From c5a2d080116270ecd0414c14eb412fa30eaaedaf Mon Sep 17 00:00:00 2001
From: ishaanam <ishaana.misra@gmail.com>
Date: Tue, 12 Aug 2025 14:41:53 -0400
Subject: [PATCH] wallet: don't return utxos from multiple truc txs in
 AvailableCoins

---
 src/wallet/spend.cpp | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp
index d76e6118379..e29ca045263 100644
--- a/src/wallet/spend.cpp
+++ b/src/wallet/spend.cpp
@@ -325,6 +325,9 @@ CoinsResult AvailableCoins(const CWallet& wallet,
     AssertLockHeld(wallet.cs_wallet);
 
     CoinsResult result;
+    // track unconfirmed truc outputs separately if we are tracking trucness
+    std::vector<std::pair<OutputType, COutput>> unconfirmed_truc_coins;
+    std::unordered_map<Txid, CAmount, SaltedTxidHasher> truc_txid_by_value;
     // Either the WALLET_FLAG_AVOID_REUSE flag is not set (in which case we always allow), or we default to avoiding, and only in the case where
     // a coin control object is provided, and has the avoid address reuse flag set to false, do we allow already used addresses
     bool allow_used_addresses = !wallet.IsWalletFlagSet(WALLET_FLAG_AVOID_REUSE) || (coinControl && !coinControl->m_avoid_address_reuse);
@@ -470,8 +473,15 @@ CoinsResult AvailableCoins(const CWallet& wallet,
             is_from_p2sh = true;
         }
 
-        result.Add(GetOutputType(type, is_from_p2sh),
-                   COutput(outpoint, output, nDepth, input_bytes, spendable, solvable, tx_safe, wtx.GetTxTime(), tx_from_me, feerate));
+        auto available_output_type = GetOutputType(type, is_from_p2sh);
+        auto available_output = COutput(outpoint, output, nDepth, input_bytes, spendable, solvable, tx_safe, wtx.GetTxTime(), tx_from_me, feerate);
+        if (wtx.tx->version == TRUC_VERSION && nDepth == 0 && params.check_version_trucness) {
+            unconfirmed_truc_coins.emplace_back(available_output_type, available_output);
+            auto [it, _] = truc_txid_by_value.try_emplace(wtx.tx->GetHash(), 0);
+            it->second += output.nValue;
+        } else {
+            result.Add(available_output_type, available_output);
+        }
 
         outpoints.push_back(outpoint);
 
@@ -488,6 +498,23 @@ CoinsResult AvailableCoins(const CWallet& wallet,
         }
     }
 
+    // Return all the coins from one TRUC transaction, that have the highest value.
+    // This could be improved in the future by encoding these restrictions in
+    // the coin selection itself so that we don't have to filter out
+    // other unconfirmed TRUC coins beforehand.
+    if (params.check_version_trucness && unconfirmed_truc_coins.size() > 0) {
+        auto highest_value_truc_tx = std::max_element(truc_txid_by_value.begin(), truc_txid_by_value.end(), [](const auto& tx1, const auto& tx2){
+                return tx1.second < tx2.second;
+                });
+
+        const Txid& truc_txid = highest_value_truc_tx->first;
+        for (const auto& [type, output] : unconfirmed_truc_coins) {
+            if (output.outpoint.hash == truc_txid) {
+                    result.Add(type, output);
+            }
+        }
+    }
+
     if (feerate.has_value()) {
         std::map<COutPoint, CAmount> map_of_bump_fees = wallet.chain().calculateIndividualBumpFees(outpoints, feerate.value());