fix: use custom probe targets for diagnostics

Move custom probe target controls into the tunnel advanced settings and reuse the configured target in tunnel diagnosis output.

go-backend/internal/http/handler/control_plane.go

@@ -978,6 +978,7 @@ func (h *Handler) prepareTunnelDiagnosis(tunnelID int64) (string, string, []diag
 
 	ipPreference := h.repo.GetTunnelIPPreference(tunnelID)
 	protocol := strings.ToLower(strings.TrimSpace(tunnel.Protocol))
+	probeTarget := effectiveTunnelProbeTargetValues(tunnel.ProbeTargetHost, tunnel.ProbeTargetPort)
 	inNodes, chainHops, outNodes := splitChainNodeGroups(chainRows)
 	workItems := make([]diagnosisWorkItem, 0, len(chainRows)*2)
 
@@ -987,8 +988,8 @@ func (h *Handler) prepareTunnelDiagnosis(tunnelID int64) (string, string, []diag
 			description := fmt.Sprintf("入口(%s)->外网", inNode.NodeName)
 			workItems = append(workItems, diagnosisWorkItem{
 				fromNodeID:  inNode.NodeID,
-				targetIP:    "www.bing.com",
-				targetPort:  443,
+				targetIP:    probeTarget.Host,
+				targetPort:  probeTarget.Port,
 				description: description,
 				protocol:    "tcp",
 				metadata: map[string]interface{}{
@@ -1079,8 +1080,8 @@ func (h *Handler) prepareTunnelDiagnosis(tunnelID int64) (string, string, []diag
 			description := fmt.Sprintf("出口(%s)->外网", outNode.NodeName)
 			workItems = append(workItems, diagnosisWorkItem{
 				fromNodeID:  outNode.NodeID,
-				targetIP:    "www.bing.com",
-				targetPort:  443,
+				targetIP:    probeTarget.Host,
+				targetPort:  probeTarget.Port,
 				description: description,
 				protocol:    "tcp",
 				metadata: map[string]interface{}{
@@ -1093,8 +1094,8 @@ func (h *Handler) prepareTunnelDiagnosis(tunnelID int64) (string, string, []diag
 			description := fmt.Sprintf("入口(%s)->外网", inNode.NodeName)
 			workItems = append(workItems, diagnosisWorkItem{
 				fromNodeID:  inNode.NodeID,
-				targetIP:    "www.bing.com",
-				targetPort:  443,
+				targetIP:    probeTarget.Host,
+				targetPort:  probeTarget.Port,
 				description: description,
 				protocol:    "tcp",
 				metadata: map[string]interface{}{

go-backend/internal/http/handler/tunnel_probe_target_api_test.go

@@ -209,6 +209,22 @@ func TestTunnelUpdateInvalidProbeTargetDoesNotCleanFederationBindings(t *testing
 	}
 }
 
+func TestTunnelDiagnosisUsesConfiguredProbeTarget(t *testing.T) {
+	h := setupProbeTargetTunnelHandler(t)
+	seedProbeTargetTunnel(t, h, 90, "diagnosis-target", "speed.example.com", 8443)
+
+	_, _, workItems, err := h.prepareTunnelDiagnosis(90)
+	if err != nil {
+		t.Fatalf("prepare tunnel diagnosis: %v", err)
+	}
+	if len(workItems) != 1 {
+		t.Fatalf("expected one diagnosis item, got %d", len(workItems))
+	}
+	if workItems[0].targetIP != "speed.example.com" || workItems[0].targetPort != 8443 {
+		t.Fatalf("expected custom diagnosis target speed.example.com:8443, got %s:%d", workItems[0].targetIP, workItems[0].targetPort)
+	}
+}
+
 func setupProbeTargetTunnelHandler(t *testing.T) *Handler {
 	t.Helper()
 	r, err := repo.Open(filepath.Join(t.TempDir(), "panel.db"))