diff --git a/go.mod b/go.mod
index 7b5f539..197f3e9 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,9 @@ module five
 
 go 1.25.0
 
-require github.com/jackc/pgx/v5 v5.9.2 // indirect
+require (
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
+	github.com/jackc/pgx/v5 v5.9.2 // indirect
+	golang.org/x/text v0.29.0 // indirect
+)
diff --git a/go.sum b/go.sum
index 9f22e7a..8c1f5e4 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,15 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
 github.com/jackc/pgx/v5 v5.9.2 h1:3ZhOzMWnR4yJ+RW1XImIPsD1aNSz4T4fyP7zlQb56hw=
 github.com/jackc/pgx/v5 v5.9.2/go.mod h1:mal1tBGAFfLHvZzaYh77YS/eC6IX9OWbRV1QIIM0Jn4=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/text v0.29.0 h1:1neNs90w9YzJ9BocxfsQNHKuAT4pkghyXc4nhZ6sJvk=
+golang.org/x/text v0.29.0/go.mod h1:7MhJOA9CD2qZyOKYazxdYMF85OwPdEr9jTtBpO7ydH4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/hbrtl/pgserver/wire_test.go b/hbrtl/pgserver/wire_test.go
new file mode 100644
index 0000000..51812ce
--- /dev/null
+++ b/hbrtl/pgserver/wire_test.go
@@ -0,0 +1,120 @@
+// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
+// All rights reserved.
+
+package pgserver
+
+import (
+	"net"
+	"testing"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgproto3"
+)
+
+// TestWireRoundtrip_Startup verifies the bare minimum protocol
+// handshake without involving the PRG side: an in-memory client
+// sends StartupMessage, the server replies AuthenticationOk +
+// ParameterStatus + BackendKeyData + ReadyForQuery, the client
+// confirms by reading exactly those messages in that order.
+//
+// Uses net.Pipe so no real TCP socket is bound — fast, robust on CI.
+// The PRG-dispatch path (runSQL → FIVE_SQL) is covered separately by
+// the psql integration test in _FiveSql2/test/pgserver/run.sh; this
+// test pins ONLY the protocol envelope.
+func TestWireRoundtrip_Startup(t *testing.T) {
+	clientConn, serverConn := net.Pipe()
+	defer clientConn.Close()
+
+	// Server side — minimal stand-in for run() that exercises the
+	// startup steps without needing a VM (no Query loop here).
+	srvDone := make(chan struct{})
+	go func() {
+		defer close(srvDone)
+		defer serverConn.Close()
+
+		s := &session{conn: serverConn, txStatus: 'I', srv: &Server{cfg: Config{}}}
+		// Step 1 — SSL/Startup peek. negotiateTLS reads 8 bytes;
+		// we don't send SSLRequest so this just buffers the bytes
+		// for the StartupMessage parse.
+		if err := s.negotiateTLS(); err != nil {
+			t.Errorf("server negotiateTLS: %v", err)
+			return
+		}
+		s.be = pgproto3.NewBackend(s.conn, s.conn)
+
+		msg, err := s.be.ReceiveStartupMessage()
+		if err != nil {
+			t.Errorf("ReceiveStartupMessage: %v", err)
+			return
+		}
+		if _, ok := msg.(*pgproto3.StartupMessage); !ok {
+			t.Errorf("expected StartupMessage, got %T", msg)
+			return
+		}
+
+		// Trust auth → AuthenticationOk
+		s.send(&pgproto3.AuthenticationOk{})
+		// Minimum ParameterStatus set
+		s.sendParameterStatus("server_version", "14.0 (FiveSql2)")
+		s.sendParameterStatus("client_encoding", "UTF8")
+		// BackendKeyData
+		s.send(&pgproto3.BackendKeyData{ProcessID: 1234, SecretKey: []byte{0, 0, 0, 0}})
+		// ReadyForQuery — idle
+		s.sendReadyForQuery()
+	}()
+
+	// Client side — drives the handshake via pgproto3.Frontend.
+	fe := pgproto3.NewFrontend(clientConn, clientConn)
+	fe.Send(&pgproto3.StartupMessage{
+		ProtocolVersion: pgproto3.ProtocolVersionNumber,
+		Parameters:      map[string]string{"user": "alice", "database": "alice"},
+	})
+	if err := fe.Flush(); err != nil {
+		t.Fatalf("client flush startup: %v", err)
+	}
+
+	// Expect AuthenticationOk
+	clientConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	msg, err := fe.Receive()
+	if err != nil {
+		t.Fatalf("client receive auth: %v", err)
+	}
+	if _, ok := msg.(*pgproto3.AuthenticationOk); !ok {
+		t.Fatalf("expected AuthenticationOk, got %T", msg)
+	}
+
+	// ParameterStatus × 2
+	for i := 0; i < 2; i++ {
+		msg, err = fe.Receive()
+		if err != nil {
+			t.Fatalf("client receive paramstatus %d: %v", i, err)
+		}
+		if _, ok := msg.(*pgproto3.ParameterStatus); !ok {
+			t.Fatalf("expected ParameterStatus, got %T", msg)
+		}
+	}
+
+	// BackendKeyData
+	msg, err = fe.Receive()
+	if err != nil {
+		t.Fatalf("client receive bkd: %v", err)
+	}
+	if _, ok := msg.(*pgproto3.BackendKeyData); !ok {
+		t.Fatalf("expected BackendKeyData, got %T", msg)
+	}
+
+	// ReadyForQuery
+	msg, err = fe.Receive()
+	if err != nil {
+		t.Fatalf("client receive rfq: %v", err)
+	}
+	rfq, ok := msg.(*pgproto3.ReadyForQuery)
+	if !ok {
+		t.Fatalf("expected ReadyForQuery, got %T", msg)
+	}
+	if rfq.TxStatus != 'I' {
+		t.Errorf("ReadyForQuery TxStatus = %c, want 'I' (idle)", rfq.TxStatus)
+	}
+
+	<-srvDone
+}