lnrpc: rename proportional fee rate on lnrpc

This field is incorrectly suffixed as "msat", when it is actually
interpreted as the proportional fee rate. This is the value that we
should be using because the sender will calculate proportional fees
accordingly. This is a breaking change to the RPC, but on an
experimental and unreleased API.

cmd/lncli/cmd_payments.go

@@ -1250,9 +1250,9 @@ func parseBlindedPaymentParameters(ctx *cli.Context) (
 		BaseFeeMsat: ctx.Uint64(
 			blindedBaseFlag.Name,
 		),
-		ProportionalFeeMsat: ctx.Uint64(
+		ProportionalFeeRate: uint32(ctx.Uint64(
 			blindedPPMFlag.Name,
-		),
+		)),
 		TotalCltvDelta: uint32(ctx.Uint64(
 			blindedCLTVFlag.Name,
 		)),

lnrpc/lightning.proto

@@ -3545,8 +3545,11 @@ message BlindedPaymentPath {
     // The base fee for the blinded path provided, expressed in msat.
     uint64 base_fee_msat = 2;
 
-    // The proportional fee for the blinded path provided, expressed in msat.
-    uint64 proportional_fee_msat = 3;
+    /*
+    The proportional fee for the blinded path provided, expressed in parts
+    per million.
+    */
+    uint32 proportional_fee_rate = 3;
 
     /*
     The total CLTV delta for the blinded path provided, including the

lnrpc/lightning.swagger.json

@@ -3523,10 +3523,10 @@
           "format": "uint64",
           "description": "The base fee for the blinded path provided, expressed in msat."
         },
-        "proportional_fee_msat": {
-          "type": "string",
-          "format": "uint64",
-          "description": "The proportional fee for the blinded path provided, expressed in msat."
+        "proportional_fee_rate": {
+          "type": "integer",
+          "format": "int64",
+          "description": "The proportional fee for the blinded path provided, expressed in parts\nper million."
         },
         "total_cltv_delta": {
           "type": "integer",

lnrpc/routerrpc/router_backend.go

@@ -487,15 +487,13 @@ func unmarshalBlindedPayment(rpcPayment *lnrpc.BlindedPaymentPath) (
 	}
 
 	return &routing.BlindedPayment{
-		BlindedPath:     path,
-		CltvExpiryDelta: uint16(rpcPayment.TotalCltvDelta),
-		BaseFee:         uint32(rpcPayment.BaseFeeMsat),
-		ProportionalFeeRate: uint32(
-			rpcPayment.ProportionalFeeMsat,
-		),
-		HtlcMinimum: rpcPayment.HtlcMinMsat,
-		HtlcMaximum: rpcPayment.HtlcMaxMsat,
-		Features:    features,
+		BlindedPath:         path,
+		CltvExpiryDelta:     uint16(rpcPayment.TotalCltvDelta),
+		BaseFee:             uint32(rpcPayment.BaseFeeMsat),
+		ProportionalFeeRate: rpcPayment.ProportionalFeeRate,
+		HtlcMinimum:         rpcPayment.HtlcMinMsat,
+		HtlcMaximum:         rpcPayment.HtlcMaxMsat,
+		Features:            features,
 	}, nil
 }