Hypotree revolutionizes agent memory by transforming passive fact accumulation into an active, self-revising belief system. It structures an agent's working knowledge as a persistent, directed acyclic graph (DAG) of hypotheses, backed by SQLite-WAL. Unlike traditional memory stores, Hypotree intelligently propagates evidence failures upstream, retracting dependent beliefs and automatically pruning entire subtrees when a premise collapses. This "memory that forgets" capability prevents agents from wasting tokens on dead ends and enables sophisticated inferential processes, making it an indispensable tool for efficient, long-running agentic R&D.