diff --git a/scripts/liveness.sh b/scripts/liveness.sh
index 451fdfb..cfcc90a 100755
--- a/scripts/liveness.sh
+++ b/scripts/liveness.sh
@@ -1,8 +1,11 @@
 #!/usr/bin/env bash
-# echoIRCd liveness probe: do a real NICK/USER register round-trip on the plaintext
-# port and, if the daemon doesn't answer with a 001 welcome, restart it. Catches a
-# hung core (process alive but not serving), which Restart=on-failure alone can't.
-# Run by echoircd-liveness.timer.
+# echoIRCd liveness probe: prove the acceptor + core are alive and responsive with a
+# pre-registration PING/PONG round-trip, and restart the daemon if it doesn't answer.
+# Catches a hung core (process alive but not serving), which Restart=on-failure can't.
+#
+# It deliberately does NOT register (no NICK/USER), so it never triggers connect/quit
+# server-notices — the probe is invisible in the oper snotice stream. Run by
+# echoircd-liveness.timer.
 set -u
 PORT="${1:-6767}"
 
@@ -12,7 +15,8 @@ port = int(sys.argv[1])
 try:
     s = socket.create_connection(("127.0.0.1", port), timeout=5)
     s.settimeout(5)
-    s.sendall(b"NICK livecheck\r\nUSER lc 0 * :liveness\r\n")
+    # a pre-registration PING is answered with a PONG, without creating a client session
+    s.sendall(b"PING :liveness\r\n")
     data = b""
     end = time.time() + 6
     while time.time() < end:
@@ -20,14 +24,10 @@ try:
         if not d:
             break
         data += d
-        if b" 001 " in data:
+        if b"PONG" in data:
             break
-    try:
-        s.sendall(b"QUIT :liveness\r\n")
-    except OSError:
-        pass
     s.close()
-    sys.exit(0 if b" 001 " in data else 1)
+    sys.exit(0 if b"PONG" in data else 1)
 except OSError:
     sys.exit(1)
 PY
@@ -35,5 +35,5 @@ then
     exit 0
 fi
 
-echo "echoircd liveness: no 001 from 127.0.0.1:${PORT} within timeout — restarting echoircd-dev.service"
+echo "echoircd liveness: no PONG from 127.0.0.1:${PORT} within timeout — restarting echoircd-dev.service"
 systemctl restart echoircd-dev.service