staticaddr/loopin: treat unconfirmed deposits as swappable

Static address deposits with no confirmation height have not started
their CSV timeout yet, so keep them eligible for loop-in selection
instead of treating them as already near expiry. Prefer confirmed
deposits before unconfirmed ones during automatic selection, and share
the remaining-lifetime calculation used by the selector.

staticaddr/loopin/manager.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"math"
 	"slices"
 	"sort"
 	"sync/atomic"
@@ -845,11 +846,11 @@ func (m *Manager) activeDepositsForLoopIn(loopIn *StaticAddressLoopIn) (
 	)
 }
 
-// SelectDeposits sorts the deposits by amount in descending order, then by
-// blocks-until-expiry in ascending order. It then selects the deposits that
-// are needed to cover the amount requested without leaving a dust change. It
-// returns an error if the sum of deposits minus dust is less than the requested
-// amount.
+// SelectDeposits sorts deposits by confirmation status first, then by amount in
+// descending order, then by blocks-until-expiry in ascending order. It then
+// selects the deposits that are needed to cover the amount requested without
+// leaving a dust change. It returns an error if the sum of deposits minus dust
+// is less than the requested amount.
 func SelectDeposits(targetAmount btcutil.Amount,
 	unfilteredDeposits []*deposit.Deposit, csvExpiry uint32,
 	blockHeight uint32) ([]*deposit.Deposit, error) {
@@ -871,14 +872,25 @@ func SelectDeposits(targetAmount btcutil.Amount,
 		deposits = append(deposits, d)
 	}
 
-	// Sort the deposits by amount in descending order, then by
-	// blocks-until-expiry in ascending order.
+	// Sort confirmed deposits ahead of unconfirmed ones so auto-selection
+	// prefers deposits the server can accept immediately. Within each group
+	// we prefer larger deposits, then earlier expiries.
 	sort.Slice(deposits, func(i, j int) bool {
+		iConfirmationHeight := uint32(deposits[i].GetConfirmationHeight())
+		jConfirmationHeight := uint32(deposits[j].GetConfirmationHeight())
+		iConfirmed := iConfirmationHeight > 0
+		jConfirmed := jConfirmationHeight > 0
+		if iConfirmed != jConfirmed {
+			return iConfirmed
+		}
+
 		if deposits[i].Value == deposits[j].Value {
-			iExp := uint32(deposits[i].GetConfirmationHeight()) +
-				csvExpiry - blockHeight
-			jExp := uint32(deposits[j].GetConfirmationHeight()) +
-				csvExpiry - blockHeight
+			iExp := blocksUntilDepositExpiry(
+				iConfirmationHeight, blockHeight, csvExpiry,
+			)
+			jExp := blocksUntilDepositExpiry(
+				jConfirmationHeight, blockHeight, csvExpiry,
+			)
 
 			return iExp < jExp
 		}
@@ -910,20 +922,33 @@ func SelectDeposits(targetAmount btcutil.Amount,
 // IsSwappable checks if a deposit is swappable. It returns true if the deposit
 // is not expired and the htlc is not too close to expiry.
 func IsSwappable(confirmationHeight, blockHeight, csvExpiry uint32) bool {
-	// The deposit expiry height is the confirmation height plus the csv
-	// expiry.
-	depositExpiryHeight := confirmationHeight + csvExpiry
-
-	// The htlc expiry height is the current height plus the htlc
-	// cltv delta.
-	htlcExpiryHeight := blockHeight + DefaultLoopInOnChainCltvDelta
-
-	// Ensure that the deposit doesn't expire before the htlc.
-	if depositExpiryHeight < htlcExpiryHeight+DepositHtlcDelta {
-		return false
+	if confirmationHeight == 0 {
+		return true
 	}
 
-	return true
+	// The deposit expiry height is the confirmation height plus the csv
+	// expiry.
+	return blocksUntilDepositExpiry(
+		confirmationHeight, blockHeight, csvExpiry,
+	) >= DefaultLoopInOnChainCltvDelta+DepositHtlcDelta
+}
+
+// blocksUntilDepositExpiry returns the remaining number of blocks until a
+// deposit expires. Unconfirmed deposits return MaxUint32 because their CSV has
+// not started yet.
+func blocksUntilDepositExpiry(confirmationHeight, blockHeight,
+	csvExpiry uint32) uint32 {
+
+	if confirmationHeight == 0 {
+		return math.MaxUint32
+	}
+
+	depositExpiryHeight := confirmationHeight + csvExpiry
+	if depositExpiryHeight <= blockHeight {
+		return 0
+	}
+
+	return depositExpiryHeight - blockHeight
 }
 
 // DeduceSwapAmount calculates the swap amount based on the selected amount and

staticaddr/loopin/manager_test.go

@@ -81,6 +81,27 @@ func TestSelectDeposits(t *testing.T) {
 			expected:    []*deposit.Deposit{d3},
 			expectedErr: "",
 		},
+		{
+			name: "prefer confirmed deposit over larger unconfirmed one",
+			deposits: []*deposit.Deposit{
+				{
+					Value:              2_000_000,
+					ConfirmationHeight: 0,
+				},
+				{
+					Value:              1_500_000,
+					ConfirmationHeight: 5_004,
+				},
+			},
+			targetValue: 1_000_000,
+			expected: []*deposit.Deposit{
+				{
+					Value:              1_500_000,
+					ConfirmationHeight: 5_004,
+				},
+			},
+			expectedErr: "",
+		},
 		{
 			name:        "single deposit insufficient by 1",
 			deposits:    []*deposit.Deposit{d1},
@@ -357,6 +378,12 @@ func TestGetAllSwapsPreservesStoreDeposits(t *testing.T) {
 	require.Equal(t, []*deposit.Deposit{currentDeposit}, swaps[0].Deposits)
 }
 
+// TestIsSwappableUnconfirmed checks that an unconfirmed deposit is considered
+// swappable because its CSV timeout has not started yet.
+func TestIsSwappableUnconfirmed(t *testing.T) {
+	require.True(t, IsSwappable(0, 5000, 1000))
+}
+
 // mockDepositManager implements DepositManager for tests.
 type mockDepositManager struct {
 	// activeDeposits is the set returned by GetActiveDepositsInState.