fix: sending transfer as fee returns amt to sender

src/admin-rpc/init.ts

@@ -16,6 +16,8 @@ export const AdminApi: FastifyPluginCallback<Record<never, never>, Server, TypeB
       schema: {
         description: 'Scan for BRC-20 operations within a block range',
         querystring: Type.Object({
+          // TIP: The first BRC-20 token was deployed at height `779832`. This should be a good
+          // place to start.
           start_block: Type.Integer(),
           end_block: Type.Integer(),
         }),

src/pg/brc20/brc20-pg-store.ts

@@ -23,6 +23,7 @@ import {
   DbBrc20ScannedInscription,
   DbBrc20MintInsert,
   DbBrc20DeployInsert,
+  DbBrc20TransferInsert,
 } from './types';
 import { Brc20Deploy, Brc20Mint, Brc20Transfer, brc20FromInscriptionContent } from './helpers';
 import { hexToBuffer } from '../../api/util/helpers';
@@ -60,12 +61,7 @@ export class Brc20PgStore {
         const block = await sql<DbBrc20ScannedInscription[]>`
           SELECT
             i.content,
-            (
-              CASE EXISTS(SELECT location_id FROM genesis_locations WHERE location_id = l.id)
-                WHEN TRUE THEN TRUE
-                ELSE FALSE
-              END
-            ) AS genesis,
+            EXISTS(SELECT location_id FROM genesis_locations WHERE location_id = l.id) AS genesis,
             ${sql(LOCATIONS_COLUMNS.map(c => `l.${c}`))}
           FROM locations AS l
           INNER JOIN inscriptions AS i ON l.inscription_id = i.id
@@ -98,8 +94,7 @@ export class Brc20PgStore {
               break;
           }
         }
-      }
-      if (!write.genesis) {
+      } else {
         await this.applyTransfer(write);
       }
     }
@@ -257,7 +252,8 @@ export class Brc20PgStore {
           inscription_id: transfer.inscription_id,
           location_id: args.id,
           brc20_deploy_id: transfer.brc20_deploy_id,
-          address: args.address,
+          // If a transfer is sent as fee, its amount must be returned to sender.
+          address: args.address ?? transfer.from_address,
           avail_balance: amount.toString(),
           trans_balance: '0',
           type: DbBrc20BalanceTypeId.transferTo,
@@ -386,7 +382,7 @@ export class Brc20PgStore {
       const available = new BigNumber(balanceRes[0].avail_balance);
       if (transAmt.gt(available)) return;
 
-      const transferInsert = {
+      const transferInsert: DbBrc20TransferInsert = {
         inscription_id: transfer.location.inscription_id,
         brc20_deploy_id: balanceRes[0].brc20_deploy_id,
         block_height: transfer.location.block_height,

src/pg/brc20/types.ts

@@ -38,6 +38,16 @@ export type DbBrc20Deploy = {
   limit?: string;
 };
 
+export type DbBrc20TransferInsert = {
+  inscription_id: string;
+  brc20_deploy_id: string;
+  block_height: string;
+  tx_id: string;
+  from_address: string;
+  to_address: string | null;
+  amount: string;
+};
+
 export type DbBrc20Transfer = {
   id: string;
   inscription_id: string;
@@ -93,7 +103,7 @@ export type DbBrc20BalanceInsert = {
   inscription_id: PgNumeric;
   location_id: PgNumeric;
   brc20_deploy_id: PgNumeric;
-  address: string | null;
+  address: string;
   avail_balance: PgNumeric;
   trans_balance: PgNumeric;
   type: DbBrc20BalanceTypeId;

tests/brc20.test.ts

@@ -1506,6 +1506,74 @@ describe('BRC-20', () => {
       expect(prevBlockJson2.results[0]).toBeUndefined();
     });
 
+    test('sending transfer as fee returns amount to sender', async () => {
+      const address = 'bc1p3cyx5e2hgh53w7kpxcvm8s4kkega9gv5wfw7c4qxsvxl0u8x834qf0u2td';
+      await deployAndMintPEPE(address);
+      await db.updateInscriptions(
+        new TestChainhookPayloadBuilder()
+          .apply()
+          .block({
+            height: 775619,
+            hash: '00000000000000000002b14f0c5dde0b2fc74d022e860696bd64f1f652756674',
+          })
+          .transaction({
+            hash: 'eee52b22397ea4a4aefe6a39931315e93a157091f5a994216c0aa9c8c6fef47a',
+          })
+          .inscriptionRevealed(
+            brc20Reveal({
+              json: {
+                p: 'brc-20',
+                op: 'transfer',
+                tick: 'PEPE',
+                amt: '9000',
+              },
+              number: 7,
+              tx_id: 'eee52b22397ea4a4aefe6a39931315e93a157091f5a994216c0aa9c8c6fef47a',
+              address: address,
+            })
+          )
+          .build()
+      );
+      await db.updateInscriptions(
+        new TestChainhookPayloadBuilder()
+          .apply()
+          .block({
+            height: 775620,
+            hash: '00000000000000000003feae13d107f0f2c4fb4dd08fb2a8b1ab553512e77f03',
+          })
+          .transaction({
+            hash: '7edaa48337a94da327b6262830505f116775a32db5ad4ad46e87ecea33f21bac',
+          })
+          .inscriptionTransferred({
+            inscription_id: 'eee52b22397ea4a4aefe6a39931315e93a157091f5a994216c0aa9c8c6fef47ai0',
+            updated_address: null, // Sent as fee
+            satpoint_pre_transfer:
+              'eee52b22397ea4a4aefe6a39931315e93a157091f5a994216c0aa9c8c6fef47a:0:0',
+            satpoint_post_transfer:
+              '7edaa48337a94da327b6262830505f116775a32db5ad4ad46e87ecea33f21bac:0:0',
+            post_transfer_output_value: null,
+            tx_index: 0,
+          })
+          .build()
+      );
+
+      const response1 = await fastify.inject({
+        method: 'GET',
+        url: `/ordinals/brc-20/balances/${address}`,
+      });
+      expect(response1.statusCode).toBe(200);
+      const json1 = response1.json();
+      expect(json1.total).toBe(1);
+      expect(json1.results).toStrictEqual([
+        {
+          available_balance: '10000',
+          overall_balance: '10000',
+          ticker: 'PEPE',
+          transferrable_balance: '0',
+        },
+      ]);
+    });
+
     test('cannot spend valid transfer twice', async () => {
       const address = 'bc1p3cyx5e2hgh53w7kpxcvm8s4kkega9gv5wfw7c4qxsvxl0u8x834qf0u2td';
       const address2 = '3QNjwPDRafjBm9XxJpshgk3ksMJh3TFxTU';