Track QUIC fabric stream capacity

agents/rap-node-agent/internal/mesh/fabric_quic_transport_test.go

@@ -224,7 +224,9 @@ func TestQUICFabricTransportPrunesIdleConnections(t *testing.T) {
 	if err != nil {
 		t.Fatalf("connect: %v", err)
 	}
-	defer session.Close()
+	if err := session.Close(); err != nil {
+		t.Fatalf("close session: %v", err)
+	}
 	time.Sleep(time.Millisecond)
 
 	snapshot := transport.Snapshot()
@@ -233,6 +235,51 @@ func TestQUICFabricTransportPrunesIdleConnections(t *testing.T) {
 	}
 }
 
+func TestQUICFabricTransportLimitsStreamsPerConnection(t *testing.T) {
+	server, err := StartQUICFabricServer(context.Background(), QUICFabricServerConfig{
+		ListenAddr: "127.0.0.1:0",
+		TLSConfig:  testQUICTLSConfig(t),
+	})
+	if err != nil {
+		t.Fatalf("start quic fabric server: %v", err)
+	}
+	defer server.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	transport := NewQUICFabricTransport(nil)
+	transport.MaxStreamsPerConn = 1
+	defer transport.Close()
+	target := FabricTransportTarget{
+		PeerID:   "node-b",
+		Endpoint: server.Addr().String(),
+		TLSConfig: &tls.Config{
+			InsecureSkipVerify: true,
+			NextProtos:         []string{fabricQUICNextProto},
+		},
+		Timeout: time.Second,
+	}
+	first, err := transport.Connect(ctx, target)
+	if err != nil {
+		t.Fatalf("first connect: %v", err)
+	}
+	if _, err := transport.Connect(ctx, target); err == nil {
+		t.Fatal("second connect succeeded past stream limit")
+	}
+	snapshot := transport.Snapshot()
+	if snapshot.ActiveStreams != 1 || snapshot.Stats.StreamLimitRejects != 1 {
+		t.Fatalf("unexpected stream limit snapshot: %+v", snapshot)
+	}
+	if err := first.Close(); err != nil {
+		t.Fatalf("close first stream: %v", err)
+	}
+	second, err := transport.Connect(ctx, target)
+	if err != nil {
+		t.Fatalf("connect after release: %v", err)
+	}
+	defer second.Close()
+}
+
 func TestQUICFabricServerHandlesFabricFrames(t *testing.T) {
 	var events []FabricSessionEventLogEntry
 	server, err := StartQUICFabricServer(context.Background(), QUICFabricServerConfig{