feat: Add Hip1261 Implementation

src/hiero_sdk_python/__init__.py

@@ -48,6 +48,13 @@
 # Errors
 from .exceptions import PrecheckError, ReceiptStatusError
 
+# Fee
+from .fees.fee_estimate import FeeEstimate
+from .fees.fee_estimate_mode import FeeEstimateMode
+from .fees.fee_estimate_response import FeeEstimateResponse
+from .fees.fee_extra import FeeExtra
+from .fees.network_fee import NetworkFee
+
 # File
 from .file.file_append_transaction import FileAppendTransaction
 from .file.file_contents_query import FileContentsQuery
@@ -77,6 +84,7 @@
 # Queries
 from .query.account_balance_query import CryptoGetAccountBalanceQuery
 from .query.account_info_query import AccountInfoQuery
+from .query.fee_estimate_query import FeeEstimateQuery
 from .query.token_info_query import TokenInfoQuery
 from .query.token_nft_info_query import TokenNftInfoQuery
 from .query.topic_info_query import TopicInfoQuery
@@ -227,6 +235,7 @@
     "TopicDeleteTransaction",
     "TopicId",
     # Queries
+    "FeeEstimateQuery",
     "TopicInfoQuery",
     "TopicMessageQuery",
     "TransactionGetReceiptQuery",
@@ -257,6 +266,12 @@
     "FileContentsQuery",
     "FileUpdateTransaction",
     "FileDeleteTransaction",
+    # Fee
+    "FeeEstimateMode",
+    "FeeEstimate",
+    "FeeEstimateResponse",
+    "FeeExtra",
+    "NetworkFee",
     # Contract
     "ContractCreateTransaction",
     "ContractCallQuery",

src/hiero_sdk_python/consensus/topic_message_submit_transaction.py

@@ -49,7 +49,7 @@ def __init__(
         self.chunk_size: int = chunk_size or 1024
         self.max_chunks: int = max_chunks or 20
 
-        self._current_index = 0
+        self._current_chunk_index = 0
         self._total_chunks = self.get_required_chunks()
         self._initial_transaction_id: TransactionId | None = None
         self._transaction_ids: list[TransactionId] = []
@@ -192,7 +192,7 @@ def _build_proto_body(self) -> consensus_submit_message_pb2.ConsensusSubmitMessa
 
         content = self.message.encode("utf-8")
 
-        start_index = self._current_index * self.chunk_size
+        start_index = self._current_chunk_index * self.chunk_size
         end_index = min(start_index + self.chunk_size, len(content))
         chunk_content = content[start_index:end_index]
 
@@ -206,7 +206,7 @@ def _build_proto_body(self) -> consensus_submit_message_pb2.ConsensusSubmitMessa
                 consensus_submit_message_pb2.ConsensusMessageChunkInfo(
                     initialTransactionID=self._initial_transaction_id._to_proto(),
                     total=self._total_chunks,
-                    number=self._current_index + 1,
+                    number=self._current_chunk_index + 1,
                 )
             )
 
@@ -371,7 +371,7 @@ def execute_all(
         responses = []
 
         for chunk_index in range(self.get_required_chunks()):
-            self._current_index = chunk_index
+            self._current_chunk_index = chunk_index
 
             if self._transaction_ids and chunk_index < len(self._transaction_ids):
                 self.transaction_id = self._transaction_ids[chunk_index]

src/hiero_sdk_python/fees/fee_estimate.py

@@ -0,0 +1,19 @@
+"""Fee estimation models for calculating base and extra fees.
+
+This module defines the FeeEstimate dataclass, which aggregates
+a base fee with optional extra fee components.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+
+from hiero_sdk_python.fees.fee_extra import FeeExtra
+
+
+@dataclass(frozen=True)
+class FeeEstimate:
+    """Represents a fee estimate composed of a base amount and optional extras."""
+
+    base: int
+    extras: list[FeeExtra] = field(default_factory=list)

src/hiero_sdk_python/fees/fee_estimate_mode.py

@@ -0,0 +1,15 @@
+"""Enumeration of fee estimation modes.
+
+Defines the available strategies for calculating fee estimates.
+"""
+
+from __future__ import annotations
+
+from enum import Enum
+
+
+class FeeEstimateMode(str, Enum):
+    """Supported modes for fee estimation."""
+
+    STATE = "STATE"
+    INTRINSIC = "INTRINSIC"

src/hiero_sdk_python/fees/fee_estimate_response.py

@@ -0,0 +1,25 @@
+"""Response model for fee estimation results.
+
+Contains the calculated fees across different categories along with
+the estimation mode and optional notes.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from hiero_sdk_python.fees.fee_estimate import FeeEstimate
+from hiero_sdk_python.fees.fee_estimate_mode import FeeEstimateMode
+from hiero_sdk_python.fees.network_fee import NetworkFee
+
+
+@dataclass(frozen=True)
+class FeeEstimateResponse:
+    """Represents the result of a fee estimation operation."""
+
+    mode: FeeEstimateMode
+    network_fee: NetworkFee | None = None
+    node_fee: FeeEstimate | None = None
+    service_fee: FeeEstimate | None = None
+    total: int = 0
+    high_volume_multiplier: int = 0

src/hiero_sdk_python/fees/fee_extra.py

@@ -0,0 +1,17 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class FeeExtra:
+    """
+    Represents additional fee details associated with a transaction or operation.
+    """
+
+    name: str | None = None
+    included: int | None = None
+    count: int | None = None
+    charged: int | None = None
+    fee_per_unit: int | None = None
+    subtotal: int | None = None

src/hiero_sdk_python/fees/network_fee.py

@@ -0,0 +1,9 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class NetworkFee:
+    multiplier: int
+    subtotal: int