diff --git a/go-backend/internal/http/handler/tunnel_quality_prober.go b/go-backend/internal/http/handler/tunnel_quality_prober.go
index bdc5683..0e2188f 100644
--- a/go-backend/internal/http/handler/tunnel_quality_prober.go
+++ b/go-backend/internal/http/handler/tunnel_quality_prober.go
@@ -229,6 +229,9 @@ func (p *tunnelQualityProber) probeTunnel(tunnelID int64) {
 		p.storeResult(snap)
 		return
 	}
+	probeTarget := effectiveTunnelProbeTargetValues(tunnel.ProbeTargetHost, tunnel.ProbeTargetPort)
+	snap.ProbeTargetHost = probeTarget.Host
+	snap.ProbeTargetPort = probeTarget.Port
 
 	chainRows, err := h.listChainNodesForTunnel(tunnelID)
 	if err != nil || len(chainRows) == 0 {
@@ -245,20 +248,13 @@ func (p *tunnelQualityProber) probeTunnel(tunnelID int64) {
 		pingTimeoutMS:  tunnelQualityPingTimeoutMs,
 		timeoutMessage: "探测超时",
 	}
-	probeTarget := effectiveTunnelProbeTargetValues(tunnel.ProbeTargetHost, tunnel.ProbeTargetPort)
-	snap.ProbeTargetHost = probeTarget.Host
-	snap.ProbeTargetPort = probeTarget.Port
 	p.probeBestExitOwners(tunnelID, inNodes, midNodesGrouped, outNodes, ipPreference, options, probeTarget)
 
 	switch tunnel.Type {
 	case 1:
-		// Port forwarding: exit/public edge → public probe target when available.
-		publicProbeNodes := inNodes
-		if len(outNodes) > 0 {
-			publicProbeNodes = outNodes
-		}
-		if len(publicProbeNodes) > 0 {
-			lat, loss, err := p.pingNode(publicProbeNodes[0].NodeID, probeTarget.Host, probeTarget.Port, options)
+		// Port forwarding: entry → public probe target only.
+		if len(inNodes) > 0 {
+			lat, loss, err := p.pingNode(inNodes[0].NodeID, probeTarget.Host, probeTarget.Port, options)
 			if err == nil {
 				snap.ExitToBingLatency = lat
 				snap.ExitToBingLoss = loss
@@ -370,13 +366,9 @@ func (p *tunnelQualityProber) probeTunnel(tunnelID int64) {
 
 		snap.Success = probeOK
 	default:
-		// Unknown type: use exit/public edge when available, otherwise entry.
-		publicProbeNodes := inNodes
-		if len(outNodes) > 0 {
-			publicProbeNodes = outNodes
-		}
-		if len(publicProbeNodes) > 0 {
-			lat, loss, err := p.pingNode(publicProbeNodes[0].NodeID, probeTarget.Host, probeTarget.Port, options)
+		// Unknown type: entry → public probe target.
+		if len(inNodes) > 0 {
+			lat, loss, err := p.pingNode(inNodes[0].NodeID, probeTarget.Host, probeTarget.Port, options)
 			if err == nil {
 				snap.ExitToBingLatency = lat
 				snap.ExitToBingLoss = loss
diff --git a/go-backend/internal/http/handler/tunnel_quality_prober_test.go b/go-backend/internal/http/handler/tunnel_quality_prober_test.go
index 34f1e7b..0b93a29 100644
--- a/go-backend/internal/http/handler/tunnel_quality_prober_test.go
+++ b/go-backend/internal/http/handler/tunnel_quality_prober_test.go
@@ -31,8 +31,11 @@ func TestTunnelQualityProberUsesConfiguredProbeTarget(t *testing.T) {
 	}
 	p.probeTunnel(77)
 
-	if !slices.Contains(calls, "30|speed.example.com|8443") {
-		t.Fatalf("expected exit probe to configured target, calls=%+v", calls)
+	if !slices.Contains(calls, "10|speed.example.com|8443") {
+		t.Fatalf("expected type 1 public probe from entry to configured target, calls=%+v", calls)
+	}
+	if slices.Contains(calls, "30|speed.example.com|8443") {
+		t.Fatalf("did not expect type 1 public probe from exit node, calls=%+v", calls)
 	}
 	snaps := p.GetAll()
 	if len(snaps) != 1 {
@@ -42,3 +45,25 @@ func TestTunnelQualityProberUsesConfiguredProbeTarget(t *testing.T) {
 		t.Fatalf("unexpected snapshot target metadata: %+v", snaps[0])
 	}
 }
+
+func TestTunnelQualityProberStoresProbeTargetWhenChainIncomplete(t *testing.T) {
+	h := setupProbeTargetTunnelHandler(t)
+	seedProbeTargetTunnel(t, h, 78, "quality-target-incomplete", "speed.example.com", 8443)
+	if err := h.repo.DB().Exec(`DELETE FROM chain_tunnel WHERE tunnel_id = ?`, 78).Error; err != nil {
+		t.Fatalf("delete chain rows: %v", err)
+	}
+
+	p := newTunnelQualityProber(h)
+	p.probeTunnel(78)
+
+	snaps := p.GetAll()
+	if len(snaps) != 1 {
+		t.Fatalf("expected one quality snapshot, got %+v", snaps)
+	}
+	if snaps[0].ErrorMessage == "" {
+		t.Fatalf("expected incomplete chain error, got %+v", snaps[0])
+	}
+	if snaps[0].ProbeTargetHost != "speed.example.com" || snaps[0].ProbeTargetPort != 8443 {
+		t.Fatalf("unexpected snapshot target metadata: %+v", snaps[0])
+	}
+}