During March 2025, Max Tu developed principled Alternative-based monad support for the leanprover-community/batteries repository, focusing on formalizing the semantics of failure and orElse within monads equipped with Alternative. Leveraging Lean and advanced functional programming concepts, Max introduced the AlternativeMonad and LawfulAlternative classes to rigorously define these behaviors, ensuring correctness and predictability in alternative-based composition. He provided robust instances for Option, OptionT, StateT, ReaderT, and StateRefT', enabling safer optional and effectful computations across common monad transformer stacks. This work demonstrated depth in type theory and monad transformers, addressing correctness concerns in effectful Lean codebases.