backend

src/langbot/pkg/workflow/__init__.py

@@ -21,12 +21,33 @@ from .entities import (
     NodeStatus,
 )
 
-from .node import WorkflowNode, NodePort, NodeConfig, workflow_node
-from .registry import NodeTypeRegistry
-from .executor import WorkflowExecutor
+from importlib import import_module
+from typing import Any
 
-# Import nodes module to trigger node registration
-from . import nodes as nodes
+from .node import WorkflowNode, workflow_node
+
+
+def __getattr__(name: str) -> Any:
+    """Lazily expose heavier workflow modules.
+
+    Loading workflow metadata should not import the executor or node modules as a
+    side effect. Node implementations are imported explicitly during boot after
+    YAML metadata has been registered.
+    """
+    if name == 'NodeTypeRegistry':
+        from .registry import NodeTypeRegistry
+
+        return NodeTypeRegistry
+
+    if name == 'WorkflowExecutor':
+        from .executor import WorkflowExecutor
+
+        return WorkflowExecutor
+
+    if name == 'nodes':
+        return import_module('.nodes', __name__)
+
+    raise AttributeError(f'module {__name__!r} has no attribute {name!r}')
 
 __all__ = [
     # Entities
@@ -43,8 +64,6 @@ __all__ = [
     'NodeStatus',
     # Node
     'WorkflowNode',
-    'NodePort',
-    'NodeConfig',
     'workflow_node',
     # Registry
     'NodeTypeRegistry',