diff --git a/internal/automation/prefix.go b/internal/automation/prefix.go
index d2c0ada..2a2d373 100644
--- a/internal/automation/prefix.go
+++ b/internal/automation/prefix.go
@@ -25,12 +25,22 @@ func PrefixProxyNames(subscriptionName string, data map[string]interface{}) []Pr
 
 	refs := renameProxies(subscriptionName, data, rename)
 	renameProxyGroups(subscriptionName, data, rename)
-	rewriteGroupProxyReferences(data, rename)
-	rewriteRuleTargets(data, rename)
+	RewriteReferences(data, rename)
 
 	return refs
 }
 
+// RewriteReferences rewrites every reference to a renamed proxy or
+// proxy-group — inside other groups' "proxies" lists and inside
+// data["rules"]' rule targets — to the new name. Exposed separately from
+// PrefixProxyNames so callers that rename groups after the fact (e.g.
+// collapsing several subscriptions' default selector group into one) can
+// reuse the same rewrite logic without re-running the proxy/group renaming.
+func RewriteReferences(data map[string]interface{}, rename map[string]string) {
+	rewriteGroupProxyReferences(data, rename)
+	rewriteRuleTargets(data, rename)
+}
+
 func renameProxies(subscriptionName string, data map[string]interface{}, rename map[string]string) []ProxyRef {
 	proxiesRaw, ok := data["proxies"].([]interface{})
 	if !ok {
diff --git a/internal/corecfg/manager.go b/internal/corecfg/manager.go
index 8b42ebd..d289611 100644
--- a/internal/corecfg/manager.go
+++ b/internal/corecfg/manager.go
@@ -350,6 +350,7 @@ func (m *Manager) resolveSubscriptions() []*model.Subscription {
 func (m *Manager) mergeSubscriptions(subs []*model.Subscription) (map[string]interface{}, []automation.ProxyRef, bool) {
 	combined := map[string]interface{}{}
 	var proxies []automation.ProxyRef
+	var selectionGroups []map[string]interface{}
 
 	for _, sub := range subs {
 		filePath := sub.GetFilePath(m.Storage.ConfigDir)
@@ -374,10 +375,14 @@ func (m *Manager) mergeSubscriptions(subs []*model.Subscription) (map[string]int
 		}
 
 		proxies = append(proxies, automation.PrefixProxyNames(sub.Name, data)...)
+		if group := popFirstProxyGroup(data); group != nil {
+			selectionGroups = append(selectionGroups, group)
+		}
 		combined = deepMerge(combined, data)
 	}
 
 	combined["rules"] = dedupeMatchRule(combined["rules"])
+	mergeProxySelection(combined, selectionGroups)
 
 	return combined, proxies, true
 }
diff --git a/internal/corecfg/merge.go b/internal/corecfg/merge.go
index 5d2af77..69d7476 100644
--- a/internal/corecfg/merge.go
+++ b/internal/corecfg/merge.go
@@ -1,5 +1,7 @@
 package corecfg
 
+import "gitea.epss.net.cn/klesh/ss/internal/automation"
+
 // deepMerge merges dict2 into dict1 in place and returns dict1, mirroring
 // corecfg_manager.py's module-level deep_merge(): nested maps recurse,
 // matching lists are concatenated, everything else is overwritten by dict2.
@@ -25,3 +27,74 @@ func deepMerge(dict1, dict2 map[string]interface{}) map[string]interface{} {
 	}
 	return dict1
 }
+
+// popFirstProxyGroup removes and returns data["proxy-groups"]' first entry —
+// by convention a subscription's default selector group, the one its own
+// rules point at — so mergeProxySelection can fold every subscription's
+// default selector into one combined group. Returns nil if there is none.
+func popFirstProxyGroup(data map[string]interface{}) map[string]interface{} {
+	groupsRaw, ok := data["proxy-groups"].([]interface{})
+	if !ok || len(groupsRaw) == 0 {
+		return nil
+	}
+
+	group, ok := groupsRaw[0].(map[string]interface{})
+	if !ok {
+		return nil
+	}
+
+	data["proxy-groups"] = groupsRaw[1:]
+	return group
+}
+
+// selectionGroupName is the name given to the proxy-group produced by
+// folding every merged subscription's default selector group together.
+const selectionGroupName = "Proxy Selection"
+
+// mergeProxySelection collapses each subscription's default selector group
+// (already popped off by popFirstProxyGroup) into a single combined group
+// named selectionGroupName, covering every subscription's proxies, and
+// rewrites every rule/group reference to the old per-subscription groups so
+// they point at it instead.
+func mergeProxySelection(combined map[string]interface{}, groups []map[string]interface{}) {
+	if len(groups) == 0 {
+		return
+	}
+
+	rename := make(map[string]string, len(groups))
+	seen := make(map[string]bool)
+	var groupType interface{}
+	var mergedProxies []interface{}
+
+	for _, group := range groups {
+		if name, ok := group["name"].(string); ok {
+			rename[name] = selectionGroupName
+		}
+		if groupType == nil {
+			groupType = group["type"]
+		}
+		if list, ok := group["proxies"].([]interface{}); ok {
+			for _, p := range list {
+				name, ok := p.(string)
+				if ok && seen[name] {
+					continue
+				}
+				if ok {
+					seen[name] = true
+				}
+				mergedProxies = append(mergedProxies, p)
+			}
+		}
+	}
+
+	merged := map[string]interface{}{
+		"name":    selectionGroupName,
+		"type":    groupType,
+		"proxies": mergedProxies,
+	}
+
+	existing, _ := combined["proxy-groups"].([]interface{})
+	combined["proxy-groups"] = append([]interface{}{merged}, existing...)
+
+	automation.RewriteReferences(combined, rename)
+}
diff --git a/internal/corecfg/merge_test.go b/internal/corecfg/merge_test.go
new file mode 100644
index 0000000..ccbd236
--- /dev/null
+++ b/internal/corecfg/merge_test.go
@@ -0,0 +1,82 @@
+package corecfg
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestPopFirstProxyGroup(t *testing.T) {
+	data := map[string]interface{}{
+		"proxy-groups": []interface{}{
+			map[string]interface{}{"name": "Proxy", "type": "select", "proxies": []interface{}{"Auto"}},
+			map[string]interface{}{"name": "Auto", "type": "url-test", "proxies": []interface{}{"HK"}},
+		},
+	}
+
+	got := popFirstProxyGroup(data)
+
+	want := map[string]interface{}{"name": "Proxy", "type": "select", "proxies": []interface{}{"Auto"}}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("got %#v, want %#v", got, want)
+	}
+
+	remaining := data["proxy-groups"].([]interface{})
+	if len(remaining) != 1 || remaining[0].(map[string]interface{})["name"] != "Auto" {
+		t.Fatalf("expected only the Auto group to remain, got %#v", remaining)
+	}
+}
+
+func TestPopFirstProxyGroupEmpty(t *testing.T) {
+	if got := popFirstProxyGroup(map[string]interface{}{}); got != nil {
+		t.Fatalf("expected nil, got %#v", got)
+	}
+}
+
+func TestMergeProxySelection(t *testing.T) {
+	combined := map[string]interface{}{
+		"proxy-groups": []interface{}{
+			map[string]interface{}{"name": "sub-a | Auto", "type": "url-test", "proxies": []interface{}{"sub-a | HK"}},
+		},
+		"rules": []interface{}{
+			"DOMAIN,example.com,sub-a | Proxy",
+			"DOMAIN,other.com,sub-b | Proxy",
+		},
+	}
+	groups := []map[string]interface{}{
+		{"name": "sub-a | Proxy", "type": "select", "proxies": []interface{}{"sub-a | Auto", "DIRECT"}},
+		{"name": "sub-b | Proxy", "type": "select", "proxies": []interface{}{"sub-b | Auto", "DIRECT"}},
+	}
+
+	mergeProxySelection(combined, groups)
+
+	proxyGroups := combined["proxy-groups"].([]interface{})
+	if len(proxyGroups) != 2 {
+		t.Fatalf("expected 2 proxy-groups (merged selection + sub-a | Auto), got %#v", proxyGroups)
+	}
+
+	merged := proxyGroups[0].(map[string]interface{})
+	if merged["name"] != selectionGroupName {
+		t.Fatalf("expected first group to be %q, got %#v", selectionGroupName, merged["name"])
+	}
+	wantProxies := []interface{}{"sub-a | Auto", "DIRECT", "sub-b | Auto"}
+	if !reflect.DeepEqual(merged["proxies"], wantProxies) {
+		t.Fatalf("got proxies %#v, want %#v", merged["proxies"], wantProxies)
+	}
+
+	wantRules := []interface{}{
+		"DOMAIN,example.com," + selectionGroupName,
+		"DOMAIN,other.com," + selectionGroupName,
+	}
+	if !reflect.DeepEqual(combined["rules"], wantRules) {
+		t.Fatalf("got rules %#v, want %#v", combined["rules"], wantRules)
+	}
+}
+
+func TestMergeProxySelectionNoGroups(t *testing.T) {
+	combined := map[string]interface{}{"proxy-groups": []interface{}{"unchanged"}}
+	mergeProxySelection(combined, nil)
+
+	if !reflect.DeepEqual(combined["proxy-groups"], []interface{}{"unchanged"}) {
+		t.Fatalf("expected combined to be untouched, got %#v", combined)
+	}
+}