != nil && *input.VolumeType != "" && *input.VolumeType != types.VolumeTypeGP3 {
 		return nil, errors.New(awserrors.ErrorUnknownVolumeType)
@@ -141,19 +145,13 @@ func (s *VolumeServiceImpl) CreateVolume(ctx context.Context, input *ec2.CreateV
 
 	if input.SnapshotId != nil && *input.SnapshotId != "" {
 		snapshotID = *input.SnapshotId
-		snapMeta, err := s.getSnapshotMetadata(ctx, snapshotID)
+		// The ownership check is the key: a snapshot outside the caller's prefix
+		// is not found, so the endpoint never confirms another account's IDs.
+		snapMeta, err := s.metadata.GetSnapshot(ctx, accountID, snapshotID)
 		if err != nil {
 			slog.ErrorContext(ctx, "CreateVolume: snapshot not found", "snapshotId", snapshotID, "err", err)
 			return nil, errors.New(awserrors.ErrorInvalidSnapshotNotFound)
 		}
-		// Not-found rather than access-denied so the endpoint does not confirm
-		// another account's snapshot IDs. An unset owner_id (pre-ownership
-		// snapshot) fails closed.
-		if snapMeta.OwnerID == "" || snapMeta.OwnerID != accountID {
-			slog.WarnContext(ctx, "CreateVolume: account does not own snapshot",
-				"snapshotId", snapshotID, "accountID", accountID, "ownerID", snapMeta.OwnerID)
-			return nil, errors.New(awserrors.ErrorInvalidSnapshotNotFound)
-		}
 		sourceVolumeName = snapMeta.VolumeID
 		snapshotSizeGiB = snapMeta.VolumeSize
 	}
@@ -322,16 +320,14 @@ func (s *VolumeServiceImpl) DescribeVolumes(ctx context.Context, input *ec2.Desc
 		return &ec2.DescribeVolumesOutput{Volumes: volumes}, nil
 	}
 
-	// Slow path: no specific IDs requested, enumerate the bucket.
-	metadata, err := s.metadata.ListVolumes(ctx)
+	// Slow path: no specific IDs requested, list the caller's prefix. No other
+	// account's document is read, so none has to be filtered out here.
+	metadata, err := s.metadata.ListVolumes(ctx, accountID)
 	if err != nil {
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 	volumes := make([]*ec2.Volume, 0, len(metadata))
 	for _, meta := range metadata {
-		if meta.TenantID != accountID {
-			continue
-		}
 		volume := metadataVolumeToEC2(meta)
 		if len(parsedFilters) == 0 || volumeMatchesFilters(volume, parsedFilters) {
 			volumes = append(volumes, volume)
@@ -488,27 +484,19 @@ func volumeStatusMatchesFilters(item *ec2.VolumeStatusItem, filters map[string][
 // static: the control plane has no per-volume health signal to report, so
 // every known volume reports ok.
 func (s *VolumeServiceImpl) describeVolumeStatus(ctx context.Context, input *ec2.DescribeVolumeStatusInput, accountID string, parsedFilters map[string][]string) (*ec2.DescribeVolumeStatusOutput, error) {
-	metas, err := s.metadata.ListVolumes(ctx)
-	if err != nil {
-		return nil, errors.New(awserrors.ErrorServerInternal)
-	}
-	byID := make(map[string]ebsmetadata.Volume, len(metas))
-	for _, meta := range metas {
-		byID[meta.VolumeID] = meta
-	}
-
 	var statusItems []*ec2.VolumeStatusItem
 
+	// Fast path: specific volume IDs requested. Fetch each document directly
+	// rather than listing the prefix to answer for a handful of volumes.
 	if len(input.VolumeIds) > 0 {
-		for _, vid := range input.VolumeIds {
-			if vid == nil {
-				continue
+		for _, r := range s.fetchVolumeMetasByIDs(ctx, input.VolumeIds, accountID) {
+			if r.err != nil {
+				return nil, r.err
 			}
-			meta, ok := byID[*vid]
-			if !ok || meta.TenantID != accountID {
-				return nil, errors.New(awserrors.ErrorInvalidVolumeNotFound)
+			if r.absent {
+				continue // nil VolumeIds entry
 			}
-			item := metadataVolumeStatusItem(meta)
+			item := metadataVolumeStatusItem(r.meta)
 			if len(parsedFilters) > 0 && !volumeStatusMatchesFilters(item, parsedFilters) {
 				continue
 			}
@@ -518,10 +506,11 @@ func (s *VolumeServiceImpl) describeVolumeStatus(ctx context.Context, input *ec2
 		return &ec2.DescribeVolumeStatusOutput{VolumeStatuses: statusItems}, nil
 	}
 
+	metas, err := s.metadata.ListVolumes(ctx, accountID)
+	if err != nil {
+		return nil, errors.New(awserrors.ErrorServerInternal)
+	}
 	for _, meta := range metas {
-		if meta.TenantID != accountID {
-			continue
-		}
 		item := metadataVolumeStatusItem(meta)
 		if len(parsedFilters) > 0 && !volumeStatusMatchesFilters(item, parsedFilters) {
 			continue
@@ -699,7 +688,7 @@ func (s *VolumeServiceImpl) DescribeVolumesModifications(ctx context.Context, in
 		return &ec2.DescribeVolumesModificationsOutput{VolumesModifications: modifications}, nil
 	}
 
-	metas, err := s.metadata.ListVolumes(ctx)
+	metas, err := s.metadata.ListVolumes(ctx, accountID)
 	if err != nil {
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
@@ -710,9 +699,6 @@ func (s *VolumeServiceImpl) DescribeVolumesModifications(ctx context.Context, in
 	}
 
 	for _, meta := range metas {
-		if meta.TenantID != accountID {
-			continue
-		}
 		if len(volumeIDFilterValues) > 0 && !filterutil.MatchesAny(volumeIDFilterValues, meta.VolumeID) {
 			continue
 		}
@@ -751,7 +737,7 @@ func (s *VolumeServiceImpl) fetchVolumeModificationsByIDs(ctx context.Context, v
 		wg.Add(1)
 		go func(idx int, volID string) {
 			defer wg.Done()
-			meta, err := s.metadata.GetVolume(ctx, volID)
+			meta, err := s.metadata.GetVolume(ctx, accountID, volID)
 			if err != nil || meta.TenantID != accountID {
 				results[idx] = volumeModificationResult{err: errors.New(awserrors.ErrorInvalidVolumeNotFound)}
 				return
@@ -764,20 +750,6 @@ func (s *VolumeServiceImpl) fetchVolumeModificationsByIDs(ctx context.Context, v
 	return results
 }
 
-// listAllVolumeIDs lists every volume ID the control plane knows about, taking
-// ebsmetadata as the index.
-func (s *VolumeServiceImpl) listAllVolumeIDs(ctx context.Context) ([]string, error) {
-	volumes, err := s.metadata.ListVolumes(ctx)
-	if err != nil {
-		return nil, errors.New(awserrors.ErrorServerInternal)
-	}
-	ids := make([]string, 0, len(volumes))
-	for _, v := range volumes {
-		ids = append(ids, v.VolumeID)
-	}
-	return ids, nil
-}
-
 // volumeFetchResult bundles a single volume-ID lookup result so the fast path
 // can preserve input ordering and surface per-ID errors after the parallel
 // fan-out, matching fetchVolumeModificationsByIDs.
@@ -787,34 +759,62 @@ type volumeFetchResult struct {
 }
 
 // fetchVolumesByIDs fetches each requested volume's ebsmetadata document
-// directly via GetVolume, instead of enumerating every volume in the bucket
-// via ListVolumes. A missing document or a cross-tenant volume both surface as
-// InvalidVolume.NotFound; any other store error surfaces as ErrorServerInternal.
+// directly via GetVolume, instead of listing the account's prefix.
 func (s *VolumeServiceImpl) fetchVolumesByIDs(ctx context.Context, volumeIDs []*string, accountID string) []volumeFetchResult {
-	results := make([]volumeFetchResult, len(volumeIDs))
+	metas := s.fetchVolumeMetasByIDs(ctx, volumeIDs, accountID)
+	results := make([]volumeFetchResult, len(metas))
+	for i, r := range metas {
+		switch {
+		case r.err != nil:
+			results[i] = volumeFetchResult{err: r.err}
+		case r.absent:
+		default:
+			results[i] = volumeFetchResult{volume: metadataVolumeToEC2(r.meta)}
+		}
+	}
+	return results
+}
+
+// volumeMetaResult bundles a per-ID document lookup. absent marks a nil entry
+// in the requested IDs, which is neither a document nor an error.
+type volumeMetaResult struct {
+	meta   ebsmetadata.Volume
+	absent bool
+	err    error
+}
+
+// fetchVolumeMetasByIDs reads each requested volume's document in parallel,
+// returning results positionally aligned with volumeIDs. A missing document or
+// a cross-tenant volume both surface as InvalidVolume.NotFound; any other store
+// error surfaces as ErrorServerInternal.
+func (s *VolumeServiceImpl) fetchVolumeMetasByIDs(ctx context.Context, volumeIDs []*string, accountID string) []volumeMetaResult {
+	results := make([]volumeMetaResult, len(volumeIDs))
 	var wg sync.WaitGroup
 
 	for i, id := range volumeIDs {
 		if id == nil {
+			results[i] = volumeMetaResult{absent: true}
 			continue
 		}
 		wg.Add(1)
 		go func(idx int, volID string) {
 			defer wg.Done()
-			meta, err := s.metadata.GetVolume(ctx, volID)
+			meta, err := s.metadata.GetVolume(ctx, accountID, volID)
 			if err != nil {
 				if objectstore.IsNoSuchKeyError(err) {
-					results[idx] = volumeFetchResult{err: errors.New(awserrors.ErrorInvalidVolumeNotFound)}
+					results[idx] = volumeMetaResult{err: errors.New(awserrors.ErrorInvalidVolumeNotFound)}
 				} else {
-					results[idx] = volumeFetchResult{err: errors.New(awserrors.ErrorServerInternal)}
+					results[idx] = volumeMetaResult{err: errors.New(awserrors.ErrorServerInternal)}
 				}
 				return
 			}
+			// The read was scoped to the caller's prefix, so the document is
+			// theirs by construction. The comparison stays as an assertion.
 			if meta.TenantID != accountID {
-				results[idx] = volumeFetchResult{err: errors.New(awserrors.ErrorInvalidVolumeNotFound)}
+				results[idx] = volumeMetaResult{err: errors.New(awserrors.ErrorInvalidVolumeNotFound)}
 				return
 			}
-			results[idx] = volumeFetchResult{volume: metadataVolumeToEC2(meta)}
+			results[idx] = volumeMetaResult{meta: meta}
 		}(i, *id)
 	}
 
@@ -869,15 +869,15 @@ func metadataVolumeToEC2(meta ebsmetadata.Volume) *ec2.Volume {
 
 // GetVolumeMetadata reads the control-plane document for a volume. It is the
 // ownership and attachment record the daemon validates attach/detach against.
-func (s *VolumeServiceImpl) GetVolumeMetadata(volumeID string) (ebsmetadata.Volume, error) {
-	return s.getVolumeMetadata(context.Background(), volumeID)
+func (s *VolumeServiceImpl) GetVolumeMetadata(accountID, volumeID string) (ebsmetadata.Volume, error) {
+	return s.getVolumeMetadata(context.Background(), accountID, volumeID)
 }
 
 // getVolumeMetadata is GetVolumeMetadata carrying the caller's context. A
 // missing document is remapped to InvalidVolume.NotFound so callers surface the
 // AWS error rather than a store error.
-func (s *VolumeServiceImpl) getVolumeMetadata(ctx context.Context, volumeID string) (ebsmetadata.Volume, error) {
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+func (s *VolumeServiceImpl) getVolumeMetadata(ctx context.Context, accountID, volumeID string) (ebsmetadata.Volume, error) {
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		if objectstore.IsNoSuchKeyError(err) {
 			slog.WarnContext(ctx, "volume metadata not found", "volumeId", volumeID)
@@ -890,9 +890,9 @@ func (s *VolumeServiceImpl) getVolumeMetadata(ctx context.Context, volumeID stri
 
 // UpdateVolumeState updates the control-plane-owned attachment state (state,
 // attachment, device) on the volume's ebsmetadata document.
-func (s *VolumeServiceImpl) UpdateVolumeState(volumeID, state, attachedInstance, deviceName string) error {
+func (s *VolumeServiceImpl) UpdateVolumeState(accountID, volumeID, state, attachedInstance, deviceName string) error {
 	ctx := context.Background()
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		return fmt.Errorf("failed to get volume metadata: %w", err)
 	}
@@ -932,7 +932,7 @@ func (s *VolumeServiceImpl) ModifyVolume(ctx context.Context, input *ec2.ModifyV
 		return nil, err
 	}
 
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil || meta.TenantID != accountID {
 		return nil, errors.New(awserrors.ErrorInvalidVolumeNotFound)
 	}
@@ -1007,7 +1007,7 @@ func (s *VolumeServiceImpl) ModifyVolume(ctx context.Context, input *ec2.ModifyV
 // is always a metadata-only clear, never a QMP call. Errors from either step
 // are returned, not swallowed.
 func (s *VolumeServiceImpl) DeleteVolumeOnTerminate(ctx context.Context, volumeID, accountID string) error {
-	if err := s.UpdateVolumeState(volumeID, "available", "", ""); err != nil {
+	if err := s.UpdateVolumeState(accountID, volumeID, "available", "", ""); err != nil {
 		// No metadata doc means the volume is already gone, per GetVolume's own
 		// contract, so absence here is success, not a teardown failure.
 		if objectstore.IsNoSuchKeyError(err) {
@@ -1025,8 +1025,8 @@ func (s *VolumeServiceImpl) DeleteVolumeOnTerminate(ctx context.Context, volumeI
 // available rather than deleting it. Metadata-only, no QMP — same rationale
 // as DeleteVolumeOnTerminate: there is no live QEMU to hot-unplug on either
 // terminate path.
-func (s *VolumeServiceImpl) DetachVolumeOnTerminate(_ context.Context, volumeID, _ string) error {
-	if err := s.UpdateVolumeState(volumeID, "available", "", ""); err != nil {
+func (s *VolumeServiceImpl) DetachVolumeOnTerminate(_ context.Context, volumeID, accountID string) error {
+	if err := s.UpdateVolumeState(accountID, volumeID, "available", "", ""); err != nil {
 		// No metadata doc means the volume is already gone, per GetVolume's own
 		// contract, so absence here is success, not a teardown failure.
 		if objectstore.IsNoSuchKeyError(err) {
@@ -1052,7 +1052,7 @@ func (s *VolumeServiceImpl) ForceDetachVolume(ctx context.Context, input *ec2.De
 	}
 	volumeID := *input.VolumeId
 
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		return nil, errors.New(awserrors.ErrorInvalidVolumeNotFound)
 	}
@@ -1061,7 +1061,7 @@ func (s *VolumeServiceImpl) ForceDetachVolume(ctx context.Context, input *ec2.De
 	}
 
 	previous := meta.AttachedInstance
-	if err := s.UpdateVolumeState(volumeID, "available", "", ""); err != nil {
+	if err := s.UpdateVolumeState(accountID, volumeID, "available", "", ""); err != nil {
 		slog.ErrorContext(ctx, "ForceDetachVolume: failed to clear attachment", "volumeId", volumeID, "err", err)
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
@@ -1090,7 +1090,7 @@ func (s *VolumeServiceImpl) DeleteVolume(ctx context.Context, input *ec2.DeleteV
 	}
 
 	// AWS-faithful: an absent volume returns InvalidVolume.NotFound.
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		return nil, errors.New(awserrors.ErrorInvalidVolumeNotFound)
 	}
@@ -1118,7 +1118,7 @@ func (s *VolumeServiceImpl) DeleteVolume(ctx context.Context, input *ec2.DeleteV
 		slog.ErrorContext(ctx, "DeleteVolume: provider deletion failed", "volumeId", volumeID, "err", err)
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
-	if err := s.metadata.DeleteVolume(ctx, volumeID); err != nil {
+	if err := s.metadata.DeleteVolume(ctx, accountID, volumeID); err != nil {
 		return nil, errors.New(awserrors.ErrorServerInternal)
 	}
 
@@ -1127,43 +1127,6 @@ func (s *VolumeServiceImpl) DeleteVolume(ctx context.Context, input *ec2.DeleteV
 	return &ec2.DeleteVolumeOutput{}, nil
 }
 
-// snapshotMetadata holds the subset of snapshot metadata needed by CreateVolume.
-// Matches the JSON written by the snapshot service's SnapshotConfig.
-type snapshotMetadata struct {
-	VolumeID   string `json:"volume_id"`
-	VolumeSize int64  `json:"volume_size"`
-	OwnerID    string `json:"owner_id"`
-}
-
-// getSnapshotMetadata reads snapshot metadata.json from S3 for CreateVolume.
-func (s *VolumeServiceImpl) getSnapshotMetadata(ctx context.Context, snapshotID string) (*snapshotMetadata, error) {
-	key := snapshotID + "/metadata.json"
-
-	getResult, err := s.store.GetObject(ctx, &s3.GetObjectInput{
-		Bucket: aws.String(s.bucketName),
-		Key:    aws.String(key),
-	})
-	if err != nil {
-		if objectstore.IsNoSuchKeyError(err) {
-			return nil, errors.New(awserrors.ErrorInvalidSnapshotNotFound)
-		}
-		return nil, fmt.Errorf("failed to get snapshot metadata: %w", err)
-	}
-	defer getResult.Body.Close()
-
-	body, err := io.ReadAll(getResult.Body)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read snapshot metadata: %w", err)
-	}
-
-	var meta snapshotMetadata
-	if err := json.Unmarshal(body, &meta); err != nil {
-		return nil, fmt.Errorf("failed to decode snapshot metadata: %w", err)
-	}
-
-	return &meta, nil
-}
-
 // checkVolumeHasNoSnapshots checks if a volume has dependent snapshots
 // using the JetStream KV index.
 func (s *VolumeServiceImpl) checkVolumeHasNoSnapshots(ctx context.Context, volumeID string) error {
@@ -1237,7 +1200,7 @@ func (s *VolumeServiceImpl) mirrorVolumeTags(ctx context.Context, resources []*s
 
 // mirrorVolumeTagsOne read-modify-writes one ebsmetadata.Volume's Tags field.
 func (s *VolumeServiceImpl) mirrorVolumeTagsOne(ctx context.Context, volumeID, accountID string, mut func(map[string]string)) error {
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		if objectstore.IsNoSuchKeyError(err) {
 			return nil
diff --git a/spinifex/handlers/ec2/volume/service_impl_encryption_test.go b/spinifex/handlers/ec2/volume/service_impl_encryption_test.go
index fc3f19031..7433eecb5 100644
--- a/spinifex/handlers/ec2/volume/service_impl_encryption_test.go
+++ b/spinifex/handlers/ec2/volume/service_impl_encryption_test.go
@@ -26,7 +26,7 @@ func TestGetVolumeMetadata_CorruptJSON(t *testing.T) {
 	const volumeID = "vol-bad-json"
 	putRawVolumeDocument(t, store, volumeID, "not valid json {{{")
 
-	_, err := svc.GetVolumeMetadata(volumeID)
+	_, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.Error(t, err)
 	assert.ErrorIs(t, err, ebsmetadata.ErrCorruptDocument)
 }
@@ -61,11 +61,11 @@ func TestCreateVolume_EncryptionKeyLoadError(t *testing.T) {
 	_, err := svc.CreateVolume(context.Background(), &ec2.CreateVolumeInput{
 		Size:             aws.Int64(1),
 		AvailabilityZone: aws.String("ap-southeast-2a"),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorServerInternal, err.Error())
 
-	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "")
+	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, out.Volumes, "a failed create must not leave a volume behind")
 }
diff --git a/spinifex/handlers/ec2/volume/service_impl_test.go b/spinifex/handlers/ec2/volume/service_impl_test.go
index 5b0747f52..a3e2c2c0e 100644
--- a/spinifex/handlers/ec2/volume/service_impl_test.go
+++ b/spinifex/handlers/ec2/volume/service_impl_test.go
@@ -206,7 +206,7 @@ func TestCreateVolume_Validation(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			svc := newTestVolumeService(tt.az)
-			_, err := svc.CreateVolume(context.Background(), tt.input, "")
+			_, err := svc.CreateVolume(context.Background(), tt.input, testVolAccountID)
 			assert.Error(t, err)
 			assert.Equal(t, tt.wantErr, err.Error())
 		})
@@ -289,7 +289,7 @@ func TestCreateVolume_PassesValidation(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			svc := newTestVolumeService("ap-southeast-2a")
-			_, err := svc.CreateVolume(context.Background(), tt.input, "")
+			_, err := svc.CreateVolume(context.Background(), tt.input, testVolAccountID)
 			if err != nil {
 				assert.NotEqual(t, awserrors.ErrorInvalidParameterValue, err.Error())
 				assert.NotEqual(t, awserrors.ErrorInvalidAvailabilityZone, err.Error())
@@ -305,27 +305,27 @@ func TestCreateVolume_UsesInjectedProvider(t *testing.T) {
 	vol, err := svc.CreateVolume(context.Background(), &ec2.CreateVolumeInput{
 		Size:             aws.Int64(8),
 		AvailabilityZone: aws.String("ap-southeast-2a"),
-	}, "acct-1")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	require.NotNil(t, vol)
 	require.NotEmpty(t, vol.VolumeId)
 
-	metadata, err := svc.metadata.GetVolume(context.Background(), aws.StringValue(vol.VolumeId))
+	metadata, err := svc.metadata.GetVolume(context.Background(), testVolAccountID, aws.StringValue(vol.VolumeId))
 	require.NoError(t, err)
-	assert.Equal(t, "acct-1", metadata.TenantID)
+	assert.Equal(t, testVolAccountID, metadata.TenantID)
 	assert.Equal(t, uint64(8), metadata.CapacityGiB)
 	assert.Equal(t, "memory://volume/"+aws.StringValue(vol.VolumeId), metadata.ProviderHandle)
-	described, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+	described, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, described.Volumes, 1)
 	assert.Equal(t, int64(8), aws.Int64Value(described.Volumes[0].Size))
-	require.NoError(t, svc.UpdateVolumeState(aws.StringValue(vol.VolumeId), "in-use", "i-123", "/dev/sda1"))
-	_, err = svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{VolumeId: vol.VolumeId}, "acct-1")
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, aws.StringValue(vol.VolumeId), "in-use", "i-123", "/dev/sda1"))
+	_, err = svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{VolumeId: vol.VolumeId}, testVolAccountID)
 	assert.EqualError(t, err, awserrors.ErrorVolumeInUse)
-	require.NoError(t, svc.UpdateVolumeState(aws.StringValue(vol.VolumeId), "available", "", ""))
-	_, err = svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{VolumeId: vol.VolumeId}, "acct-1")
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, aws.StringValue(vol.VolumeId), "available", "", ""))
+	_, err = svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{VolumeId: vol.VolumeId}, testVolAccountID)
 	require.NoError(t, err)
-	_, err = svc.metadata.GetVolume(context.Background(), aws.StringValue(vol.VolumeId))
+	_, err = svc.metadata.GetVolume(context.Background(), testVolAccountID, aws.StringValue(vol.VolumeId))
 	assert.Error(t, err)
 }
 
@@ -338,13 +338,13 @@ func TestDescribeVolumes_Provider_FilterAndTenantIsolation(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	volA, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	volA, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
-	_, err = svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(16), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-2")
+	_, err = svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(16), AvailabilityZone: aws.String("ap-southeast-2a")}, "000000000002")
 	require.NoError(t, err)
 
 	t.Run("tenant isolation", func(t *testing.T) {
-		out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{}, "acct-1")
+		out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{}, testVolAccountID)
 		require.NoError(t, err)
 		require.Len(t, out.Volumes, 1)
 		assert.Equal(t, aws.StringValue(volA.VolumeId), aws.StringValue(out.Volumes[0].VolumeId))
@@ -353,14 +353,14 @@ func TestDescribeVolumes_Provider_FilterAndTenantIsolation(t *testing.T) {
 	t.Run("filter match", func(t *testing.T) {
 		out, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{
 			Filters: []*ec2.Filter{{Name: aws.String("size"), Values: []*string{aws.String("8")}}},
-		}, "acct-1")
+		}, testVolAccountID)
 		require.NoError(t, err)
 		require.Len(t, out.Volumes, 1)
 		assert.Equal(t, aws.StringValue(volA.VolumeId), aws.StringValue(out.Volumes[0].VolumeId))
 	})
 
 	t.Run("unknown volume id is InvalidVolume.NotFound", func(t *testing.T) {
-		_, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{aws.String("vol-does-not-exist")}}, "acct-1")
+		_, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{aws.String("vol-does-not-exist")}}, testVolAccountID)
 		require.EqualError(t, err, awserrors.ErrorInvalidVolumeNotFound)
 	})
 }
@@ -373,35 +373,35 @@ func TestModifyVolume_Provider(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{OnlineExpansion: true}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
 	volumeID := aws.StringValue(vol.VolumeId)
 
 	t.Run("grow succeeds", func(t *testing.T) {
-		out, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(16)}, "acct-1")
+		out, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(16)}, testVolAccountID)
 		require.NoError(t, err)
 		require.NotNil(t, out.VolumeModification)
 		assert.Equal(t, int64(8), aws.Int64Value(out.VolumeModification.OriginalSize))
 		assert.Equal(t, int64(16), aws.Int64Value(out.VolumeModification.TargetSize))
 
-		meta, err := svc.metadata.GetVolume(ctx, volumeID)
+		meta, err := svc.metadata.GetVolume(ctx, testVolAccountID, volumeID)
 		require.NoError(t, err)
 		assert.Equal(t, uint64(16), meta.CapacityGiB)
 	})
 
 	t.Run("shrink is rejected", func(t *testing.T) {
-		_, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(8)}, "acct-1")
+		_, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(8)}, testVolAccountID)
 		require.EqualError(t, err, awserrors.ErrorInvalidParameterValue)
 	})
 
 	t.Run("in-use is rejected", func(t *testing.T) {
-		require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", "i-123", "/dev/sda1"))
-		_, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(32)}, "acct-1")
+		require.NoError(t, svc.UpdateVolumeState(testVolAccountID, volumeID, "in-use", "i-123", "/dev/sda1"))
+		_, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(32)}, testVolAccountID)
 		require.EqualError(t, err, awserrors.ErrorIncorrectState)
 	})
 
 	t.Run("unknown volume id is InvalidVolume.NotFound", func(t *testing.T) {
-		_, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: aws.String("vol-does-not-exist"), Size: aws.Int64(32)}, "acct-1")
+		_, err := svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: aws.String("vol-does-not-exist"), Size: aws.Int64(32)}, testVolAccountID)
 		require.EqualError(t, err, awserrors.ErrorInvalidVolumeNotFound)
 	})
 }
@@ -416,14 +416,14 @@ func TestModifyVolume_Provider_PersistsAndDescribesModification(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{OnlineExpansion: true}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
 	volumeID := aws.StringValue(vol.VolumeId)
 
-	_, err = svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(16), Iops: aws.Int64(4000)}, "acct-1")
+	_, err = svc.ModifyVolume(ctx, &ec2.ModifyVolumeInput{VolumeId: vol.VolumeId, Size: aws.Int64(16), Iops: aws.Int64(4000)}, testVolAccountID)
 	require.NoError(t, err)
 
-	meta, err := svc.metadata.GetVolume(ctx, volumeID)
+	meta, err := svc.metadata.GetVolume(ctx, testVolAccountID, volumeID)
 	require.NoError(t, err)
 	require.NotNil(t, meta.Modification, "ModifyVolume must persist the modification on the ebsmetadata.Volume document")
 	assert.Equal(t, int64(8), meta.Modification.OriginalSize)
@@ -433,7 +433,7 @@ func TestModifyVolume_Provider_PersistsAndDescribesModification(t *testing.T) {
 	t.Run("fast path", func(t *testing.T) {
 		out, err := svc.DescribeVolumesModifications(ctx, &ec2.DescribeVolumesModificationsInput{
 			VolumeIds: []*string{vol.VolumeId},
-		}, "acct-1")
+		}, testVolAccountID)
 		require.NoError(t, err)
 		require.Len(t, out.VolumesModifications, 1)
 		assert.Equal(t, volumeID, aws.StringValue(out.VolumesModifications[0].VolumeId))
@@ -441,18 +441,18 @@ func TestModifyVolume_Provider_PersistsAndDescribesModification(t *testing.T) {
 	})
 
 	t.Run("slow path", func(t *testing.T) {
-		out, err := svc.DescribeVolumesModifications(ctx, &ec2.DescribeVolumesModificationsInput{}, "acct-1")
+		out, err := svc.DescribeVolumesModifications(ctx, &ec2.DescribeVolumesModificationsInput{}, testVolAccountID)
 		require.NoError(t, err)
 		require.Len(t, out.VolumesModifications, 1)
 		assert.Equal(t, volumeID, aws.StringValue(out.VolumesModifications[0].VolumeId))
 	})
 
 	t.Run("unmodified volume has no modification record", func(t *testing.T) {
-		other, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+		other, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 		require.NoError(t, err)
 		out, err := svc.DescribeVolumesModifications(ctx, &ec2.DescribeVolumesModificationsInput{
 			VolumeIds: []*string{other.VolumeId},
-		}, "acct-1")
+		}, testVolAccountID)
 		require.NoError(t, err)
 		assert.Empty(t, out.VolumesModifications)
 	})
@@ -467,24 +467,24 @@ func TestDescribeVolumeStatus_Provider(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
 
 	t.Run("fast path", func(t *testing.T) {
-		out, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+		out, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 		require.NoError(t, err)
 		require.Len(t, out.VolumeStatuses, 1)
 		assert.Equal(t, aws.StringValue(vol.VolumeId), aws.StringValue(out.VolumeStatuses[0].VolumeId))
 	})
 
 	t.Run("slow path", func(t *testing.T) {
-		out, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{}, "acct-1")
+		out, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{}, testVolAccountID)
 		require.NoError(t, err)
 		require.Len(t, out.VolumeStatuses, 1)
 	})
 
 	t.Run("cross tenant is not found", func(t *testing.T) {
-		_, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{VolumeIds: []*string{vol.VolumeId}}, "acct-2")
+		_, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{VolumeIds: []*string{vol.VolumeId}}, "000000000002")
 		require.EqualError(t, err, awserrors.ErrorInvalidVolumeNotFound)
 	})
 }
@@ -498,11 +498,11 @@ func TestCreateVolume_Provider_EncryptedFollowsConfig(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
 	assert.False(t, aws.BoolValue(vol.Encrypted), "no encryption key file configured, so the volume must not report encrypted")
 
-	described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+	described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, described.Volumes, 1)
 	assert.False(t, aws.BoolValue(described.Volumes[0].Encrypted))
@@ -516,10 +516,10 @@ func TestVolumeLeakReaper_Provider(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
 	volumeID := aws.StringValue(vol.VolumeId)
-	require.NoError(t, svc.UpdateVolumeState(volumeID, "in-use", "i-gone0000000000", "/dev/sda1"))
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, volumeID, "in-use", "i-gone0000000000", "/dev/sda1"))
 
 	reaper := svc.NewVolumeLeakReaper(func() (map[string]bool, error) {
 		return map[string]bool{"i-gone0000000000": true}, nil
@@ -529,13 +529,13 @@ func TestVolumeLeakReaper_Provider(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 1, marked)
 
-	meta, err := svc.metadata.GetVolume(ctx, volumeID)
+	meta, err := svc.metadata.GetVolume(ctx, testVolAccountID, volumeID)
 	require.NoError(t, err)
 	assert.NotEmpty(t, meta.Tags[orphanTagKey], "the reaper must mark the provider-managed volume orphaned in ebsmetadata")
 	assert.Equal(t, "available", meta.State, "the reaper must reconcile the stale attachment")
 	assert.Empty(t, meta.AttachedInstance)
 
-	described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+	described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, described.Volumes, 1)
 	assert.NotEmpty(t, filterutil.EC2TagsToMap(described.Volumes[0].Tags)[orphanTagKey],
@@ -556,15 +556,15 @@ func TestApplyRecordTags_Provider_VisibleViaDescribeVolumes(t *testing.T) {
 	svc.SetEBSProvider(ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{}))
 	ctx := context.Background()
 
-	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, "acct-1")
+	vol, err := svc.CreateVolume(ctx, &ec2.CreateVolumeInput{Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a")}, testVolAccountID)
 	require.NoError(t, err)
 
 	require.NoError(t, svc.ApplyRecordTags(&ec2.CreateTagsInput{
 		Resources: []*string{vol.VolumeId},
 		Tags:      []*ec2.Tag{{Key: aws.String("owner"), Value: aws.String("control-plane")}},
-	}, "acct-1"))
+	}, testVolAccountID))
 
-	described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+	described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, described.Volumes, 1)
 	assert.Equal(t, "control-plane", filterutil.EC2TagsToMap(described.Volumes[0].Tags)["owner"],
@@ -573,9 +573,9 @@ func TestApplyRecordTags_Provider_VisibleViaDescribeVolumes(t *testing.T) {
 	require.NoError(t, svc.RemoveRecordTags(&ec2.DeleteTagsInput{
 		Resources: []*string{vol.VolumeId},
 		Tags:      []*ec2.Tag{{Key: aws.String("owner"), Value: aws.String("control-plane")}},
-	}, "acct-1"))
+	}, testVolAccountID))
 
-	described, err = svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+	described, err = svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, described.Volumes, 1)
 	_, hasOwnerTag := filterutil.EC2TagsToMap(described.Volumes[0].Tags)["owner"]
@@ -585,8 +585,8 @@ func TestApplyRecordTags_Provider_VisibleViaDescribeVolumes(t *testing.T) {
 		require.NoError(t, svc.ApplyRecordTags(&ec2.CreateTagsInput{
 			Resources: []*string{vol.VolumeId},
 			Tags:      []*ec2.Tag{{Key: aws.String("owner"), Value: aws.String("intruder")}},
-		}, "acct-2"))
-		described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, "acct-1")
+		}, "000000000002"))
+		described, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{VolumeIds: []*string{vol.VolumeId}}, testVolAccountID)
 		require.NoError(t, err)
 		_, hasOwnerTag := filterutil.EC2TagsToMap(described.Volumes[0].Tags)["owner"]
 		assert.False(t, hasOwnerTag, "a caller who does not own the volume must not be able to tag it")
@@ -596,7 +596,7 @@ func TestApplyRecordTags_Provider_VisibleViaDescribeVolumes(t *testing.T) {
 		require.NoError(t, svc.ApplyRecordTags(&ec2.CreateTagsInput{
 			Resources: []*string{aws.String("vol-does-not-exist")},
 			Tags:      []*ec2.Tag{{Key: aws.String("owner"), Value: aws.String("control-plane")}},
-		}, "acct-1"))
+		}, testVolAccountID))
 	})
 }
 
@@ -625,7 +625,7 @@ func (s *prefixFailingObjectStore) PutObject(ctx context.Context, input *s3.PutO
 // provider has already allocated the volume, CreateVolume must delete the
 // just-created provider volume rather than orphan it.
 func TestCreateVolume_Provider_RollbackOnMetadataWriteFailure(t *testing.T) {
-	store := &prefixFailingObjectStore{ObjectStore: objectstore.NewMemoryObjectStore(), failPrefix: "spinifex/ebsmetadata/v1/volumes/"}
+	store := &prefixFailingObjectStore{ObjectStore: objectstore.NewMemoryObjectStore(), failPrefix: "spinifex/ebsmetadata/v2/volumes/"}
 	cfg := &config.Config{AZ: "ap-southeast-2a", Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
 	svc := NewVolumeServiceImplWithStore(cfg, store, nil)
 	provider := ebsprovider.NewMemoryProvider(ebsprovider.Capabilities{})
@@ -633,7 +633,7 @@ func TestCreateVolume_Provider_RollbackOnMetadataWriteFailure(t *testing.T) {
 
 	_, err := svc.CreateVolume(context.Background(), &ec2.CreateVolumeInput{
 		Size: aws.Int64(8), AvailabilityZone: aws.String("ap-southeast-2a"),
-	}, "acct-1")
+	}, testVolAccountID)
 	require.EqualError(t, err, awserrors.ErrorServerInternal)
 	require.NotEmpty(t, store.attemptedKey, "the metadata write must have been attempted")
 
@@ -690,7 +690,7 @@ func TestDescribeVolumeStatus_NilInputDefaults(t *testing.T) {
 	// nil input is defaulted to empty, then hits the slow path which
 	// calls listAllVolumeIDs. With an empty MemoryObjectStore, no
 	// volumes are found and an empty result is returned.
-	output, err := svc.DescribeVolumeStatus(context.Background(), nil, "")
+	output, err := svc.DescribeVolumeStatus(context.Background(), nil, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, output.VolumeStatuses)
 }
@@ -703,7 +703,7 @@ func TestDescribeVolumeStatus_WithVolumeIDs(t *testing.T) {
 	// InvalidVolume.NotFound error is returned.
 	_, err := svc.DescribeVolumeStatus(context.Background(), &ec2.DescribeVolumeStatusInput{
 		VolumeIds: []*string{aws.String("vol-abc123")},
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 }
@@ -726,23 +726,16 @@ func newTestVolumeServiceWithStore(az string, store *objectstore.MemoryObjectSto
 	return svc
 }
 
-// putTestSnapshotMetadata writes snapshot metadata in the store, matching the
-// spinifex snapshot service format.
+// putTestSnapshotMetadata writes the snapshot's control-plane document under
+// the account that owns it.
 func putTestSnapshotMetadata(t *testing.T, store *objectstore.MemoryObjectStore, snapshotID, ownerID string, sizeGiB int64) {
 	t.Helper()
-	snapData, err := json.Marshal(snapshotMetadata{
+	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+		SnapshotID: snapshotID,
 		VolumeID:   "vol-source",
 		VolumeSize: sizeGiB,
 		OwnerID:    ownerID,
-	})
-	require.NoError(t, err)
-
-	_, err = store.PutObject(context.Background(), &s3.PutObjectInput{
-		Bucket: aws.String("test-bucket"),
-		Key:    aws.String(snapshotID + "/metadata.json"),
-		Body:   strings.NewReader(string(snapData)),
-	})
-	require.NoError(t, err)
+	}))
 }
 
 func TestCreateVolume_FromSnapshot_PassesValidation(t *testing.T) {
@@ -838,9 +831,11 @@ func TestCreateVolume_FromSnapshot_CorruptMetadata(t *testing.T) {
 	snapshotID := "snap-corrupt"
 
 	// Put invalid JSON as snapshot metadata
-	_, err := store.PutObject(context.Background(), &s3.PutObjectInput{
+	key, err := ebsmetadata.SnapshotKey(testVolAccountID, snapshotID)
+	require.NoError(t, err)
+	_, err = store.PutObject(context.Background(), &s3.PutObjectInput{
 		Bucket: aws.String("test-bucket"),
-		Key:    aws.String(snapshotID + "/metadata.json"),
+		Key:    aws.String(key),
 		Body:   strings.NewReader("not valid json{{{"),
 	})
 	require.NoError(t, err)
@@ -880,23 +875,38 @@ func TestCreateVolume_FromSnapshot_OtherAccountDenied(t *testing.T) {
 	assertNoVolumeCreated(t, store)
 }
 
-// A snapshot written before owner_id was recorded fails closed, including for
-// a caller whose own account ID is empty.
+// A snapshot recording no owner fails closed. An empty caller is refused
+// earlier still, at the boundary, before the snapshot is ever read.
 func TestCreateVolume_FromSnapshot_EmptyOwnerDenied(t *testing.T) {
-	for _, accountID := range []string{testVolAccountID, ""} {
-		t.Run("caller="+accountID, func(t *testing.T) {
+	// An untenanted snapshot document cannot be written, so it cannot exist:
+	// the state this used to guard against is unreachable rather than denied.
+	store := objectstore.NewMemoryObjectStore()
+	require.Error(t, ebsmetadata.NewStore(store, "test-bucket").PutSnapshot(context.Background(), ebsmetadata.Snapshot{
+		SnapshotID: "snap-untenanted", VolumeID: "vol-source", VolumeSize: 50,
+	}))
+
+	tests := []struct {
+		accountID string
+		wantErr   string
+	}{
+		{accountID: "000000000002", wantErr: awserrors.ErrorInvalidSnapshotNotFound},
+		{accountID: "", wantErr: awserrors.ErrorAuthFailure},
+	}
+
+	for _, tt := range tests {
+		t.Run("caller="+tt.accountID, func(t *testing.T) {
 			store := objectstore.NewMemoryObjectStore()
 			svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
-			snapshotID := "snap-legacy"
-			putTestSnapshotMetadata(t, store, snapshotID, "", 50)
+			snapshotID := "snap-owned"
+			putTestSnapshotMetadata(t, store, snapshotID, testVolAccountID, 50)
 
 			_, err := svc.CreateVolume(context.Background(), &ec2.CreateVolumeInput{
 				AvailabilityZone: aws.String("ap-southeast-2a"),
 				SnapshotId:       aws.String(snapshotID),
-			}, accountID)
+			}, tt.accountID)
 			require.Error(t, err)
-			assert.Equal(t, awserrors.ErrorInvalidSnapshotNotFound, err.Error())
+			assert.Equal(t, tt.wantErr, err.Error())
 			assertNoVolumeCreated(t, store)
 		})
 	}
@@ -942,7 +952,7 @@ func TestDeleteVolume_BlockedByKV(t *testing.T) {
 	// DeleteVolume should be blocked
 	_, err = svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{
 		VolumeId: aws.String(volumeID),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Contains(t, err.Error(), awserrors.ErrorVolumeInUse)
 }
@@ -960,7 +970,7 @@ func TestDeleteVolume_AllowedByKV(t *testing.T) {
 	// No KV entry → delete allowed
 	_, err := svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{
 		VolumeId: aws.String(volumeID),
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 }
 
@@ -975,7 +985,7 @@ func TestDeleteVolume_ErrorWhenKVNil(t *testing.T) {
 	// Should fail because snapshotKV is nil
 	_, err := svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{
 		VolumeId: aws.String(volumeID),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Contains(t, err.Error(), awserrors.ErrorServerInternal)
 }
@@ -995,7 +1005,7 @@ func createVolumeInStoreWithMeta(t *testing.T, svc *VolumeServiceImpl, store *ob
 // cannot express: a corrupt document, or one predating a field.
 func putRawVolumeDocument(t *testing.T, store *objectstore.MemoryObjectStore, volumeID, body string) {
 	t.Helper()
-	key, err := ebsmetadata.VolumeKey(volumeID)
+	key, err := ebsmetadata.VolumeKey(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	_, err = store.PutObject(context.Background(), &s3.PutObjectInput{
 		Bucket: aws.String("test-bucket"),
@@ -1011,7 +1021,7 @@ func putRawVolumeDocument(t *testing.T, store *objectstore.MemoryObjectStore, vo
 // DescribeVolumes does, so the read and the projection are covered together.
 func volumeByID(t *testing.T, svc *VolumeServiceImpl, volumeID string) *ec2.Volume {
 	t.Helper()
-	meta, err := svc.GetVolumeMetadata(volumeID)
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, err)
 	return metadataVolumeToEC2(meta)
 }
@@ -1110,7 +1120,7 @@ func TestGetVolumeByID_ThroughputOmitted_PreFieldVolume(t *testing.T) {
 
 	// Simulate a pre-field volume by writing a document with no throughput key.
 	putRawVolumeDocument(t, store, "vol-prefield",
-		`{"schema_version":1,"volume_id":"vol-prefield","capacity_gib":5,"state":"available","volume_type":"gp3","iops":3000}`)
+		`{"schema_version":2,"volume_id":"vol-prefield","tenant_id":"123456789012","capacity_gib":5,"state":"available","volume_type":"gp3","iops":3000}`)
 
 	vol := volumeByID(t, svc, "vol-prefield")
 
@@ -1132,7 +1142,7 @@ func TestGetVolumeByID_NotFound(t *testing.T) {
 	store := objectstore.NewMemoryObjectStore()
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
-	_, err := svc.GetVolumeMetadata("vol-nonexistent")
+	_, err := svc.GetVolumeMetadata(testVolAccountID, "vol-nonexistent")
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 }
@@ -1148,7 +1158,7 @@ func TestDescribeVolumes_NilInput(t *testing.T) {
 		VolumeID: "vol-nil1", CapacityGiB: 10, State: "available",
 	})
 
-	output, err := svc.DescribeVolumes(context.Background(), nil, "")
+	output, err := svc.DescribeVolumes(context.Background(), nil, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, output.Volumes, 1)
 }
@@ -1157,7 +1167,7 @@ func TestDescribeVolumes_EmptyStore(t *testing.T) {
 	store := objectstore.NewMemoryObjectStore()
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
-	output, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "")
+	output, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, output.Volumes)
 }
@@ -1172,7 +1182,7 @@ func TestDescribeVolumes_SlowPath_MultipleVolumes(t *testing.T) {
 		})
 	}
 
-	output, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "")
+	output, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, output.Volumes, 3)
 }
@@ -1189,7 +1199,7 @@ func TestDescribeVolumes_FastPath_SpecificIDs(t *testing.T) {
 
 	output, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		VolumeIds: []*string{aws.String("vol-x"), aws.String("vol-z")},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, output.Volumes, 2)
 
@@ -1212,7 +1222,7 @@ func TestDescribeVolumes_FastPath_MixedExistingAndMissing(t *testing.T) {
 	// AWS returns InvalidVolume.NotFound when any requested ID is missing
 	_, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		VolumeIds: []*string{aws.String("vol-exists"), aws.String("vol-ghost")},
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 }
@@ -1227,7 +1237,7 @@ func TestDescribeVolumes_FastPath_NilVolumeID(t *testing.T) {
 
 	output, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		VolumeIds: []*string{nil, aws.String("vol-ok")},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, output.Volumes, 1)
 }
@@ -1374,7 +1384,7 @@ func TestModifyVolume_NilVolumeID(t *testing.T) {
 
 	_, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: nil,
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeIDMalformed, err.Error())
 }
@@ -1384,7 +1394,7 @@ func TestModifyVolume_EmptyVolumeID(t *testing.T) {
 
 	_, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String(""),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeIDMalformed, err.Error())
 }
@@ -1395,7 +1405,7 @@ func TestModifyVolume_VolumeNotFound(t *testing.T) {
 	_, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String("vol-nonexistent"),
 		Size:     aws.Int64(20),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidVolumeNotFound, err.Error())
 }
@@ -1411,7 +1421,7 @@ func TestModifyVolume_ShrinkRejected(t *testing.T) {
 	_, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String("vol-shrink"),
 		Size:     aws.Int64(5),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidParameterValue, err.Error())
 }
@@ -1427,7 +1437,7 @@ func TestModifyVolume_SameSizeRejected(t *testing.T) {
 	_, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String("vol-same"),
 		Size:     aws.Int64(10),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidParameterValue, err.Error())
 }
@@ -1446,7 +1456,7 @@ func TestModifyVolume_AttachedInUse(t *testing.T) {
 	_, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String("vol-inuse"),
 		Size:     aws.Int64(20),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorIncorrectState, err.Error())
 }
@@ -1466,7 +1476,7 @@ func TestModifyVolume_SuccessfulGrow(t *testing.T) {
 	output, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String("vol-grow"),
 		Size:     aws.Int64(20),
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 
 	mod := output.VolumeModification
@@ -1477,7 +1487,7 @@ func TestModifyVolume_SuccessfulGrow(t *testing.T) {
 	assert.Equal(t, int64(100), *mod.Progress)
 
 	// Verify persisted config
-	meta, err := svc.GetVolumeMetadata("vol-grow")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-grow")
 	require.NoError(t, err)
 	assert.Equal(t, uint64(20), meta.CapacityGiB)
 }
@@ -1499,7 +1509,7 @@ func TestModifyVolume_ModifyTypeAndIOPS(t *testing.T) {
 		Size:       aws.Int64(20),
 		VolumeType: aws.String("io1"),
 		Iops:       aws.Int64(10000),
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 
 	mod := output.VolumeModification
@@ -1524,7 +1534,7 @@ func TestModifyVolume_AvailableWithAttachment(t *testing.T) {
 	output, err := svc.ModifyVolume(context.Background(), &ec2.ModifyVolumeInput{
 		VolumeId: aws.String("vol-stopinst"),
 		Size:     aws.Int64(20),
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Equal(t, int64(20), *output.VolumeModification.TargetSize)
 }
@@ -1539,10 +1549,10 @@ func TestUpdateVolumeState_AttachVolume(t *testing.T) {
 		VolumeID: "vol-attach", CapacityGiB: 10, State: "available",
 	})
 
-	err := svc.UpdateVolumeState("vol-attach", "in-use", "i-abc123", "/dev/nbd0")
+	err := svc.UpdateVolumeState(testVolAccountID, "vol-attach", "in-use", "i-abc123", "/dev/nbd0")
 	require.NoError(t, err)
 
-	meta, err := svc.GetVolumeMetadata("vol-attach")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-attach")
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", meta.State)
 	assert.Equal(t, "i-abc123", meta.AttachedInstance)
@@ -1562,10 +1572,10 @@ func TestUpdateVolumeState_DetachVolume(t *testing.T) {
 		DeviceName:       "/dev/nbd1",
 	})
 
-	err := svc.UpdateVolumeState("vol-detach2", "available", "", "")
+	err := svc.UpdateVolumeState(testVolAccountID, "vol-detach2", "available", "", "")
 	require.NoError(t, err)
 
-	meta, err := svc.GetVolumeMetadata("vol-detach2")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-detach2")
 	require.NoError(t, err)
 	assert.Equal(t, "available", meta.State)
 	assert.Empty(t, meta.AttachedInstance)
@@ -1575,7 +1585,7 @@ func TestUpdateVolumeState_DetachVolume(t *testing.T) {
 func TestUpdateVolumeState_VolumeNotFound(t *testing.T) {
 	svc := newTestVolumeService("ap-southeast-2a")
 
-	err := svc.UpdateVolumeState("vol-missing", "available", "", "")
+	err := svc.UpdateVolumeState(testVolAccountID, "vol-missing", "available", "", "")
 	require.Error(t, err)
 	assert.Contains(t, err.Error(), "failed to get volume metadata")
 }
@@ -1590,7 +1600,7 @@ func TestUpdateVolumeState_PreservesProviderConfig(t *testing.T) {
 	seedProviderConfig(t, store, "vol-vbstate")
 	before := getStoredConfig(t, store, "vol-vbstate")
 
-	err := svc.UpdateVolumeState("vol-vbstate", "in-use", "i-preserve", "/dev/nbd0")
+	err := svc.UpdateVolumeState(testVolAccountID, "vol-vbstate", "in-use", "i-preserve", "/dev/nbd0")
 	require.NoError(t, err)
 
 	// config.json belongs to the live VB, which rewrites it from its own state.
@@ -1598,15 +1608,15 @@ func TestUpdateVolumeState_PreservesProviderConfig(t *testing.T) {
 	assert.Equal(t, string(before), string(getStoredConfig(t, store, "vol-vbstate")),
 		"UpdateVolumeState must not rewrite provider-owned config.json")
 
-	readback, err := svc.GetVolumeMetadata("vol-vbstate")
+	readback, err := svc.GetVolumeMetadata(testVolAccountID, "vol-vbstate")
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", readback.State)
 	assert.Equal(t, "i-preserve", readback.AttachedInstance)
 }
 
-// --- Group 6: listAllVolumeIDs tests ---
+// --- Group 6: whole-cluster volume listing tests ---
 
-func TestListAllVolumeIDs_FiltersCorrectly(t *testing.T) {
+func TestListAllVolumes_FiltersCorrectly(t *testing.T) {
 	store := objectstore.NewMemoryObjectStore()
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
@@ -1626,29 +1636,29 @@ func TestListAllVolumeIDs_FiltersCorrectly(t *testing.T) {
 		require.NoError(t, err)
 	}
 
-	ids, err := svc.listAllVolumeIDs(context.Background())
+	volumes, err := svc.metadata.ListAllVolumes(context.Background())
 	require.NoError(t, err)
 
 	// Should only contain vol-abc and vol-def (not efi/cloudinit/ami/snap)
-	assert.Len(t, ids, 2)
+	assert.Len(t, volumes, 2)
 	idSet := map[string]bool{}
-	for _, id := range ids {
-		idSet[id] = true
+	for _, v := range volumes {
+		idSet[v.VolumeID] = true
 	}
 	assert.True(t, idSet["vol-abc"])
 	assert.True(t, idSet["vol-def"])
 }
 
-func TestListAllVolumeIDs_EmptyBucket(t *testing.T) {
+func TestListAllVolumes_EmptyBucket(t *testing.T) {
 	store := objectstore.NewMemoryObjectStore()
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
-	ids, err := svc.listAllVolumeIDs(context.Background())
+	volumes, err := svc.metadata.ListAllVolumes(context.Background())
 	require.NoError(t, err)
-	assert.Empty(t, ids)
+	assert.Empty(t, volumes)
 }
 
-func TestListAllVolumeIDs_NilPrefix(t *testing.T) {
+func TestListAllVolumes_SingleDocument(t *testing.T) {
 	store := objectstore.NewMemoryObjectStore()
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
@@ -1657,10 +1667,10 @@ func TestListAllVolumeIDs_NilPrefix(t *testing.T) {
 		VolumeID: "vol-only", CapacityGiB: 10, State: "available",
 	})
 
-	ids, err := svc.listAllVolumeIDs(context.Background())
+	volumes, err := svc.metadata.ListAllVolumes(context.Background())
 	require.NoError(t, err)
-	assert.Len(t, ids, 1)
-	assert.Equal(t, "vol-only", ids[0])
+	require.Len(t, volumes, 1)
+	assert.Equal(t, "vol-only", volumes[0].VolumeID)
 }
 
 // --- Group 7: DeleteVolume remaining tests ---
@@ -1680,7 +1690,7 @@ func TestDeleteVolume_VolumeInUse(t *testing.T) {
 
 	_, err := svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{
 		VolumeId: aws.String("vol-busy"),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorVolumeInUse, err.Error())
 }
@@ -1703,7 +1713,7 @@ func TestDeleteVolume_VolumeAttachedButAvailable(t *testing.T) {
 
 	_, err := svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{
 		VolumeId: aws.String("vol-attached"),
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorVolumeInUse, err.Error())
 }
@@ -1724,7 +1734,7 @@ func TestDeleteVolume_EmptyStateUnattachedDeletable(t *testing.T) {
 
 	_, err := svc.DeleteVolume(context.Background(), &ec2.DeleteVolumeInput{
 		VolumeId: aws.String("vol-drift"),
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 }
 
@@ -1750,10 +1760,10 @@ func TestDeleteVolumeOnTerminate_ClearsAttachmentThenDeletes(t *testing.T) {
 		AttachedInstance: "i-stopped",
 	})
 
-	err := svc.DeleteVolumeOnTerminate(context.Background(), volumeID, "")
+	err := svc.DeleteVolumeOnTerminate(context.Background(), volumeID, testVolAccountID)
 	require.NoError(t, err, "terminate implies detach: a stale attachment must not block the terminate delete")
 
-	_, err = svc.GetVolumeMetadata(volumeID)
+	_, err = svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.Error(t, err, "the volume must actually be deleted, not merely detached")
 	assert.Contains(t, err.Error(), awserrors.ErrorInvalidVolumeNotFound)
 }
@@ -1769,7 +1779,7 @@ func TestDeleteVolumeOnTerminate_AlreadyGoneMetadataIsSuccess(t *testing.T) {
 	svc.snapshotKV = kv
 
 	// No metadata doc is ever written for this volume ID.
-	err := svc.DeleteVolumeOnTerminate(context.Background(), "vol-already-gone", "")
+	err := svc.DeleteVolumeOnTerminate(context.Background(), "vol-already-gone", testVolAccountID)
 	require.NoError(t, err, "a volume with no metadata document is already gone, not a teardown failure")
 }
 
@@ -1782,7 +1792,7 @@ func TestDetachVolumeOnTerminate_AlreadyGoneMetadataIsSuccess(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 	svc.snapshotKV = kv
 
-	err := svc.DetachVolumeOnTerminate(context.Background(), "vol-already-gone", "")
+	err := svc.DetachVolumeOnTerminate(context.Background(), "vol-already-gone", testVolAccountID)
 	require.NoError(t, err, "a volume with no metadata document is already gone, not a teardown failure")
 }
 
@@ -1811,11 +1821,11 @@ func TestDeleteVolumeOnTerminate_SurfacesDeleteFailure(t *testing.T) {
 	_, err = kv.Put(t.Context(), volumeID, snapData)
 	require.NoError(t, err)
 
-	err = svc.DeleteVolumeOnTerminate(context.Background(), volumeID, "")
+	err = svc.DeleteVolumeOnTerminate(context.Background(), volumeID, testVolAccountID)
 	require.Error(t, err, "a DeleteVolume failure must be surfaced, not swallowed")
 	assert.Contains(t, err.Error(), awserrors.ErrorVolumeInUse)
 
-	meta, getErr := svc.GetVolumeMetadata(volumeID)
+	meta, getErr := svc.GetVolumeMetadata(testVolAccountID, volumeID)
 	require.NoError(t, getErr, "the volume must still exist after a failed delete")
 	assert.Empty(t, meta.AttachedInstance, "the attachment clear runs before delete and is not rolled back on a later delete failure")
 }
@@ -1846,8 +1856,8 @@ func TestUpdateVolumeState_EmptyUnattachedNormalizesToAvailable(t *testing.T) {
 
 	// A detach writeback that clears the attachment without a state must not
 	// strand the volume with an empty State.
-	require.NoError(t, svc.UpdateVolumeState("vol-norm", "", "", ""))
-	meta, err := svc.GetVolumeMetadata("vol-norm")
+	require.NoError(t, svc.UpdateVolumeState(testVolAccountID, "vol-norm", "", "", ""))
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-norm")
 	require.NoError(t, err)
 	assert.Equal(t, "available", meta.State)
 	assert.Empty(t, meta.AttachedInstance)
@@ -1866,7 +1876,7 @@ func TestDescribeVolumeStatus_SlowPath_WithVolumes(t *testing.T) {
 		})
 	}
 
-	output, err := svc.DescribeVolumeStatus(context.Background(), nil, "")
+	output, err := svc.DescribeVolumeStatus(context.Background(), nil, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, output.VolumeStatuses, 2)
 
@@ -1890,7 +1900,7 @@ func TestDescribeVolumeStatus_FastPath_WithVolumes(t *testing.T) {
 
 	output, err := svc.DescribeVolumeStatus(context.Background(), &ec2.DescribeVolumeStatusInput{
 		VolumeIds: []*string{aws.String("vol-status1")},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, output.VolumeStatuses, 1)
 	assert.Equal(t, "vol-status1", *output.VolumeStatuses[0].VolumeId)
@@ -1904,17 +1914,17 @@ func TestDescribeVolumes_FilterByStatus(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-avail", ebsmetadata.Volume{
-		VolumeID: "vol-avail", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-avail", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-inuse", ebsmetadata.Volume{
-		VolumeID: "vol-inuse", CapacityGiB: 20, State: "in-use", TenantID: "acct1",
+		VolumeID: "vol-inuse", CapacityGiB: 20, State: "in-use", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("status"), Values: []*string{aws.String("available")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-avail", *out.Volumes[0].VolumeId)
@@ -1925,17 +1935,17 @@ func TestDescribeVolumes_FilterByVolumeType(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-gp3", ebsmetadata.Volume{
-		VolumeID: "vol-gp3", CapacityGiB: 10, State: "available", VolumeType: "gp3", TenantID: "acct1",
+		VolumeID: "vol-gp3", CapacityGiB: 10, State: "available", VolumeType: "gp3", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-io1", ebsmetadata.Volume{
-		VolumeID: "vol-io1", CapacityGiB: 10, State: "available", VolumeType: "io1", TenantID: "acct1",
+		VolumeID: "vol-io1", CapacityGiB: 10, State: "available", VolumeType: "io1", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-type"), Values: []*string{aws.String("gp3")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-gp3", *out.Volumes[0].VolumeId)
@@ -1946,17 +1956,17 @@ func TestDescribeVolumes_FilterBySize(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-small", ebsmetadata.Volume{
-		VolumeID: "vol-small", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-small", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-big", ebsmetadata.Volume{
-		VolumeID: "vol-big", CapacityGiB: 100, State: "available", TenantID: "acct1",
+		VolumeID: "vol-big", CapacityGiB: 100, State: "available", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("size"), Values: []*string{aws.String("100")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-big", *out.Volumes[0].VolumeId)
@@ -1968,17 +1978,17 @@ func TestDescribeVolumes_FilterByAttachmentInstanceId(t *testing.T) {
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-att", ebsmetadata.Volume{
 		VolumeID: "vol-att", CapacityGiB: 10, State: "in-use",
-		AttachedInstance: "i-12345", DeviceName: "/dev/nbd0", TenantID: "acct1",
+		AttachedInstance: "i-12345", DeviceName: "/dev/nbd0", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-free", ebsmetadata.Volume{
-		VolumeID: "vol-free", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-free", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("attachment.instance-id"), Values: []*string{aws.String("i-12345")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-att", *out.Volumes[0].VolumeId)
@@ -1990,18 +2000,18 @@ func TestDescribeVolumes_FilterByAttachmentDevice(t *testing.T) {
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-nbd0", ebsmetadata.Volume{
 		VolumeID: "vol-nbd0", CapacityGiB: 10, State: "in-use",
-		AttachedInstance: "i-12345", DeviceName: "/dev/nbd0", TenantID: "acct1",
+		AttachedInstance: "i-12345", DeviceName: "/dev/nbd0", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-nbd1", ebsmetadata.Volume{
 		VolumeID: "vol-nbd1", CapacityGiB: 10, State: "in-use",
-		AttachedInstance: "i-12345", DeviceName: "/dev/nbd1", TenantID: "acct1",
+		AttachedInstance: "i-12345", DeviceName: "/dev/nbd1", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("attachment.device"), Values: []*string{aws.String("/dev/nbd1")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-nbd1", *out.Volumes[0].VolumeId)
@@ -2013,18 +2023,18 @@ func TestDescribeVolumes_FilterByAZ(t *testing.T) {
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-az1", ebsmetadata.Volume{
 		VolumeID: "vol-az1", CapacityGiB: 10, State: "available",
-		AvailabilityZone: "ap-southeast-2a", TenantID: "acct1",
+		AvailabilityZone: "ap-southeast-2a", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-az2", ebsmetadata.Volume{
 		VolumeID: "vol-az2", CapacityGiB: 10, State: "available",
-		AvailabilityZone: "ap-southeast-2b", TenantID: "acct1",
+		AvailabilityZone: "ap-southeast-2b", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("availability-zone"), Values: []*string{aws.String("ap-southeast-2a")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-az1", *out.Volumes[0].VolumeId)
@@ -2035,21 +2045,21 @@ func TestDescribeVolumes_FilterMultipleValues_OR(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-avail", ebsmetadata.Volume{
-		VolumeID: "vol-avail", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-avail", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-inuse", ebsmetadata.Volume{
 		VolumeID: "vol-inuse", CapacityGiB: 10, State: "in-use",
-		AttachedInstance: "i-1", DeviceName: "/dev/nbd0", TenantID: "acct1",
+		AttachedInstance: "i-1", DeviceName: "/dev/nbd0", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-del", ebsmetadata.Volume{
-		VolumeID: "vol-del", CapacityGiB: 10, State: "deleted", TenantID: "acct1",
+		VolumeID: "vol-del", CapacityGiB: 10, State: "deleted", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("status"), Values: []*string{aws.String("available"), aws.String("in-use")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 2)
 }
@@ -2060,11 +2070,11 @@ func TestDescribeVolumes_FilterMultipleFilters_AND(t *testing.T) {
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-match", ebsmetadata.Volume{
 		VolumeID: "vol-match", CapacityGiB: 10, State: "available",
-		VolumeType: "gp3", TenantID: "acct1",
+		VolumeType: "gp3", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-nomatch", ebsmetadata.Volume{
 		VolumeID: "vol-nomatch", CapacityGiB: 10, State: "in-use",
-		VolumeType: "gp3", AttachedInstance: "i-1", DeviceName: "/dev/nbd0", TenantID: "acct1",
+		VolumeType: "gp3", AttachedInstance: "i-1", DeviceName: "/dev/nbd0", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
@@ -2072,7 +2082,7 @@ func TestDescribeVolumes_FilterMultipleFilters_AND(t *testing.T) {
 			{Name: aws.String("status"), Values: []*string{aws.String("available")}},
 			{Name: aws.String("volume-type"), Values: []*string{aws.String("gp3")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-match", *out.Volumes[0].VolumeId)
@@ -2086,7 +2096,7 @@ func TestDescribeVolumes_FilterUnknownName_Error(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("bogus-filter"), Values: []*string{aws.String("val")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidParameterValue, err.Error())
 }
@@ -2096,14 +2106,14 @@ func TestDescribeVolumes_FilterNoResults(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-one", ebsmetadata.Volume{
-		VolumeID: "vol-one", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-one", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("status"), Values: []*string{aws.String("deleted")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Empty(t, out.Volumes)
 }
@@ -2113,13 +2123,13 @@ func TestDescribeVolumes_FilterNoFilters(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-a", ebsmetadata.Volume{
-		VolumeID: "vol-a", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-a", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-b", ebsmetadata.Volume{
-		VolumeID: "vol-b", CapacityGiB: 20, State: "available", TenantID: "acct1",
+		VolumeID: "vol-b", CapacityGiB: 20, State: "available", TenantID: "000000000001",
 	})
 
-	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "acct1")
+	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 2)
 }
@@ -2130,18 +2140,18 @@ func TestDescribeVolumes_FilterWildcard(t *testing.T) {
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-az1", ebsmetadata.Volume{
 		VolumeID: "vol-az1", CapacityGiB: 10, State: "available",
-		AvailabilityZone: "ap-southeast-2a", TenantID: "acct1",
+		AvailabilityZone: "ap-southeast-2a", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-az2", ebsmetadata.Volume{
 		VolumeID: "vol-az2", CapacityGiB: 10, State: "available",
-		AvailabilityZone: "us-east-1a", TenantID: "acct1",
+		AvailabilityZone: "us-east-1a", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("availability-zone"), Values: []*string{aws.String("ap-*")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-az1", *out.Volumes[0].VolumeId)
@@ -2152,18 +2162,18 @@ func TestDescribeVolumes_FilterByTag(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-tagged", ebsmetadata.Volume{
-		VolumeID: "vol-tagged", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-tagged", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 		Tags: map[string]string{"Environment": "prod"},
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-untagged", ebsmetadata.Volume{
-		VolumeID: "vol-untagged", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-untagged", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 
 	out, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{
 		Filters: []*ec2.Filter{
 			{Name: aws.String("tag:Environment"), Values: []*string{aws.String("prod")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-tagged", *out.Volumes[0].VolumeId)
@@ -2174,11 +2184,11 @@ func TestDescribeVolumes_FilterWithVolumeIds(t *testing.T) {
 	svc := newTestVolumeServiceWithStore("ap-southeast-2a", store)
 
 	createVolumeInStoreWithMeta(t, svc, store, "vol-a", ebsmetadata.Volume{
-		VolumeID: "vol-a", CapacityGiB: 10, State: "available", TenantID: "acct1",
+		VolumeID: "vol-a", CapacityGiB: 10, State: "available", TenantID: "000000000001",
 	})
 	createVolumeInStoreWithMeta(t, svc, store, "vol-b", ebsmetadata.Volume{
 		VolumeID: "vol-b", CapacityGiB: 10, State: "in-use",
-		AttachedInstance: "i-1", DeviceName: "/dev/nbd0", TenantID: "acct1",
+		AttachedInstance: "i-1", DeviceName: "/dev/nbd0", TenantID: "000000000001",
 	})
 
 	// Request both by ID but filter to only available
@@ -2187,7 +2197,7 @@ func TestDescribeVolumes_FilterWithVolumeIds(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("status"), Values: []*string{aws.String("available")}},
 		},
-	}, "acct1")
+	}, "000000000001")
 	require.NoError(t, err)
 	assert.Len(t, out.Volumes, 1)
 	assert.Equal(t, "vol-a", *out.Volumes[0].VolumeId)
@@ -2208,7 +2218,7 @@ func TestDescribeVolumeStatus_FilterByVolumeId(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-id"), Values: []*string{aws.String("vol-vs1")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	require.Len(t, out.VolumeStatuses, 1)
 	assert.Equal(t, "vol-vs1", *out.VolumeStatuses[0].VolumeId)
@@ -2227,7 +2237,7 @@ func TestDescribeVolumeStatus_FilterByStatus(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-status.status"), Values: []*string{aws.String("ok")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, out.VolumeStatuses, 1)
 
@@ -2235,7 +2245,7 @@ func TestDescribeVolumeStatus_FilterByStatus(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-status.status"), Values: []*string{aws.String("impaired")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, out.VolumeStatuses)
 }
@@ -2252,7 +2262,7 @@ func TestDescribeVolumeStatus_FilterByAZ(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("availability-zone"), Values: []*string{aws.String("ap-southeast-2a")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, out.VolumeStatuses, 1)
 
@@ -2260,7 +2270,7 @@ func TestDescribeVolumeStatus_FilterByAZ(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("availability-zone"), Values: []*string{aws.String("us-east-1a")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, out.VolumeStatuses)
 }
@@ -2283,7 +2293,7 @@ func TestDescribeVolumeStatus_FilterMultipleValues_OR(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-id"), Values: []*string{aws.String("vol-vsor1"), aws.String("vol-vsor3")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, out.VolumeStatuses, 2)
 }
@@ -2302,7 +2312,7 @@ func TestDescribeVolumeStatus_FilterMultipleFilters_AND(t *testing.T) {
 			{Name: aws.String("volume-id"), Values: []*string{aws.String("vol-vsand")}},
 			{Name: aws.String("volume-status.status"), Values: []*string{aws.String("ok")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, out.VolumeStatuses, 1)
 
@@ -2312,7 +2322,7 @@ func TestDescribeVolumeStatus_FilterMultipleFilters_AND(t *testing.T) {
 			{Name: aws.String("volume-id"), Values: []*string{aws.String("vol-vsand")}},
 			{Name: aws.String("availability-zone"), Values: []*string{aws.String("us-east-1a")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, out.VolumeStatuses)
 }
@@ -2325,7 +2335,7 @@ func TestDescribeVolumeStatus_FilterUnknownName_Error(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("bogus-filter"), Values: []*string{aws.String("x")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	assert.Error(t, err)
 }
 
@@ -2341,7 +2351,7 @@ func TestDescribeVolumeStatus_FilterWildcard(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-id"), Values: []*string{aws.String("vol-vswild*")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, out.VolumeStatuses, 1)
 }
@@ -2358,7 +2368,7 @@ func TestDescribeVolumeStatus_FilterNoResults(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("volume-id"), Values: []*string{aws.String("vol-nonexistent")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Empty(t, out.VolumeStatuses)
 }
@@ -2380,7 +2390,7 @@ func TestDescribeVolumeStatus_FilterWithVolumeIds(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("availability-zone"), Values: []*string{aws.String("ap-southeast-2a")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.NoError(t, err)
 	assert.Len(t, out.VolumeStatuses, 1)
 	assert.Equal(t, "vol-vsf1", *out.VolumeStatuses[0].VolumeId)
@@ -2407,7 +2417,7 @@ func TestDescribeVolumesModifications_RoundTrip(t *testing.T) {
 	require.NoError(t, err)
 
 	// Confirm Modification was persisted on cfg.
-	meta, err := svc.GetVolumeMetadata("vol-rt")
+	meta, err := svc.GetVolumeMetadata("111111111111", "vol-rt")
 	require.NoError(t, err)
 	require.NotNil(t, meta.Modification)
 	assert.Equal(t, int64(10), meta.Modification.OriginalSize)
@@ -2618,7 +2628,7 @@ func TestDescribeVolumesModifications_UnknownFilter(t *testing.T) {
 		Filters: []*ec2.Filter{
 			{Name: aws.String("not-a-real-filter"), Values: []*string{aws.String("x")}},
 		},
-	}, "")
+	}, testVolAccountID)
 	require.Error(t, err)
 	assert.Equal(t, awserrors.ErrorInvalidParameterValue, err.Error())
 }
diff --git a/spinifex/handlers/ec2/volume/testhelpers_test.go b/spinifex/handlers/ec2/volume/testhelpers_test.go
index 90f0e37a8..ba5fc9014 100644
--- a/spinifex/handlers/ec2/volume/testhelpers_test.go
+++ b/spinifex/handlers/ec2/volume/testhelpers_test.go
@@ -26,6 +26,11 @@ func startTestNATS(t *testing.T) *nats.Conn {
 // exist as far as the control plane is concerned.
 func seedVolumeDocument(t *testing.T, store objectstore.ObjectStore, volume ebsmetadata.Volume) {
 	t.Helper()
+	// The owning account is a key segment, so a fixture that does not care
+	// which account owns it still has to have one.
+	if volume.TenantID == "" {
+		volume.TenantID = testVolAccountID
+	}
 	require.NoError(t, ebsmetadata.NewStore(store, "test-bucket").PutVolume(context.Background(), volume))
 }
 
diff --git a/spinifex/handlers/ec2/volume/volume_leak_reaper.go b/spinifex/handlers/ec2/volume/volume_leak_reaper.go
index 672f61c95..f7acb3194 100644
--- a/spinifex/handlers/ec2/volume/volume_leak_reaper.go
+++ b/spinifex/handlers/ec2/volume/volume_leak_reaper.go
@@ -53,23 +53,23 @@ func (r *VolumeLeakReaper) Sweep(ctx context.Context) (int, error) {
 		return 0, nil
 	}
 
-	ids, err := r.svc.listAllVolumeIDs(ctx)
+	// The sweep is node-local GC with no caller account, so each volume's own
+	// document supplies the account its key is under. Listing documents rather
+	// than IDs is what makes that available without a second read.
+	volumes, err := r.svc.metadata.ListAllVolumes(ctx)
 	if err != nil {
 		return 0, err
 	}
 
 	marked := 0
-	for _, id := range ids {
+	for _, meta := range volumes {
 		select {
 		case <-ctx.Done():
 			return marked, ctx.Err()
 		default:
 		}
 
-		meta, err := r.svc.metadata.GetVolume(ctx, id)
-		if err != nil {
-			continue
-		}
+		id := meta.VolumeID
 		attachedInstance, tags, sizeGiB := meta.AttachedInstance, meta.Tags, meta.CapacityGiB
 
 		if attachedInstance == "" || !leaked[attachedInstance] {
@@ -79,7 +79,7 @@ func (r *VolumeLeakReaper) Sweep(ctx context.Context) (int, error) {
 			continue // already surfaced; idempotent
 		}
 
-		if err := r.svc.markVolumeOrphaned(ctx, id, tags, attachedInstance); err != nil {
+		if err := r.svc.markVolumeOrphaned(ctx, meta.TenantID, id, tags, attachedInstance); err != nil {
 			slog.Error("volume-leak: failed to mark orphaned volume", "volumeId", id, "err", err)
 			continue
 		}
@@ -92,7 +92,7 @@ func (r *VolumeLeakReaper) Sweep(ctx context.Context) (int, error) {
 		// owning instance is definitively terminated (this node's leaked
 		// set), so nothing still claims the volume; clearing the stale
 		// attachment lets an operator DeleteVolume it after seeing the alarm.
-		if err := r.svc.UpdateVolumeState(id, "available", "", ""); err != nil {
+		if err := r.svc.UpdateVolumeState(meta.TenantID, id, "available", "", ""); err != nil {
 			slog.Error("volume-leak: failed to reconcile orphaned volume attachment", "volumeId", id, "err", err)
 		}
 		marked++
@@ -103,14 +103,14 @@ func (r *VolumeLeakReaper) Sweep(ctx context.Context) (int, error) {
 // markVolumeOrphaned tags the volume as orphaned. tags is the volume's
 // current, already-authoritative tag set; the volume's data and state remain
 // untouched.
-func (s *VolumeServiceImpl) markVolumeOrphaned(ctx context.Context, volumeID string, tags map[string]string, attachedInstance string) error {
+func (s *VolumeServiceImpl) markVolumeOrphaned(ctx context.Context, accountID, volumeID string, tags map[string]string, attachedInstance string) error {
 	if tags == nil {
 		tags = make(map[string]string)
 	}
 	tags[orphanTagKey] = time.Now().UTC().Format(time.RFC3339)
 	tags[orphanInstanceTagKey] = attachedInstance
 
-	meta, err := s.metadata.GetVolume(ctx, volumeID)
+	meta, err := s.metadata.GetVolume(ctx, accountID, volumeID)
 	if err != nil {
 		return err
 	}
diff --git a/spinifex/handlers/ec2/volume/volume_leak_reaper_test.go b/spinifex/handlers/ec2/volume/volume_leak_reaper_test.go
index a06e61b19..352de11ff 100644
--- a/spinifex/handlers/ec2/volume/volume_leak_reaper_test.go
+++ b/spinifex/handlers/ec2/volume/volume_leak_reaper_test.go
@@ -28,7 +28,7 @@ func TestVolumeLeakReaper_ReconcilesAttachmentNeverDeletesData(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 1, marked)
 
-	meta, err := svc.GetVolumeMetadata("vol-leaked-reconcile")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-leaked-reconcile")
 	require.NoError(t, err, "the reaper must never delete the volume, only mark + reconcile it")
 	assert.NotEmpty(t, meta.Tags[orphanTagKey], "the volume must still be marked orphaned")
 	assert.Equal(t, "available", meta.State,
@@ -62,7 +62,7 @@ func TestVolumeLeakReaper_LiveOwnerAttachmentUntouched(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 0, marked)
 
-	meta, err := svc.GetVolumeMetadata("vol-live-reconcile")
+	meta, err := svc.GetVolumeMetadata(testVolAccountID, "vol-live-reconcile")
 	require.NoError(t, err)
 	assert.Equal(t, "in-use", meta.State, "a live-owner volume's attachment must never be reconciled")
 	assert.Equal(t, "i-running00000000", meta.AttachedInstance)
diff --git a/spinifex/handlers/ec2/volume/volume_partition_test.go b/spinifex/handlers/ec2/volume/volume_partition_test.go
new file mode 100644
index 000000000..3c8c2ba74
--- /dev/null
+++ b/spinifex/handlers/ec2/volume/volume_partition_test.go
@@ -0,0 +1,150 @@
+// These tests reach svc.metadata and the unexported describes, all
+// package-internal.
+//
+//test:in-package
+package handlers_ec2_volume
+
+import (
+	"context"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/mulgadc/spinifex/spinifex/config"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
+	"github.com/mulgadc/spinifex/spinifex/testutil/recordingstore"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const otherVolAccountID = "210987654321"
+
+// volumePartitionService returns a service over a recording store holding one
+// volume for each of two accounts, with the seeding writes already forgotten.
+func volumePartitionService(t *testing.T) (*VolumeServiceImpl, *recordingstore.Store) {
+	t.Helper()
+	objects := recordingstore.New()
+	cfg := &config.Config{AZ: "ap-southeast-2a", Predastore: config.PredastoreConfig{Bucket: "test-bucket"}}
+	svc := NewVolumeServiceImplWithStore(cfg, objects, nil)
+
+	ctx := context.Background()
+	for _, volume := range []ebsmetadata.Volume{
+		{VolumeID: "vol-mine", TenantID: testVolAccountID, CapacityGiB: 8, State: "available",
+			AvailabilityZone: "ap-southeast-2a"},
+		{VolumeID: "vol-theirs", TenantID: otherVolAccountID, CapacityGiB: 16, State: "available",
+			AvailabilityZone: "ap-southeast-2a"},
+	} {
+		require.NoError(t, svc.metadata.PutVolume(ctx, volume))
+	}
+	objects.Reset()
+	return svc, objects
+}
+
+// otherAccountPrefix is spelled out rather than derived: it is the layout claim
+// itself, and deriving it from the code under test would assert nothing.
+const otherAccountPrefix = "spinifex/ebsmetadata/v2/volumes/" + otherVolAccountID + "/"
+
+// Isolation must be enforced *by* the read, not by a filter after it. A
+// whole-tree listing plus a correct in-memory filter would return the same
+// volumes, so this asserts the access pattern: the listing prefix is the
+// caller's own, and no key under another account's prefix is fetched.
+func TestDescribeVolumes_TouchesNoOtherAccountsPrefix(t *testing.T) {
+	svc, objects := volumePartitionService(t)
+
+	listed, err := svc.DescribeVolumes(context.Background(), &ec2.DescribeVolumesInput{}, testVolAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.Volumes, 1)
+	assert.Equal(t, "vol-mine", aws.StringValue(listed.Volumes[0].VolumeId))
+
+	assert.False(t, objects.TouchedPrefix(otherAccountPrefix),
+		"a describe must not read or list another account's prefix: %v %v", objects.ListPrefixes(), objects.Gets())
+}
+
+func TestDescribeVolumeStatus_TouchesNoOtherAccountsPrefix(t *testing.T) {
+	svc, objects := volumePartitionService(t)
+
+	listed, err := svc.DescribeVolumeStatus(context.Background(), &ec2.DescribeVolumeStatusInput{}, testVolAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.VolumeStatuses, 1)
+	assert.Equal(t, "vol-mine", aws.StringValue(listed.VolumeStatuses[0].VolumeId))
+
+	assert.False(t, objects.TouchedPrefix(otherAccountPrefix),
+		"a status describe must not read or list another account's prefix: %v %v", objects.ListPrefixes(), objects.Gets())
+}
+
+func TestDescribeVolumesModifications_TouchesNoOtherAccountsPrefix(t *testing.T) {
+	svc, objects := volumePartitionService(t)
+
+	_, err := svc.DescribeVolumesModifications(context.Background(), &ec2.DescribeVolumesModificationsInput{}, testVolAccountID)
+	require.NoError(t, err)
+
+	assert.False(t, objects.TouchedPrefix(otherAccountPrefix),
+		"a modifications describe must not read or list another account's prefix: %v %v", objects.ListPrefixes(), objects.Gets())
+}
+
+// Given explicit IDs the status describe fetches each document, exactly as
+// DescribeVolumes does. Enumerating the prefix to answer for one volume is the
+// bug this fast path exists to remove, so the assertion is that nothing lists.
+func TestDescribeVolumeStatus_ByIDDoesNotList(t *testing.T) {
+	svc, objects := volumePartitionService(t)
+
+	listed, err := svc.DescribeVolumeStatus(context.Background(),
+		&ec2.DescribeVolumeStatusInput{VolumeIds: []*string{aws.String("vol-mine")}}, testVolAccountID)
+	require.NoError(t, err)
+	require.Len(t, listed.VolumeStatuses, 1)
+	assert.Equal(t, "vol-mine", aws.StringValue(listed.VolumeStatuses[0].VolumeId))
+
+	assert.Empty(t, objects.ListPrefixes(), "a by-ID status describe must fetch documents, not enumerate a prefix")
+}
+
+// A volume outside the caller's prefix is absent rather than denied: the key is
+// the ownership check, and the by-ID path reports it as not-found.
+func TestDescribeVolumeStatus_ByIDOtherAccountIsNotFound(t *testing.T) {
+	svc, _ := volumePartitionService(t)
+
+	_, err := svc.DescribeVolumeStatus(context.Background(),
+		&ec2.DescribeVolumeStatusInput{VolumeIds: []*string{aws.String("vol-theirs")}}, testVolAccountID)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "InvalidVolume.NotFound")
+}
+
+// A caller with no account cannot name a prefix, so the listing fails rather
+// than widening to every account's volumes.
+func TestVolumeDescribes_RefuseACallerWithNoAccount(t *testing.T) {
+	svc, _ := volumePartitionService(t)
+	ctx := context.Background()
+
+	for name, describe := range map[string]func() error{
+		"DescribeVolumes": func() error {
+			_, err := svc.DescribeVolumes(ctx, &ec2.DescribeVolumesInput{}, "")
+			return err
+		},
+		"DescribeVolumeStatus": func() error {
+			_, err := svc.DescribeVolumeStatus(ctx, &ec2.DescribeVolumeStatusInput{}, "")
+			return err
+		},
+		"DescribeVolumesModifications": func() error {
+			_, err := svc.DescribeVolumesModifications(ctx, &ec2.DescribeVolumesModificationsInput{}, "")
+			return err
+		},
+	} {
+		require.Error(t, describe(), name)
+	}
+}
+
+// The whole-cluster verb is what the leak reaper and the admin scans want, and
+// it must reach every account's documents rather than the caller's alone.
+func TestListAllVolumes_ReachesEveryAccount(t *testing.T) {
+	svc, objects := volumePartitionService(t)
+
+	all, err := svc.metadata.ListAllVolumes(context.Background())
+	require.NoError(t, err)
+
+	ids := make([]string, 0, len(all))
+	for _, volume := range all {
+		ids = append(ids, volume.VolumeID)
+	}
+	assert.ElementsMatch(t, []string{"vol-mine", "vol-theirs"}, ids)
+	assert.Equal(t, []string{"spinifex/ebsmetadata/v2/volumes/"}, objects.ListPrefixes(),
+		"the whole-cluster verb lists across accounts, not under one")
+}
diff --git a/spinifex/services/viperblockd/list_volumes_test.go b/spinifex/services/viperblockd/list_volumes_test.go
index 28c4bdeca..7b913f175 100644
--- a/spinifex/services/viperblockd/list_volumes_test.go
+++ b/spinifex/services/viperblockd/list_volumes_test.go
@@ -33,7 +33,7 @@ func TestListVolumePrefixes_SkipsWhatIsNotAVolume(t *testing.T) {
 	putListObject(t, store, "ami-dd7f063caded1ff82/config.json")
 	putListObject(t, store, "snap-ami-dd7f063caded1ff82/config.json")
 	putListObject(t, store, "keys/cluster.key")
-	putListObject(t, store, "spinifex/ebsmetadata/v1/volumes/vol-0123456789abc.json")
+	putListObject(t, store, "spinifex/ebsmetadata/v2/volumes/000000000001/vol-0123456789abc.json")
 
 	ids, err := listVolumePrefixes(t.Context(), store, listTestBucket)
 	require.NoError(t, err)
diff --git a/spinifex/testutil/recordingstore/recordingstore.go b/spinifex/testutil/recordingstore/recordingstore.go
new file mode 100644
index 000000000..5cae6ae28
--- /dev/null
+++ b/spinifex/testutil/recordingstore/recordingstore.go
@@ -0,0 +1,86 @@
+// Package recordingstore provides an objectstore.ObjectStore fake that records
+// every key it is asked to read and every prefix it is asked to list. It exists
+// so tests can assert an access pattern rather than only an answer: that an
+// account-scoped listing never touched another account's prefix, which an
+// in-memory filter over a whole-cluster read would satisfy just as well.
+package recordingstore
+
+import (
+	"context"
+	"strings"
+	"sync"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/mulgadc/spinifex/spinifex/objectstore"
+)
+
+// Store wraps a MemoryObjectStore, appending to Gets and ListPrefixes before
+// delegating. Both slices are safe to read once the call under test returns.
+type Store struct {
+	*objectstore.MemoryObjectStore
+
+	mu           sync.Mutex
+	gets         []string
+	listPrefixes []string
+}
+
+// New returns a recording store backed by an empty in-memory store.
+func New() *Store {
+	return &Store{MemoryObjectStore: objectstore.NewMemoryObjectStore()}
+}
+
+var _ objectstore.ObjectStore = (*Store)(nil)
+
+func (s *Store) GetObject(ctx context.Context, input *s3.GetObjectInput) (*s3.GetObjectOutput, error) {
+	s.mu.Lock()
+	s.gets = append(s.gets, aws.StringValue(input.Key))
+	s.mu.Unlock()
+	return s.MemoryObjectStore.GetObject(ctx, input)
+}
+
+func (s *Store) ListObjectsV2(ctx context.Context, input *s3.ListObjectsV2Input) (*s3.ListObjectsV2Output, error) {
+	s.mu.Lock()
+	s.listPrefixes = append(s.listPrefixes, aws.StringValue(input.Prefix))
+	s.mu.Unlock()
+	return s.MemoryObjectStore.ListObjectsV2(ctx, input)
+}
+
+// Gets returns every key read so far.
+func (s *Store) Gets() []string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return append([]string(nil), s.gets...)
+}
+
+// ListPrefixes returns every prefix listed so far.
+func (s *Store) ListPrefixes() []string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return append([]string(nil), s.listPrefixes...)
+}
+
+// Reset drops what has been recorded, so a test can seed fixtures and then
+// assert only on the call it is actually exercising.
+func (s *Store) Reset() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.gets, s.listPrefixes = nil, nil
+}
+
+// TouchedPrefix reports whether any recorded get or listing named a key under
+// prefix. This is the blast-radius assertion: it must be false for every
+// account other than the caller's.
+func (s *Store) TouchedPrefix(prefix string) bool {
+	for _, key := range s.Gets() {
+		if strings.HasPrefix(key, prefix) {
+			return true
+		}
+	}
+	for _, listed := range s.ListPrefixes() {
+		if strings.HasPrefix(listed, prefix) || strings.HasPrefix(prefix, listed) {
+			return true
+		}
+	}
+	return false
+}
diff --git a/spinifex/vm/instance_type_resolver.go b/spinifex/vm/instance_type_resolver.go
index 402d65740..5143d2884 100644
--- a/spinifex/vm/instance_type_resolver.go
+++ b/spinifex/vm/instance_type_resolver.go
@@ -35,5 +35,5 @@ type ResourceController interface {
 // VolumeStateUpdater is the narrow slice of the volume service the manager
 // touches: marking boot volumes "in-use" once a VM is confirmed running.
 type VolumeStateUpdater interface {
-	UpdateVolumeState(volumeID, state, instanceID, attachmentDevice string) error
+	UpdateVolumeState(accountID, volumeID, state, instanceID, attachmentDevice string) error
 }
diff --git a/spinifex/vm/lifecycle.go b/spinifex/vm/lifecycle.go
index 9b5e1cc0a..98e51bb4e 100644
--- a/spinifex/vm/lifecycle.go
+++ b/spinifex/vm/lifecycle.go
@@ -331,7 +331,7 @@ func (m *Manager) markAttachedVolumesInUse(instance *VM) error {
 		if m.deps.VolumeStateUpdater == nil {
 			return errors.New("volume state updater not wired")
 		}
-		if err := m.deps.VolumeStateUpdater.UpdateVolumeState(ebsReq.Name, "in-use", instance.ID, ebsReq.DeviceName); err != nil {
+		if err := m.deps.VolumeStateUpdater.UpdateVolumeState(instance.AccountID, ebsReq.Name, "in-use", instance.ID, ebsReq.DeviceName); err != nil {
 			return fmt.Errorf("persist in-use state for volume %s: %w", ebsReq.Name, err)
 		}
 	}
diff --git a/spinifex/vm/manager_deps_test.go b/spinifex/vm/manager_deps_test.go
index 4646eade5..8d7b076fa 100644
--- a/spinifex/vm/manager_deps_test.go
+++ b/spinifex/vm/manager_deps_test.go
@@ -214,15 +214,20 @@ type fakeVolumeStateUpdater struct {
 	onUpdate func(volumeStateUpdate)
 }
 
+// AccountID is recorded because it is the account segment of the document's
+// key: a call that passes anything but the instance's own account writes to a
+// key that does not exist, and nothing else in the suite would catch it.
 type volumeStateUpdate struct {
+	AccountID        string
 	VolumeID         string
 	State            string
 	InstanceID       string
 	AttachmentDevice string
 }
 
-func (f *fakeVolumeStateUpdater) UpdateVolumeState(volumeID, state, instanceID, attachmentDevice string) error {
+func (f *fakeVolumeStateUpdater) UpdateVolumeState(accountID, volumeID, state, instanceID, attachmentDevice string) error {
 	update := volumeStateUpdate{
+		AccountID:        accountID,
 		VolumeID:         volumeID,
 		State:            state,
 		InstanceID:       instanceID,
diff --git a/spinifex/vm/vm.go b/spinifex/vm/vm.go
index c2e84126d..ae26a41f1 100644
--- a/spinifex/vm/vm.go
+++ b/spinifex/vm/vm.go
@@ -118,8 +118,8 @@ type VM struct {
 	// Health tracks crash detection and auto-restart state
 	Health InstanceHealthState `json:"health"`
 
-	// AccountID is the AWS account that owns this instance. Empty for legacy
-	// resources visible only to the root account.
+	// AccountID is the AWS account that owns this instance, and is the account
+	// its volume documents are keyed under.
 	AccountID string `json:"account_id,omitempty"`
 
 	// VPC networking: ENI attached to this instance (set by RunInstances when VPC mode is active)
diff --git a/spinifex/vm/volume_state_account_test.go b/spinifex/vm/volume_state_account_test.go
new file mode 100644
index 000000000..af4e2b673
--- /dev/null
+++ b/spinifex/vm/volume_state_account_test.go
@@ -0,0 +1,148 @@
+// These tests reuse fakeVolumeStateUpdater, newMockQMPClient and qmpRecorder,
+// all package-internal.
+//
+//test:in-package
+package vm
+
+import (
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/mulgadc/spinifex/spinifex/qmp"
+	"github.com/mulgadc/spinifex/spinifex/types"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// stateAccountID is the instance-owning account these tests seed. It is a real
+// account ID rather than a placeholder because the production key builder
+// rejects anything utils.IsAccountID refuses.
+const stateAccountID = "000000000042"
+
+// Volume documents are keyed under the owning account, so UpdateVolumeState's
+// leading argument is a key segment rather than a label. The five production
+// call sites all pass instance.AccountID; passing anything else — the instance
+// ID is the very next argument and is also an untyped string — builds a key
+// that does not exist and leaves the attachment record stranded. These tests
+// are the only thing asserting that argument.
+
+// TestAttachVolume_KeysStateOnTheInstanceAccount covers vm/volumes.go:190.
+func TestAttachVolume_KeysStateOnTheInstanceAccount(t *testing.T) {
+	qmpClient, cancel := newMockQMPClient(t, func(cmd qmp.QMPCommand) map[string]any { return nil })
+	defer cancel()
+
+	stateUpdater := &fakeVolumeStateUpdater{}
+	mounter := &fakeVolumeMounter{mountOneURI: "nbd:unix:/tmp/test.sock"}
+	m := NewManagerWithDeps(Deps{VolumeMounter: mounter, VolumeStateUpdater: stateUpdater})
+	m.Insert(&VM{
+		ID: "i-1", Status: StateRunning, Instance: &ec2.Instance{},
+		QMPClient: qmpClient, AccountID: stateAccountID,
+	})
+
+	_, err := m.AttachVolume(t.Context(), "i-1", "vol-1", "/dev/sdf")
+	require.NoError(t, err)
+
+	calls := stateUpdater.snapshot()
+	require.Len(t, calls, 1)
+	assert.Equal(t, stateAccountID, calls[0].AccountID,
+		"the in-use write must be keyed on the instance's own account")
+	assert.Equal(t, "in-use", calls[0].State)
+}
+
+// TestAttachVolume_RollbackKeysStateOnTheInstanceAccount covers the rollback at
+// vm/volumes.go:213, which runs after device_add fails and is the path that
+// would silently leave a volume stuck in-use if it wrote to the wrong key.
+func TestAttachVolume_RollbackKeysStateOnTheInstanceAccount(t *testing.T) {
+	qmpClient, cancel := newMockQMPClient(t, func(cmd qmp.QMPCommand) map[string]any {
+		switch cmd.Execute {
+		case "query-block":
+			return map[string]any{"return": []qmp.BlockDevice{}}
+		case "device_add":
+			return map[string]any{"error": map[string]any{"class": "GenericError", "desc": "no PCI slot"}}
+		}
+		return nil
+	})
+	defer cancel()
+
+	stateUpdater := &fakeVolumeStateUpdater{}
+	mounter := &fakeVolumeMounter{mountOneURI: "nbd:unix:/tmp/test.sock"}
+	m := NewManagerWithDeps(Deps{VolumeMounter: mounter, VolumeStateUpdater: stateUpdater})
+	m.Insert(&VM{
+		ID: "i-1", Status: StateRunning, Instance: &ec2.Instance{},
+		QMPClient: qmpClient, AccountID: stateAccountID,
+	})
+
+	_, err := m.AttachVolume(t.Context(), "i-1", "vol-1", "/dev/sdf")
+	require.Error(t, err)
+
+	calls := stateUpdater.snapshot()
+	require.Len(t, calls, 2)
+	for i, call := range calls {
+		assert.Equalf(t, stateAccountID, call.AccountID,
+			"call %d (%s) must be keyed on the instance's own account", i, call.State)
+	}
+	assert.Equal(t, "available", calls[1].State)
+}
+
+// TestDetachVolume_KeysStateOnTheInstanceAccount covers vm/volumes.go:444.
+// Detach only logs an UpdateVolumeState failure, so a wrong account here leaves
+// the document reading in-use with no disk in the guest and no error anywhere.
+func TestDetachVolume_KeysStateOnTheInstanceAccount(t *testing.T) {
+	qmpClient, cancel := newMockQMPClientWithEvents(t, func(cmd qmp.QMPCommand, srv *mockQMPServer) map[string]any {
+		return nil
+	})
+	defer cancel()
+
+	stateUpdater := &fakeVolumeStateUpdater{}
+	mounter := &fakeVolumeMounter{}
+	m := NewManagerWithDeps(Deps{
+		VolumeMounter: mounter, VolumeStateUpdater: stateUpdater,
+		DeviceDeletedTimeout: 30 * time.Millisecond,
+	})
+	m.Insert(&VM{
+		ID: "i-1", Status: StateRunning, Instance: &ec2.Instance{},
+		QMPClient: qmpClient, AccountID: stateAccountID,
+		EBSRequests: types.EBSRequests{
+			Requests: []types.EBSRequest{{Name: "vol-1", DeviceName: "/dev/sdf"}},
+		},
+	})
+
+	_, err := m.DetachVolume(t.Context(), "i-1", "vol-1", "", false)
+	require.NoError(t, err)
+
+	calls := stateUpdater.snapshot()
+	require.Len(t, calls, 1)
+	assert.Equal(t, stateAccountID, calls[0].AccountID,
+		"the available write must be keyed on the instance's own account")
+	assert.Equal(t, "available", calls[0].State)
+}
+
+// TestAttachVolume_StateUpdateErrorSurfacesTheAccount pins that a key-builder
+// rejection is not swallowed: an instance whose AccountID cannot key a document
+// must fail the attach rather than proceed to device_add.
+func TestAttachVolume_StateUpdateErrorSurfacesTheAccount(t *testing.T) {
+	recorder := &qmpRecorder{}
+	qmpClient, cancel := newMockQMPClient(t, func(cmd qmp.QMPCommand) map[string]any {
+		recorder.record(cmd)
+		return nil
+	})
+	defer cancel()
+
+	keyErr := errors.New(`invalid EBS metadata account ID ""`)
+	stateUpdater := &fakeVolumeStateUpdater{err: keyErr}
+	mounter := &fakeVolumeMounter{mountOneURI: "nbd:unix:/tmp/test.sock"}
+	m := NewManagerWithDeps(Deps{VolumeMounter: mounter, VolumeStateUpdater: stateUpdater})
+	m.Insert(&VM{ID: "i-1", Status: StateRunning, Instance: &ec2.Instance{}, QMPClient: qmpClient})
+
+	_, err := m.AttachVolume(t.Context(), "i-1", "vol-1", "/dev/sdf")
+	require.Error(t, err)
+	assert.ErrorIs(t, err, keyErr)
+	assert.NotContains(t, recorder.executes(), "device_add",
+		"an unkeyable account must not reach the guest")
+
+	calls := stateUpdater.snapshot()
+	require.Len(t, calls, 1)
+	assert.Empty(t, calls[0].AccountID, "the untenanted instance's account is what reached the store")
+}
diff --git a/spinifex/vm/volumes.go b/spinifex/vm/volumes.go
index b8a6c0816..16838ad76 100644
--- a/spinifex/vm/volumes.go
+++ b/spinifex/vm/volumes.go
@@ -187,7 +187,7 @@ func (m *Manager) AttachVolume(ctx context.Context, id, volumeID, device string)
 		m.rollbackHotAttach(ctx, instance, ebsRequest, nodeName, iothreadID)
 		return "", errors.New("volume state updater not wired")
 	}
-	if err := m.deps.VolumeStateUpdater.UpdateVolumeState(volumeID, "in-use", instance.ID, device); err != nil {
+	if err := m.deps.VolumeStateUpdater.UpdateVolumeState(instance.AccountID, volumeID, "in-use", instance.ID, device); err != nil {
 		m.rollbackHotAttach(ctx, instance, ebsRequest, nodeName, iothreadID)
 		return "", fmt.Errorf("persist in-use state for volume %s: %w", volumeID, err)
 	}
@@ -210,7 +210,7 @@ func (m *Manager) AttachVolume(ctx context.Context, id, volumeID, device string)
 		slog.ErrorContext(ctx, "AttachVolume: QMP device_add failed, rolling back blockdev",
 			"volumeId", volumeID, "err", err)
 		if m.rollbackHotAttach(ctx, instance, ebsRequest, nodeName, iothreadID) {
-			if stateErr := m.deps.VolumeStateUpdater.UpdateVolumeState(volumeID, "available", "", ""); stateErr != nil {
+			if stateErr := m.deps.VolumeStateUpdater.UpdateVolumeState(instance.AccountID, volumeID, "available", "", ""); stateErr != nil {
 				slog.ErrorContext(ctx, "AttachVolume: failed to restore available state after rollback",
 					"volumeId", volumeID, "err", stateErr)
 			}
@@ -441,7 +441,7 @@ func (m *Manager) DetachVolume(ctx context.Context, id, volumeID, device string,
 	})
 
 	if m.deps.VolumeStateUpdater != nil {
-		if err := m.deps.VolumeStateUpdater.UpdateVolumeState(volumeID, "available", "", ""); err != nil {
+		if err := m.deps.VolumeStateUpdater.UpdateVolumeState(instance.AccountID, volumeID, "available", "", ""); err != nil {
 			slog.ErrorContext(ctx, "DetachVolume: failed to update volume metadata",
 				"volumeId", volumeID, "err", err)
 		}
diff --git a/tests/integration/image_test.go b/tests/integration/image_test.go
index 5712bfff7..e52ca0f2f 100644
--- a/tests/integration/image_test.go
+++ b/tests/integration/image_test.go
@@ -7,7 +7,7 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/ec2"
-	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
+	"github.com/mulgadc/spinifex/spinifex/ebsmetadata"
 	"github.com/stretchr/testify/require"
 )
 
@@ -26,7 +26,7 @@ func TestImage(t *testing.T) {
 	ec2Cli := gw.EC2Client(t)
 
 	const snapshotID = "snap-integration-test-image"
-	require.NoError(t, handlers_ec2_snapshot.WriteSnapshotConfig(store, testImageBucket, snapshotID, &handlers_ec2_snapshot.SnapshotConfig{
+	require.NoError(t, ebsmetadata.NewStore(store, testImageBucket).PutSnapshot(t.Context(), ebsmetadata.Snapshot{
 		SnapshotID: snapshotID,
 		VolumeID:   "vol-integration-test-image",
 		VolumeSize: 8,