About Experience Open Source Notes

Jicheng (Jeremy) Wang

Post-training and evaluation of LLM agents

Jicheng Wang

Training and evaluating LLM agents rest on the same thing: a signal that says whether the agent did the task. The question I keep returning to is:

How can we train LLM agents on feedback we can verify, and know that their gains hold beyond the benchmark?

A flaw in how we measure an agent becomes a flaw in what it learns, so I treat evaluation and training as one problem: a score is worth trusting only if the evidence behind it can be checked, and a model is worth training only on signals that pass that test, during training and, as I am exploring now, at test time.

I was fortunate to be advised by Prof. Hao Chen (IEEE Fellow) in the Security Lab at UC Davis. My work there began with a narrower question: can a model learn from what its environment reports, such as the execution of its own code, rather than from labels? Once the model acts as an agent, the bottleneck moves to the signal itself: an agent can reach the right answer while ignoring what its tools told it, and a score can be gamed. The questions that followed are the ones I still work on: how can an evaluation check the evidence behind a result, not just the result? And once that evidence exists, how much more can it do than grade: can it repair an action that has been hijacked, choose among programs by executing them, and supervise a model on its own rollouts? As an undergraduate, I worked on natural language understanding with Prof. Min Peng at the Wuhan University AI Lab. I currently work at AWS SageMaker AI, where I build evaluation for LLM agents that fine-tune and deploy models.

I am always glad to talk about research and explore collaborations. Feel free to reach out by email or schedule a meeting.

ReviewerNeurIPS · ICML · ICLR · EMNLP · REALM

Selected Publications

* equal contribution

ContractBench: Can LLM Agents Preserve Observation Contracts?

Jicheng Wang, Yifeng He, Zili Wang, Hanwen Xing, Arkaprava De, Hao Chen

NeurIPS 2026

AgentECC: Repairing Hijacked Agent Actions Wherever the Environment Keeps a Witness

Jicheng Wang, Zili Wang, Cheng Lin, X. Ding, Jiachen Liu, Yifeng He, Hao Chen

Under review at ICLR 2027

ForkLeft: Entropy-First Rollouts for Prefix-Aligned Autoregressive-to-Diffusion Distillation

Junming Liu*, Jicheng Wang*, Yifeng He, Hao Chen, Jianzhong Qi

Under review at ICLR 2027

RepoGenReflex: Enhancing Repository-Level Code Completion with Verbal Reinforcement and Retrieval-Augmented Generation

Jicheng Wang, Yifeng He, Hao Chen

Dissertation · UC Davis, 2025

FuzzAug: Data Augmentation by Coverage-guided Fuzzing for Neural Test Generation

Yifeng He, Jicheng Wang, Yuyang Rong, Hao Chen

Findings of EMNLP 2025

The Greatness of Science Cannot Be Planned: Agentic Auto-Research is Fuzz Testing

Yifeng He, Jicheng Wang, Yinzhe Zhao, Chengyang Shi, Jiachen Liu, Hao Chen

NeurIPS 2026 Workshop

Is Progressive Disclosure All You Need for Long-Context Agents?

Yifeng He, Yinzhe Zhao, Jicheng Wang, Hao Chen

REALM @ EMNLP 2026

Code Generation by Differential Test Time Scaling

Yifeng He, Ethan Wang, Jicheng Wang, Xuanxin Ouyang, Hao Chen

Under review at TMLR

Open-Endedness Bench: Measuring Epistemic Process from Agent Records

C. Shi, X. Ji, J. Huang, Jicheng Wang, Yifeng He, Jiachen Liu

Under review at ICLR 2027

BenchShield: Formal Model-Backed Instrumentation for Reward Integrity in LLM-Agent Evaluation Infrastructure

Shenghan Zheng, Zonglin Di, …, Jicheng Wang, …, Dawn Song, Christophe Hauser

Under review at USENIX Security 2027

Full list on Google Scholar