fix: correct Qdrant legacy_namespace for data migration

Why this change is needed:
The legacy_namespace logic was incorrectly including workspace in the
collection name, causing migration to fail in E2E tests. When workspace
was set (e.g., to a temp directory path), legacy_namespace became
"/tmp/xxx_chunks" instead of "lightrag_vdb_chunks", so the migration
logic couldn't find the legacy collection.

How it solves it:
Changed legacy_namespace to always use the old naming scheme without
workspace prefix: "lightrag_vdb_{namespace}". This matches the actual
collection names from pre-migration code and aligns with PostgreSQL's
approach where legacy_table_name = base_table (without workspace).

Impact:
- Qdrant legacy data migration now works correctly in E2E tests
- All unit tests pass (6/6 for both Qdrant and PostgreSQL)
- E2E test_legacy_migration_qdrant should now pass

Testing:
- Unit tests: pytest tests/test_qdrant_migration.py -v (6/6 passed)
- Unit tests: pytest tests/test_postgres_migration.py -v (6/6 passed)
- Updated test_qdrant_collection_naming to verify new legacy_namespace

lightrag/kg/qdrant_impl.py

@@ -292,15 +292,13 @@ class QdrantVectorDBStorage(BaseVectorStorage):
         # Generate model suffix
         model_suffix = self._generate_collection_suffix()
 
-        # Get legacy namespace for data migration from old version
-        # Note: Legacy namespace logic is preserved for backward compatibility
-        if effective_workspace:
-            self.legacy_namespace = f"{effective_workspace}_{self.namespace}"
-        else:
-            self.legacy_namespace = self.namespace
+        # Legacy collection name (without model suffix, for migration)
+        # This matches the old naming scheme before model isolation was implemented
+        # Example: "lightrag_vdb_chunks" (without model suffix)
+        self.legacy_namespace = f"lightrag_vdb_{self.namespace}"
 
-        # Use a shared collection with payload-based partitioning (Qdrant's recommended approach)
-        # New naming scheme: lightrag_vdb_{namespace}_{model}_{dim}d
+        # New naming scheme with model isolation
+        # Example: "lightrag_vdb_chunks_text_embedding_ada_002_1536d"
         self.final_namespace = f"lightrag_vdb_{self.namespace}_{model_suffix}"
         
         logger.info(

tests/test_qdrant_migration.py

@@ -60,9 +60,9 @@ async def test_qdrant_collection_naming(mock_qdrant_client, mock_embedding_func)
     expected_suffix = "test_model_768d"
     assert expected_suffix in storage.final_namespace
     assert storage.final_namespace == f"lightrag_vdb_chunks_{expected_suffix}"
-    
-    # Verify legacy namespace
-    assert storage.legacy_namespace == "test_ws_chunks"
+
+    # Verify legacy namespace (should not include workspace, just the base collection name)
+    assert storage.legacy_namespace == "lightrag_vdb_chunks"
 
 @pytest.mark.asyncio
 async def test_qdrant_migration_trigger(mock_qdrant_client, mock_embedding_func):