diff --git a/api/agent.yaml b/api/agent.yaml
index 00d4fd8..95a0339 100644
--- a/api/agent.yaml
+++ b/api/agent.yaml
@@ -315,7 +315,7 @@ components:
 
     SubnetCreateRequest:
       type: object
-      required: [name, vpc, vxlan_id, gateway_ip, cidr]
+      required: [name, vpc, gateway_ip, cidr]
       properties:
         name:
           type: string
@@ -325,9 +325,18 @@ components:
           type: string
           description: Parent VPC name
           example: vpc1
+        mode:
+          type: string
+          description: >
+            Subnet mode. "vxlan" (default): creates a VXLAN tunnel and a host bridge.
+            "bridge": attaches directly to an existing bridge resolved from iface_type in the agent config.
+            "vlan" is reserved for future use.
+          enum: [vxlan, bridge]
+          default: vxlan
+          example: vxlan
         vxlan_id:
           type: integer
-          description: VXLAN VNI identifier
+          description: VXLAN VNI identifier. Required when mode is "vxlan", ignored otherwise.
           example: 100
         iface_type:
           type: string
@@ -356,12 +365,17 @@ components:
         vpc:
           type: string
           example: vpc1
+        mode:
+          type: string
+          enum: [vxlan, bridge]
+          example: vxlan
         vxlan_id:
           type: integer
+          description: VXLAN VNI. Present only when mode is "vxlan".
           example: 100
         local_iface:
           type: string
-          description: Resolved interface name
+          description: Resolved interface name from agent config
           example: br-000000
         gateway_ip:
           type: string
diff --git a/internal/api/agent/models.go b/internal/api/agent/models.go
index f13407b..9622ef9 100644
--- a/internal/api/agent/models.go
+++ b/internal/api/agent/models.go
@@ -12,6 +12,7 @@ type VPC struct {
 type SubnetCreateRequest struct {
 	Name      string `json:"name"`
 	VPC       string `json:"vpc"`
+	Mode      string `json:"mode"`
 	VxlanID   int    `json:"vxlan_id"`
 	IfaceType string `json:"iface_type"`
 	GatewayIP string `json:"gateway_ip"`
@@ -22,6 +23,7 @@ type Subnet struct {
 	Name       string `json:"name"`
 	State      string `json:"state"`
 	VPC        string `json:"vpc"`
+	Mode       string `json:"mode"`
 	VxlanID    int    `json:"vxlan_id"`
 	LocalIface string `json:"local_iface"`
 	GatewayIP  string `json:"gateway_ip"`