fix: psbt_nostr: don't allow to save tx without txid

Stops the psbt nostr plugin from trying to save transactions without
txid to the wallet history and doesn't give the user the option to do
so.

electrum/plugins/psbt_nostr/psbt_nostr.py

@@ -278,6 +278,7 @@ class CosignerWallet(Logger):
         on_failure: Callable = None,
         on_success: Callable = None
     ) -> None:
+        assert tx.txid(), "Shouldn't allow to save tx without txid"
         try:
             # TODO: adding tx should be handled more gracefully here:
             # 1) don't replace tx with same tx with less signatures

electrum/plugins/psbt_nostr/qml.py

@@ -48,7 +48,7 @@ class QReceiveSignalObject(QObject):
         QObject.__init__(self)
         self._plugin = plugin
 
-    cosignerReceivedPsbt = pyqtSignal(str, str, str, str)
+    cosignerReceivedPsbt = pyqtSignal(str, str, str, str, bool)
     sendPsbtFailed = pyqtSignal(str, arguments=['reason'])
     sendPsbtSuccess = pyqtSignal()
 
@@ -138,7 +138,8 @@ class QmlCosignerWallet(EventListener, CosignerWallet):
     def on_event_psbt_nostr_received(self, wallet, pubkey, event_id, tx: 'PartialTransaction', label: str):
         if self.wallet == wallet:
             self.tx = tx
-            self.plugin.so.cosignerReceivedPsbt.emit(pubkey, event_id, tx.serialize(), label)
+            can_be_saved = tx.txid() is not None
+            self.plugin.so.cosignerReceivedPsbt.emit(pubkey, event_id, tx.serialize(), label, can_be_saved)
 
     def close(self):
         super().close()
@@ -173,5 +174,5 @@ class QmlCosignerWallet(EventListener, CosignerWallet):
     def reject_psbt(self, event_id):
         self.mark_pending_event_rcvd(event_id)
 
-    def on_add_fail(self):
-        self.logger.error('failed to add tx to wallet')
+    def on_add_fail(self, error_msg: str):
+        self.logger.error(f'failed to add tx to wallet: {error_msg}')

electrum/plugins/psbt_nostr/qml/PsbtReceiveDialog.qml

@@ -17,6 +17,7 @@ ElDialog {
     }
 
     property string tx_label
+    property bool can_be_saved
     property int choice: PsbtReceiveDialog.Choice.None
 
     // TODO: it might be better to defer popup until no dialogs are shown
@@ -81,6 +82,7 @@ ElDialog {
                 Layout.preferredWidth: 1
                 text: qsTr('Save to Wallet')
                 icon.source: Qt.resolvedUrl('../../../gui/icons/wallet.png')
+                visible: dialog.can_be_saved
                 onClicked: {
                     choice = PsbtReceiveDialog.Choice.Save
                     doAccept()

electrum/plugins/psbt_nostr/qml/main.qml

@@ -7,9 +7,10 @@ import "../../../gui/qml/components/controls"
 Item {
     Connections {
         target: AppController ? AppController.plugin('psbt_nostr') : null
-        function onCosignerReceivedPsbt(pubkey, event, tx, label) {
+        function onCosignerReceivedPsbt(pubkey, event, tx, label, can_be_saved) {
             var dialog = psbtReceiveDialog.createObject(app, {
-                tx_label: label
+                tx_label: label,
+                can_be_saved: can_be_saved
             })
             dialog.accepted.connect(function () {
                 if (dialog.choice == PsbtReceiveDialog.Choice.Open) {

electrum/plugins/psbt_nostr/qt.py

@@ -102,7 +102,8 @@ class QtCosignerWallet(EventListener, CosignerWallet):
             self.obj.cosignerReceivedPsbt.emit(*args)  # put on UI thread via signal
 
     def send_to_cosigners(self, tx: Union['Transaction', 'PartialTransaction'], label: str):
-        self.add_transaction_to_wallet(tx, label=label, on_failure=self.on_add_fail)
+        if tx.txid():
+            self.add_transaction_to_wallet(tx, label=label, on_failure=self.on_add_fail)
         self.send_psbt(tx, label)
 
     def do_send(self, messages: List[Tuple[str, dict]], txid: Optional[str] = None):
@@ -120,8 +121,10 @@ class QtCosignerWallet(EventListener, CosignerWallet):
         except Exception as e:
             self.window.show_error(str(e))
             return
-        self.window.show_message(
-            _("Your transaction was sent to your cosigners via Nostr.") + '\n\n' + txid)
+        message = _("Your transaction was sent to your cosigners via Nostr.")
+        if txid:
+            message += '\n\n' + txid
+        self.window.show_message(message)
 
     def on_receive(self, pubkey, event_id, tx, label):
         msg = '<br/>'.join([
@@ -129,13 +132,17 @@ class QtCosignerWallet(EventListener, CosignerWallet):
             _("A transaction was received from your cosigner with label: <br/><big>{}</big><br/>").format(label),
             _("Do you want to open it now?")
         ])
-        result = self.window.show_message(msg, rich_text=True, icon=QMessageBox.Icon.Question, buttons=[
-                QMessageBox.StandardButton.Open,
-                (QPushButton('Discard'), QMessageBox.ButtonRole.DestructiveRole, 100),
-                (QPushButton('Save to wallet'), QMessageBox.ButtonRole.AcceptRole, 101)]
-        )
+        buttons = [
+            QMessageBox.StandardButton.Open,
+            (QPushButton('Discard'), QMessageBox.ButtonRole.DestructiveRole, 100),
+        ]
+        if tx.txid():  # cannot add tx without txid to wallet history (e.g. unsigned legacy tx)
+            buttons.append(
+                (QPushButton('Save to wallet'), QMessageBox.ButtonRole.AcceptRole, 101)  # type: ignore
+            )
+        result = self.window.show_message(msg, rich_text=True, icon=QMessageBox.Icon.Question, buttons=buttons)
         if result == QMessageBox.StandardButton.Open:
-            if label:
+            if label and tx.txid():
                 self.wallet.set_label(tx.txid(), label)
             show_transaction(tx, parent=self.window, prompt_if_unsaved=True, on_closed=partial(self.on_tx_dialog_closed, event_id))
         else: