From 89d09566431f57034d9a7df32547ceb13d79c62c Mon Sep 17 00:00:00 2001
From: Murch <murch@murch.one>
Date: Tue, 13 Jun 2023 15:56:18 -0400
Subject: [PATCH] opt: Tie-break UTXO sort by waste for BnB

Since we are searching for the minimal waste, we sort UTXOs with equal
effective value by ascending waste to be able to cut barren branches
earlier.
---
 src/wallet/coinselection.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/wallet/coinselection.cpp b/src/wallet/coinselection.cpp
index 7d15a9997afd3..570fac6900346 100644
--- a/src/wallet/coinselection.cpp
+++ b/src/wallet/coinselection.cpp
@@ -25,10 +25,14 @@ static util::Result<SelectionResult> ErrorMaxWeightExceeded()
                          "Please try sending a smaller amount or manually consolidating your wallet's UTXOs")};
 }
 
-// Descending order comparator
+// Sort by descending (effective) value prefer lower waste on tie
 struct {
     bool operator()(const OutputGroup& a, const OutputGroup& b) const
     {
+        if (a.GetSelectionAmount() == b.GetSelectionAmount()) {
+            // Lower waste is better when effective_values are tied
+            return (a.fee - a.long_term_fee) < (b.fee - b.long_term_fee);
+        }
         return a.GetSelectionAmount() > b.GetSelectionAmount();
     }
 } descending;