feat: Add max query payment support to Query

CHANGELOG.md

@@ -95,6 +95,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Added `Client.from_env()` and network-specific factory methods (e.g., `Client.for_testnet()`) to simplify client initialization and reduce boilerplate. [[#1251](https://github.com/hiero-ledger/hiero-sdk-python/issues/1251)]
 - Improved unit test coverage for `TransactionId` class, covering parsing logic, hashing, and scheduled transactions.
 - Add contract_id support for CryptoGetAccountBalanceQuery([#1293](https://github.com/hiero-ledger/hiero-sdk-python/issues/1293))
+- Support for setting `max_query_payment`, `Query.set_max_query_payment()` allows setting a per-query maximum Hbar payment and `Client.set_default_max_query_payment()` sets a client-wide default maximum payment.
 - Chained Good First Issue assignment with mentor assignment to bypass GitHub's anti-recursion protection - mentor assignment now occurs immediately after successful user assignment in the same workflow execution. (#1369)
 - Add GitHub Actions script and workflow for automatic spam list updates.
 - Added technical docstrings and hardening (set -euo pipefail) to the pr-check-test-files.sh script (#1336)

examples/contract/contract_call_query.py

@@ -114,15 +114,18 @@ def query_contract_call():
 
     contract_id = create_contract(client, file_id)
 
-    result = (
+    query = (
         ContractCallQuery()
         .set_contract_id(contract_id)
         .set_gas(2000000)
         .set_function(
             "getMessageAndOwner"
         )  # Call the contract's getMessageAndOwner() function
-        .execute(client)
     )
+    cost = query.get_cost(client)
+    query.set_max_query_payment(cost)
+
+    result = query.execute(client)
     # You can also use set_function_parameters() instead of set_function() e.g.:
     # .set_function_parameters(ContractFunctionParameters("getMessageAndOwner"))
 

examples/contract/contract_execute_transaction.py

@@ -107,14 +107,18 @@ def create_contract(client, file_id):
 def get_contract_message(client, contract_id):
     """Get the message from the contract"""
     # Query the contract function to verify that the message was set
-    result = (
+    query = (
         ContractCallQuery()
         .set_contract_id(contract_id)
         .set_gas(2000000)
         .set_function("getMessage")
-        .execute(client)
     )
 
+    cost = query.get_cost(client)
+    query.set_max_query_payment(cost)
+
+    result = query.execute(client)
+
     # The contract returns bytes32, which we decode to string
     # This removes any padding and converts to readable text
     return result.get_bytes32(0).decode("utf-8")

examples/contract/ethereum_transaction.py

@@ -146,14 +146,18 @@ def create_contract(client, file_id):
 def get_contract_message(client, contract_id):
     """Get the message from the contract"""
     # Query the contract function to verify that the message was set
-    result = (
+    query = (
         ContractCallQuery()
         .set_contract_id(contract_id)
         .set_gas(2000000)
         .set_function("getMessage")
-        .execute(client)
     )
 
+    cost = query.get_cost(client)
+    query.set_max_query_payment(cost)
+
+    result = query.execute(client)
+
     # The contract returns bytes32, which we decode
     # Remove null bytes padding and decode as UTF-8 text
     message_bytes = result.get_bytes32(0).rstrip(b"\x00")

src/hiero_sdk_python/client/client.py

@@ -2,11 +2,13 @@
 Client module for interacting with the Hedera network.
 """
 
+from decimal import Decimal
 import os
 from typing import NamedTuple, List, Union, Optional, Literal
 from dotenv import load_dotenv
 import grpc
 
+from hiero_sdk_python.hbar import Hbar
 from hiero_sdk_python.logger.logger import Logger, LogLevel
 from hiero_sdk_python.hapi.mirror import (
     consensus_service_pb2_grpc as mirror_consensus_grpc,
@@ -18,6 +20,8 @@
 
 from .network import Network
 
+DEFAULT_MAX_QUERY_PAYMENT = Hbar(1)
+
 NetworkName = Literal["mainnet", "testnet", "previewnet"]
 
 class Operator(NamedTuple):
@@ -45,6 +49,7 @@ def __init__(self, network: Network = None) -> None:
         self.mirror_stub: mirror_consensus_grpc.ConsensusServiceStub = None
 
         self.max_attempts: int = 10
+        self.default_max_query_payment: Hbar = DEFAULT_MAX_QUERY_PAYMENT
 
         self._init_mirror_stub()
 
@@ -240,6 +245,37 @@ def get_tls_root_certificates(self) -> Optional[bytes]:
         Retrieve the configured root certificates for TLS connections.
         """
         return self.network.get_tls_root_certificates()
+
+    def set_default_max_query_payment(self, max_query_payment: Union[int, float, Decimal, Hbar]) -> "Client":
+        """
+        Sets the default maximum Hbar amount allowed for any query executed by this client.
+
+        The SDK fetches the actual query cost and fails early if it exceeds this limit.
+        Individual queries may override this value via `Query.set_max_query_payment()`.
+
+        Args:
+            max_query_payment (Union[int, float, Decimal, Hbar]):
+                The maximum amount of Hbar that any single query is allowed to cost.
+        Returns:
+            Client: The current client instance for method chaining.
+        """
+        if isinstance(max_query_payment, bool) or not isinstance(max_query_payment, (int, float, Decimal, Hbar)):
+            raise TypeError(
+                "max_query_payment must be int, float, Decimal, or Hbar, "
+                f"got {type(max_query_payment).__name__}"
+            )
+
+        value = (
+            max_query_payment 
+            if isinstance(max_query_payment, Hbar)
+            else Hbar(max_query_payment)
+        )
+
+        if value < Hbar(0):
+            raise ValueError("max_query_payment must be non-negative")
+
+        self.default_max_query_payment = value
+        return self
 
     def __enter__(self) -> "Client":
         """

src/hiero_sdk_python/hbar.py

@@ -6,6 +6,7 @@
 and validating amounts of the network utility token (HBAR).
 """
 
+import math
 import re
 import warnings
 from decimal import Decimal
@@ -39,6 +40,11 @@ def __init__(
             amount: The numeric amount of hbar or tinybar.
             unit: Unit of the provided amount.
         """
+        if isinstance(amount, bool) or not isinstance(amount, (int, float, Decimal)):
+            raise TypeError("Amount must be of type int, float, or Decimal")
+
+        if isinstance(amount, float) and not math.isfinite(amount):
+            raise ValueError("Hbar amount must be finite")
 
         if  unit == HbarUnit.TINYBAR:
             if not isinstance(amount, int):
@@ -48,12 +54,11 @@ def __init__(
 
         if isinstance(amount, (float, int)):
             amount = Decimal(str(amount))
-        elif not isinstance(amount, Decimal):
-            raise TypeError("Amount must be of type int, float, or Decimal")
 
         tinybar = amount * Decimal(unit.tinybar)
         if tinybar % 1 != 0:
             raise ValueError("Fractional tinybar value not allowed")
+
         self._amount_in_tinybar = int(tinybar)
 
     def to(self, unit: HbarUnit) -> float:
@@ -104,7 +109,7 @@ def from_tinybars(cls, tinybars: int) -> "Hbar":
         Returns:
             Hbar: A new Hbar instance.
         """
-        if not isinstance(tinybars, int):
+        if isinstance(tinybars, bool) or not isinstance(tinybars, int):
             raise TypeError("tinybars must be an int.")
         return cls(tinybars, unit=HbarUnit.TINYBAR)
 

src/hiero_sdk_python/query/query.py

@@ -2,8 +2,9 @@
 Base class for all network queries.
 """
 
+from decimal import Decimal
 import time
-from typing import Any, List, Optional, Union
+from typing import Any, Optional, Union
 
 from hiero_sdk_python.account.account_id import AccountId
 from hiero_sdk_python.channels import _Channel
@@ -18,8 +19,7 @@
     query_header_pb2,
     query_pb2,
     transaction_pb2,
-    transaction_contents_pb2,
-    transaction_pb2,
+    transaction_contents_pb2
 )
 from hiero_sdk_python.hbar import Hbar
 from hiero_sdk_python.response_code import ResponseCode
@@ -57,6 +57,7 @@ def __init__(self) -> None:
         self.operator: Optional[Operator] = None
         self.node_index: int = 0
         self.payment_amount: Optional[Hbar] = None
+        self.max_query_payment: Optional[Hbar] = None
 
     def _get_query_response(self, response: Any) -> query_pb2.Query:
         """
@@ -91,6 +92,40 @@ def set_query_payment(self, payment_amount: Hbar) -> "Query":
         """
         self.payment_amount = payment_amount
         return self
+
+    def set_max_query_payment(self, max_query_payment: Union[int, float, Decimal, Hbar]) -> "Query":
+        """
+        Sets the maximum Hbar amount that this query is allowed to cost.
+
+        Before executing a paid query, the SDK will fetch the actual query cost
+        from the network and compare it against this value. If the cost exceeds
+        the specified maximum, execution will fail early with an error instead
+        of submitting the query.
+
+        Args:
+            max_query_payment (Union[int, float, Decimal, Hbar]):
+                The maximum amount of Hbar that any single query is allowed to cost.
+
+        Returns:
+            Query: The current query instance for method chaining.
+        """
+        if isinstance(max_query_payment, bool) or not isinstance(max_query_payment, (int, float, Decimal, Hbar)):
+            raise TypeError(
+                "max_query_payment must be int, float, Decimal, or Hbar, "
+                f"got {type(max_query_payment).__name__}"
+            )
+
+        value = (
+            max_query_payment 
+            if isinstance(max_query_payment, Hbar)
+            else Hbar(max_query_payment)
+        )
+
+        if value < Hbar(0):
+            raise ValueError("max_query_payment must be non-negative")
+
+        self.max_query_payment = value
+        return self
 
     def _before_execute(self, client: Client) -> None:
         """
@@ -111,6 +146,20 @@ def _before_execute(self, client: Client) -> None:
         # get the cost from the network and set it as the payment amount
         if self.payment_amount is None and self._is_payment_required():
             self.payment_amount = self.get_cost(client)
+
+            # if max_query_payment not set fall back to the client-level default max query payment
+            max_payment = (
+                self.max_query_payment 
+                if self.max_query_payment is not None 
+                else client.default_max_query_payment
+            )
+
+            if self.payment_amount > max_payment:
+                raise ValueError(
+                    f"Query cost ℏ{self.payment_amount.to_hbars()} HBAR "
+                    f"exceeds max set query payment: ℏ{max_payment.to_hbars()} HBAR"
+                )
+
 
     def _make_request_header(self) -> query_header_pb2.QueryHeader:
         """

tests/integration/contract_call_query_e2e_test.py

@@ -63,14 +63,18 @@ def test_integration_contract_call_query_can_execute_with_constructor(env):
     contract_id = receipt.contract_id
     assert contract_id is not None, "Contract ID should not be None"
 
-    result = (
+    query = (
         ContractCallQuery()
         .set_contract_id(contract_id)
         .set_gas(10000000)
         .set_function("getMessage")
-        .execute(env.client)
     )
 
+    cost = query.get_cost(env.client)
+    query.set_max_query_payment(cost)
+
+    result = query.execute(env.client)
+
     assert result is not None, "Contract call result should not be None"
     assert result.get_bytes32(0) == message
 
@@ -109,14 +113,17 @@ def test_integration_contract_call_query_can_execute(env):
     contract_id = receipt.contract_id
     assert contract_id is not None, "Contract ID should not be None"
 
-    result = (
+    query = (
         ContractCallQuery()
         .set_contract_id(contract_id)
         .set_gas(10000000)
         .set_function("greet")
-        .execute(env.client)
     )
 
+    cost = query.get_cost(env.client)
+    query.set_max_query_payment(cost)
+
+    result = query.execute(env.client)
     assert result is not None, "Contract call result should not be None"
     assert result.get_string(0) == "Hello, world!"
 

tests/integration/query_e2e_test.py

@@ -6,9 +6,10 @@
 from hiero_sdk_python.exceptions import PrecheckError
 from hiero_sdk_python.hbar import Hbar
 from hiero_sdk_python.query.account_balance_query import CryptoGetAccountBalanceQuery
+from hiero_sdk_python.query.account_info_query import AccountInfoQuery
 from hiero_sdk_python.query.token_info_query import TokenInfoQuery
 from hiero_sdk_python.response_code import ResponseCode
-from tests.integration.utils import IntegrationTestEnv, create_fungible_token
+from tests.integration.utils import IntegrationTestEnv, env, create_fungible_token
 
 @pytest.mark.integration
 def test_integration_free_query_no_cost():
@@ -236,4 +237,24 @@ def test_integration_paid_query_payment_too_high_fails():
         with pytest.raises(PrecheckError, match="failed precheck with status: INSUFFICIENT_PAYER_BALANCE"):
             query.execute(env.client)
     finally:
-        env.close()
+        env.close()
+
+@pytest.mark.integration
+def test_integration_query_exceeds_max_payment(env):
+    """Test that Query fails when cost exceeds max_query_payment."""
+    receipt = env.create_account(1)
+    account_id = receipt.id
+
+    # Set max payment below actual cost
+    query = (
+        AccountInfoQuery()
+        .set_account_id(account_id)
+        .set_max_query_payment(Hbar.from_tinybars(1))  # Intentionally too low to fail
+    )
+
+    with pytest.raises(ValueError) as e:
+        query.execute(env.client)
+
+    msg = str(e.value)
+    assert "Query cost" in msg and "exceeds max set query payment:" in msg
+