Fix group status updates broken by API service

The URL test history update hook and the Clash mode update hook were
single-slot: the API service's attached service overwrote the hook set
by the daemon, so clients stopped receiving group updates. Replace both
with multicast hook lists.

Also share a single URL test history storage via context: Clash API
looked it up under a key nobody registered and fell back to its own
empty storage, so dashboards showed no delay once an API service was
configured. Selector changes now notify through the shared storage,
covering selections made from any API surface.

protocol/group/selector.go

@@ -8,6 +8,7 @@ import (
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-box/adapter/outbound"
 	"github.com/sagernet/sing-box/common/interrupt"
+	"github.com/sagernet/sing-box/common/urltest"
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
@@ -40,6 +41,7 @@ type Selector struct {
 	defaultTag                   string
 	outbounds                    map[string]adapter.Outbound
 	selected                     common.TypedValue[adapter.Outbound]
+	history                      *urltest.HistoryStorage
 	interruptGroup               *interrupt.Group
 	interruptExternalConnections bool
 }
@@ -54,6 +56,7 @@ func NewSelector(ctx context.Context, router adapter.Router, logger log.ContextL
 		tags:                         options.Outbounds,
 		defaultTag:                   options.Default,
 		outbounds:                    make(map[string]adapter.Outbound),
+		history:                      service.PtrFromContext[urltest.HistoryStorage](ctx),
 		interruptGroup:               interrupt.NewGroup(),
 		interruptExternalConnections: options.InterruptExistConnections,
 	}
@@ -137,6 +140,9 @@ func (s *Selector) SelectOutbound(tag string) bool {
 		}
 	}
 	s.interruptGroup.Interrupt(s.interruptExternalConnections)
+	if s.history != nil {
+		s.history.NotifyUpdated()
+	}
 	return true
 }
 

protocol/group/urltest.go

@@ -195,7 +195,7 @@ type URLTestGroup struct {
 	interval                     time.Duration
 	tolerance                    uint16
 	idleTimeout                  time.Duration
-	history                      adapter.URLTestHistoryStorage
+	history                      *urltest.HistoryStorage
 	checking                     atomic.Bool
 	selectedOutboundTCP          adapter.Outbound
 	selectedOutboundUDP          adapter.Outbound
@@ -221,13 +221,9 @@ func NewURLTestGroup(ctx context.Context, outboundManager adapter.OutboundManage
 	if interval > idleTimeout {
 		return nil, E.New("interval must be less or equal than idle_timeout")
 	}
-	var history adapter.URLTestHistoryStorage
-	if historyFromCtx := service.PtrFromContext[urltest.HistoryStorage](ctx); historyFromCtx != nil {
-		history = historyFromCtx
-	} else if clashServer := service.FromContext[adapter.ClashServer](ctx); clashServer != nil {
-		history = clashServer.HistoryStorage()
-	} else {
-		history = urltest.NewHistoryStorage()
+	history := service.PtrFromContext[urltest.HistoryStorage](ctx)
+	if history == nil {
+		return nil, E.New("missing URL test history storage")
 	}
 	return &URLTestGroup{
 		ctx:                          ctx,