feat(swap): check if Monero redeem is already present on chain before publishing

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- ASB+GUI: Skip publishing the Monero redeem/refund transaction if it is already present on chain (e.g. after a restart)
+
 ## [4.8.4] - 2026-06-09
 
 ## [4.8.3] - 2026-06-08

monero-wallet/src/wallets.rs

@@ -292,6 +292,20 @@ impl Wallets {
         rpc_client
     }
 
+    pub async fn is_transaction_present(&self, tx_hash: &TxHash) -> Result<bool> {
+        use monero_wallet_ng::rpc::{ProvidesTransactionStatus, TransactionStatus};
+
+        let rpc_client = self.rpc_client().await;
+        let tx_id = tx_hash_to_bytes(tx_hash)?;
+
+        let status = rpc_client
+            .transaction_status(tx_id)
+            .await
+            .context("Failed to query Monero transaction status")?;
+
+        Ok(!matches!(status, TransactionStatus::Unknown))
+    }
+
     pub async fn direct_rpc_block_height(&self) -> Result<u64> {
         use monero_daemon_rpc::prelude::ProvidesBlockchainMeta;
         let rpc_client = self.rpc_client().await;

swap/src/protocol/alice/swap.rs

@@ -753,6 +753,17 @@ where
             retry(
                 "Publishing Monero refund transaction",
                 || async {
+                    let is_present = monero_wallet
+                        .is_transaction_present(&xmr_refund_tx_hash)
+                        .await
+                        .context("Failed to check whether Monero refund transaction is already present on chain")
+                        .map_err(backoff::Error::transient)?;
+
+                    if is_present {
+                        tracing::info!(%swap_id, %xmr_refund_tx_hash, "Monero refund transaction is already present on chain, skipping publish");
+                        return Ok(());
+                    }
+
                     monero_wallet
                         .rpc_client()
                         .await

swap/src/protocol/bob/swap.rs

@@ -793,6 +793,17 @@ async fn next_state(
             retry(
                 "Publishing Monero redeem transaction",
                 || async {
+                    let is_present = monero_wallet
+                        .is_transaction_present(&xmr_redeem_tx_hash)
+                        .await
+                        .context("Failed to check whether Monero redeem transaction is already present on chain")
+                        .map_err(backoff::Error::transient)?;
+
+                    if is_present {
+                        tracing::info!(%swap_id, %xmr_redeem_tx_hash, "Monero redeem transaction is already present on chain, skipping publish");
+                        return Ok(());
+                    }
+
                     monero_wallet
                         .rpc_client()
                         .await