fix(mining): only offer to mine on a node that is ours

Start Mining was live regardless of which daemon the wallet was talking
to. It is a `start_mining` RPC to the connected node, so on a remote one
it is either refused — the button appearing to do nothing — or, if the
operator left the RPC open, it sets someone else's machine mining to our
address. Neither is a thing a wallet should offer.

The axe now greys out unless `Nodes::connection().isLocal()`, hovering it
explains why, and clicking anyway flashes the same notice rather than
silently doing nothing. `onStartMining` refuses too: the QML disables the
control, but a signal is not a promise.

isLocal() counts localhost, .local, 127/8 and the RFC1918 ranges, so the
embedded node and a daemon on the LAN both qualify.

Claude-Session: https://claude.ai/code/session_01VLQ5DsgKv23osGANoFT3zF

src/MainWindow.cpp

@@ -252,7 +252,7 @@ void MainWindow::initWidgets() {
     });
 
     // [Mining] — wowlet: the pixel-art mining tab (mining.qml + embedded-node solo miner)
-    m_miningWidget = new MiningWidget(m_wallet, this);
+    m_miningWidget = new MiningWidget(m_wallet, m_nodes, this);
     ui->tabWidget->addTab(m_miningWidget, "Mining");
 
     // [Notes]

src/assets/qml/mining.qml

@@ -512,6 +512,10 @@ Rectangle {
                     Image {
                         id: imgAxe
                         visible: mining.daemonMiningState === 0
+                        // Greyed out while the wallet is on someone else's node:
+                        // solo mining is an RPC to the daemon we are connected
+                        // to, and that daemon has to be ours.
+                        opacity: mining.canMine ? 1.0 : 0.35
                         source: "qrc:/mining/axe.png"
                         width: 73
                         height: 75
@@ -551,7 +555,11 @@ Rectangle {
                         cursorShape: Qt.PointingHandCursor
 
                         onClicked: {
-                            if(mining.daemonMiningState === 0) {
+                            if (mining.daemonMiningState === 0) {
+                                if (!mining.canMine) {
+                                    remoteNodeNotice.flash();
+                                    return;
+                                }
                                 root.startMining();
                                 root.calcAvailableHeightConsoleLines();
                             }
@@ -559,14 +567,56 @@ Rectangle {
                                 root.stopMining();
                         }
                         onEntered: {
-                            imgAxe.height = 64
-                            imgAxe.width = 64
+                            if (mining.canMine) {
+                                imgAxe.height = 64
+                                imgAxe.width = 64
+                            } else {
+                                remoteNodeNotice.show();
+                            }
                         }
                         onExited: {
                             imgAxe.height = 75
                             imgAxe.width = 73
+                            remoteNodeNotice.hideSoon();
                         }
                     }
+
+                    // Why the axe is greyed out. Shown on hover, and flashed if
+                    // the axe is clicked anyway.
+                    Rectangle {
+                        id: remoteNodeNotice
+                        z: parent.z + 5
+                        visible: opacity > 0.01
+                        opacity: 0.0
+                        width: 250
+                        height: noticeText.implicitHeight + 16
+                        radius: 6
+                        color: "#231a10"
+                        border.color: "#e0b062"
+                        border.width: 1
+                        anchors.right: parent.left
+                        anchors.rightMargin: 8
+                        anchors.verticalCenter: parent.verticalCenter
+
+                        Text {
+                            id: noticeText
+                            anchors.centerIn: parent
+                            width: parent.width - 16
+                            wrapMode: Text.WordWrap
+                            horizontalAlignment: Text.AlignHCenter
+                            color: "#f2dcb4"
+                            font.pointSize: 9
+                            text: "Mining needs your own node.\nYou are connected to a remote one — " +
+                                  "start the built-in node or point the wallet at a local daemon " +
+                                  "under Settings to mine."
+                        }
+
+                        Behavior on opacity { NumberAnimation { duration: 160 } }
+                        Timer { id: noticeHide; interval: 2600; onTriggered: remoteNodeNotice.opacity = 0.0 }
+                        function show()     { noticeHide.stop(); opacity = 1.0 }
+                        function hideSoon() { noticeHide.restart() }
+                        function flash()    { show(); noticeHide.restart() }
+                    }
                 }
             }
         }

src/widgets/MiningWidget.cpp

@@ -3,6 +3,8 @@
 
 #include "MiningWidget.h"
 
+#include "utils/nodes.h"
+
 #include <algorithm>
 
 #include <QVBoxLayout>
@@ -20,9 +22,10 @@ static QString formatUptime(qint64 secs) {
         .arg(secs % 60, 2, 10, QChar('0'));
 }
 
-MiningWidget::MiningWidget(Wallet *wallet, QWidget *parent)
+MiningWidget::MiningWidget(Wallet *wallet, Nodes *nodes, QWidget *parent)
     : QWidget(parent)
     , m_wallet(wallet)
+    , m_nodes(nodes)
     , m_quickWidget(new QQuickWidget(this))
     , m_backend(new MiningBackend(this))
     , m_timer(new QTimer(this))
@@ -46,6 +49,10 @@ MiningWidget::MiningWidget(Wallet *wallet, QWidget *parent)
 }
 
 void MiningWidget::onStartMining() {
+    // The QML disables the control, but the signal is not a promise: refuse
+    // here too rather than send start_mining to a stranger's daemon.
+    if (!m_backend->canMine())
+        return;
     int threads = std::max(1, QThread::idealThreadCount() / 2);
     if (m_wallet->startMining(threads))
         m_backend->setState(3);
@@ -57,6 +64,8 @@ void MiningWidget::onStopMining() {
 }
 
 void MiningWidget::poll() {
+    m_backend->setCanMine(m_nodes && m_nodes->connection().isLocal());
+
     bool mining = m_wallet->isMining();
     m_backend->setState(mining ? 3 : 0);
 

src/widgets/MiningWidget.h

@@ -5,6 +5,8 @@
 #define WOWLET_MININGWIDGET_H
 
 #include <QWidget>
+
+class Nodes;
 #include <QTimer>
 #include <QQuickWidget>
 
@@ -16,16 +18,24 @@ class MiningBackend : public QObject {
 Q_OBJECT
     Q_PROPERTY(int daemonMiningState READ daemonMiningState NOTIFY daemonMiningStateChanged)
     Q_PROPERTY(bool reducedMotion READ reducedMotion NOTIFY reducedMotionChanged)
+    Q_PROPERTY(bool canMine READ canMine NOTIFY canMineChanged)
 public:
     explicit MiningBackend(QObject *parent = nullptr) : QObject(parent) {}
     int daemonMiningState() const { return m_state; }
     void setState(int s) { if (m_state != s) { m_state = s; emit daemonMiningStateChanged(); } }
     bool reducedMotion() const { return m_reducedMotion; }
     void setReducedMotion(bool r) { if (m_reducedMotion != r) { m_reducedMotion = r; emit reducedMotionChanged(); } }
+    // Solo mining is a start_mining RPC to whichever daemon the wallet is
+    // connected to. Against a remote node that is either refused outright or —
+    // worse, if the operator left the RPC open — it puts someone else's machine
+    // to work on our address. It is only ever ours to ask of our own node.
+    bool canMine() const { return m_canMine; }
+    void setCanMine(bool c) { if (m_canMine != c) { m_canMine = c; emit canMineChanged(); } }
 
 signals:
     void daemonMiningStateChanged();
     void reducedMotionChanged();
+    void canMineChanged();
     void daemonOutput(const QString &line);
     void syncStatus(int from, int to, int pct);
     void uptimeChanged(const QString &uptime);
@@ -34,6 +44,7 @@ signals:
 private:
     int m_state = 0;   // 0:idle 1:startup 2:syncing 3:mining
     bool m_reducedMotion = false;
+    bool m_canMine = false;
 };
 
 // wowlet: the pixel-art mining tab. Hosts mining.qml and wires its pick-axe to the wallet's solo
@@ -41,7 +52,7 @@ private:
 class MiningWidget : public QWidget {
 Q_OBJECT
 public:
-    explicit MiningWidget(Wallet *wallet, QWidget *parent = nullptr);
+    explicit MiningWidget(Wallet *wallet, Nodes *nodes, QWidget *parent = nullptr);
 
 private slots:
     void onStartMining();
@@ -50,6 +61,7 @@ private slots:
 
 private:
     Wallet *m_wallet;
+    Nodes *m_nodes;
     QQuickWidget *m_quickWidget;
     MiningBackend *m_backend;
     QTimer *m_timer;