FEATURE: Show replication group in cluster list

docs/2-cluster-guide.md

@@ -362,9 +362,9 @@ arcusctl cluster list
 현재 운영 장비에 저장된 배포 정보를 기준으로 Arcus 클러스터 목록을 다음과 같이 출력합니다.
 
 ```text
-SERVICECODE      VERSION   EDITION     NODES  DEPLOYED_AT
-my-cluster       1.16.1    community   3      2026-08-01 12:30:02
-my-repl-cluster  0.12.1-E  enterprise  4      2026-09-01 01:00:13
+SERVICECODE      VERSION   EDITION     NODES  GROUPS  DEPLOYED_AT
+my-cluster       1.16.1    community   3      -       2026-08-01 12:30:02
+my-repl-cluster  0.12.1-E  enterprise  4      2       2026-09-01 01:00:13
 ```
 
 다음 정보를 표시합니다.
@@ -373,6 +373,7 @@ my-repl-cluster  0.12.1-E  enterprise  4      2026-09-01 01:00:13
 - Arcus 버전
 - Edition
 - 캐시 서버 수
+- replication group 수
 - 배포 시간
 
 `list`는 실행 중인 캐시 서버를 자동으로 탐색하지 않습니다.

internal/cluster/list.go

@@ -3,9 +3,11 @@ package cluster
 import (
 	"fmt"
 	"os"
+	"strconv"
 	"text/tabwriter"
 
 	"github.com/jam2in/arcusctl/internal/store"
+	"github.com/jam2in/arcusctl/internal/topology"
 )
 
 func List() error {
@@ -20,26 +22,30 @@ func List() error {
 	}
 
 	w := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
-	fmt.Fprintln(w, "SERVICECODE\tVERSION\tEDITION\tNODES\tDEPLOYED_AT")
+	fmt.Fprintln(w, "SERVICECODE\tVERSION\tEDITION\tNODES\tGROUPS\tDEPLOYED_AT")
 
 	for _, serviceCode := range serviceCodes {
 		meta, err := store.LoadClusterMeta(serviceCode)
 		if err != nil {
-			fmt.Fprintf(w, "%s\t<error>\t\t\t%v\n", serviceCode, err)
+			fmt.Fprintf(w, "%s\t<error>\t\t\t\t%v\n", serviceCode, err)
 			continue
 		}
 
 		edition := "<unknown>"
 		servers := 0
+		groups := "-"
 		if topo, err := store.LoadClusterTopology(serviceCode); err == nil {
 			servers = len(topo.Servers)
 			if e, err := topo.Edition(); err == nil {
 				edition = string(e)
+				if e == topology.EnterpriseEdition {
+					groups = strconv.Itoa(topo.GroupCount())
+				}
 			}
 		}
 
-		fmt.Fprintf(w, "%s\t%s\t%s\t%d\t%s\n",
-			serviceCode, meta.Version, edition, servers,
+		fmt.Fprintf(w, "%s\t%s\t%s\t%d\t%s\t%s\n",
+			serviceCode, meta.Version, edition, servers, groups,
 			meta.DeployedAt.Format("2006-01-02 15:04:05"),
 		)
 	}

internal/topology/cluster.go

@@ -152,3 +152,14 @@ func (s *CacheServer) IsMaster() bool {
 func (s *CacheServer) Host() string {
 	return strings.SplitN(s.Address, ":", 2)[0]
 }
+
+func (topo *ClusterTopology) GroupCount() int {
+	names := make(map[string]struct{}, len(topo.Servers))
+	for _, server := range topo.Servers {
+		if server.Group != nil {
+			names[server.Group.Name] = struct{}{}
+		}
+	}
+
+	return len(names)
+}

internal/topology/cluster_test.go

@@ -0,0 +1,57 @@
+package topology
+
+import "testing"
+
+func TestClusterTopology_GroupCount(t *testing.T) {
+	tests := []struct {
+		name    string
+		servers []CacheServer
+		want    int
+	}{
+		{
+			name: "no groups",
+			servers: []CacheServer{
+				{Address: "10.0.0.1:11211"},
+				{Address: "10.0.0.2:11211"},
+			},
+			want: 0,
+		},
+		{
+			name: "duplicate group names are counted once",
+			servers: []CacheServer{
+				{Address: "10.0.0.1:11211", Group: &GroupInfo{Name: "g1", Role: "master", Port: 22322}},
+				{Address: "10.0.0.2:11211", Group: &GroupInfo{Name: "g1", Role: "slave", Port: 22322}},
+			},
+			want: 1,
+		},
+		{
+			name: "multiple groups",
+			servers: []CacheServer{
+				{Address: "10.0.0.1:11211", Group: &GroupInfo{Name: "g1", Role: "master"}},
+				{Address: "10.0.0.2:11211", Group: &GroupInfo{Name: "g1", Role: "slave"}},
+				{Address: "10.0.0.3:11211", Group: &GroupInfo{Name: "g2", Role: "master"}},
+				{Address: "10.0.0.4:11211", Group: &GroupInfo{Name: "g2", Role: "slave"}},
+			},
+			want: 2,
+		},
+		{
+			name: "multiple groups only masters",
+			servers: []CacheServer{
+				{Address: "10.0.0.1:11211", Group: &GroupInfo{Name: "g1", Role: "master"}},
+				{Address: "10.0.0.2:11211", Group: &GroupInfo{Name: "g2", Role: "master"}},
+				{Address: "10.0.0.3:11211", Group: &GroupInfo{Name: "g3", Role: "master"}},
+			},
+			want: 3,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			topo := &ClusterTopology{Servers: test.servers}
+
+			if got := topo.GroupCount(); got != test.want {
+				t.Errorf("GroupCount() = %d, want %d", got, test.want)
+			}
+		})
+	}
+}