diff --git a/docs/PACKAGE_BOUNDARY_MIGRATION.md b/docs/PACKAGE_BOUNDARY_MIGRATION.md
index 570d9ea25..14d5246eb 100644
--- a/docs/PACKAGE_BOUNDARY_MIGRATION.md
+++ b/docs/PACKAGE_BOUNDARY_MIGRATION.md
@@ -189,6 +189,7 @@ while the branch is in flight; they do not describe the umbrella repository's
 | `78fd017e0` | `spinifex/types/telemetry.go` (`GuestTelemetryMeta`) | `contracts/telemetry/v1/guest_meta.go` | QMP collector sidecar JSON is a versioned file contract between VM runtime and telemetry role; `guest_meta_test.go` pins its filename and payload. |
 | `4b35a2a33` | `spinifex/types/node.go` (`NodeVMsResponse`, `VMInfo`, `VMGPUInfo`) | `contracts/cluster/v1/node_vms.go` | VM inventory is a versioned cluster fan-out payload used by SPX CLI and EKS host lookup; `node_vms_test.go` pins its subject and JSON shape. |
 | `08bd335f0` | `spinifex/types/node.go` (`NodeStatusResponse`, capacity and GPU inventory) | `contracts/cluster/v1/status.go` | Node status is a versioned fan-out observation contract for operator inspection and EC2/EKS scheduling consumers; `status_test.go` pins its subject and JSON shape. |
+| `f4cb550c9` | `spinifex/types/ebs.go` (GP3 policy constants) | `spinifex/domains/ec2/ebs/policy/gp3.go` | The supported GP3 product envelope is EC2 EBS domain policy, not generic runtime or Viperblockd wire state; `gp3_test.go` pins the deployed values. |
 
 The EC2 contract row is intentionally different from the directory moves: it creates
 a compatibility boundary. `ec2.cmd.*` retains its deployed one-token NATS
diff --git a/spinifex/services/viperblockd/conformance_test.go b/spinifex/services/viperblockd/conformance_test.go
index 17a86ec30..90577f43c 100644
--- a/spinifex/services/viperblockd/conformance_test.go
+++ b/spinifex/services/viperblockd/conformance_test.go
@@ -74,7 +74,7 @@ func inProcessProvider(t *testing.T) (func(t *testing.T) ebsprovider.EBSProvider
 		cfg.AccessKey = fixture.AccessKey
 		cfg.SecretKey = fixture.SecretKey
 		cfg.PluginPath = pluginPath
-		cfg.NBDTransport = types.NBDTransportTCP
+		cfg.NBDTransport = NBDTransportTCP
 		cfg.NodeName = name
 		// The lease owner is derived from NodeName, and setupTestConfig built
 		// the store before this function could set it. Rebuild it, or both
diff --git a/spinifex/services/viperblockd/nbd_transport.go b/spinifex/services/viperblockd/nbd_transport.go
new file mode 100644
index 000000000..c76b30a20
--- /dev/null
+++ b/spinifex/services/viperblockd/nbd_transport.go
@@ -0,0 +1,11 @@
+package viperblockd
+
+// NBDTransport controls how Viperblockd exports a mounted volume.
+type NBDTransport string
+
+const (
+	// NBDTransportSocket uses Unix domain sockets (faster, local only).
+	NBDTransportSocket NBDTransport = "socket"
+	// NBDTransportTCP uses TCP connections (required for remote/DPU scenarios).
+	NBDTransportTCP NBDTransport = "tcp"
+)
diff --git a/spinifex/services/viperblockd/nbd_transport_test.go b/spinifex/services/viperblockd/nbd_transport_test.go
new file mode 100644
index 000000000..e1451f24c
--- /dev/null
+++ b/spinifex/services/viperblockd/nbd_transport_test.go
@@ -0,0 +1,9 @@
+package viperblockd
+
+import "testing"
+
+func TestNBDTransportValues(t *testing.T) {
+	if NBDTransportSocket != "socket" || NBDTransportTCP != "tcp" {
+		t.Fatal("unexpected NBD transport values")
+	}
+}
diff --git a/spinifex/services/viperblockd/provider_handlers.go b/spinifex/services/viperblockd/provider_handlers.go
index e2a8bff6e..592a65682 100644
--- a/spinifex/services/viperblockd/provider_handlers.go
+++ b/spinifex/services/viperblockd/provider_handlers.go
@@ -1408,7 +1408,7 @@ func mountVolume(ctx context.Context, cfg *Config, nc *nats.Conn, volumeName str
 
 	mountSpan.SetAttributes(attribute.Int64("volume.size_bytes", safecast.Uint64ToInt64(vb.GetVolumeSize())))
 
-	useTCP := cfg.NBDTransport == types.NBDTransportTCP
+	useTCP := cfg.NBDTransport == NBDTransportTCP
 
 	var nbdURI string
 	var nbdSocket string
diff --git a/spinifex/services/viperblockd/viperblockd.go b/spinifex/services/viperblockd/viperblockd.go
index 1fd8c1169..514a7a033 100644
--- a/spinifex/services/viperblockd/viperblockd.go
+++ b/spinifex/services/viperblockd/viperblockd.go
@@ -149,7 +149,7 @@ type Config struct {
 
 	// NBDTransport controls the transport type: "socket" (default) or "tcp"
 	// Socket is faster for local connections, TCP required for remote/DPU scenarios
-	NBDTransport types.NBDTransport
+	NBDTransport NBDTransport
 
 	// ShardWAL enables sharded WAL for mounted volumes (default false)
 	ShardWAL bool
diff --git a/spinifex/types/ebs.go b/spinifex/types/ebs.go
index 804928a75..937851b2a 100644
--- a/spinifex/types/ebs.go
+++ b/spinifex/types/ebs.go
@@ -24,16 +24,6 @@ type EBSRequest struct {
 	HotplugPort int `json:"HotplugPort,omitempty"`
 }
 
-// NBDTransport defines the transport type for NBD connections.
-type NBDTransport string
-
-const (
-	// NBDTransportSocket uses Unix domain sockets (faster, local only).
-	NBDTransportSocket NBDTransport = "socket"
-	// NBDTransportTCP uses TCP connections (required for remote/DPU scenarios).
-	NBDTransportTCP NBDTransport = "tcp"
-)
-
 type EBSMountResponse struct {
 	URI     string `json:"URI"`
 	Mounted bool   `json:"Mounted"`