fix: 优化客户端错误提示和校验诊断信息

Common/DeviceIdentityHelper.cpp

@@ -257,12 +257,34 @@ bool DeviceIdentityHelper::ensureIssued(
     timer.stop();
 
     const int status = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
+    const QString networkError = reply->errorString();
     const QByteArray raw = reply->readAll();
     reply->deleteLater();
     if (status != 200) {
-        m_error = QCoreApplication::translate("DeviceIdentityHelper", "Device identity request failed (HTTP %1): %2")
-                      .arg(status)
-                      .arg(QString::fromUtf8(raw));
+        QJsonParseError responseError;
+        const QJsonDocument errorDoc = QJsonDocument::fromJson(raw, &responseError);
+        QString serverMessage;
+        if (responseError.error == QJsonParseError::NoError && errorDoc.isObject()) {
+            const QJsonValue detail = errorDoc.object().value(QStringLiteral("detail"));
+            serverMessage = detail.isObject()
+                ? detail.toObject().value(QStringLiteral("msg")).toString()
+                : detail.toString();
+        }
+        if (serverMessage.isEmpty())
+            serverMessage = QString::fromUtf8(raw).trimmed();
+
+        if (status == 0) {
+            m_error = QCoreApplication::translate(
+                "DeviceIdentityHelper",
+                "Cannot contact the update server to issue device identity.\nServer: %1\nApp: %2\nChannel: %3\nNetwork error: %4\nTimeout: %5 ms")
+                .arg(trimmedBaseUrl, appId, channel, networkError, QString::number(timeoutMs));
+        } else {
+            m_error = QCoreApplication::translate(
+                "DeviceIdentityHelper",
+                "Device identity request was rejected by the update server.\nServer: %1\nHTTP status: %2\nApp: %3\nChannel: %4\nServer message: %5")
+                .arg(trimmedBaseUrl, QString::number(status), appId, channel,
+                     serverMessage.isEmpty() ? QCoreApplication::translate("DeviceIdentityHelper", "<empty response>") : serverMessage);
+        }
         return false;
     }