From d5a25736577f37adbe759119f2c3c4b9a2c4ec71 Mon Sep 17 00:00:00 2001
From: ekzyis <ek@stacker.news>
Date: Fri, 8 Aug 2025 18:05:33 +0200
Subject: [PATCH] Add proxy fee to minSendable of lnurl-pay (#2404)

---
 api/paidAction/receive.js            | 4 ++--
 lib/constants.js                     | 1 +
 pages/api/lnurlp/[username]/index.js | 9 +++++++--
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/api/paidAction/receive.js b/api/paidAction/receive.js
index c2400138..9abbe36a 100644
--- a/api/paidAction/receive.js
+++ b/api/paidAction/receive.js
@@ -1,4 +1,4 @@
-import { PAID_ACTION_PAYMENT_METHODS } from '@/lib/constants'
+import { PAID_ACTION_PAYMENT_METHODS, PROXY_RECEIVE_FEE_PERCENT } from '@/lib/constants'
 import { toPositiveBigInt, numWithUnits, msatsToSats } from '@/lib/format'
 import { notifyDeposit } from '@/lib/webPush'
 import { getInvoiceableWallets } from '@/wallets/server'
@@ -29,7 +29,7 @@ export async function getInvoiceablePeer (_, { me, models, cost, paymentMethod }
 }
 
 export async function getSybilFeePercent () {
-  return 10n
+  return PROXY_RECEIVE_FEE_PERCENT
 }
 
 export async function perform ({
diff --git a/lib/constants.js b/lib/constants.js
index 76bdf5ca..f1a92ae7 100644
--- a/lib/constants.js
+++ b/lib/constants.js
@@ -92,6 +92,7 @@ export const MAX_INVOICE_DESCRIPTION_LENGTH = 640
 export const RESERVED_MAX_USER_ID = 615
 export const GLOBAL_SEED = USER_ID.k00b
 export const FREEBIE_BASE_COST_THRESHOLD = 10
+export const PROXY_RECEIVE_FEE_PERCENT = 10n
 
 export const SANCTIONED_COUNTRY_CODES = process.env.SANCTIONED_COUNTRY_CODES?.split(',') || []
 
diff --git a/pages/api/lnurlp/[username]/index.js b/pages/api/lnurlp/[username]/index.js
index bc8be79c..68626eb0 100644
--- a/pages/api/lnurlp/[username]/index.js
+++ b/pages/api/lnurlp/[username]/index.js
@@ -1,7 +1,7 @@
 import { getPublicKey } from 'nostr'
 import models from '@/api/models'
 import { lnurlPayMetadataString } from '@/lib/lnurl'
-import { LNURLP_COMMENT_MAX_LENGTH } from '@/lib/constants'
+import { LNURLP_COMMENT_MAX_LENGTH, PROXY_RECEIVE_FEE_PERCENT } from '@/lib/constants'
 
 export default async ({ query: { username } }, res) => {
   const user = await models.user.findUnique({ where: { name: username } })
@@ -9,10 +9,15 @@ export default async ({ query: { username } }, res) => {
     return res.status(400).json({ status: 'ERROR', reason: `user @${username} does not exist` })
   }
 
+  let minSendable = 1000n
+  if (user.proxyReceive) {
+    minSendable += minSendable * PROXY_RECEIVE_FEE_PERCENT / 100n
+  }
+
   const url = process.env.NODE_ENV === 'development' ? process.env.SELF_URL : process.env.NEXT_PUBLIC_URL
   return res.status(200).json({
     callback: `${url}/api/lnurlp/${username}/pay`, // The URL from LN SERVICE which will accept the pay request parameters
-    minSendable: 1000, // Min amount LN SERVICE is willing to receive, can not be less than 1 or more than `maxSendable`
+    minSendable: Number(minSendable), // Min amount LN SERVICE is willing to receive, can not be less than 1 or more than `maxSendable`
     maxSendable: 1000000000,
     metadata: lnurlPayMetadataString(username), // Metadata json which must be presented as raw string here, this is required to pass signature verification at a later step
     commentAllowed: LNURLP_COMMENT_MAX_LENGTH, // LUD-12 Comments for payRequests https://github.com/lnurl/luds/blob/luds/12.md