looprpc: expose static autoloop output

Extend the public rpc surface for static autoloop integration
without turning the planner on yet. SuggestSwaps responses can
now carry static-address loop-in requests and the new planner
reason for missing static candidates is mapped over rpc.

Author: starius

liquidity/liquidity.go

@@ -933,6 +933,10 @@ type Suggestions struct {
 	// InSwaps is the set of loop in swaps that we suggest executing.
 	InSwaps []loop.LoopInRequest
 
+	// StaticInSwaps is the set of static-address loop-ins that we suggest
+	// executing.
+	StaticInSwaps []loop.StaticAddressLoopInRequest
+
 	// DisqualifiedChans maps the set of channels that we do not recommend
 	// swaps on to the reason that we did not recommend a swap.
 	DisqualifiedChans map[lnwire.ShortChannelID]Reason

liquidity/reasons.go

@@ -73,6 +73,11 @@ const (
 	// ReasonCustomChannelData indicates that the channel is not standard
 	// and should not be used for swaps.
 	ReasonCustomChannelData
+
+	// ReasonStaticLoopInNoCandidate indicates that static loop-in
+	// autoloop was selected, but no full-deposit static candidate was
+	// available for the target peer.
+	ReasonStaticLoopInNoCandidate
 )
 
 // String returns a string representation of a reason.
@@ -123,6 +128,9 @@ func (r Reason) String() string {
 	case ReasonLoopInUnreachable:
 		return "loop in unreachable"
 
+	case ReasonStaticLoopInNoCandidate:
+		return "no static loop-in candidate"
+
 	default:
 		return "unknown"
 	}

loopd/swapclient_server.go

@@ -1426,6 +1426,10 @@ func (s *swapClientServer) SuggestSwaps(ctx context.Context,
 		LoopIn: make(
 			[]*looprpc.LoopInRequest, len(suggestions.InSwaps),
 		),
+		StaticLoopIn: make(
+			[]*looprpc.StaticAddressLoopInRequest,
+			len(suggestions.StaticInSwaps),
+		),
 	}
 
 	for i, swap := range suggestions.OutSwaps {
@@ -1456,6 +1460,24 @@ func (s *swapClientServer) SuggestSwaps(ctx context.Context,
 		resp.LoopIn[i] = loopIn
 	}
 
+	for i, swap := range suggestions.StaticInSwaps {
+		request := &looprpc.StaticAddressLoopInRequest{
+			Outpoints:             swap.DepositOutpoints,
+			MaxSwapFeeSatoshis:    int64(swap.MaxSwapFee),
+			Label:                 swap.Label,
+			Initiator:             swap.Initiator,
+			PaymentTimeoutSeconds: swap.PaymentTimeoutSeconds,
+			Amount:                int64(swap.SelectedAmount),
+			Fast:                  swap.Fast,
+		}
+
+		if swap.LastHop != nil {
+			request.LastHop = swap.LastHop[:]
+		}
+
+		resp.StaticLoopIn[i] = request
+	}
+
 	for id, reason := range suggestions.DisqualifiedChans {
 		autoloopReason, err := rpcAutoloopReason(reason)
 		if err != nil {
@@ -2416,6 +2438,10 @@ func rpcAutoloopReason(reason liquidity.Reason) (looprpc.AutoReason, error) {
 	case liquidity.ReasonFeePPMInsufficient:
 		return looprpc.AutoReason_AUTO_REASON_SWAP_FEE, nil
 
+	case liquidity.ReasonStaticLoopInNoCandidate:
+		return looprpc.AutoReason_AUTO_REASON_STATIC_LOOP_IN_NO_CANDIDATE,
+			nil
+
 	default:
 		return 0, fmt.Errorf("unknown autoloop reason: %v", reason)
 	}

loopd/swapclient_server_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/lightninglabs/loop"
 	"github.com/lightninglabs/loop/fsm"
 	"github.com/lightninglabs/loop/labels"
+	"github.com/lightninglabs/loop/liquidity"
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/looprpc"
 	"github.com/lightninglabs/loop/staticaddr/address"
@@ -279,6 +280,20 @@ func TestStaticAddressLoopInRejectsReservedLabel(t *testing.T) {
 	require.ErrorContains(t, err, labels.ErrReservedPrefix.Error())
 }
 
+// TestRPCAutoloopReasonStaticLoopInNoCandidate verifies that the new planner
+// reason is exposed over rpc.
+func TestRPCAutoloopReasonStaticLoopInNoCandidate(t *testing.T) {
+	reason, err := rpcAutoloopReason(
+		liquidity.ReasonStaticLoopInNoCandidate,
+	)
+	require.NoError(t, err)
+	require.Equal(
+		t,
+		looprpc.AutoReason_AUTO_REASON_STATIC_LOOP_IN_NO_CANDIDATE,
+		reason,
+	)
+}
+
 // TestSwapClientServerStopDaemon ensures that calling StopDaemon triggers the
 // daemon shutdown.
 func TestSwapClientServerStopDaemon(t *testing.T) {