feat: auto discovery of packages and fix passage gen for diskann

packages/leann-core/src/leann/__init__.py

@@ -0,0 +1,7 @@
+# packages/leann-core/src/leann/__init__.py
+from .api import LeannBuilder, LeannChat, LeannSearcher
+from .registry import BACKEND_REGISTRY, autodiscover_backends
+
+autodiscover_backends()
+
+__all__ = ["LeannBuilder", "LeannSearcher", "LeannChat", "BACKEND_REGISTRY"]

packages/leann-core/src/leann/registry.py

@@ -1,6 +1,9 @@
 # packages/leann-core/src/leann/registry.py
 
 from typing import Dict, TYPE_CHECKING
+import importlib
+import importlib.metadata
+
 if TYPE_CHECKING:
     from leann.interface import LeannBackendFactoryInterface
 
@@ -12,4 +15,22 @@ def register_backend(name: str):
         print(f"INFO: Registering backend '{name}'")
         BACKEND_REGISTRY[name] = cls
         return cls
-    return decorator
+    return decorator
+
+def autodiscover_backends():
+    """Automatically discovers and imports all 'leann-backend-*' packages."""
+    print("INFO: Starting backend auto-discovery...")
+    discovered_backends = []
+    for dist in importlib.metadata.distributions():
+        dist_name = dist.metadata['name']
+        if dist_name.startswith('leann-backend-'):
+            backend_module_name = dist_name.replace('-', '_')
+            discovered_backends.append(backend_module_name)
+            
+    for backend_module_name in sorted(discovered_backends): # sort for deterministic loading
+        try:
+            importlib.import_module(backend_module_name)
+            # Registration message is printed by the decorator
+        except ImportError as e:
+            print(f"WARN: Could not import backend module '{backend_module_name}': {e}")
+    print("INFO: Backend auto-discovery finished.")