diff --git a/contracts/viperblockd/legacy/v1/README.md b/contracts/viperblockd/legacy/v1/README.md
index 44ec05a69..2c0eeed5b 100644
--- a/contracts/viperblockd/legacy/v1/README.md
+++ b/contracts/viperblockd/legacy/v1/README.md
@@ -1,10 +1,10 @@
 # Viperblockd legacy contracts, version 1
 
-This package owns the deployed, transitional request/reply protocol between
-Spinifex's legacy control-plane EBS routes and `viperblockd`. It makes the
-existing compatibility boundary explicit while the generic `providers/ebs`
-contract is adopted; it is not the EBS provider abstraction and new provider
-integrations must not depend on it.
+This package owns the deployed, transitional configuration-update and
+state-reload request/reply protocols between Spinifex's legacy control plane
+and `viperblockd`. It makes those existing compatibility boundaries explicit
+while the generic `providers/ebs` contract is adopted; it is not the EBS
+provider abstraction and new provider integrations must not depend on it.
 
 ## Configuration update routes
 
@@ -22,6 +22,19 @@ Both routes carry `EBSConfigUpdateRequest` and respond with
 request/reply semantics are deployed compatibility behaviour. Incompatible
 changes require a new contract version or an explicit migration plan.
 
+## State reload route
+
+`SyncSubject` is `ebs.sync`. After a successful EC2 `ModifyVolume`, the daemon
+uses request/reply to ask a `spinifex-workers` queue-group member to reload the
+volume's state from its backend. The selected Viperblockd worker responds with
+`EBSSyncResponse`; it returns an error when it does not own a live mount of the
+volume. The daemon records that error as a warning after the API response has
+already been returned. This is deployed legacy behaviour, not a guarantee that
+every modification has reached its owning mount.
+
+The route carries `EBSSyncRequest` and `EBSSyncResponse`. Their JSON shape and
+the queue-group route are compatibility behaviour.
+
 This package does not authorize requests, validate a volume ID, store volume
 state, or define the generic storage-provider API. Those concerns remain with
 the consuming daemon, the EC2 domain, and `providers/ebs` respectively.
diff --git a/contracts/viperblockd/legacy/v1/sync.go b/contracts/viperblockd/legacy/v1/sync.go
new file mode 100644
index 000000000..867791510
--- /dev/null
+++ b/contracts/viperblockd/legacy/v1/sync.go
@@ -0,0 +1,22 @@
+package viperblocklegacyv1
+
+const (
+	// SyncSubject is the legacy queue-group route that asks a viperblockd
+	// worker to reload a mounted volume's state from its backend.
+	SyncSubject = "ebs.sync"
+)
+
+// EBSSyncRequest identifies the volume whose mounted Viperblock state should
+// be reloaded by the selected legacy worker.
+type EBSSyncRequest struct {
+	Volume string `json:"Volume"`
+}
+
+// EBSSyncResponse reports the selected worker's reload result. A worker that
+// does not own the mounted volume returns an error rather than forwarding the
+// request.
+type EBSSyncResponse struct {
+	Volume string `json:"Volume"`
+	Synced bool   `json:"Synced"`
+	Error  string `json:"Error"`
+}
diff --git a/contracts/viperblockd/legacy/v1/sync_test.go b/contracts/viperblockd/legacy/v1/sync_test.go
new file mode 100644
index 000000000..2bf4142be
--- /dev/null
+++ b/contracts/viperblockd/legacy/v1/sync_test.go
@@ -0,0 +1,28 @@
+package viperblocklegacyv1
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSyncSubject(t *testing.T) {
+	require.Equal(t, "ebs.sync", SyncSubject)
+}
+
+func TestSyncRequestJSONContract(t *testing.T) {
+	data, err := json.Marshal(EBSSyncRequest{Volume: "vol-123"})
+	require.NoError(t, err)
+	require.JSONEq(t, `{"Volume":"vol-123"}`, string(data))
+}
+
+func TestSyncResponseJSONContract(t *testing.T) {
+	data, err := json.Marshal(EBSSyncResponse{
+		Volume: "vol-123",
+		Synced: true,
+		Error:  "",
+	})
+	require.NoError(t, err)
+	require.JSONEq(t, `{"Volume":"vol-123","Synced":true,"Error":""}`, string(data))
+}
diff --git a/docs/PACKAGE_BOUNDARY_MIGRATION.md b/docs/PACKAGE_BOUNDARY_MIGRATION.md
index cbb5d41f2..9fb4270a7 100644
--- a/docs/PACKAGE_BOUNDARY_MIGRATION.md
+++ b/docs/PACKAGE_BOUNDARY_MIGRATION.md
@@ -191,6 +191,7 @@ while the branch is in flight; they do not describe the umbrella repository's
 | `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. |
 | `adb55de33` | `spinifex/types/ebs.go` (`NBDTransport`) | `spinifex/services/viperblockd/nbd_transport.go` | NBD endpoint transport selection is Viperblockd-local delivery configuration, not generic EBS state or a provider contract; `nbd_transport_test.go` pins the socket and TCP forms. |
+| `94a6e7af2` | `spinifex/types/ebs.go` (`EBSConfigUpdateRequest`, `EBSConfigUpdateResponse`) | `contracts/viperblockd/legacy/v1/config_update.go` | Legacy configuration updates have deployed queue and volume-addressed NATS routes; the versioned compatibility contract is expressly transitional and separate from `providers/ebs`. |
 
 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/docs/service-interfaces.yaml b/docs/service-interfaces.yaml
index d411a2402..69eb8b87e 100644
--- a/docs/service-interfaces.yaml
+++ b/docs/service-interfaces.yaml
@@ -169,9 +169,10 @@ services:
       - "vpc.dhcp.acquire"
       - "vpc.dhcp.release"
       # → viperblockd
-      # Legacy configuration-update payloads and routes are owned by
-      # contracts/viperblockd/legacy/v1; they are transitional and distinct
-      # from the generic providers/ebs protocol.
+      # The migrated legacy ebs.config and ebs.sync payloads and routes are
+      # owned by contracts/viperblockd/legacy/v1. They are transitional and
+      # distinct from the generic providers/ebs protocol; other legacy ebs.*
+      # routes remain to be migrated separately.
       - "ebs.mount"
       - "ebs.unmount"
       - "ebs.delete"
@@ -227,8 +228,9 @@ services:
     # mulga/viperblock submodule. Submodule pointer bump → selector forces
     # "run all" (contract changes can be invisible at the spinifex source
     # level).
-    # The legacy ebs.config routes are versioned by
-    # contracts/viperblockd/legacy/v1, not by providers/ebs.
+    # The migrated legacy ebs.config and ebs.sync routes are versioned by
+    # contracts/viperblockd/legacy/v1, not by providers/ebs. Other legacy
+    # ebs.* routes remain to be migrated separately.
     subscribes:
       - "ebs.mount"
       - "ebs.unmount"
diff --git a/spinifex/daemon/daemon_handlers_test.go b/spinifex/daemon/daemon_handlers_test.go
index b321f9522..b6194299e 100644
--- a/spinifex/daemon/daemon_handlers_test.go
+++ b/spinifex/daemon/daemon_handlers_test.go
@@ -19,6 +19,7 @@ import (
 
 	clusterv1 "github.com/mulgadc/spinifex/contracts/cluster/v1"
 	"github.com/mulgadc/spinifex/contracts/ec2/v1"
+	viperblocklegacyv1 "github.com/mulgadc/spinifex/contracts/viperblockd/legacy/v1"
 	"github.com/mulgadc/spinifex/internal/testkit"
 	"github.com/mulgadc/spinifex/internal/testkit/ebsfake"
 	"github.com/mulgadc/spinifex/spinifex/domains/ec2/ebs/metadata"
@@ -2675,7 +2676,7 @@ func TestHandleEC2ModifyVolume_Success(t *testing.T) {
 	})
 
 	// Subscribe a dummy ebs.sync handler so the NATS Request doesn't time out
-	syncSub, err := daemon.natsConn.Subscribe("ebs.sync", func(msg *nats.Msg) {
+	syncSub, err := daemon.natsConn.Subscribe(viperblocklegacyv1.SyncSubject, func(msg *nats.Msg) {
 		_ = msg.Respond([]byte(`{}`))
 	})
 	require.NoError(t, err)
diff --git a/spinifex/daemon/daemon_handlers_volume.go b/spinifex/daemon/daemon_handlers_volume.go
index ab561073a..6d9a15b1e 100644
--- a/spinifex/daemon/daemon_handlers_volume.go
+++ b/spinifex/daemon/daemon_handlers_volume.go
@@ -9,10 +9,10 @@ import (
 
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"github.com/mulgadc/spinifex/contracts/ec2/v1"
+	viperblocklegacyv1 "github.com/mulgadc/spinifex/contracts/viperblockd/legacy/v1"
 	"github.com/mulgadc/spinifex/spinifex/foundation/aws/errors"
 	handlers_ec2_snapshot "github.com/mulgadc/spinifex/spinifex/handlers/ec2/snapshot"
 	"github.com/mulgadc/spinifex/spinifex/runtime/compute/vm"
-	"github.com/mulgadc/spinifex/spinifex/types"
 	"github.com/mulgadc/spinifex/spinifex/utils"
 	"github.com/nats-io/nats.go"
 )
@@ -241,11 +241,11 @@ func (d *Daemon) handleEC2ModifyVolume(msg *nats.Msg) string {
 
 	// Notify viperblockd to reload state after volume modification (e.g. resize)
 	if modifyVolumeInput.VolumeId != nil {
-		syncData, err := json.Marshal(types.EBSSyncRequest{Volume: *modifyVolumeInput.VolumeId})
+		syncData, err := json.Marshal(viperblocklegacyv1.EBSSyncRequest{Volume: *modifyVolumeInput.VolumeId})
 		if err != nil {
 			slog.ErrorContext(ctx, "failed to marshal ebs.sync request", "volumeId", *modifyVolumeInput.VolumeId, "err", err)
 		} else {
-			_, syncErr := d.natsConn.Request("ebs.sync", syncData, 5*time.Second)
+			_, syncErr := d.natsConn.Request(viperblocklegacyv1.SyncSubject, syncData, 5*time.Second)
 			if syncErr != nil {
 				slog.WarnContext(ctx, "ebs.sync notification failed (volume may not be mounted)",
 					"volumeId", *modifyVolumeInput.VolumeId, "err", syncErr)
diff --git a/spinifex/services/viperblockd/viperblockd.go b/spinifex/services/viperblockd/viperblockd.go
index 012292d47..729f80f53 100644
--- a/spinifex/services/viperblockd/viperblockd.go
+++ b/spinifex/services/viperblockd/viperblockd.go
@@ -895,20 +895,20 @@ func launchService(cfg *Config) (err error) {
 		return fmt.Errorf("failed to subscribe to %s: %w", abandonTopic, err)
 	}
 
-	if _, err := nc.QueueSubscribe("ebs.sync", "spinifex-workers", func(msg *nats.Msg) {
+	if _, err := nc.QueueSubscribe(viperblocklegacyv1.SyncSubject, "spinifex-workers", func(msg *nats.Msg) {
 		ctx, span := utils.StartConsumerSpan(msg)
 		defer span.End()
 		slog.InfoContext(ctx, "Received ebs.sync message")
 
-		var syncRequest types.EBSSyncRequest
+		var syncRequest viperblocklegacyv1.EBSSyncRequest
 		if err := json.Unmarshal(msg.Data, &syncRequest); err != nil {
 			slog.ErrorContext(ctx, "Failed to unmarshal ebs.sync message", "err", err)
 			utils.MarkSpanError(span, err)
-			respondJSON(msg, types.EBSSyncResponse{Error: fmt.Sprintf("bad request: %v", err)})
+			respondJSON(msg, viperblocklegacyv1.EBSSyncResponse{Error: fmt.Sprintf("bad request: %v", err)})
 			return
 		}
 
-		syncResponse := types.EBSSyncResponse{Volume: syncRequest.Volume}
+		syncResponse := viperblocklegacyv1.EBSSyncResponse{Volume: syncRequest.Volume}
 		defer func() {
 			if syncResponse.Error != "" {
 				utils.MarkSpanError(span, errors.New(syncResponse.Error))
diff --git a/spinifex/services/viperblockd/viperblockd_handlers_test.go b/spinifex/services/viperblockd/viperblockd_handlers_test.go
index 102eabe43..7d2625886 100644
--- a/spinifex/services/viperblockd/viperblockd_handlers_test.go
+++ b/spinifex/services/viperblockd/viperblockd_handlers_test.go
@@ -324,11 +324,11 @@ func TestIntegration_EBSSyncVolumeNotMounted(t *testing.T) {
 	require.NoError(t, err)
 	defer nc.Close()
 
-	reqData, _ := json.Marshal(types.EBSSyncRequest{Volume: "vol-not-here"})
-	msg, err := nc.Request("ebs.sync", reqData, 3*time.Second)
+	reqData, _ := json.Marshal(viperblocklegacyv1.EBSSyncRequest{Volume: "vol-not-here"})
+	msg, err := nc.Request(viperblocklegacyv1.SyncSubject, reqData, 3*time.Second)
 	require.NoError(t, err)
 
-	var resp types.EBSSyncResponse
+	var resp viperblocklegacyv1.EBSSyncResponse
 	require.NoError(t, json.Unmarshal(msg.Data, &resp))
 	assert.False(t, resp.Synced)
 	assert.Contains(t, resp.Error, "not mounted")
@@ -354,11 +354,11 @@ func TestIntegration_EBSSyncVolumeNoVBInstance(t *testing.T) {
 	require.NoError(t, err)
 	defer nc.Close()
 
-	reqData, _ := json.Marshal(types.EBSSyncRequest{Volume: "vol-no-vb"})
-	msg, err := nc.Request("ebs.sync", reqData, 3*time.Second)
+	reqData, _ := json.Marshal(viperblocklegacyv1.EBSSyncRequest{Volume: "vol-no-vb"})
+	msg, err := nc.Request(viperblocklegacyv1.SyncSubject, reqData, 3*time.Second)
 	require.NoError(t, err)
 
-	var resp types.EBSSyncResponse
+	var resp viperblocklegacyv1.EBSSyncResponse
 	require.NoError(t, json.Unmarshal(msg.Data, &resp))
 	assert.False(t, resp.Synced)
 	assert.Contains(t, resp.Error, "not mounted")
@@ -381,10 +381,10 @@ func TestIntegration_EBSSyncInvalidJSON(t *testing.T) {
 	require.NoError(t, err)
 	defer nc.Close()
 
-	msg, err := nc.Request("ebs.sync", []byte("garbage"), 3*time.Second)
+	msg, err := nc.Request(viperblocklegacyv1.SyncSubject, []byte("garbage"), 3*time.Second)
 	require.NoError(t, err)
 
-	var resp types.EBSSyncResponse
+	var resp viperblocklegacyv1.EBSSyncResponse
 	require.NoError(t, json.Unmarshal(msg.Data, &resp))
 	assert.Contains(t, resp.Error, "bad request:")
 }
@@ -491,11 +491,11 @@ func TestIntegration_EBSSyncWithVBInstance(t *testing.T) {
 	require.NoError(t, err)
 	defer nc.Close()
 
-	reqData, _ := json.Marshal(types.EBSSyncRequest{Volume: "vol-sync-vb"})
-	msg, err := nc.Request("ebs.sync", reqData, 3*time.Second)
+	reqData, _ := json.Marshal(viperblocklegacyv1.EBSSyncRequest{Volume: "vol-sync-vb"})
+	msg, err := nc.Request(viperblocklegacyv1.SyncSubject, reqData, 3*time.Second)
 	require.NoError(t, err)
 
-	var resp types.EBSSyncResponse
+	var resp viperblocklegacyv1.EBSSyncResponse
 	require.NoError(t, json.Unmarshal(msg.Data, &resp))
 	assert.True(t, resp.Synced)
 	assert.Empty(t, resp.Error)
diff --git a/spinifex/types/ebs.go b/spinifex/types/ebs.go
index 03e06c6a2..af5e10956 100644
--- a/spinifex/types/ebs.go
+++ b/spinifex/types/ebs.go
@@ -44,16 +44,6 @@ type EBSUnMountResponse struct {
 	Reaped bool `json:"Reaped,omitempty"`
 }
 
-type EBSSyncRequest struct {
-	Volume string `json:"Volume"`
-}
-
-type EBSSyncResponse struct {
-	Volume string `json:"Volume"`
-	Synced bool   `json:"Synced"`
-	Error  string `json:"Error"`
-}
-
 type EBSDeleteRequest struct {
 	Volume string `json:"Volume"`
 }