Function readSavedIdFromFile

src/core/GpuSelector.cpp:178–196

Startup read: parse the persisted "Graphics" → "gpu" id straight from the settings XML. Constructing AppSettings::instance() this early would run its migrateSettingsPath() before setApplicationName(), computing the wrong AppConfigLocation path and permanently skipping the old→new migration for upgrading users. Reading the file by hand (like the UiScale bootstrap) avoids touching the singleton at

// upgrading users.  Reading the file by hand (like the UiScale bootstrap) avoids
// touching the singleton at all.
QString readSavedIdFromFile()
{
    const QString fallback = QString::fromLatin1(GpuSelector::kAutoId);
    QFile f(settingsFilePath());
    if (!f.open(QIODevice::ReadOnly | QIODevice::Text)) {
        return fallback;
    }
    QXmlStreamReader xml(&f);
    while (!xml.atEnd()) {
        if (xml.readNext() == QXmlStreamReader::StartElement
                && xml.name() == QLatin1String("Graphics")) {
            // readElementText() unescapes the XML entities, yielding the raw JSON.
            const QJsonObject o =
                QJsonDocument::fromJson(xml.readElementText().toUtf8()).object();
            return o.value(QStringLiteral("gpu")).toString(fallback);
        }
    }
    return fallback;
}

} // namespace