qt: show sat/sats balance with pluralization in wallet badge

WalletBadge previously showed "s" as a fixed satoshi unit symbol.
Add a balanceSatoshi property (typed as qint64 via Q_PROPERTY so the
full 64-bit value reaches QML) and wire it from DesktopWallets so the
badge can pluralize correctly: "sat" for exactly 1 satoshi, "sats"
otherwise. The balance is also moved to a suffix position to match
standard display conventions.

Add displayUnitLabelForAmount() to OptionsQmlModel as a testable helper
for the pluralization logic, and update the QML unit tests accordingly.

Author: epicleafies

qml/models/options_model.cpp

@@ -283,6 +283,12 @@ QString OptionsQmlModel::displayUnitLabel() const
     return (m_display_unit == 1) ? QStringLiteral("sat") : QStringLiteral("BTC");
 }
 
+QString OptionsQmlModel::displayUnitLabelForAmount(qint64 satoshi) const
+{
+    if (m_display_unit != 1) return QStringLiteral("₿");
+    return (qAbs(satoshi) == 1) ? QStringLiteral("sat") : QStringLiteral("sats");
+}
+
 
 void OptionsQmlModel::onboard()
 {

qml/models/options_model.h

@@ -82,6 +82,7 @@ class OptionsQmlModel : public QObject
     int displayUnit() const { return m_display_unit; }
     void setDisplayUnit(int new_display_unit);
     QString displayUnitLabel() const;
+    Q_INVOKABLE QString displayUnitLabelForAmount(qint64 satoshi) const;
 
 public Q_SLOTS:
     void setCustomDataDirString(const QString &new_custom_datadir_string) {

qml/models/walletqmlmodel.cpp

@@ -101,7 +101,7 @@ QString WalletQmlModel::balance() const
     return QmlBitcoinUnits::format(unit, m_wallet->getBalance());
 }
 
-CAmount WalletQmlModel::balanceSatoshi() const
+qint64 WalletQmlModel::balanceSatoshi() const
 {
     if (!m_wallet) {
         return 0;

qml/models/walletqmlmodel.h

@@ -27,6 +27,7 @@ class WalletQmlModel : public QObject
     Q_OBJECT
     Q_PROPERTY(QString name READ name NOTIFY nameChanged)
     Q_PROPERTY(QString balance READ balance NOTIFY balanceChanged)
+    Q_PROPERTY(qint64 balanceSatoshi READ balanceSatoshi NOTIFY balanceChanged)
     Q_PROPERTY(ActivityListModel* activityListModel READ activityListModel CONSTANT)
     Q_PROPERTY(CoinsListModel* coinsListModel READ coinsListModel CONSTANT)
     Q_PROPERTY(SendRecipientsListModel* recipients READ sendRecipientList CONSTANT)
@@ -43,7 +44,7 @@ class WalletQmlModel : public QObject
 
     QString name() const;
     QString balance() const;
-    CAmount balanceSatoshi() const;
+    qint64 balanceSatoshi() const;
     Q_INVOKABLE void commitPaymentRequest();
 
     ActivityListModel* activityListModel() const { return m_activity_list_model; }

qml/pages/wallet/DesktopWallets.qml

@@ -37,6 +37,7 @@ Page {
             implicitHeight: 46
             text: walletController.selectedWallet.name
             balance: walletController.selectedWallet.balance
+            balanceSatoshi: walletController.selectedWallet.balanceSatoshi
             loading: !walletController.initialized
             noWalletLoaded: !walletController.isWalletLoaded
             noWalletsFound: walletController.noWalletsFound

qml/pages/wallet/WalletBadge.qml

@@ -22,6 +22,7 @@ Button {
     property bool showBalance: true
     property bool showIcon: true
     property string balance: "0.0 000 000"
+    property var balanceSatoshi: 0
     property bool loading: false
     property bool noWalletLoaded: false
     property bool noWalletsFound: false
@@ -143,7 +144,7 @@ Button {
                 CoreText {
                     id: balanceText
                     visible: root.showBalance
-                    text: (optionsModel.displayUnit === 1 ? "s" : "₿") + " " + root.balance
+                    text: root.balance + " " + (optionsModel.displayUnit === 1 ? (root.balanceSatoshi === 1 ? qsTr("sat") : qsTr("sats")) : "₿")
                     color: Theme.color.neutral7
                 }
             }

test/qml/qml_tests_main.cpp

@@ -25,6 +25,10 @@ class MockOptionsModel : public QObject
         if (u != m_displayUnit) { m_displayUnit = u; Q_EMIT displayUnitChanged(u); }
     }
     QString displayUnitLabel() const { return m_displayUnit == 1 ? "sat" : "BTC"; }
+    Q_INVOKABLE QString displayUnitLabelForAmount(qint64 satoshi) const {
+        if (m_displayUnit != 1) return QString("₿");
+        return (qAbs(satoshi) == 1) ? QString("sat") : QString("sats");
+    }
     QString language() const { return m_language; }
     void setLanguage(const QString& l) {
         if (l != m_language) { m_language = l; Q_EMIT languageChanged(); }

test/qml/tst_displaysettings.qml

@@ -97,61 +97,60 @@ TestCase {
         compare(optionsModel.displayUnit, 0)
     }
 
-    // Mirrors the balance prefix expression in WalletBadge.qml.
+    // Mirrors the balance suffix expression in WalletBadge.qml.
+    // balanceSatoshi=1000 → plural "sats"; balanceSatoshi=1 → singular "sat".
     Component {
-        id: balancePrefixComponent
+        id: balanceSuffixComponent
         Text {
             property string balance: "1 000"
-            text: (optionsModel.displayUnit === 1 ? "s" : "₿") + " " + balance
+            property var balanceSatoshi: 1000
+            text: balance + " " + (optionsModel.displayUnit === 1 ? (balanceSatoshi === 1 ? "sat" : "sats") : "₿")
         }
     }
 
-    function test_walletBadge_prefix_is_s_in_sat_mode() {
+    function test_walletBadge_suffix_is_sats_in_sat_mode() {
         optionsModel.displayUnit = 1
-        const obj = createTemporaryObject(balancePrefixComponent, this)
+        const obj = createTemporaryObject(balanceSuffixComponent, this)
         verify(obj !== null)
-        compare(obj.text, "s 1 000")
+        compare(obj.text, "1 000 sats")
         optionsModel.displayUnit = 0
     }
 
-    function test_walletBadge_prefix_is_btc_symbol_in_btc_mode() {
+    function test_walletBadge_suffix_is_sat_singular_in_sat_mode() {
+        optionsModel.displayUnit = 1
+        const obj = createTemporaryObject(balanceSuffixComponent, this)
+        verify(obj !== null)
+        obj.balanceSatoshi = 1
+        compare(obj.text, "1 000 sat")
         optionsModel.displayUnit = 0
-        const obj = createTemporaryObject(balancePrefixComponent, this)
+    }
+
+    function test_walletBadge_suffix_is_btc_symbol_in_btc_mode() {
+        optionsModel.displayUnit = 0
+        const obj = createTemporaryObject(balanceSuffixComponent, this)
         verify(obj !== null)
-        compare(obj.text, "₿ 1 000")
+        compare(obj.text, "1 000 ₿")
     }
 
-    // Mirrors the Loader + Component pattern in BitcoinAmountInputField.qml,
-    // Send.qml, and RequestPayment.qml.
-    Component {
-        id: unitLabelComponent
-        Item {
-            id: wrapper
-            property int unit: 0
-            Loader {
-                objectName: "unitLabelLoader"
-                sourceComponent: wrapper.unit === 1 ? satComponent : btcComponent
-            }
-            Component { id: btcComponent; Text { text: "₿" } }
-            Component { id: satComponent; Text { text: "s" } }
-        }
+    // Tests displayUnitLabelForAmount pluralization logic.
+    function test_displayUnitLabelForAmount_singular_in_sat_mode() {
+        optionsModel.displayUnit = 1
+        compare(optionsModel.displayUnitLabelForAmount(1), "sat")
+        compare(optionsModel.displayUnitLabelForAmount(-1), "sat")
+        optionsModel.displayUnit = 0
     }
 
-    function test_unitLabel_shows_s_in_sat_mode() {
-        const obj = createTemporaryObject(unitLabelComponent, this)
-        obj.unit = 1
-        waitForRendering(obj)
-        const loader = findChild(obj, "unitLabelLoader")
-        verify(loader.item !== null)
-        compare(loader.item.text, "s")
+    function test_displayUnitLabelForAmount_plural_in_sat_mode() {
+        optionsModel.displayUnit = 1
+        compare(optionsModel.displayUnitLabelForAmount(0), "sats")
+        compare(optionsModel.displayUnitLabelForAmount(2), "sats")
+        compare(optionsModel.displayUnitLabelForAmount(1000), "sats")
+        optionsModel.displayUnit = 0
     }
 
-    function test_unitLabel_shows_btc_symbol_in_btc_mode() {
-        const obj = createTemporaryObject(unitLabelComponent, this)
-        obj.unit = 0
-        waitForRendering(obj)
-        const loader = findChild(obj, "unitLabelLoader")
-        verify(loader.item !== null)
-        compare(loader.item.text, "₿")
+    function test_displayUnitLabelForAmount_btc_symbol_in_btc_mode() {
+        optionsModel.displayUnit = 0
+        compare(optionsModel.displayUnitLabelForAmount(1), "₿")
+        compare(optionsModel.displayUnitLabelForAmount(1000), "₿")
     }
 }