feat: implement dimension compatibility checks for PostgreSQL and Qdrant migrations

This update introduces checks for vector dimension compatibility before migrating legacy data in both PostgreSQL and Qdrant storage implementations. If a dimension mismatch is detected, the migration is skipped to prevent data loss, and a new empty table or collection is created for the new embedding model.

Key changes include:
- Added dimension checks in `PGVectorStorage` and `QdrantVectorDBStorage` classes.
- Enhanced logging to inform users about dimension mismatches and the creation of new storage.
- Updated E2E tests to validate the new behavior, ensuring legacy data is preserved and new structures are created correctly.

Impact:
- Prevents potential data corruption during migrations with mismatched dimensions.
- Improves user experience by providing clear logging and maintaining legacy data integrity.

Testing:
- New tests confirm that the system behaves as expected when encountering dimension mismatches.

lightrag/kg/postgres_impl.py

@@ -2344,6 +2344,71 @@ class PGVectorStorage(BaseVectorStorage):
                 await db._create_vector_index(table_name, embedding_dim)
                 return
 
+            # Check vector dimension compatibility before migration
+            legacy_dim = None
+            try:
+                # Try to get vector dimension from pg_attribute metadata
+                dim_query = """
+                SELECT
+                    CASE
+                        WHEN typname = 'vector' THEN
+                            COALESCE(atttypmod, -1)
+                        ELSE -1
+                    END as vector_dim
+                FROM pg_attribute a
+                JOIN pg_type t ON a.atttypid = t.oid
+                WHERE a.attrelid = $1::regclass
+                AND a.attname = 'content_vector'
+                """
+                dim_result = await db.query(dim_query, [legacy_table_name])
+                legacy_dim = dim_result.get("vector_dim", -1) if dim_result else -1
+
+                if legacy_dim <= 0:
+                    # Alternative: Try to detect by sampling a vector
+                    logger.info(
+                        "PostgreSQL: Metadata dimension check failed, trying vector sampling..."
+                    )
+                    sample_query = (
+                        f"SELECT content_vector FROM {legacy_table_name} LIMIT 1"
+                    )
+                    sample_result = await db.query(sample_query, [])
+                    if sample_result and sample_result.get("content_vector"):
+                        vector_data = sample_result["content_vector"]
+                        # pgvector returns list directly
+                        if isinstance(vector_data, (list, tuple)):
+                            legacy_dim = len(vector_data)
+                        elif isinstance(vector_data, str):
+                            import json
+
+                            vector_list = json.loads(vector_data)
+                            legacy_dim = len(vector_list)
+
+                if legacy_dim > 0 and embedding_dim and legacy_dim != embedding_dim:
+                    logger.warning(
+                        f"PostgreSQL: Dimension mismatch detected! "
+                        f"Legacy table '{legacy_table_name}' has {legacy_dim}d vectors, "
+                        f"but new embedding model expects {embedding_dim}d. "
+                        f"Migration skipped to prevent data loss. "
+                        f"Legacy table preserved as '{legacy_table_name}'. "
+                        f"Creating new empty table '{table_name}' for new data."
+                    )
+
+                    # Create new table but skip migration
+                    await _pg_create_table(db, table_name, base_table, embedding_dim)
+                    await db._create_vector_index(table_name, embedding_dim)
+
+                    logger.info(
+                        f"PostgreSQL: New table '{table_name}' created. "
+                        f"To query legacy data, please use a {legacy_dim}d embedding model."
+                    )
+                    return
+
+            except Exception as e:
+                logger.warning(
+                    f"PostgreSQL: Could not verify legacy table vector dimension: {e}. "
+                    f"Proceeding with caution..."
+                )
+
             # Create new table first
             logger.info(f"PostgreSQL: Creating new table '{table_name}'")
             await _pg_create_table(db, table_name, base_table, embedding_dim)

lightrag/kg/qdrant_impl.py

@@ -251,6 +251,51 @@ class QdrantVectorDBStorage(BaseVectorStorage):
                 )
                 return
 
+            # Check vector dimension compatibility before migration
+            try:
+                legacy_info = client.get_collection(legacy_collection)
+                legacy_dim = legacy_info.config.params.vectors.size
+
+                # Get expected dimension from kwargs
+                new_dim = (
+                    kwargs.get("vectors_config").size
+                    if "vectors_config" in kwargs
+                    else None
+                )
+
+                if new_dim and legacy_dim != new_dim:
+                    logger.warning(
+                        f"Qdrant: Dimension mismatch detected! "
+                        f"Legacy collection '{legacy_collection}' has {legacy_dim}d vectors, "
+                        f"but new embedding model expects {new_dim}d. "
+                        f"Migration skipped to prevent data loss. "
+                        f"Legacy collection preserved as '{legacy_collection}'. "
+                        f"Creating new empty collection '{collection_name}' for new data."
+                    )
+
+                    # Create new collection but skip migration
+                    client.create_collection(collection_name, **kwargs)
+                    client.create_payload_index(
+                        collection_name=collection_name,
+                        field_name=WORKSPACE_ID_FIELD,
+                        field_schema=models.KeywordIndexParams(
+                            type=models.KeywordIndexType.KEYWORD,
+                            is_tenant=True,
+                        ),
+                    )
+
+                    logger.info(
+                        f"Qdrant: New collection '{collection_name}' created. "
+                        f"To query legacy data, please use a {legacy_dim}d embedding model."
+                    )
+                    return
+
+            except Exception as e:
+                logger.warning(
+                    f"Qdrant: Could not verify legacy collection dimension: {e}. "
+                    f"Proceeding with caution..."
+                )
+
             # Create new collection first
             logger.info(f"Qdrant: Creating new collection '{collection_name}'")
             client.create_collection(collection_name, **kwargs)

tests/test_dimension_mismatch.py

@@ -0,0 +1,290 @@
+"""
+Tests for dimension mismatch handling during migration.
+
+This test module verifies that both PostgreSQL and Qdrant storage backends
+properly detect and handle vector dimension mismatches when migrating from
+legacy collections/tables to new ones with different embedding models.
+"""
+
+import pytest
+from unittest.mock import MagicMock, AsyncMock, patch
+
+from lightrag.kg.qdrant_impl import QdrantVectorDBStorage
+from lightrag.kg.postgres_impl import PGVectorStorage
+
+
+class TestQdrantDimensionMismatch:
+    """Test suite for Qdrant dimension mismatch handling."""
+
+    def test_qdrant_dimension_mismatch_skip_migration(self):
+        """
+        Test that Qdrant skips migration when dimensions don't match.
+
+        Scenario: Legacy collection has 1536d vectors, new model expects 3072d.
+        Expected: Migration skipped, new empty collection created, legacy preserved.
+        """
+        from qdrant_client import models
+
+        # Setup mock client
+        client = MagicMock()
+
+        # Mock legacy collection with 1536d vectors
+        legacy_collection_info = MagicMock()
+        legacy_collection_info.config.params.vectors.size = 1536
+
+        # Setup collection existence checks
+        def collection_exists_side_effect(name):
+            if name == "lightrag_chunks":  # legacy
+                return True
+            elif name == "lightrag_chunks_model_3072d":  # new
+                return False
+            return False
+
+        client.collection_exists.side_effect = collection_exists_side_effect
+        client.get_collection.return_value = legacy_collection_info
+        client.count.return_value.count = 100  # Legacy has data
+
+        # Call setup_collection with 3072d (different from legacy 1536d)
+        QdrantVectorDBStorage.setup_collection(
+            client,
+            "lightrag_chunks_model_3072d",
+            namespace="chunks",
+            workspace="test",
+            vectors_config=models.VectorParams(
+                size=3072, distance=models.Distance.COSINE
+            ),
+        )
+
+        # Verify new collection was created
+        client.create_collection.assert_called_once()
+
+        # Verify migration was NOT attempted (no scroll/upsert calls)
+        client.scroll.assert_not_called()
+        client.upsert.assert_not_called()
+
+    def test_qdrant_dimension_match_proceed_migration(self):
+        """
+        Test that Qdrant proceeds with migration when dimensions match.
+
+        Scenario: Legacy collection has 1536d vectors, new model also expects 1536d.
+        Expected: Migration proceeds normally.
+        """
+        from qdrant_client import models
+
+        client = MagicMock()
+
+        # Mock legacy collection with 1536d vectors (matching new)
+        legacy_collection_info = MagicMock()
+        legacy_collection_info.config.params.vectors.size = 1536
+
+        def collection_exists_side_effect(name):
+            if name == "lightrag_chunks":  # legacy
+                return True
+            elif name == "lightrag_chunks_model_1536d":  # new
+                return False
+            return False
+
+        client.collection_exists.side_effect = collection_exists_side_effect
+        client.get_collection.return_value = legacy_collection_info
+        client.count.return_value.count = 100  # Legacy has data
+
+        # Mock scroll to return sample data
+        sample_point = MagicMock()
+        sample_point.id = "test_id"
+        sample_point.vector = [0.1] * 1536
+        sample_point.payload = {"id": "test"}
+        client.scroll.return_value = ([sample_point], None)
+
+        # Call setup_collection with matching 1536d
+        QdrantVectorDBStorage.setup_collection(
+            client,
+            "lightrag_chunks_model_1536d",
+            namespace="chunks",
+            workspace="test",
+            vectors_config=models.VectorParams(
+                size=1536, distance=models.Distance.COSINE
+            ),
+        )
+
+        # Verify migration WAS attempted
+        client.create_collection.assert_called_once()
+        client.scroll.assert_called()
+        client.upsert.assert_called()
+
+
+class TestPostgresDimensionMismatch:
+    """Test suite for PostgreSQL dimension mismatch handling."""
+
+    @pytest.mark.asyncio
+    async def test_postgres_dimension_mismatch_skip_migration_metadata(self):
+        """
+        Test that PostgreSQL skips migration when dimensions don't match (via metadata).
+
+        Scenario: Legacy table has 1536d vectors (detected via pg_attribute),
+                  new model expects 3072d.
+        Expected: Migration skipped, new empty table created, legacy preserved.
+        """
+        # Setup mock database
+        db = AsyncMock()
+
+        # Mock table existence and dimension checks
+        async def query_side_effect(query, params, **kwargs):
+            if "information_schema.tables" in query:
+                if params[0] == "lightrag_doc_chunks":  # legacy
+                    return {"exists": True}
+                elif params[0] == "lightrag_doc_chunks_model_3072d":  # new
+                    return {"exists": False}
+            elif "COUNT(*)" in query:
+                return {"count": 100}  # Legacy has data
+            elif "pg_attribute" in query:
+                return {"vector_dim": 1536}  # Legacy has 1536d vectors
+            return {}
+
+        db.query.side_effect = query_side_effect
+        db.execute = AsyncMock()
+        db._create_vector_index = AsyncMock()
+
+        # Call setup_table with 3072d (different from legacy 1536d)
+        await PGVectorStorage.setup_table(
+            db,
+            "lightrag_doc_chunks_model_3072d",
+            legacy_table_name="lightrag_doc_chunks",
+            base_table="lightrag_doc_chunks",
+            embedding_dim=3072,
+        )
+
+        # Verify new table was created (DDL executed)
+        create_table_calls = [
+            call
+            for call in db.execute.call_args_list
+            if call[0][0] and "CREATE TABLE" in call[0][0]
+        ]
+        assert len(create_table_calls) > 0, "New table should be created"
+
+        # Verify migration was NOT attempted (no INSERT calls)
+        insert_calls = [
+            call
+            for call in db.execute.call_args_list
+            if call[0][0] and "INSERT INTO" in call[0][0]
+        ]
+        assert len(insert_calls) == 0, "Migration should be skipped"
+
+    @pytest.mark.asyncio
+    async def test_postgres_dimension_mismatch_skip_migration_sampling(self):
+        """
+        Test that PostgreSQL skips migration when dimensions don't match (via sampling).
+
+        Scenario: Legacy table dimension detection fails via metadata,
+                  falls back to vector sampling, detects 1536d vs expected 3072d.
+        Expected: Migration skipped, new empty table created, legacy preserved.
+        """
+        db = AsyncMock()
+
+        # Mock table existence and dimension checks
+        async def query_side_effect(query, params, **kwargs):
+            if "information_schema.tables" in query:
+                if params[0] == "lightrag_doc_chunks":  # legacy
+                    return {"exists": True}
+                elif params[0] == "lightrag_doc_chunks_model_3072d":  # new
+                    return {"exists": False}
+            elif "COUNT(*)" in query:
+                return {"count": 100}  # Legacy has data
+            elif "pg_attribute" in query:
+                return {"vector_dim": -1}  # Metadata check fails
+            elif "SELECT content_vector FROM" in query:
+                # Return sample vector with 1536 dimensions
+                return {"content_vector": [0.1] * 1536}
+            return {}
+
+        db.query.side_effect = query_side_effect
+        db.execute = AsyncMock()
+        db._create_vector_index = AsyncMock()
+
+        # Call setup_table with 3072d (different from legacy 1536d)
+        await PGVectorStorage.setup_table(
+            db,
+            "lightrag_doc_chunks_model_3072d",
+            legacy_table_name="lightrag_doc_chunks",
+            base_table="lightrag_doc_chunks",
+            embedding_dim=3072,
+        )
+
+        # Verify new table was created
+        create_table_calls = [
+            call
+            for call in db.execute.call_args_list
+            if call[0][0] and "CREATE TABLE" in call[0][0]
+        ]
+        assert len(create_table_calls) > 0, "New table should be created"
+
+        # Verify migration was NOT attempted
+        insert_calls = [
+            call
+            for call in db.execute.call_args_list
+            if call[0][0] and "INSERT INTO" in call[0][0]
+        ]
+        assert len(insert_calls) == 0, "Migration should be skipped"
+
+    @pytest.mark.asyncio
+    async def test_postgres_dimension_match_proceed_migration(self):
+        """
+        Test that PostgreSQL proceeds with migration when dimensions match.
+
+        Scenario: Legacy table has 1536d vectors, new model also expects 1536d.
+        Expected: Migration proceeds normally.
+        """
+        db = AsyncMock()
+
+        async def query_side_effect(query, params, **kwargs):
+            multirows = kwargs.get("multirows", False)
+
+            if "information_schema.tables" in query:
+                if params[0] == "lightrag_doc_chunks":  # legacy
+                    return {"exists": True}
+                elif params[0] == "lightrag_doc_chunks_model_1536d":  # new
+                    return {"exists": False}
+            elif "COUNT(*)" in query:
+                return {"count": 100}  # Legacy has data
+            elif "pg_attribute" in query:
+                return {"vector_dim": 1536}  # Legacy has matching 1536d
+            elif "SELECT * FROM" in query and multirows:
+                # Return sample data for migration (first batch)
+                if params[0] == 0:  # offset = 0
+                    return [
+                        {
+                            "id": "test1",
+                            "content_vector": [0.1] * 1536,
+                            "workspace": "test",
+                        },
+                        {
+                            "id": "test2",
+                            "content_vector": [0.2] * 1536,
+                            "workspace": "test",
+                        },
+                    ]
+                else:  # offset > 0
+                    return []  # No more data
+            return {}
+
+        db.query.side_effect = query_side_effect
+        db.execute = AsyncMock()
+        db._create_vector_index = AsyncMock()
+
+        # Call setup_table with matching 1536d
+        await PGVectorStorage.setup_table(
+            db,
+            "lightrag_doc_chunks_model_1536d",
+            legacy_table_name="lightrag_doc_chunks",
+            base_table="lightrag_doc_chunks",
+            embedding_dim=1536,
+        )
+
+        # Verify migration WAS attempted (INSERT calls made)
+        insert_calls = [
+            call
+            for call in db.execute.call_args_list
+            if call[0][0] and "INSERT INTO" in call[0][0]
+        ]
+        assert (
+            len(insert_calls) > 0
+        ), "Migration should proceed with matching dimensions"

tests/test_e2e_multi_instance.py

@@ -1169,56 +1169,73 @@ async def test_dimension_mismatch_postgres(
 
         print("📦 Initializing LightRAG with new model (3072d)...")
 
-        # This should handle dimension mismatch gracefully
-        # Either: 1) Create new table for new model, or 2) Raise clear error
-        try:
-            rag = LightRAG(
-                working_dir=temp_dir,
-                llm_model_func=mock_llm_func,
-                embedding_func=embedding_func_new,
-                tokenizer=mock_tokenizer,
-                kv_storage="PGKVStorage",
-                vector_storage="PGVectorStorage",
-                doc_status_storage="PGDocStatusStorage",
-                vector_db_storage_cls_kwargs={
-                    **pg_config,
-                    "cosine_better_than_threshold": 0.8,
-                },
-            )
+        # With our fix, this should handle dimension mismatch gracefully:
+        # Expected behavior:
+        # 1. Detect dimension mismatch (1536d legacy vs 3072d new)
+        # 2. Skip migration to prevent data corruption
+        # 3. Preserve legacy table with original data
+        # 4. Create new empty table for 3072d model
+        # 5. System initializes successfully
 
-            await rag.initialize_storages()
+        rag = LightRAG(
+            working_dir=temp_dir,
+            llm_model_func=mock_llm_func,
+            embedding_func=embedding_func_new,
+            tokenizer=mock_tokenizer,
+            kv_storage="PGKVStorage",
+            vector_storage="PGVectorStorage",
+            doc_status_storage="PGDocStatusStorage",
+            vector_db_storage_cls_kwargs={
+                **pg_config,
+                "cosine_better_than_threshold": 0.8,
+            },
+        )
 
-            # Check what happened
-            new_table = rag.chunks_vdb.table_name
-            print(f"✅ Initialization succeeded, new table: {new_table}")
+        await rag.initialize_storages()
 
-            # Verify new table has correct dimension (3072d)
-            # Check if both tables exist
-            check_legacy = f"SELECT EXISTS (SELECT FROM information_schema.tables WHERE table_name = '{legacy_table}')"
-            check_new = f"SELECT EXISTS (SELECT FROM information_schema.tables WHERE table_name = '{new_table.lower()}')"
+        # Verify expected behavior
+        new_table = rag.chunks_vdb.table_name
+        print(f"✅ Initialization succeeded, new table: {new_table}")
 
-            legacy_exists = await pg_cleanup.query(check_legacy, [])
-            new_exists = await pg_cleanup.query(check_new, [])
+        # 1. New table should exist and be created with model suffix
+        assert "text_embedding_3_large_3072d" in new_table.lower()
+        check_new = f"SELECT EXISTS (SELECT FROM information_schema.tables WHERE table_name = '{new_table.lower()}')"
+        new_exists = await pg_cleanup.query(check_new, [])
+        assert new_exists.get("exists") is True, "New table should exist"
+        print(f"✅ New table created: {new_table}")
 
-            print(f"✅ Legacy table exists: {legacy_exists.get('exists')}")
-            print(f"✅ New table exists: {new_exists.get('exists')}")
+        # 2. Legacy table should be preserved (not deleted)
+        check_legacy = f"SELECT EXISTS (SELECT FROM information_schema.tables WHERE table_name = '{legacy_table}')"
+        legacy_exists = await pg_cleanup.query(check_legacy, [])
+        assert (
+            legacy_exists.get("exists") is True
+        ), "Legacy table should be preserved when dimensions don't match"
+        print(f"✅ Legacy table preserved: {legacy_table}")
 
-            # Test should verify proper handling:
-            # - New table created with 3072d
-            # - Legacy table preserved (or migrated to dimension-matched table)
-            # - System is operational
+        # 3. Legacy table should still have original data (not migrated)
+        legacy_count_result = await pg_cleanup.query(
+            f"SELECT COUNT(*) as count FROM {legacy_table}", []
+        )
+        legacy_count = legacy_count_result.get("count", 0)
+        assert (
+            legacy_count == 3
+        ), f"Legacy table should still have 3 records, got {legacy_count}"
+        print(f"✅ Legacy data preserved: {legacy_count} records")
 
-            await rag.finalize_storages()
+        # 4. New table should be empty (migration skipped)
+        new_count_result = await pg_cleanup.query(
+            f"SELECT COUNT(*) as count FROM {new_table}", []
+        )
+        new_count = new_count_result.get("count", 0)
+        assert (
+            new_count == 0
+        ), f"New table should be empty (migration skipped), got {new_count}"
+        print(f"✅ New table is empty (migration correctly skipped): {new_count} records")
 
-        except Exception as e:
-            # If it raises an error, it should be a clear, actionable error
-            print(f"⚠️ Initialization raised exception: {e}")
-            # Verify error message is clear and actionable
-            assert any(
-                keyword in str(e).lower()
-                for keyword in ["dimension", "mismatch", "1536", "3072"]
-            ), f"Error message should mention dimension mismatch: {e}"
-            print("✅ Clear error message provided to user")
+        # 5. System should be operational
+        print("✅ System initialized successfully despite dimension mismatch")
+
+        await rag.finalize_storages()
 
     finally:
         shutil.rmtree(temp_dir, ignore_errors=True)
@@ -1293,50 +1310,72 @@ async def test_dimension_mismatch_qdrant(
 
         print("📦 Initializing LightRAG with new model (1024d)...")
 
-        # This should handle dimension mismatch gracefully
-        try:
-            rag = LightRAG(
-                working_dir=temp_dir,
-                llm_model_func=mock_llm_func,
-                embedding_func=embedding_func_new,
-                tokenizer=mock_tokenizer,
-                vector_storage="QdrantVectorDBStorage",
-                vector_db_storage_cls_kwargs={
-                    **qdrant_config,
-                    "cosine_better_than_threshold": 0.8,
-                },
-            )
+        # With our fix, this should handle dimension mismatch gracefully:
+        # Expected behavior:
+        # 1. Detect dimension mismatch (768d legacy vs 1024d new)
+        # 2. Skip migration to prevent data corruption
+        # 3. Preserve legacy collection with original data
+        # 4. Create new empty collection for 1024d model
+        # 5. System initializes successfully
 
-            await rag.initialize_storages()
+        rag = LightRAG(
+            working_dir=temp_dir,
+            llm_model_func=mock_llm_func,
+            embedding_func=embedding_func_new,
+            tokenizer=mock_tokenizer,
+            vector_storage="QdrantVectorDBStorage",
+            vector_db_storage_cls_kwargs={
+                **qdrant_config,
+                "cosine_better_than_threshold": 0.8,
+            },
+        )
 
-            # Check what happened
-            new_collection = rag.chunks_vdb.final_namespace
-            print(f"✅ Initialization succeeded, new collection: {new_collection}")
+        await rag.initialize_storages()
 
-            # Verify collections
-            legacy_exists = client.collection_exists(legacy_collection)
-            new_exists = client.collection_exists(new_collection)
+        # Verify expected behavior
+        new_collection = rag.chunks_vdb.final_namespace
+        print(f"✅ Initialization succeeded, new collection: {new_collection}")
 
-            print(f"✅ Legacy collection exists: {legacy_exists}")
-            print(f"✅ New collection exists: {new_exists}")
+        # 1. New collection should exist with model suffix
+        assert "bge_large_1024d" in new_collection
+        assert client.collection_exists(
+            new_collection
+        ), f"New collection {new_collection} should exist"
+        print(f"✅ New collection created: {new_collection}")
 
-            # Verify new collection has correct dimension
-            collection_info = client.get_collection(new_collection)
-            new_dim = collection_info.config.params.vectors.size
-            print(f"✅ New collection dimension: {new_dim}d")
-            assert new_dim == 1024, f"New collection should have 1024d, got {new_dim}d"
+        # 2. Legacy collection should be preserved (not deleted)
+        legacy_exists = client.collection_exists(legacy_collection)
+        assert (
+            legacy_exists
+        ), "Legacy collection should be preserved when dimensions don't match"
+        print(f"✅ Legacy collection preserved: {legacy_collection}")
 
-            await rag.finalize_storages()
+        # 3. Legacy collection should still have original data (not migrated)
+        legacy_count = client.count(legacy_collection).count
+        assert (
+            legacy_count == 3
+        ), f"Legacy collection should still have 3 vectors, got {legacy_count}"
+        print(f"✅ Legacy data preserved: {legacy_count} vectors")
 
-        except Exception as e:
-            # If it raises an error, it should be a clear, actionable error
-            print(f"⚠️ Initialization raised exception: {e}")
-            # Verify error message is clear and actionable
-            assert any(
-                keyword in str(e).lower()
-                for keyword in ["dimension", "mismatch", "768", "1024"]
-            ), f"Error message should mention dimension mismatch: {e}"
-            print("✅ Clear error message provided to user")
+        # 4. New collection should be empty (migration skipped)
+        new_count = client.count(new_collection).count
+        assert (
+            new_count == 0
+        ), f"New collection should be empty (migration skipped), got {new_count}"
+        print(
+            f"✅ New collection is empty (migration correctly skipped): {new_count} vectors"
+        )
+
+        # 5. Verify new collection has correct dimension
+        collection_info = client.get_collection(new_collection)
+        new_dim = collection_info.config.params.vectors.size
+        assert new_dim == 1024, f"New collection should have 1024d, got {new_dim}d"
+        print(f"✅ New collection dimension verified: {new_dim}d")
+
+        # 6. System should be operational
+        print("✅ System initialized successfully despite dimension mismatch")
+
+        await rag.finalize_storages()
 
     finally:
         shutil.rmtree(temp_dir, ignore_errors=True)

tests/test_qdrant_migration.py

@@ -12,9 +12,11 @@ def mock_qdrant_client():
         client = mock_client_cls.return_value
         client.collection_exists.return_value = False
         client.count.return_value.count = 0
-        # Mock payload schema for get_collection
+        # Mock payload schema and vector config for get_collection
         collection_info = MagicMock()
         collection_info.payload_schema = {}
+        # Mock vector dimension to match mock_embedding_func (768d)
+        collection_info.config.params.vectors.size = 768
         client.get_collection.return_value = collection_info
         yield client
 
@@ -254,6 +256,12 @@ async def test_scenario_2_legacy_upgrade_migration(
         lambda name: name == legacy_collection
     )
 
+    # Mock legacy collection info with 1536d vectors
+    legacy_collection_info = MagicMock()
+    legacy_collection_info.payload_schema = {}
+    legacy_collection_info.config.params.vectors.size = 1536
+    mock_qdrant_client.get_collection.return_value = legacy_collection_info
+
     # Mock legacy data
     mock_qdrant_client.count.return_value.count = 150