refactor: unify rag storage with instance-specific client support (#3455)

- ignore line length errors globally
- migrate knowledge/memory and crew query_knowledge to `SearchResult`
- remove legacy chromadb utils; fix empty metadata handling
- restore openai as default embedding provider; support instance-specific clients
- update and fix tests for `SearchResult` migration and rag changes

tests/knowledge/test_knowledge_searchresult.py

@@ -0,0 +1,191 @@
+"""Tests for Knowledge SearchResult type conversion and integration."""
+
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from crewai.knowledge.knowledge import Knowledge  # type: ignore[import-untyped]
+from crewai.knowledge.source.string_knowledge_source import (  # type: ignore[import-untyped]
+    StringKnowledgeSource,
+)
+from crewai.knowledge.utils.knowledge_utils import (  # type: ignore[import-untyped]
+    extract_knowledge_context,
+)
+
+
+def test_knowledge_query_returns_searchresult() -> None:
+    """Test that Knowledge.query returns SearchResult format."""
+    with patch("crewai.knowledge.knowledge.KnowledgeStorage") as mock_storage_class:
+        mock_storage = MagicMock()
+        mock_storage_class.return_value = mock_storage
+        mock_storage.search.return_value = [
+            {
+                "content": "AI is fascinating",
+                "score": 0.9,
+                "metadata": {"source": "doc1"},
+            },
+            {
+                "content": "Machine learning rocks",
+                "score": 0.8,
+                "metadata": {"source": "doc2"},
+            },
+        ]
+
+        sources = [StringKnowledgeSource(content="Test knowledge content")]
+        knowledge = Knowledge(collection_name="test_collection", sources=sources)
+
+        results = knowledge.query(
+            ["AI technology"], results_limit=5, score_threshold=0.3
+        )
+
+        mock_storage.search.assert_called_once_with(
+            ["AI technology"], limit=5, score_threshold=0.3
+        )
+
+        assert isinstance(results, list)
+        assert len(results) == 2
+
+        for result in results:
+            assert isinstance(result, dict)
+            assert "content" in result
+            assert "score" in result
+            assert "metadata" in result
+
+        assert results[0]["content"] == "AI is fascinating"
+        assert results[0]["score"] == 0.9
+        assert results[1]["content"] == "Machine learning rocks"
+        assert results[1]["score"] == 0.8
+
+
+def test_knowledge_query_with_empty_results() -> None:
+    """Test Knowledge.query with empty search results."""
+    with patch("crewai.knowledge.knowledge.KnowledgeStorage") as mock_storage_class:
+        mock_storage = MagicMock()
+        mock_storage_class.return_value = mock_storage
+        mock_storage.search.return_value = []
+
+        sources = [StringKnowledgeSource(content="Test content")]
+        knowledge = Knowledge(collection_name="empty_test", sources=sources)
+
+        results = knowledge.query(["nonexistent query"])
+
+        assert isinstance(results, list)
+        assert len(results) == 0
+
+
+def test_extract_knowledge_context_with_searchresult() -> None:
+    """Test extract_knowledge_context works with SearchResult format."""
+    search_results = [
+        {"content": "Python is great for AI", "score": 0.95, "metadata": {}},
+        {"content": "Machine learning algorithms", "score": 0.88, "metadata": {}},
+        {"content": "Deep learning frameworks", "score": 0.82, "metadata": {}},
+    ]
+
+    context = extract_knowledge_context(search_results)
+
+    assert "Additional Information:" in context
+    assert "Python is great for AI" in context
+    assert "Machine learning algorithms" in context
+    assert "Deep learning frameworks" in context
+
+    expected_content = (
+        "Python is great for AI\nMachine learning algorithms\nDeep learning frameworks"
+    )
+    assert expected_content in context
+
+
+def test_extract_knowledge_context_with_empty_content() -> None:
+    """Test extract_knowledge_context handles empty or invalid content."""
+    search_results = [
+        {"content": "", "score": 0.5, "metadata": {}},
+        {"content": None, "score": 0.4, "metadata": {}},
+        {"score": 0.3, "metadata": {}},
+    ]
+
+    context = extract_knowledge_context(search_results)
+
+    assert context == ""
+
+
+def test_extract_knowledge_context_filters_invalid_results() -> None:
+    """Test that extract_knowledge_context filters out invalid results."""
+    search_results: list[dict[str, Any] | None] = [
+        {"content": "Valid content 1", "score": 0.9, "metadata": {}},
+        {"content": "", "score": 0.8, "metadata": {}},
+        {"content": "Valid content 2", "score": 0.7, "metadata": {}},
+        None,
+        {"content": None, "score": 0.6, "metadata": {}},
+    ]
+
+    context = extract_knowledge_context(search_results)
+
+    assert "Additional Information:" in context
+    assert "Valid content 1" in context
+    assert "Valid content 2" in context
+    assert context.count("\n") == 1
+
+
+@patch("crewai.rag.config.utils.get_rag_client")
+@patch("crewai.knowledge.storage.knowledge_storage.KnowledgeStorage")
+def test_knowledge_storage_exception_handling(
+    mock_storage_class: MagicMock, mock_get_client: MagicMock
+) -> None:
+    """Test Knowledge handles storage exceptions gracefully."""
+    mock_storage = MagicMock()
+    mock_storage_class.return_value = mock_storage
+    mock_storage.search.side_effect = Exception("Storage error")
+
+    sources = [StringKnowledgeSource(content="Test content")]
+    knowledge = Knowledge(collection_name="error_test", sources=sources)
+
+    with pytest.raises(ValueError, match="Storage is not initialized"):
+        knowledge.storage = None
+        knowledge.query(["test query"])
+
+
+def test_knowledge_add_sources_integration() -> None:
+    """Test Knowledge.add_sources integrates properly with storage."""
+    with patch("crewai.knowledge.knowledge.KnowledgeStorage") as mock_storage_class:
+        mock_storage = MagicMock()
+        mock_storage_class.return_value = mock_storage
+
+        sources = [
+            StringKnowledgeSource(content="Content 1"),
+            StringKnowledgeSource(content="Content 2"),
+        ]
+        knowledge = Knowledge(collection_name="add_sources_test", sources=sources)
+
+        knowledge.add_sources()
+
+        for source in sources:
+            assert source.storage == mock_storage
+
+
+def test_knowledge_reset_integration() -> None:
+    """Test Knowledge.reset integrates with storage."""
+    with patch("crewai.knowledge.knowledge.KnowledgeStorage") as mock_storage_class:
+        mock_storage = MagicMock()
+        mock_storage_class.return_value = mock_storage
+
+        sources = [StringKnowledgeSource(content="Test content")]
+        knowledge = Knowledge(collection_name="reset_test", sources=sources)
+
+        knowledge.reset()
+
+        mock_storage.reset.assert_called_once()
+
+
+@patch("crewai.rag.config.utils.get_rag_client")
+@patch("crewai.knowledge.storage.knowledge_storage.KnowledgeStorage")
+def test_knowledge_reset_without_storage(
+    mock_storage_class: MagicMock, mock_get_client: MagicMock
+) -> None:
+    """Test Knowledge.reset raises error when storage is None."""
+    sources = [StringKnowledgeSource(content="Test content")]
+    knowledge = Knowledge(collection_name="no_storage_test", sources=sources)
+
+    knowledge.storage = None
+
+    with pytest.raises(ValueError, match="Storage is not initialized"):
+        knowledge.reset()