Fix build breakers and remaining runtime bugs across stack.

Remove corrupt empty main.go files, harden WebSocket reconnect and pre-auth handling, complete live stats in the dashboard hook, wire AI share counts, and refresh PROBLEMS.md.

server/internal/api/websocket.go

@@ -187,18 +187,24 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 	defer func() {
 		if agentID != "" {
 			h.mu.Lock()
-			delete(h.agents, agentID)
-			delete(h.agentConfigs, agentID)
-			delete(h.agentLogs, agentID)
-			h.mu.Unlock()
-			if h.aiHandler != nil {
-				h.aiHandler.RemoveEngine(agentID)
+			cur := h.agents[agentID]
+			// Only tear down fleet state if this connection is still the active one.
+			if cur != nil && cur.Conn == conn {
+				delete(h.agents, agentID)
+				delete(h.agentConfigs, agentID)
+				delete(h.agentLogs, agentID)
+				h.mu.Unlock()
+				if h.aiHandler != nil {
+					h.aiHandler.RemoveEngine(agentID)
+				}
+				h.db.SetAgentOffline(agentID)
+				h.broadcastDashboard(Message{
+					Type:    "agent_offline",
+					Payload: mustMarshal(map[string]string{"agent_id": agentID}),
+				})
+			} else {
+				h.mu.Unlock()
 			}
-			h.db.SetAgentOffline(agentID)
-			h.broadcastDashboard(Message{
-				Type:    "agent_offline",
-				Payload: mustMarshal(map[string]string{"agent_id": agentID}),
-			})
 		}
 		conn.Close()
 	}()
@@ -328,6 +334,12 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 			}
 
 			h.mu.Lock()
+			if old, ok := h.agents[agentID]; ok && old.Conn != conn {
+				oldConn := old.Conn
+				h.mu.Unlock()
+				oldConn.Close()
+				h.mu.Lock()
+			}
 			h.agents[agentID] = &AgentConnection{AgentID: agentID, Conn: conn}
 			h.mu.Unlock()
 
@@ -342,6 +354,9 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 			})
 
 		case "stats":
+			if agentID == "" {
+				continue
+			}
 			var stats struct {
 				Hashrate15s     float64 `json:"hashrate_15s"`
 				Hashrate1m      float64 `json:"hashrate_1m"`
@@ -383,6 +398,9 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 			})
 
 		case "submit_share":
+			if agentID == "" {
+				continue
+			}
 			var share models.Share
 			if err := json.Unmarshal(msg.Payload, &share); err != nil {
 				continue
@@ -460,9 +478,12 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 				wallet = h.defaultPool.Wallet
 			}
 
-			proxy.SubmitShare(agentID, wallet, share.JobID, share.Nonce, share.Hash, sendShareResult)
+			go proxy.SubmitShare(agentID, wallet, share.JobID, share.Nonce, share.Hash, sendShareResult)
 
 		case "get_job":
+			if agentID == "" {
+				continue
+			}
 			var proxy *pool.Proxy
 			if h.poolManager != nil {
 				poolCfg := h.agentPoolConfig(agentID)
@@ -485,6 +506,9 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 			}
 
 		case "log_tail":
+			if agentID == "" {
+				continue
+			}
 			var payload struct {
 				Content string `json:"content"`
 				Lines   int    `json:"lines"`
@@ -501,6 +525,9 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 			})
 
 		case "command_result":
+			if agentID == "" {
+				continue
+			}
 			var payload map[string]interface{}
 			if err := json.Unmarshal(msg.Payload, &payload); err != nil {
 				continue