Add ability to get the aggsig additional data from full node RPC (#17241)

* add melting related function rpc api

* add rpc_client version of new functions

* add get_additional_data to rpc and test it

* remove melt_cats

* remove cat_set_tail

* black

* lint fix

* rpc_client returns bytes32

* black test file

chia/rpc/full_node_rpc_api.py

@@ -102,6 +102,7 @@ class FullNodeRpcApi:
             "/get_unfinished_block_headers": self.get_unfinished_block_headers,
             "/get_network_space": self.get_network_space,
             "/get_additions_and_removals": self.get_additions_and_removals,
+            "/get_aggsig_additional_data": self.get_aggsig_additional_data,
             # this function is just here for backwards-compatibility. It will probably
             # be removed in the future
             "/get_initial_freeze_period": self.get_initial_freeze_period,
@@ -805,6 +806,9 @@ class FullNodeRpcApi:
             "removals": [coin_record_dict_backwards_compat(cr.to_json_dict()) for cr in removals],
         }
 
+    async def get_aggsig_additional_data(self, _: Dict[str, Any]) -> EndpointResult:
+        return {"additional_data": self.service.constants.AGG_SIG_ME_ADDITIONAL_DATA.hex()}
+
     async def get_all_mempool_tx_ids(self, _: Dict[str, Any]) -> EndpointResult:
         ids = list(self.service.mempool_manager.mempool.all_item_ids())
         return {"tx_ids": ids}

chia/rpc/full_node_rpc_client.py

@@ -159,6 +159,10 @@ class FullNodeRpcClient(RpcClient):
         response = await self.fetch("get_coin_records_by_parent_ids", d)
         return [CoinRecord.from_json_dict(coin_record_dict_backwards_compat(coin)) for coin in response["coin_records"]]
 
+    async def get_aggsig_additional_data(self) -> bytes32:
+        result = await self.fetch("get_aggsig_additional_data", {})
+        return bytes32.from_hexstr(result["additional_data"])
+
     async def get_coin_records_by_hint(
         self,
         hint: bytes32,

tests/core/test_full_node_rpc.py

@@ -631,6 +631,10 @@ async def test_get_blockchain_state(one_wallet_and_one_simulator_services, self_
         # When supplying genesis block, there are no older blocks so `None` should be returned
         assert await get_average_block_time(full_node_api_1.full_node.blockchain, block_records[0], 4608) is None
         assert await get_average_block_time(full_node_api_1.full_node.blockchain, block_records[-1], 4608) is not None
+        # Test that get_aggsig_additional_data() returns correctly
+        assert (
+            full_node_api_1.full_node.constants.AGG_SIG_ME_ADDITIONAL_DATA == await client.get_aggsig_additional_data()
+        )
 
     finally:
         # Checks that the RPC manages to stop the node