EvoFSM: Controllable Self-Evolution for Deep Research with Finite State Machines
Authors: name: Shuo Zhang, name: Chaofa Yuan, name: Ryan Guo, name: Xiaomin Yu, name: Rui Xu, name: Zhangquan Chen, name: Zinuo Li, name: Zhi Yang, name: Shuhao Guan, name: Zhenheng Tang, name: Sen Hu, name: Liwen Zhang, name: Ronghao Chen, name: Huacan Wang
Organization: QuantaAlpha

While LLM-based agents have shown promise for deep research, most existing approaches rely on fixed workflows that struggle to adapt to real-world, open-ended queries. Recent work therefore explores self-evolution by allowing agents to rewrite their own code or prompts to improve problem-solving ability, but unconstrained optimization often triggers instability, hallucinations, and instruction drift. We propose EvoFSM, a structured self-evolving framework that achieves both adaptability and control by evolving an explicit Finite State Machine (FSM) instead of relying on free-form rewriting. EvoFSM decouples the optimization space into macroscopic Flow (state-transition logic) and microscopic Skill (state-specific behaviors), enabling targeted improvements under clear behavioral boundaries. Guided by a critic mechanism, EvoFSM refines the FSM through a small set of constrained operations, and further incorporates a self-evolving memory that distills successful trajectories as reusable priors and failure patterns as constraints for future queries. Extensive evaluations on five multi-hop QA benchmarks demonstrate the effectiveness of EvoFSM. In particular, EvoFSM reaches 58.0% accuracy on the DeepSearch benchmark. Additional results on interactive decision-making tasks further validate its generalization.