Long-horizon reasoning exposes a core weakness in AI agents: context windows fill up fast, and retrieval pipelines return noise instead of signal. To solve this, researchers at the National University of Singapore developed MRAgent, a framework that abandons the static “retrieve-then-reason” approach. Instead, it uses a mechanism that allows an agent to dynamically develop its memory based on accumulating evidence.  This multi-step memory reconstruction is integrated into the reasoning process of the large language model (LLM). While not the only framework in this space, MRAgent significantly reduces token consumption and runtime costs compared to other agentic memory management approaches. The limits of passive retrieval in long-horizon tasks In classic retrieval pipelines, documents are retrieved through vector search or graph traversal and passed on to an LLM for reasoning. This passive approach fails because it cannot combine reasoning with memory access, creating three major bottlenecks: These systems cannot revise their retrieval strategy mid-reasoning. If an agent fetches a document and discovers a crucial missing cue — a specific date or person — it has no way …