fix(wallet): surface background sync failures

apps/shared/wallet/qml/WalletControl.qml

@@ -14,6 +14,7 @@ Item {
     property real viewportWidth: width
     property int selectedIndex: 0
     property bool busy: false
+    property string handledSyncError: ""
 
     readonly property bool connected: root.wallet !== null && root.wallet.isWalletOpen
     readonly property string syncStatus: root.wallet
@@ -74,6 +75,19 @@ Item {
         messageDialog.open()
     }
 
+    function handleSyncFailure() {
+        if (!root.wallet || root.syncStatus !== "error") {
+            root.handledSyncError = ""
+            return
+        }
+        const error = String(root.wallet.walletSyncError || "")
+        if (error.length === 0 || error === root.handledSyncError)
+            return
+        root.handledSyncError = error
+        root.busy = false
+        root.showError(qsTr("Wallet synchronization failed: %1").arg(error))
+    }
+
     function openWallet() {
         if (!root.wallet || root.busy)
             return
@@ -116,6 +130,14 @@ Item {
         function onRowsRemoved() { root.clampSelection() }
     }
 
+    Connections {
+        target: root.wallet
+        ignoreUnknownSignals: true
+
+        function onWalletSyncStatusChanged() { root.handleSyncFailure() }
+        function onWalletSyncErrorChanged() { root.handleSyncFailure() }
+    }
+
     onConnectedChanged: {
         if (!root.connected) {
             root.selectedIndex = 0

apps/shared/wallet/tests/qml/tst_WalletControl.qml

@@ -14,6 +14,9 @@ Item {
             property bool isWalletOpen: false
             property bool walletExists: true
             property string walletHome: "/wallet"
+            property string walletSyncStatus: "closed"
+            property string walletSyncError: ""
+            property bool deferOpen: false
             property int openCalls: 0
             property int createCalls: 0
             property int publicAccountCalls: 0
@@ -22,7 +25,12 @@ Item {
 
             function openExisting() {
                 openCalls++
-                isWalletOpen = true
+                if (deferOpen) {
+                    walletSyncStatus = "opening"
+                } else {
+                    isWalletOpen = true
+                    walletSyncStatus = "ready"
+                }
                 return true
             }
 
@@ -133,6 +141,19 @@ Item {
             tryCompare(fixture.control, "connected", true)
         }
 
+        function test_surfacesDeferredOpenFailure() {
+            const fixture = createControl({ walletExists: true, deferOpen: true }, [])
+            mouseClick(findChild(fixture.control, "walletConnectButton"))
+            compare(fixture.backend.openCalls, 1)
+            compare(fixture.control.syncStatus, "opening")
+
+            fixture.backend.walletSyncStatus = "error"
+            fixture.backend.walletSyncError = "open_failed"
+            const dialog = findChild(fixture.control, "walletMessageDialog")
+            tryCompare(dialog, "opened", true)
+            verify(dialog.message.includes("open_failed"))
+        }
+
         function test_requiresSeedBackupAcknowledgement() {
             const fixture = createControl({ walletExists: false }, [])
             mouseClick(findChild(fixture.control, "walletConnectButton"))