feat: add default storage dependencies and optimize imports

- Add nano-vectordb and networkx to pyproject.toml dependencies
- Replace dynamic imports with direct imports for 4 default storage implementations
- Improve startup performance while maintaining backward compatibility

lightrag/kg/nano_vector_db_impl.py

@@ -9,12 +9,8 @@ from lightrag.utils import (
     logger,
     compute_mdhash_id,
 )
-import pipmaster as pm
+
 from lightrag.base import BaseVectorStorage
-
-if not pm.is_installed("nano-vectordb"):
-    pm.install("nano-vectordb")
-
 from nano_vectordb import NanoVectorDB
 from .shared_storage import (
     get_storage_lock,

lightrag/kg/networkx_impl.py

@@ -6,12 +6,6 @@ from lightrag.types import KnowledgeGraph, KnowledgeGraphNode, KnowledgeGraphEdg
 from lightrag.utils import logger
 from lightrag.base import BaseGraphStorage
 from lightrag.constants import GRAPH_FIELD_SEP
-
-import pipmaster as pm
-
-if not pm.is_installed("networkx"):
-    pm.install("networkx")
-
 import networkx as nx
 from .shared_storage import (
     get_storage_lock,

lightrag/lightrag.py

@@ -605,6 +605,25 @@ class LightRAG:
         )
 
     def _get_storage_class(self, storage_name: str) -> Callable[..., Any]:
+        # Direct imports for default storage implementations
+        if storage_name == "JsonKVStorage":
+            from lightrag.kg.json_kv_impl import JsonKVStorage
+
+            return JsonKVStorage
+        elif storage_name == "NanoVectorDBStorage":
+            from lightrag.kg.nano_vector_db_impl import NanoVectorDBStorage
+
+            return NanoVectorDBStorage
+        elif storage_name == "NetworkXStorage":
+            from lightrag.kg.networkx_impl import NetworkXStorage
+
+            return NetworkXStorage
+        elif storage_name == "JsonDocStatusStorage":
+            from lightrag.kg.json_doc_status_impl import JsonDocStatusStorage
+
+            return JsonDocStatusStorage
+        else:
+            # Fallback to dynamic import for other storage implementations
             import_path = STORAGES[storage_name]
             storage_class = lazy_external_import(import_path, storage_name)
             return storage_class

pyproject.toml

@@ -25,6 +25,8 @@ dependencies = [
     "configparser",
     "dotenv",
     "future",
+    "nano-vectordb",
+    "networkx",
     "numpy",
     "pandas>=2.0.0",
     "pipmaster",