MEMENTO: Leveraging Web as a Learning Signal for Low-Data Domains

Real-world tasks often lack large labeled datasets, motivating extensive work on learning in low-data regimes. Existing approaches such as few-shot prompting, instruction tuning, and synthetic data generation, continue to treat labeled or pseudo-labeled data as the primary learning signal. In contrast, human practitioners acquire expertise through repeated, self-directed interaction with the open web, progressively refining both domain knowledge and search strategies. We propose MEMENTO, a framework that treats the web as a learning signal rather than a stateless retrieval interface. MEMENTO operates at two levels: within each session, it conducts iterative web exploration via an Adaptive Exploration Tree (AET) that decomposes tasks into evolving questions and reflects on intermediate findings; across sessions, it accumulates experience through dual-channel memory, separating declarative knowledge (facts) from procedural knowledge (search strategies). This design enables agents to learn reusable research strategies and domain expertise from trajectories of web interaction without additional model training. We evaluate MEMENTO on three structurally distinct low-data domains: Sales Automation, Legal Outcome Prediction, and Subpopulation Opinion Prediction. Our empirical results show consistent improvement in performance over ReAct baselines (+25.6% on sales, +36.5% on legal research, and 29.6% TVD reduction on opinion prediction), demonstrating that the web can serve as a scalable learning source for acquiring task-specific expertise in data-scarce settings.