swap: expose derived Lightning routing terms

rpc/swapclientrpc/swap_client.proto

@@ -144,6 +144,16 @@ message QuotePayResponse {
     bool exceeds_max_fee = 7;
 
     CreditQuote credit_quote = 8;
+
+    // server_fee_sat is the service fee retained by the swap server.
+    uint64 server_fee_sat = 9;
+
+    // estimated_routing_fee_sat is the current whole-satoshi route estimate.
+    uint64 estimated_routing_fee_sat = 10;
+
+    // routing_fee_budget_sat is the client-funded Lightning routing allowance
+    // that would be charged into the vHTLC as part of fee_sat.
+    uint64 routing_fee_budget_sat = 11;
 }
 
 message StartPayRequest {
@@ -429,4 +439,11 @@ message SwapSummary {
     // available_credit_sat is the balance considered when the receive route was
     // planned.
     uint64 available_credit_sat = 26;
+
+    // server_fee_sat is the service fee retained by the swap server.
+    uint64 server_fee_sat = 27;
+
+    // routing_fee_budget_sat is the client-funded Lightning routing
+    // allowance charged into the vHTLC as part of fee_sat.
+    uint64 routing_fee_budget_sat = 28;
 }

rpc/wavewalletrpc/wallet.proto

@@ -426,6 +426,16 @@ message PrepareSendResponse {
     // credit_preview is populated when the invoice send will or can use
     // sat-native server credits.
     CreditPreview credit_preview = 15;
+
+    // server_fee_sat is the service fee retained by the swap server.
+    uint64 server_fee_sat = 16;
+
+    // estimated_routing_fee_sat is the current whole-satoshi route estimate.
+    uint64 estimated_routing_fee_sat = 17;
+
+    // routing_fee_budget_sat is the client-funded Lightning routing allowance
+    // that Send would charge into the vHTLC as part of fee_sat.
+    uint64 routing_fee_budget_sat = 18;
 }
 
 // SendRequest dispatches a previously prepared send by consuming the

sdk/swaps/client.go

@@ -61,6 +61,10 @@ type CreditQuote struct {
 	ArkFundingSat      uint64
 }
 
+// AllAvailableCredit authorizes the server to consider the caller's complete
+// available credit balance.
+const AllAvailableCredit = ^uint64(0)
+
 // CreditFundingSource identifies how value enters a credit account.
 type CreditFundingSource string
 
@@ -191,6 +195,13 @@ type SwapSummary struct {
 	// FeeSat is the negotiated swap-server fee in satoshis when known.
 	FeeSat uint64
 
+	// ServerFeeSat is the service fee retained by the swap server.
+	ServerFeeSat uint64
+
+	// RoutingFeeBudgetSat is the client-funded Lightning routing
+	// allowance included in FeeSat.
+	RoutingFeeBudgetSat uint64
+
 	// PayerFeeMsat is the payer-paid Lightning route fee quoted for
 	// receive swaps. It is not deducted from AmountSat.
 	PayerFeeMsat uint64
@@ -622,6 +633,13 @@ type InSwapConfig struct {
 	// for this swap.
 	FeeSat uint64
 
+	// ServerFeeSat is the service fee retained by the swap server.
+	ServerFeeSat uint64
+
+	// RoutingFeeBudgetSat is the client-funded Lightning routing
+	// allowance included in FeeSat.
+	RoutingFeeBudgetSat uint64
+
 	// ServerPubkey is the swap server's public key for this swap
 	// instance.
 	ServerPubkey *btcec.PublicKey
@@ -664,6 +682,17 @@ type InSwapQuote struct {
 	// FeeSat is the fee in satoshis charged by the swap server.
 	FeeSat uint64
 
+	// ServerFeeSat is the service fee retained by the swap server.
+	ServerFeeSat uint64
+
+	// EstimatedRoutingFeeSat is the server's current whole-satoshi route
+	// estimate.
+	EstimatedRoutingFeeSat uint64
+
+	// RoutingFeeBudgetSat is the Lightning routing allowance that would be
+	// included in FeeSat.
+	RoutingFeeBudgetSat uint64
+
 	// Expiry is the wall-clock deadline by which the quoted swap must
 	// complete before it is considered stale.
 	Expiry time.Time
@@ -680,6 +709,17 @@ type InSwapQuote struct {
 	CreditQuote *CreditQuote
 }
 
+// InSwapOptions contains caller-controlled fee and credit limits for an
+// Ark-to-Lightning payment.
+type InSwapOptions struct {
+	// MaxFeeSat is the maximum total fee the caller accepts.
+	MaxFeeSat uint64
+
+	// MaxCreditSat is the maximum credit amount the caller authorizes.
+	// MaxUint64 requests a quote using all available credit.
+	MaxCreditSat uint64
+}
+
 // SwapServerConn abstracts the connection to the swap server's
 // gRPC service. This allows the client to talk to the swap server
 // without importing the server module.