feat: 接线 serve 真实 auth/注册/管理/MQTT 与消息循环

internal/app/message/conn.go

@@ -67,6 +67,17 @@ func (c *MemoryConns) Current(endpointID string) (LiveConn, bool) {
 	return v, ok
 }
 
+// Snapshot 返回当前连接表副本（供推送循环遍历）。
+func (c *MemoryConns) Snapshot() map[string]LiveConn {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	out := make(map[string]LiveConn, len(c.m))
+	for k, v := range c.m {
+		out[k] = v
+	}
+	return out
+}
+
 // RecordingDownlink 记录下行发布，供测试断言。
 type RecordingDownlink struct {
 	mu        sync.Mutex

internal/broker/broker.go

@@ -58,11 +58,16 @@ func (AllowAuthenticator) Authenticate(context.Context, string, []byte, string)
 	return AuthResult{OK: true}, nil
 }
 
+// PublishDroppedFunc 下行未写入发送队列时回调（对接消息线 OnPublishDropped）。
+type PublishDroppedFunc func(ctx context.Context, endpointID string, connID port.ConnID, payload []byte)
+
 // Options 装配 broker。
 type Options struct {
 	Authenticator Authenticator
 	Uplink        port.UplinkHandler
 	Logger        *slog.Logger
+	// OnPublishDropped 可选；nil 时仅打 debug 日志。
+	OnPublishDropped PublishDroppedFunc
 }
 
 // Broker 内置 mochi，不自带监听端口。
@@ -71,6 +76,7 @@ type Broker struct {
 	auth   Authenticator
 	uplink port.UplinkHandler
 	log    *slog.Logger
+	onDrop PublishDroppedFunc
 
 	hook *nixHook
 
@@ -144,6 +150,7 @@ func New(opts Options) (*Broker, error) {
 		auth:     auth,
 		uplink:   uplink,
 		log:      log,
+		onDrop:   opts.OnPublishDropped,
 		current:  make(map[string]*connState),
 		byClient: make(map[*mqtt.Client]*connState),
 		queues:   make(map[string]*uplinkQueue),

internal/broker/hooks.go

@@ -159,6 +159,16 @@ func (h *nixHook) OnSubscribed(cl *mqtt.Client, pk packets.Packet, reasonCodes [
 
 func (h *nixHook) OnPublishDropped(cl *mqtt.Client, pk packets.Packet) {
 	h.b.log.Debug("publish dropped", "client", cl.ID, "topic", pk.TopicName, "size", len(pk.Payload))
+	if h.b.onDrop == nil {
+		return
+	}
+	h.b.connsMu.RLock()
+	st := h.b.byClient[cl]
+	h.b.connsMu.RUnlock()
+	if st == nil {
+		return
+	}
+	h.b.onDrop(context.Background(), st.endpointID, st.connID, append([]byte(nil), pk.Payload...))
 }
 
 func (h *nixHook) OnSessionEstablished(cl *mqtt.Client, _ packets.Packet) {

internal/broker/session.go

@@ -101,6 +101,11 @@ func (s *Session) Attach(b *Broker) {
 	s.b = b
 }
 
+// SetPresence 接线时在创建最终 presence 实现后注入（可替换占位）。
+func (s *Session) SetPresence(p PresenceSink) {
+	s.presence = p
+}
+
 func (s *Session) OnSessionEstablished(ctx context.Context, conn port.ConnInfo) error {
 	if s.b != nil {
 		s.b.startHandshakeDeadline(conn.EndpointID, conn.ConnID, handshakeTimeout)