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/rag/chromadb/test_utils.py

@@ -0,0 +1,95 @@
+"""Tests for ChromaDB utility functions."""
+
+from crewai.rag.chromadb.utils import (
+    MAX_COLLECTION_LENGTH,
+    MIN_COLLECTION_LENGTH,
+    _is_ipv4_pattern,
+    _sanitize_collection_name,
+)
+
+
+class TestChromaDBUtils:
+    """Test suite for ChromaDB utility functions."""
+
+    def test_sanitize_collection_name_long_name(self) -> None:
+        """Test sanitizing a very long collection name."""
+        long_name = "This is an extremely long role name that will definitely exceed the ChromaDB collection name limit of 63 characters and cause an error when used as a collection name"
+        sanitized = _sanitize_collection_name(long_name)
+        assert len(sanitized) <= MAX_COLLECTION_LENGTH
+        assert sanitized[0].isalnum()
+        assert sanitized[-1].isalnum()
+        assert all(c.isalnum() or c in ["_", "-"] for c in sanitized)
+
+    def test_sanitize_collection_name_special_chars(self) -> None:
+        """Test sanitizing a name with special characters."""
+        special_chars = "Agent@123!#$%^&*()"
+        sanitized = _sanitize_collection_name(special_chars)
+        assert sanitized[0].isalnum()
+        assert sanitized[-1].isalnum()
+        assert all(c.isalnum() or c in ["_", "-"] for c in sanitized)
+
+    def test_sanitize_collection_name_short_name(self) -> None:
+        """Test sanitizing a very short name."""
+        short_name = "A"
+        sanitized = _sanitize_collection_name(short_name)
+        assert len(sanitized) >= MIN_COLLECTION_LENGTH
+        assert sanitized[0].isalnum()
+        assert sanitized[-1].isalnum()
+
+    def test_sanitize_collection_name_bad_ends(self) -> None:
+        """Test sanitizing a name with non-alphanumeric start/end."""
+        bad_ends = "_Agent_"
+        sanitized = _sanitize_collection_name(bad_ends)
+        assert sanitized[0].isalnum()
+        assert sanitized[-1].isalnum()
+
+    def test_sanitize_collection_name_none(self) -> None:
+        """Test sanitizing a None value."""
+        sanitized = _sanitize_collection_name(None)
+        assert sanitized == "default_collection"
+
+    def test_sanitize_collection_name_ipv4_pattern(self) -> None:
+        """Test sanitizing an IPv4 address."""
+        ipv4 = "192.168.1.1"
+        sanitized = _sanitize_collection_name(ipv4)
+        assert sanitized.startswith("ip_")
+        assert sanitized[0].isalnum()
+        assert sanitized[-1].isalnum()
+        assert all(c.isalnum() or c in ["_", "-"] for c in sanitized)
+
+    def test_is_ipv4_pattern(self) -> None:
+        """Test IPv4 pattern detection."""
+        assert _is_ipv4_pattern("192.168.1.1") is True
+        assert _is_ipv4_pattern("not.an.ip.address") is False
+
+    def test_sanitize_collection_name_properties(self) -> None:
+        """Test that sanitized collection names always meet ChromaDB requirements."""
+        test_cases: list[str] = [
+            "A" * 100,  # Very long name
+            "_start_with_underscore",
+            "end_with_underscore_",
+            "contains@special#characters",
+            "192.168.1.1",  # IPv4 address
+            "a" * 2,  # Too short
+        ]
+        for test_case in test_cases:
+            sanitized = _sanitize_collection_name(test_case)
+            assert len(sanitized) >= MIN_COLLECTION_LENGTH
+            assert len(sanitized) <= MAX_COLLECTION_LENGTH
+            assert sanitized[0].isalnum()
+            assert sanitized[-1].isalnum()
+
+    def test_sanitize_collection_name_empty_string(self) -> None:
+        """Test sanitizing an empty string."""
+        sanitized = _sanitize_collection_name("")
+        assert sanitized == "default_collection"
+
+    def test_sanitize_collection_name_whitespace_only(self) -> None:
+        """Test sanitizing a string with only whitespace."""
+        sanitized = _sanitize_collection_name("   ")
+        assert (
+            sanitized == "a__z"
+        )  # Spaces become underscores, padded to meet requirements
+        assert len(sanitized) >= MIN_COLLECTION_LENGTH
+        assert sanitized[0].isalnum()
+        assert sanitized[-1].isalnum()