diff --git a/go.mod b/go.mod
index e5a265a..0883734 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module git.noahlan.cn/noahlan/nnet/v2
 
-go 1.25
+go 1.26.5
 
 require (
 	github.com/gorilla/websocket v1.5.3
diff --git a/internal/server/helpers_test.go b/internal/server/helpers_test.go
index 01a0692..2fae8de 100644
--- a/internal/server/helpers_test.go
+++ b/internal/server/helpers_test.go
@@ -3,6 +3,7 @@ package server
 import (
 	"testing"
 
+	protocolnnet "git.noahlan.cn/noahlan/nnet/v2/internal/protocol/nnet"
 	internalunpacker "git.noahlan.cn/noahlan/nnet/v2/internal/unpacker"
 	unpackerpkg "git.noahlan.cn/noahlan/nnet/v2/pkg/unpacker"
 )
@@ -46,3 +47,71 @@ func TestProcessDataWithUnpackerConsumesIncompleteInput(t *testing.T) {
 		t.Fatalf("message=%q, want %q", string(messages[0]), "\x03abc")
 	}
 }
+
+func TestProcessDataWithUnpackerIsolatesConnectionBuffers(t *testing.T) {
+	u1 := internalunpacker.NewLengthFieldUnpacker(unpackerpkg.LengthFieldUnpacker{
+		LengthFieldOffset:   0,
+		LengthFieldLength:   1,
+		LengthAdjustment:    0,
+		InitialBytesToStrip: 0,
+	})
+	u2 := internalunpacker.NewLengthFieldUnpacker(unpackerpkg.LengthFieldUnpacker{
+		LengthFieldOffset:   0,
+		LengthFieldLength:   1,
+		LengthAdjustment:    0,
+		InitialBytesToStrip: 0,
+	})
+
+	messages, _, hasRemaining, err := processDataWithUnpacker([]byte{3, 'a'}, u1)
+	if err != nil {
+		t.Fatalf("first connection partial error: %v", err)
+	}
+	if len(messages) != 0 || !hasRemaining {
+		t.Fatalf("first connection messages=%d hasRemaining=%v, want 0/true", len(messages), hasRemaining)
+	}
+
+	messages, _, hasRemaining, err = processDataWithUnpacker([]byte{1, 'z'}, u2)
+	if err != nil {
+		t.Fatalf("second connection complete error: %v", err)
+	}
+	if hasRemaining || len(messages) != 1 || string(messages[0]) != "\x01z" {
+		t.Fatalf("second connection messages=%q hasRemaining=%v, want isolated complete frame", messages, hasRemaining)
+	}
+
+	messages, _, hasRemaining, err = processDataWithUnpacker([]byte{'b', 'c'}, u1)
+	if err != nil {
+		t.Fatalf("first connection completion error: %v", err)
+	}
+	if hasRemaining || len(messages) != 1 || string(messages[0]) != "\x03abc" {
+		t.Fatalf("first connection messages=%q hasRemaining=%v, want original buffered frame", messages, hasRemaining)
+	}
+}
+
+func TestSplitWebSocketMessagesKeepsPartialFrameState(t *testing.T) {
+	protocol := protocolnnet.NewNNetProtocol("1.0")
+	provider, ok := protocol.(interface{ Unpacker() unpackerpkg.Unpacker })
+	if !ok {
+		t.Fatal("protocol should provide an unpacker")
+	}
+	unpacker := provider.Unpacker()
+	packet, err := protocol.Encode([]byte("hello"), nil)
+	if err != nil {
+		t.Fatalf("encode error: %v", err)
+	}
+
+	messages, err := splitWebSocketMessages(packet[:6], unpacker)
+	if err != nil {
+		t.Fatalf("partial split error: %v", err)
+	}
+	if len(messages) != 0 {
+		t.Fatalf("partial messages=%d, want 0", len(messages))
+	}
+
+	messages, err = splitWebSocketMessages(packet[6:], unpacker)
+	if err != nil {
+		t.Fatalf("completion split error: %v", err)
+	}
+	if len(messages) != 1 || string(messages[0]) != string(packet) {
+		t.Fatalf("messages=%q, want complete packet", messages)
+	}
+}