Composing Experience Across Tasks: Hierarchical Process Experience Memory for Interactive Agents

Interactive agents repeatedly face tasks that share reusable subprocesses, but memories based on complete trajectories, task-specific reflections, or standalone routines do not always preserve how subprocesses combine or whether locally plausible guidance helps the final task. We introduce Hierarchical Process Experience Memory (HPEM), an external plug-in memory that organizes task-parameter-independent experience into leaf processes and composed workflows. Each node records an objective, interaction stage, subgoals, applicability and failure boundaries, evidence, maturity, and ordered child relations. HPEM learns process abstractions from successful interactions, composes compatible experience into higher-level workflows, and updates node reliability using both local feedback and downstream task outcomes. At inference time, HPEM retrieves a relevant leaf process or composed workflow as optional guidance; the host agent retains full control of reasoning and environment actions. Memory is frozen before evaluation to separate experience acquisition from cross-task reuse. Extensive experiments show gains in task success and interaction efficiency in multiple settings with official host agents, while frozen evaluations confirm retrieval of learned high-level workflows.