multiprocess: silence liveness-probe close as benign

primaryAlive() opens a QLocalSocket then disconnects without writing
any payload to verify a primary is listening. The primary's
receiveMessage() saw the empty PeerClosedError connection and logged
"failed to receive data from secondary process" plus a popup, even
though the real NXM/shortcut message arrived on the next connection
and was processed correctly.

Treat zero-byte PeerClosedError/UnknownSocketError closes as the
expected probe pattern (debug log, no error). Other errors still
report loudly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

1 files changed, 15 insertions, 4 deletions

diff --git a/src/src/multiprocess.cpp b/src/src/multiprocess.cpp
index b22ada3..3ac4c72 100644
--- a/src/src/multiprocess.cpp
+++ b/src/src/multiprocess.cpp
@@ -172,11 +172,22 @@ void MOMultiProcess::receiveMessage()
     const auto av = socket->bytesAvailable();

 

     if (av <= 0) {

-      MOBase::log::error("failed to receive data from secondary process: {}",

-                         socket->errorString());

+      // primaryAlive() liveness probes connect then disconnect without sending

+      // any data — these are expected, not errors. A real secondary that

+      // failed to deliver its payload will leave a non-PeerClosed error.

+      const auto err = socket->error();

+      const bool isProbe = err == QLocalSocket::PeerClosedError ||

+                           err == QLocalSocket::UnknownSocketError;

+      if (isProbe) {

+        MOBase::log::debug(

+            "secondary closed without sending data (liveness probe)");

+      } else {

+        MOBase::log::error("failed to receive data from secondary process: {}",

+                           socket->errorString());

 

-      reportError(tr("failed to receive data from secondary process: %1")

-                      .arg(socket->errorString()));

+        reportError(tr("failed to receive data from secondary process: %1")

+                        .arg(socket->errorString()));

+      }

       return;

     }

   }