From e6cb2f9587005c27ce47f2ebc8ed50b665d3bcf3 Mon Sep 17 00:00:00 2001
From: The MMGen Project <mmgen@tuta.io>
Date: Tue, 20 Oct 2026 17:38:48 +0000
Subject: [PATCH] CoinProtocol.Base: new `has_chg` attr

---
 mmgen/proto/btc/params.py | 1 +
 mmgen/protocol.py         | 1 +
 mmgen/tx/new_swap.py      | 6 ++----
 test/cmdtest_d/swap.py    | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/mmgen/proto/btc/params.py b/mmgen/proto/btc/params.py
index d54ce07f..7d35cf70 100644
--- a/mmgen/proto/btc/params.py
+++ b/mmgen/proto/btc/params.py
@@ -28,6 +28,7 @@ class mainnet(CoinProtocol.Secp256k1): # chainparams.cpp
 	dfl_mmtype      = 'L'
 	coin_amt        = 'BTCAmt'
 	max_tx_fee      = 0.003
+	has_chg         = True
 	sighash_type    = 'ALL'
 	block0          = '000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f'
 	forks           = [
diff --git a/mmgen/protocol.py b/mmgen/protocol.py
index 83ce6f38..2bf77970 100644
--- a/mmgen/protocol.py
+++ b/mmgen/protocol.py
@@ -56,6 +56,7 @@ class CoinProtocol(MMGenObject):
 		chain_names = None
 		is_vm = False
 		is_evm = False
+		has_chg = False
 		has_usr_fee = True
 		coin_amt = None
 		max_tx_fee = None
diff --git a/mmgen/tx/new_swap.py b/mmgen/tx/new_swap.py
index 085cf2e1..8f7623f0 100644
--- a/mmgen/tx/new_swap.py
+++ b/mmgen/tx/new_swap.py
@@ -105,9 +105,7 @@ class NewSwap(BaseSwapMethods, New):
 				arg = get_arg()
 
 			# arg 3: optional chg_spec (change address spec, requires amt)
-			if args.send_amt and not (
-					self.proto.is_vm or
-					arg in sa.recv): # is change arg
+			if self.proto.has_chg and args.send_amt and not arg in sa.recv: # is change arg
 				nonlocal chg_output
 				if not self.cfg.quote:
 					chg_output = await self.get_chg_output(arg, addrfiles)
@@ -154,7 +152,7 @@ class NewSwap(BaseSwapMethods, New):
 				get_char('Press any key to continue: ')
 				msg('')
 
-		if args.send_amt and not (chg_output or self.proto.is_vm):
+		if self.proto.has_chg and args.send_amt and not chg_output:
 			chg_output = await self.get_chg_output(None, addrfiles)
 
 		if self.refnum:
diff --git a/test/cmdtest_d/swap.py b/test/cmdtest_d/swap.py
index 791a87eb..e77346f9 100644
--- a/test/cmdtest_d/swap.py
+++ b/test/cmdtest_d/swap.py
@@ -233,7 +233,7 @@ class CmdTestSwapMethods:
 			t.expect('(Y/n): ', 'y')        # fee ok?
 			t.expect('(Y/n): ', 'y')        # change ok?
 		else:
-			if not (self.proto.is_vm or single_output):
+			if self.proto.has_chg and not single_output:
 				t.expect('ENTER for the change output): ', '\n')
 				t.expect('(Y/n): ', 'y')    # confirm deduct from chg output
 			t.expect('to continue: ', '\n') # exit swap quote