feat: add a warning for high tx fee

Author: Chaitanya-Keyal

l10n/messages.pot

@@ -6,9 +6,9 @@
 #, fuzzy
 msgid ""
 msgstr ""
-"Project-Id-Version: seedsigner 0.8.5-rc1\n"
+"Project-Id-Version: seedsigner 0.8.5\n"
 "Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
-"POT-Creation-Date: 2025-01-28 13:28-0600\n"
+"POT-Creation-Date: 2025-04-13 21:25+0000\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -854,6 +854,20 @@ msgid ""
 " wallet."
 msgstr ""
 
+#: src/seedsigner/views/psbt_views.py
+msgid "High Fee!"
+msgstr ""
+
+#. Variable is the percentage of the total output value (excluding change) that
+#. the fee exceeds. (e.g. "This PSBT has a fee higher than 25% of the total
+#. output value (excluding change).")
+#: src/seedsigner/views/psbt_views.py
+#, python-format
+msgid ""
+"This PSBT has a fee higher than {}% of the total output value (excluding "
+"change)."
+msgstr ""
+
 #. Future-tense used to indicate that this transaction will send this amount,
 #. as opposed to "Send" on its own which could be misread as an instant command
 #. (e.g. "Send Now").
@@ -1254,11 +1268,11 @@ msgid "Review SeedQR"
 msgstr ""
 
 #: src/seedsigner/views/seed_views.py
-msgid "Your transcribed SeedQR successfully scanned and yielded the same seed."
+msgid "Your transcribed SeedQR could not be read!"
 msgstr ""
 
 #: src/seedsigner/views/seed_views.py
-msgid "Your transcribed SeedQR could not be read!"
+msgid "Your transcribed SeedQR successfully scanned and yielded the same seed."
 msgstr ""
 
 #: src/seedsigner/views/seed_views.py

src/seedsigner/models/psbt_parser.py

@@ -390,3 +390,13 @@ def verify_multisig_output(self, descriptor: Descriptor, change_num: int) -> boo
         is_owner = descriptor.owns(output)
         # print(f"{self.psbt.tx.vout[i].script_pubkey.address()} | {output.value} | {is_owner}")
         return is_owner
+
+    
+    def get_sum_of_outputs_excluding_change(self):
+        """
+            Returns the sum of all outputs excluding change amount.
+            This is used to to calculate whether the fee is relatively high
+            and show a warning screen if it is.
+        """
+        total_outputs = sum(out.value for out in self.psbt.tx.vout)
+        return total_outputs - self.change_amount

src/seedsigner/views/psbt_views.py

@@ -83,6 +83,9 @@ def run(self):
 
 
 class PSBTOverviewView(View):
+    # TODO: Possibly make this configurable via settings
+    HIGH_FEES_WARNING_THRESHOLD = 25 # in percent
+    
     def __init__(self):
         super().__init__()
 
@@ -151,10 +154,17 @@ def run(self):
             self.controller.psbt_seed = None
             return Destination(BackStackView)
 
+        sum_of_all_outputs_excluding_change = psbt_parser.get_sum_of_outputs_excluding_change()
+
         # expecting p2sh (legacy multisig) and p2pkh to have no policy set
         # skip change warning and psbt math view
         if psbt_parser.policy == None:
             return Destination(PSBTUnsupportedScriptTypeWarningView)
+
+        # High Fee warning if fee amount > <HIGH_FEES_WARNING_THRESHOLD> % of sum of all outputs excluding change
+        # Skip the warning when there is no output other than change
+        elif sum_of_all_outputs_excluding_change > 0 and psbt_parser.fee_amount > self.HIGH_FEES_WARNING_THRESHOLD/100 * (sum_of_all_outputs_excluding_change):
+            return Destination(PSBTHighFeeWarningView, view_args={"warning_threshold_percent": self.HIGH_FEES_WARNING_THRESHOLD})
 
         elif psbt_parser.change_amount == 0:
             return Destination(PSBTNoChangeWarningView)
@@ -204,6 +214,38 @@ def run(self):
 
 
 
+class PSBTHighFeeWarningView(View):
+    def __init__(self, warning_threshold_percent: int):
+        super().__init__()
+        
+        self.warning_threshold_percent = warning_threshold_percent
+    
+    def run(self):
+        selected_menu_num = WarningScreen(
+            status_headline=_("High Fee!"),
+            # TRANSLATOR_NOTE: Variable is the percentage of the total output value (excluding change) that the fee exceeds. (e.g. "This PSBT has a fee higher than 25% of the total output value (excluding change).")
+            text=_("This PSBT has a fee higher than {}% of the total output value (excluding change).").format(self.warning_threshold_percent),
+            button_data=[ButtonOption("Continue")],
+        ).display()
+
+        if selected_menu_num == RET_CODE__BACK_BUTTON:
+            return Destination(BackStackView)
+
+        # PSBT may have high fee + no change
+        if self.controller.psbt_parser.change_amount == 0:
+            return Destination(
+                PSBTNoChangeWarningView,
+                skip_current_view=True,  # Prevent going BACK to WarningViews
+            )
+
+        else:
+            return Destination(
+                PSBTMathView,
+                skip_current_view=True,  # Prevent going BACK to WarningViews
+            )
+
+
+
 class PSBTMathView(View):
     """
         Follows the Overview pictogram. Shows:

tests/screenshot_generator/generator.py

@@ -324,6 +324,7 @@ def PSBTOpReturnView_raw_hex_data_cb_before():
                 ScreenshotConfig(psbt_views.PSBTOverviewView, run_before=load_basic_psbt_cb),
                 ScreenshotConfig(psbt_views.PSBTUnsupportedScriptTypeWarningView),
                 ScreenshotConfig(psbt_views.PSBTNoChangeWarningView),
+                ScreenshotConfig(psbt_views.PSBTHighFeeWarningView, dict(warning_threshold_percent=25)),
                 ScreenshotConfig(psbt_views.PSBTMathView),
                 ScreenshotConfig(psbt_views.PSBTAddressDetailsView, dict(address_num=0)),
 

tests/test_psbt_parser.py

@@ -1,6 +1,8 @@
 from binascii import a2b_base64
+from types import SimpleNamespace
 from embit import psbt
 from embit.descriptor import Descriptor
+import pytest
 
 from seedsigner.models.psbt_parser import PSBTParser
 from seedsigner.models.seed import Seed
@@ -201,3 +203,58 @@ def test_parse_op_return_content():
     assert psbt_parser.change_amount == 99992296
     assert psbt_parser.destination_addresses == []
     assert psbt_parser.destination_amounts == []
+
+
+@pytest.mark.parametrize("vout_values, change_amount, expected", [
+    # single destination + single change
+    ([100, 200], 200, 100),
+    # multiple destinations + single change
+    ([50, 75, 25], 25, 50 + 75),
+    # no change outputs at all
+    ([10, 20, 30], 0, 10 + 20 + 30),
+    # only change outputs
+    ([123], 123, 0),
+])
+def test_get_sum_of_outputs_excluding_change_logic(vout_values, change_amount, expected):
+    """
+        get_sum_of_outputs_excluding_change() should return
+        sum(vout_values) - change_amount.
+    """
+    # Build a dummy parser without running .parse()
+    parser = PSBTParser.__new__(PSBTParser)
+    
+    # Stub out parser.psbt.tx.vout as list of objects with a .value attribute
+    parser.psbt = SimpleNamespace(
+        tx=SimpleNamespace(
+            vout=[SimpleNamespace(value=v) for v in vout_values]
+        )
+    )
+    parser.change_amount = change_amount
+
+    assert parser.get_sum_of_outputs_excluding_change() == expected
+
+
+def test_get_sum_of_outputs_excluding_change_integration():
+    """
+    Integration test for get_sum_of_outputs_excluding_change() using a real PSBT.
+    PSBT from test_p2tr_change_detection has:
+      - Destination output: 319,049,328 sats
+      - Change output:      2,871,443,918 sats
+      - Total outputs:      3,190,493,246 sats
+      - Excluding change:   319,049,328 sats
+    """
+    # This is the same PSBT as in test_p2tr_change_detection
+    psbt_base64 = "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"
+    
+    raw = a2b_base64(psbt_base64)
+    tx = psbt.PSBT.parse(raw)
+    
+    mnemonic = "goddess rough corn exclude cream trial fee trumpet million prevent gaze power".split()
+    pw = ""
+    seed = Seed(mnemonic, passphrase=pw)
+
+    pp = PSBTParser(p=tx, seed=seed, network=SettingsConstants.REGTEST)
+    
+    # Expected: only the destination output (319,049,328 sats)
+    expected = 319049328
+    assert pp.get_sum_of_outputs_excluding_change() == expected