fix(server): suppress expected websocket close write errors

server/hdl_websock.go

@@ -214,11 +214,22 @@ func (sess *Session) writeWSFrame(mt int, msg any) error {
 	}
 	reason := classifyWSError(err)
 	immetrics.ObserveWSWrite(frame, "error", reason, started, payloadBytes)
-	logs.Err.Printf("ws: writeLoop sid=%s uid=%s frame=%s queue=%d capacity=%d reason=%s err=%v",
-		sess.sid, sess.uid.UserId(), frame, len(sess.send), cap(sess.send), reason, err)
+	if shouldLogWSWriteError(reason) {
+		logs.Err.Printf("ws: writeLoop sid=%s uid=%s frame=%s queue=%d capacity=%d reason=%s err=%v",
+			sess.sid, sess.uid.UserId(), frame, len(sess.send), cap(sess.send), reason, err)
+	}
 	return err
 }
 
+func shouldLogWSWriteError(reason string) bool {
+	switch reason {
+	case "close_normal", "close_going_away", "closed", "eof", "broken_pipe", "connection_reset":
+		return false
+	default:
+		return true
+	}
+}
+
 func classifyWSError(err error) string {
 	if err == nil {
 		return "none"

server/hdl_websock_test.go

@@ -37,6 +37,31 @@ func TestClassifyWSError(t *testing.T) {
 	}
 }
 
+func TestShouldLogWSWriteError(t *testing.T) {
+	tests := []struct {
+		reason string
+		want   bool
+	}{
+		{reason: "close_normal", want: false},
+		{reason: "close_going_away", want: false},
+		{reason: "closed", want: false},
+		{reason: "eof", want: false},
+		{reason: "broken_pipe", want: false},
+		{reason: "connection_reset", want: false},
+		{reason: "timeout", want: true},
+		{reason: "close_abnormal", want: true},
+		{reason: "other", want: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.reason, func(t *testing.T) {
+			if got := shouldLogWSWriteError(tc.reason); got != tc.want {
+				t.Fatalf("shouldLogWSWriteError(%q)=%v want %v", tc.reason, got, tc.want)
+			}
+		})
+	}
+}
+
 func TestWebSocketOutboundQueueTiming(t *testing.T) {
 	sess := &Session{proto: WEBSOCK, send: make(chan any, 2)}
 	payload := []byte("message")