diff --git a/api/core/workflow/graph_engine/command_channels/in_memory_channel.py b/api/core/workflow/graph_engine/command_channels/in_memory_channel.py
index ef498e6890..bdaf236796 100644
--- a/api/core/workflow/graph_engine/command_channels/in_memory_channel.py
+++ b/api/core/workflow/graph_engine/command_channels/in_memory_channel.py
@@ -6,10 +6,12 @@ within a single process. Each instance handles commands for one workflow executi
 """
 
 from queue import Queue
+from typing import final
 
 from ..entities.commands import GraphEngineCommand
 
 
+@final
 class InMemoryChannel:
     """
     In-memory command channel implementation using a thread-safe queue.
diff --git a/api/core/workflow/graph_engine/command_channels/redis_channel.py b/api/core/workflow/graph_engine/command_channels/redis_channel.py
index 0350044690..7809e43e32 100644
--- a/api/core/workflow/graph_engine/command_channels/redis_channel.py
+++ b/api/core/workflow/graph_engine/command_channels/redis_channel.py
@@ -7,7 +7,7 @@ Each instance uses a unique key for its command queue.
 """
 
 import json
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, final
 
 from ..entities.commands import AbortCommand, CommandType, GraphEngineCommand
 
@@ -15,6 +15,7 @@ if TYPE_CHECKING:
     from extensions.ext_redis import RedisClientWrapper
 
 
+@final
 class RedisChannel:
     """
     Redis-based command channel implementation for distributed systems.
diff --git a/api/core/workflow/graph_engine/command_processing/command_handlers.py b/api/core/workflow/graph_engine/command_processing/command_handlers.py
index f8bae5e21a..9f8d20b1b9 100644
--- a/api/core/workflow/graph_engine/command_processing/command_handlers.py
+++ b/api/core/workflow/graph_engine/command_processing/command_handlers.py
@@ -3,6 +3,7 @@ Command handler implementations.
 """
 
 import logging
+from typing import final
 
 from ..domain.graph_execution import GraphExecution
 from ..entities.commands import AbortCommand, GraphEngineCommand
@@ -11,6 +12,7 @@ from .command_processor import CommandHandler
 logger = logging.getLogger(__name__)
 
 
+@final
 class AbortCommandHandler(CommandHandler):
     """Handles abort commands."""
 
diff --git a/api/core/workflow/graph_engine/command_processing/command_processor.py b/api/core/workflow/graph_engine/command_processing/command_processor.py
index 06b3a8d8a4..2521058ef2 100644
--- a/api/core/workflow/graph_engine/command_processing/command_processor.py
+++ b/api/core/workflow/graph_engine/command_processing/command_processor.py
@@ -3,7 +3,7 @@ Main command processor for handling external commands.
 """
 
 import logging
-from typing import Protocol
+from typing import Protocol, final
 
 from ..domain.graph_execution import GraphExecution
 from ..entities.commands import GraphEngineCommand
@@ -18,6 +18,7 @@ class CommandHandler(Protocol):
     def handle(self, command: GraphEngineCommand, execution: GraphExecution) -> None: ...
 
 
+@final
 class CommandProcessor:
     """
     Processes external commands sent to the engine.
diff --git a/api/core/workflow/graph_engine/error_handling/abort_strategy.py b/api/core/workflow/graph_engine/error_handling/abort_strategy.py
index ba2a7b514f..6a805bd124 100644
--- a/api/core/workflow/graph_engine/error_handling/abort_strategy.py
+++ b/api/core/workflow/graph_engine/error_handling/abort_strategy.py
@@ -3,6 +3,7 @@ Abort error strategy implementation.
 """
 
 import logging
+from typing import final
 
 from core.workflow.graph import Graph
 from core.workflow.graph_events import GraphNodeEventBase, NodeRunFailedEvent
@@ -10,6 +11,7 @@ from core.workflow.graph_events import GraphNodeEventBase, NodeRunFailedEvent
 logger = logging.getLogger(__name__)
 
 
+@final
 class AbortStrategy:
     """
     Error strategy that aborts execution on failure.
diff --git a/api/core/workflow/graph_engine/error_handling/default_value_strategy.py b/api/core/workflow/graph_engine/error_handling/default_value_strategy.py
index 19e5b4c0ae..61d36399aa 100644
--- a/api/core/workflow/graph_engine/error_handling/default_value_strategy.py
+++ b/api/core/workflow/graph_engine/error_handling/default_value_strategy.py
@@ -2,12 +2,15 @@
 Default value error strategy implementation.
 """
 
+from typing import final
+
 from core.workflow.enums import ErrorStrategy, WorkflowNodeExecutionMetadataKey, WorkflowNodeExecutionStatus
 from core.workflow.graph import Graph
 from core.workflow.graph_events import GraphNodeEventBase, NodeRunExceptionEvent, NodeRunFailedEvent
 from core.workflow.node_events import NodeRunResult
 
 
+@final
 class DefaultValueStrategy:
     """
     Error strategy that uses default values on failure.
diff --git a/api/core/workflow/graph_engine/error_handling/fail_branch_strategy.py b/api/core/workflow/graph_engine/error_handling/fail_branch_strategy.py
index d3be64539e..437c2bc7da 100644
--- a/api/core/workflow/graph_engine/error_handling/fail_branch_strategy.py
+++ b/api/core/workflow/graph_engine/error_handling/fail_branch_strategy.py
@@ -2,12 +2,15 @@
 Fail branch error strategy implementation.
 """
 
+from typing import final
+
 from core.workflow.enums import ErrorStrategy, WorkflowNodeExecutionMetadataKey, WorkflowNodeExecutionStatus
 from core.workflow.graph import Graph
 from core.workflow.graph_events import GraphNodeEventBase, NodeRunExceptionEvent, NodeRunFailedEvent
 from core.workflow.node_events import NodeRunResult
 
 
+@final
 class FailBranchStrategy:
     """
     Error strategy that continues execution via a fail branch.
diff --git a/api/core/workflow/graph_engine/error_handling/retry_strategy.py b/api/core/workflow/graph_engine/error_handling/retry_strategy.py
index af1058569f..e4010b6bdb 100644
--- a/api/core/workflow/graph_engine/error_handling/retry_strategy.py
+++ b/api/core/workflow/graph_engine/error_handling/retry_strategy.py
@@ -3,11 +3,13 @@ Retry error strategy implementation.
 """
 
 import time
+from typing import final
 
 from core.workflow.graph import Graph
 from core.workflow.graph_events import GraphNodeEventBase, NodeRunFailedEvent, NodeRunRetryEvent
 
 
+@final
 class RetryStrategy:
     """
     Error strategy that retries failed nodes.
diff --git a/api/core/workflow/graph_engine/event_management/event_collector.py b/api/core/workflow/graph_engine/event_management/event_collector.py
index 20c1419324..a41dcf5b10 100644
--- a/api/core/workflow/graph_engine/event_management/event_collector.py
+++ b/api/core/workflow/graph_engine/event_management/event_collector.py
@@ -3,12 +3,14 @@ Event collector for buffering and managing events.
 """
 
 import threading
+from typing import final
 
 from core.workflow.graph_events import GraphEngineEvent
 
 from ..layers.base import Layer
 
 
+@final
 class ReadWriteLock:
     """
     A read-write lock implementation that allows multiple concurrent readers
@@ -56,6 +58,7 @@ class ReadWriteLock:
         return WriteLockContext(self)
 
 
+@final
 class ReadLockContext:
     """Context manager for read locks."""
 
@@ -70,6 +73,7 @@ class ReadLockContext:
         self._lock.release_read()
 
 
+@final
 class WriteLockContext:
     """Context manager for write locks."""
 
@@ -84,6 +88,7 @@ class WriteLockContext:
         self._lock.release_write()
 
 
+@final
 class EventCollector:
     """
     Collects and buffers events for later retrieval.
diff --git a/api/core/workflow/graph_engine/event_management/event_emitter.py b/api/core/workflow/graph_engine/event_management/event_emitter.py
index 36f9d5d5a2..6fb0b96e8c 100644
--- a/api/core/workflow/graph_engine/event_management/event_emitter.py
+++ b/api/core/workflow/graph_engine/event_management/event_emitter.py
@@ -5,12 +5,14 @@ Event emitter for yielding events to external consumers.
 import threading
 import time
 from collections.abc import Generator
+from typing import final
 
 from core.workflow.graph_events import GraphEngineEvent
 
 from .event_collector import EventCollector
 
 
+@final
 class EventEmitter:
     """
     Emits collected events as a generator for external consumption.
diff --git a/api/core/workflow/graph_engine/graph_engine.py b/api/core/workflow/graph_engine/graph_engine.py
index df194de909..dd98536fba 100644
--- a/api/core/workflow/graph_engine/graph_engine.py
+++ b/api/core/workflow/graph_engine/graph_engine.py
@@ -9,7 +9,7 @@ import contextvars
 import logging
 import queue
 from collections.abc import Generator, Mapping
-from typing import Any
+from typing import final
 
 from flask import Flask, current_app
 
@@ -45,6 +45,7 @@ from .worker_management import ActivityTracker, DynamicScaler, WorkerFactory, Wo
 logger = logging.getLogger(__name__)
 
 
+@final
 class GraphEngine:
     """
     Queue-based graph execution engine.
@@ -63,7 +64,7 @@ class GraphEngine:
         invoke_from: InvokeFrom,
         call_depth: int,
         graph: Graph,
-        graph_config: Mapping[str, Any],
+        graph_config: Mapping[str, object],
         graph_runtime_state: GraphRuntimeState,
         max_execution_steps: int,
         max_execution_time: int,
@@ -186,7 +187,7 @@ class GraphEngine:
             event_handler=self.event_handler_registry,
             event_collector=self.event_collector,
             command_processor=self.command_processor,
-            worker_pool=self.worker_pool,
+            worker_pool=self._worker_pool,
         )
 
         self.dispatcher = Dispatcher(
@@ -219,8 +220,8 @@ class GraphEngine:
         context_vars = contextvars.copy_context()
 
         # Create worker management components
-        self.activity_tracker = ActivityTracker()
-        self.dynamic_scaler = DynamicScaler(
+        self._activity_tracker = ActivityTracker()
+        self._dynamic_scaler = DynamicScaler(
             min_workers=(self._min_workers if self._min_workers is not None else dify_config.GRAPH_ENGINE_MIN_WORKERS),
             max_workers=(self._max_workers if self._max_workers is not None else dify_config.GRAPH_ENGINE_MAX_WORKERS),
             scale_up_threshold=(
@@ -234,15 +235,15 @@ class GraphEngine:
                 else dify_config.GRAPH_ENGINE_SCALE_DOWN_IDLE_TIME
             ),
         )
-        self.worker_factory = WorkerFactory(flask_app, context_vars)
+        self._worker_factory = WorkerFactory(flask_app, context_vars)
 
-        self.worker_pool = WorkerPool(
+        self._worker_pool = WorkerPool(
             ready_queue=self.ready_queue,
             event_queue=self.event_queue,
             graph=self.graph,
-            worker_factory=self.worker_factory,
-            dynamic_scaler=self.dynamic_scaler,
-            activity_tracker=self.activity_tracker,
+            worker_factory=self._worker_factory,
+            dynamic_scaler=self._dynamic_scaler,
+            activity_tracker=self._activity_tracker,
         )
 
     def _validate_graph_state_consistency(self) -> None:
@@ -320,10 +321,10 @@ class GraphEngine:
     def _start_execution(self) -> None:
         """Start execution subsystems."""
         # Calculate initial worker count
-        initial_workers = self.dynamic_scaler.calculate_initial_workers(self.graph)
+        initial_workers = self._dynamic_scaler.calculate_initial_workers(self.graph)
 
         # Start worker pool
-        self.worker_pool.start(initial_workers)
+        self._worker_pool.start(initial_workers)
 
         # Register response nodes
         for node in self.graph.nodes.values():
@@ -341,7 +342,7 @@ class GraphEngine:
     def _stop_execution(self) -> None:
         """Stop execution subsystems."""
         self.dispatcher.stop()
-        self.worker_pool.stop()
+        self._worker_pool.stop()
         # Don't mark complete here as the dispatcher already does it
 
         # Notify layers
diff --git a/api/core/workflow/graph_engine/graph_traversal/branch_handler.py b/api/core/workflow/graph_engine/graph_traversal/branch_handler.py
index 4bc3bd1e0a..b371f3bc73 100644
--- a/api/core/workflow/graph_engine/graph_traversal/branch_handler.py
+++ b/api/core/workflow/graph_engine/graph_traversal/branch_handler.py
@@ -3,6 +3,7 @@ Branch node handling for graph traversal.
 """
 
 from collections.abc import Sequence
+from typing import final
 
 from core.workflow.graph import Graph
 from core.workflow.graph_events.node import NodeRunStreamChunkEvent
@@ -12,6 +13,7 @@ from .edge_processor import EdgeProcessor
 from .skip_propagator import SkipPropagator
 
 
+@final
 class BranchHandler:
     """
     Handles branch node logic during graph traversal.
diff --git a/api/core/workflow/graph_engine/graph_traversal/edge_processor.py b/api/core/workflow/graph_engine/graph_traversal/edge_processor.py
index 76e6d819bf..ac2c658b4b 100644
--- a/api/core/workflow/graph_engine/graph_traversal/edge_processor.py
+++ b/api/core/workflow/graph_engine/graph_traversal/edge_processor.py
@@ -3,6 +3,7 @@ Edge processing logic for graph traversal.
 """
 
 from collections.abc import Sequence
+from typing import final
 
 from core.workflow.enums import NodeExecutionType
 from core.workflow.graph import Edge, Graph
@@ -12,6 +13,7 @@ from ..response_coordinator import ResponseStreamCoordinator
 from ..state_management import EdgeStateManager, NodeStateManager
 
 
+@final
 class EdgeProcessor:
     """
     Processes edges during graph execution.
diff --git a/api/core/workflow/graph_engine/graph_traversal/node_readiness.py b/api/core/workflow/graph_engine/graph_traversal/node_readiness.py
index 29e74e2f3f..59bce3942c 100644
--- a/api/core/workflow/graph_engine/graph_traversal/node_readiness.py
+++ b/api/core/workflow/graph_engine/graph_traversal/node_readiness.py
@@ -2,10 +2,13 @@
 Node readiness checking for execution.
 """
 
+from typing import final
+
 from core.workflow.enums import NodeState
 from core.workflow.graph import Graph
 
 
+@final
 class NodeReadinessChecker:
     """
     Checks if nodes are ready for execution based on their dependencies.
diff --git a/api/core/workflow/graph_engine/graph_traversal/skip_propagator.py b/api/core/workflow/graph_engine/graph_traversal/skip_propagator.py
index d4bceeb333..5ac445d405 100644
--- a/api/core/workflow/graph_engine/graph_traversal/skip_propagator.py
+++ b/api/core/workflow/graph_engine/graph_traversal/skip_propagator.py
@@ -3,12 +3,14 @@ Skip state propagation through the graph.
 """
 
 from collections.abc import Sequence
+from typing import final
 
 from core.workflow.graph import Edge, Graph
 
 from ..state_management import EdgeStateManager, NodeStateManager
 
 
+@final
 class SkipPropagator:
     """
     Propagates skip states through the graph.
diff --git a/api/core/workflow/graph_engine/layers/debug_logging.py b/api/core/workflow/graph_engine/layers/debug_logging.py
index 73db3260b1..3052600161 100644
--- a/api/core/workflow/graph_engine/layers/debug_logging.py
+++ b/api/core/workflow/graph_engine/layers/debug_logging.py
@@ -7,7 +7,7 @@ graph execution for debugging purposes.
 
 import logging
 from collections.abc import Mapping
-from typing import Any
+from typing import Any, final
 
 from core.workflow.graph_events import (
     GraphEngineEvent,
@@ -34,6 +34,7 @@ from core.workflow.graph_events import (
 from .base import Layer
 
 
+@final
 class DebugLoggingLayer(Layer):
     """
     A layer that provides comprehensive logging of GraphEngine execution.
diff --git a/api/core/workflow/graph_engine/layers/execution_limits.py b/api/core/workflow/graph_engine/layers/execution_limits.py
index 71b6e045fd..efda0bacbe 100644
--- a/api/core/workflow/graph_engine/layers/execution_limits.py
+++ b/api/core/workflow/graph_engine/layers/execution_limits.py
@@ -11,6 +11,7 @@ When limits are exceeded, the layer automatically aborts execution.
 import logging
 import time
 from enum import Enum
+from typing import final
 
 from core.workflow.graph_engine.entities.commands import AbortCommand, CommandType
 from core.workflow.graph_engine.layers import Layer
@@ -28,6 +29,7 @@ class LimitType(Enum):
     TIME_LIMIT = "time_limit"
 
 
+@final
 class ExecutionLimitsLayer(Layer):
     """
     Layer that enforces execution limits for workflows.
diff --git a/api/core/workflow/graph_engine/manager.py b/api/core/workflow/graph_engine/manager.py
index 3c9f347816..ed62209acb 100644
--- a/api/core/workflow/graph_engine/manager.py
+++ b/api/core/workflow/graph_engine/manager.py
@@ -6,11 +6,14 @@ using the new Redis command channel, without requiring user permission checks.
 Supports stop, pause, and resume operations.
 """
 
+from typing import final
+
 from core.workflow.graph_engine.command_channels.redis_channel import RedisChannel
 from core.workflow.graph_engine.entities.commands import AbortCommand
 from extensions.ext_redis import redis_client
 
 
+@final
 class GraphEngineManager:
     """
     Manager for sending control commands to GraphEngine instances.
diff --git a/api/core/workflow/graph_engine/orchestration/dispatcher.py b/api/core/workflow/graph_engine/orchestration/dispatcher.py
index 87ad3d0117..694355298c 100644
--- a/api/core/workflow/graph_engine/orchestration/dispatcher.py
+++ b/api/core/workflow/graph_engine/orchestration/dispatcher.py
@@ -6,7 +6,7 @@ import logging
 import queue
 import threading
 import time
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, final
 
 from core.workflow.graph_events.base import GraphNodeEventBase
 
@@ -19,6 +19,7 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
+@final
 class Dispatcher:
     """
     Main dispatcher that processes events from the event queue.
diff --git a/api/core/workflow/graph_engine/orchestration/execution_coordinator.py b/api/core/workflow/graph_engine/orchestration/execution_coordinator.py
index 899cb6a0d5..5f95b5b29e 100644
--- a/api/core/workflow/graph_engine/orchestration/execution_coordinator.py
+++ b/api/core/workflow/graph_engine/orchestration/execution_coordinator.py
@@ -2,7 +2,7 @@
 Execution coordinator for managing overall workflow execution.
 """
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, final
 
 from ..command_processing import CommandProcessor
 from ..domain import GraphExecution
@@ -14,6 +14,7 @@ if TYPE_CHECKING:
     from ..event_management import EventHandlerRegistry
 
 
+@final
 class ExecutionCoordinator:
     """
     Coordinates overall execution flow between subsystems.
diff --git a/api/core/workflow/graph_engine/output_registry/registry.py b/api/core/workflow/graph_engine/output_registry/registry.py
index 6ffc6b178a..4df7da207c 100644
--- a/api/core/workflow/graph_engine/output_registry/registry.py
+++ b/api/core/workflow/graph_engine/output_registry/registry.py
@@ -7,7 +7,7 @@ thread-safe storage for node outputs.
 
 from collections.abc import Sequence
 from threading import RLock
-from typing import TYPE_CHECKING, Union
+from typing import TYPE_CHECKING, Union, final
 
 from core.variables import Segment
 from core.workflow.entities.variable_pool import VariablePool
@@ -18,6 +18,7 @@ if TYPE_CHECKING:
     from core.workflow.graph_events import NodeRunStreamChunkEvent
 
 
+@final
 class OutputRegistry:
     """
     Thread-safe registry for storing and retrieving node outputs.
diff --git a/api/core/workflow/graph_engine/output_registry/stream.py b/api/core/workflow/graph_engine/output_registry/stream.py
index e9a097d85f..8a99b56d1f 100644
--- a/api/core/workflow/graph_engine/output_registry/stream.py
+++ b/api/core/workflow/graph_engine/output_registry/stream.py
@@ -5,12 +5,13 @@ This module contains the private Stream class used internally by OutputRegistry
 to manage streaming data chunks.
 """
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, final
 
 if TYPE_CHECKING:
     from core.workflow.graph_events import NodeRunStreamChunkEvent
 
 
+@final
 class Stream:
     """
     A stream that holds NodeRunStreamChunkEvent objects and tracks read position.
diff --git a/api/core/workflow/graph_engine/response_coordinator/coordinator.py b/api/core/workflow/graph_engine/response_coordinator/coordinator.py
index 380f5de04c..4c3cc167fa 100644
--- a/api/core/workflow/graph_engine/response_coordinator/coordinator.py
+++ b/api/core/workflow/graph_engine/response_coordinator/coordinator.py
@@ -9,7 +9,7 @@ import logging
 from collections import deque
 from collections.abc import Sequence
 from threading import RLock
-from typing import TypeAlias
+from typing import TypeAlias, final
 from uuid import uuid4
 
 from core.workflow.enums import NodeExecutionType, NodeState
@@ -28,6 +28,7 @@ NodeID: TypeAlias = str
 EdgeID: TypeAlias = str
 
 
+@final
 class ResponseStreamCoordinator:
     """
     Manages response streaming sessions without relying on global state.
diff --git a/api/core/workflow/graph_engine/state_management/edge_state_manager.py b/api/core/workflow/graph_engine/state_management/edge_state_manager.py
index 32d6ca5780..747062284a 100644
--- a/api/core/workflow/graph_engine/state_management/edge_state_manager.py
+++ b/api/core/workflow/graph_engine/state_management/edge_state_manager.py
@@ -4,7 +4,7 @@ Manager for edge states during graph execution.
 
 import threading
 from collections.abc import Sequence
-from typing import TypedDict
+from typing import TypedDict, final
 
 from core.workflow.enums import NodeState
 from core.workflow.graph import Edge, Graph
@@ -18,6 +18,7 @@ class EdgeStateAnalysis(TypedDict):
     all_skipped: bool
 
 
+@final
 class EdgeStateManager:
     """
     Manages edge states and transitions during graph execution.
diff --git a/api/core/workflow/graph_engine/state_management/execution_tracker.py b/api/core/workflow/graph_engine/state_management/execution_tracker.py
index 2008f30777..01fa80f2ce 100644
--- a/api/core/workflow/graph_engine/state_management/execution_tracker.py
+++ b/api/core/workflow/graph_engine/state_management/execution_tracker.py
@@ -3,8 +3,10 @@ Tracker for currently executing nodes.
 """
 
 import threading
+from typing import final
 
 
+@final
 class ExecutionTracker:
     """
     Tracks nodes that are currently being executed.
diff --git a/api/core/workflow/graph_engine/state_management/node_state_manager.py b/api/core/workflow/graph_engine/state_management/node_state_manager.py
index 61bb639cda..d5ed42ad1d 100644
--- a/api/core/workflow/graph_engine/state_management/node_state_manager.py
+++ b/api/core/workflow/graph_engine/state_management/node_state_manager.py
@@ -4,11 +4,13 @@ Manager for node states during graph execution.
 
 import queue
 import threading
+from typing import final
 
 from core.workflow.enums import NodeState
 from core.workflow.graph import Graph
 
 
+@final
 class NodeStateManager:
     """
     Manages node states and the ready queue for execution.
diff --git a/api/core/workflow/graph_engine/worker.py b/api/core/workflow/graph_engine/worker.py
index b7eedbc871..dacf6f0435 100644
--- a/api/core/workflow/graph_engine/worker.py
+++ b/api/core/workflow/graph_engine/worker.py
@@ -11,6 +11,7 @@ import threading
 import time
 from collections.abc import Callable
 from datetime import datetime
+from typing import final
 from uuid import uuid4
 
 from flask import Flask
@@ -22,6 +23,7 @@ from core.workflow.nodes.base.node import Node
 from libs.flask_utils import preserve_flask_contexts
 
 
+@final
 class Worker(threading.Thread):
     """
     Worker thread that executes nodes from the ready queue.
diff --git a/api/core/workflow/graph_engine/worker_management/activity_tracker.py b/api/core/workflow/graph_engine/worker_management/activity_tracker.py
index 5203fc6b6c..b2125a0158 100644
--- a/api/core/workflow/graph_engine/worker_management/activity_tracker.py
+++ b/api/core/workflow/graph_engine/worker_management/activity_tracker.py
@@ -4,8 +4,10 @@ Activity tracker for monitoring worker activity.
 
 import threading
 import time
+from typing import final
 
 
+@final
 class ActivityTracker:
     """
     Tracks worker activity for scaling decisions.
diff --git a/api/core/workflow/graph_engine/worker_management/dynamic_scaler.py b/api/core/workflow/graph_engine/worker_management/dynamic_scaler.py
index 7a1920a724..7450b02618 100644
--- a/api/core/workflow/graph_engine/worker_management/dynamic_scaler.py
+++ b/api/core/workflow/graph_engine/worker_management/dynamic_scaler.py
@@ -2,9 +2,12 @@
 Dynamic scaler for worker pool sizing.
 """
 
+from typing import final
+
 from core.workflow.graph import Graph
 
 
+@final
 class DynamicScaler:
     """
     Manages dynamic scaling decisions for the worker pool.
diff --git a/api/core/workflow/graph_engine/worker_management/worker_factory.py b/api/core/workflow/graph_engine/worker_management/worker_factory.py
index 8714ee88d1..673ca11f26 100644
--- a/api/core/workflow/graph_engine/worker_management/worker_factory.py
+++ b/api/core/workflow/graph_engine/worker_management/worker_factory.py
@@ -5,6 +5,7 @@ Factory for creating worker instances.
 import contextvars
 import queue
 from collections.abc import Callable
+from typing import final
 
 from flask import Flask
 
@@ -13,6 +14,7 @@ from core.workflow.graph import Graph
 from ..worker import Worker
 
 
+@final
 class WorkerFactory:
     """
     Factory for creating worker instances with proper context.
diff --git a/api/core/workflow/graph_engine/worker_management/worker_pool.py b/api/core/workflow/graph_engine/worker_management/worker_pool.py
index 8faa9da156..55250809cd 100644
--- a/api/core/workflow/graph_engine/worker_management/worker_pool.py
+++ b/api/core/workflow/graph_engine/worker_management/worker_pool.py
@@ -4,6 +4,7 @@ Worker pool management.
 
 import queue
 import threading
+from typing import final
 
 from core.workflow.graph import Graph
 
@@ -13,6 +14,7 @@ from .dynamic_scaler import DynamicScaler
 from .worker_factory import WorkerFactory
 
 
+@final
 class WorkerPool:
     """
     Manages a pool of worker threads for executing nodes.