fix(wallet): off-by-one error checking coinbase maturity in optional UTxOs

The `preselect_utxos` method (now `filter_utxos`) had an off-by-one
error that was making the selection of optional UTxOs too restrictive,
by requiring the coinbase outputs to surpass or equal coinbase maturity
time at the current height of the selection, and not in the block in
which the transaction may be included in the blockchain (be spent),
probably, the next one.

The bug is still in `filter_utxos`.

The changes in this commit fix it by making use of the correctly defined
`FullTxOut<A>::is_mature` method, which test positively a UTxO as mature
if it is elegible for inclusion in the next mined block.

Author: nymius

crates/wallet/src/wallet/mod.rs

@@ -36,7 +36,7 @@ use bdk_chain::{
 use bitcoin::{
     absolute,
     consensus::encode::serialize,
-    constants::{genesis_block, COINBASE_MATURITY},
+    constants::genesis_block,
     psbt,
     secp256k1::Secp256k1,
     sighash::{EcdsaSighashType, TapSighashType},
@@ -2010,9 +2010,22 @@ impl Wallet {
             vec![]
         // only process optional UTxOs if manually_selected_only is false
         } else {
-            self
+            self.indexed_graph
+                .graph()
                 // get all unspent UTxOs from wallet
-                .list_unspent()
+                // NOTE: the UTxOs returned by the following method already belong to wallet as the
+                // call chain uses get_tx_node infallibly
+                .filter_chain_unspents(
+                    &self.chain,
+                    self.chain.tip().block_id(),
+                    self.indexed_graph.index.outpoints().iter().cloned(),
+                )
+                // only create LocalOutput if UTxO is mature
+                .filter_map(move |((k, i), full_txo)| {
+                    full_txo
+                        .is_mature(current_height)
+                        .then(|| new_local_utxo(k, i, full_txo))
+                })
                 // only process UTxOs not selected manually, they will be considered later in the chain
                 // NOTE: this avoid UTxOs in both required and optional list
                 .filter(|may_spend| !params.utxos.contains(may_spend))
@@ -2027,23 +2040,6 @@ impl Wallet {
                 .filter(|local_output| {
                     params.bumping_fee.is_none() || local_output.chain_position.is_confirmed()
                 })
-                // only use UTxOs we posess and are mature if the origin tx is coinbase
-                .filter(move |local_output| {
-                    self.indexed_graph
-                        .graph()
-                        .get_tx(local_output.outpoint.txid)
-                        .is_some_and(|tx| {
-                            !tx.is_coinbase()
-                                || (local_output.chain_position.is_confirmed()
-                                    && local_output
-                                        .chain_position
-                                        .confirmation_height_upper_bound()
-                                        .is_some_and(|local_output_height| {
-                                            current_height.saturating_sub(local_output_height)
-                                                >= COINBASE_MATURITY
-                                        }))
-                        })
-                })
                 .map(|utxo| WeightedUtxo {
                     satisfaction_weight: self
                         .public_descriptor(utxo.keychain)

crates/wallet/tests/wallet.rs

@@ -3875,8 +3875,16 @@ fn test_spend_coinbase() {
     };
     insert_anchor(&mut wallet, txid, anchor);
 
-    let not_yet_mature_time = confirmation_height + COINBASE_MATURITY - 1;
-    let maturity_time = confirmation_height + COINBASE_MATURITY;
+    // NOTE: A transaction spending an output coming from the coinbase tx at height h, is eligible
+    // to be included in block h + [100 = COINBASE_MATURITY] or higher.
+    // Tx elibible to be included in the next block will be accepted in the mempool, used in block
+    // templates and relayed on the network.
+    // Miners may include such tx in a block when their chaintip is at h + [99 = COINBASE_MATURITY - 1].
+    // This means these coins are available for selection at height h + 99.
+    //
+    // By https://bitcoin.stackexchange.com/a/119017
+    let not_yet_mature_time = confirmation_height + COINBASE_MATURITY - 2;
+    let maturity_time = confirmation_height + COINBASE_MATURITY - 1;
 
     let balance = wallet.balance();
     assert_eq!(