chore(llm.py): remove unused merge_chat_history function to clean up codebase

chore(test_fallback_handler.py): remove references to the removed merge_chat_history function in tests to maintain consistency

ra_aid/llm.py

@@ -322,22 +322,3 @@ def validate_provider_env(provider: str) -> bool:
     if key:
         return bool(os.getenv(key))
     return False
-
-
-def merge_chat_history(
-    original_history: List[BaseMessage], fallback_history: List[BaseMessage]
-) -> List[BaseMessage]:
-    """Merge original and fallback chat histories while preserving order.
-
-    Args:
-        original_history: The original chat message history
-        fallback_history: Additional messages from fallback attempts
-
-    Returns:
-        List[BaseMessage]: Combined message history preserving chronological order
-
-    Note:
-        The function appends fallback messages to maintain context for future
-        interactions while preserving the original conversation flow.
-    """
-    return original_history + fallback_history

tests/ra_aid/test_fallback_handler.py

@@ -60,19 +60,14 @@ class TestFallbackHandler(unittest.TestCase):
 
             return DummyModel()
 
-        def dummy_merge_chat_history():
-            return ["merged"]
-
         def dummy_validate_provider_env(provider):
             return True
 
         import ra_aid.llm as llm
 
         original_initialize = llm.initialize_llm
-        original_merge = llm.merge_chat_history
         original_validate = llm.validate_provider_env
         llm.initialize_llm = dummy_initialize_llm
-        llm.merge_chat_history = dummy_merge_chat_history
         llm.validate_provider_env = dummy_validate_provider_env
 
         self.fallback_handler.tool_failure_consecutive_failures = 2
@@ -81,7 +76,6 @@ class TestFallbackHandler(unittest.TestCase):
         self.assertEqual(self.fallback_handler.tool_failure_consecutive_failures, 0)
 
         llm.initialize_llm = original_initialize
-        llm.merge_chat_history = original_merge
         llm.validate_provider_env = original_validate
 
     def test_load_fallback_tool_models(self):