wallet: kill negative conf numbers for TxMinedInfo

fixes https://github.com/spesmilo/electrum/issues/8240

#8240 was triggering an AssertionError in wallet.get_invoice_status,
as code there was assuming conf >= 0. To trigger, force-close
a LN channel, and while the sweep is waiting on the CSV, try to
make a payment in the Send tab to the ismine change address used
for the sweep in the future_tx. (order of events can also be reversed)

electrum/address_synchronizer.py

@@ -674,10 +674,9 @@ class AddressSynchronizer(Logger, EventListener):
             elif tx_hash in self.unconfirmed_tx:
                 height = self.unconfirmed_tx[tx_hash]
                 return TxMinedInfo(height=height, conf=0)
-            elif tx_hash in self.future_tx:
-                num_blocks_remainining = self.future_tx[tx_hash] - self.get_local_height()
-                if num_blocks_remainining > 0:
-                    return TxMinedInfo(height=TX_HEIGHT_FUTURE, conf=-num_blocks_remainining)
+            elif wanted_height := self.future_tx.get(tx_hash):
+                if wanted_height > self.get_local_height():
+                    return TxMinedInfo(height=TX_HEIGHT_FUTURE, conf=0, wanted_height=wanted_height)
                 else:
                     return TxMinedInfo(height=TX_HEIGHT_LOCAL, conf=0)
             else:

electrum/gui/qt/history_list.py

@@ -425,11 +425,16 @@ class HistoryModel(CustomModel, Logger):
 
     @staticmethod
     def tx_mined_info_from_tx_item(tx_item):
-        tx_mined_info = TxMinedInfo(height=tx_item['height'],
-                                    conf=tx_item['confirmations'],
-                                    timestamp=tx_item['timestamp'])
+        # FIXME a bit hackish to have to reconstruct the TxMinedInfo...
+        tx_mined_info = TxMinedInfo(
+            height=tx_item['height'],
+            conf=tx_item['confirmations'],
+            timestamp=tx_item['timestamp'],
+            wanted_height=tx_item.get('wanted_height', None),
+        )
         return tx_mined_info
 
+
 class HistoryList(MyTreeView, AcceptFileDragDrop):
     filter_columns = [HistoryColumns.STATUS,
                       HistoryColumns.DESCRIPTION,

electrum/util.py

@@ -1275,10 +1275,11 @@ def with_lock(func):
 
 class TxMinedInfo(NamedTuple):
     height: int                        # height of block that mined tx
-    conf: Optional[int] = None         # number of confirmations, SPV verified (None means unknown)
+    conf: Optional[int] = None         # number of confirmations, SPV verified. >=0, or None (None means unknown)
     timestamp: Optional[int] = None    # timestamp of block that mined tx
     txpos: Optional[int] = None        # position of tx in serialized block
     header_hash: Optional[str] = None  # hash of block that mined tx
+    wanted_height: Optional[int] = None  # in case of timelock, min abs block height
 
 
 class ShortID(bytes):

electrum/wallet.py

@@ -1000,7 +1000,7 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         monotonic_timestamp = 0
         for hist_item in self.adb.get_history(domain=domain):
             monotonic_timestamp = max(monotonic_timestamp, (hist_item.tx_mined_status.timestamp or 999_999_999_999))
-            yield {
+            d = {
                 'txid': hist_item.txid,
                 'fee_sat': hist_item.fee,
                 'height': hist_item.tx_mined_status.height,
@@ -1014,6 +1014,9 @@ class Abstract_Wallet(ABC, Logger, EventListener):
                 'label': self.get_label_for_txid(hist_item.txid),
                 'txpos_in_block': hist_item.tx_mined_status.txpos,
             }
+            if wanted_height := hist_item.tx_mined_status.wanted_height:
+                d['wanted_height'] = wanted_height
+            yield d
 
     def create_invoice(self, *, outputs: List[PartialTxOutput], message, pr, URI) -> Invoice:
         height = self.adb.get_local_height()
@@ -1473,8 +1476,8 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         conf = tx_mined_info.conf
         timestamp = tx_mined_info.timestamp
         if height == TX_HEIGHT_FUTURE:
-            assert conf < 0, conf
-            num_blocks_remainining = -conf
+            num_blocks_remainining = tx_mined_info.wanted_height - self.adb.get_local_height()
+            num_blocks_remainining = max(0, num_blocks_remainining)
             return 2, f'in {num_blocks_remainining} blocks'
         if conf == 0:
             tx = self.db.get_transaction(tx_hash)