Fix inverted guard in MarkSkippedNonce so failed nonces are reused

spamoor/wallet.go

@@ -621,7 +621,9 @@ func (wallet *Wallet) MarkSkippedNonce(nonce uint64) {
 	wallet.nonceMutex.Lock()
 	defer wallet.nonceMutex.Unlock()
 
-	if nonce >= wallet.confirmedTxCount {
+	// Only nonces at or above the confirmed count are still pending and can be
+	// reused. Nonces below it are already confirmed on chain, so ignore them.
+	if nonce < wallet.confirmedTxCount {
 		return
 	}
 

spamoor/wallet_skippednonce_test.go

@@ -0,0 +1,52 @@
+package spamoor
+
+import "testing"
+
+// A transaction that fails to submit keeps a nonce at or above the confirmed
+// count. MarkSkippedNonce should record it so the next allocation reuses it
+// instead of leaving a permanent gap.
+func TestMarkSkippedNonceReusesFailedNonce(t *testing.T) {
+	w := &Wallet{}
+	w.confirmedTxCount = 100
+	w.pendingTxCount.Store(100)
+
+	n := w.GetNextNonce() // allocates 100, pending count moves to 101
+	if n != 100 {
+		t.Fatalf("expected first allocation 100, got %d", n)
+	}
+
+	w.MarkSkippedNonce(n) // submit failed, make the nonce reusable
+
+	if reused := w.GetNextNonce(); reused != 100 {
+		t.Fatalf("expected nonce 100 to be reused, got %d", reused)
+	}
+}
+
+// Nonces at or above the confirmed count are still pending, so they should be
+// recorded for reuse.
+func TestMarkSkippedNonceRecordsPendingNonces(t *testing.T) {
+	w := &Wallet{}
+	w.confirmedTxCount = 100
+	w.pendingTxCount.Store(103)
+
+	w.MarkSkippedNonce(101)
+	w.MarkSkippedNonce(102)
+
+	if len(w.skippedNonces) != 2 {
+		t.Fatalf("expected 101 and 102 to be recorded, got %v", w.skippedNonces)
+	}
+}
+
+// Nonces below the confirmed count are already confirmed on chain and cannot be
+// reused, so they should be ignored.
+func TestMarkSkippedNonceIgnoresConfirmedNonces(t *testing.T) {
+	w := &Wallet{}
+	w.confirmedTxCount = 100
+	w.pendingTxCount.Store(105)
+
+	w.MarkSkippedNonce(50)
+
+	if len(w.skippedNonces) != 0 {
+		t.Fatalf("expected a confirmed nonce to be ignored, got %v", w.skippedNonces)
+	}
+}