Stanford CS / AI systems / LLM agents / infrastructure

Tianyi (Tim) Chen

I am a Master's student in Computer Science at Stanford University, focusing on AI and systems, with recent work across LLM agents, backend infrastructure, and scalable framework design.

About

Systems instincts, AI focus.

I am a Master's student in Computer Science at Stanford University, focusing on AI and systems. My recent industry experience includes a backend engineering internship at Stripe, and I will be returning to Stripe's Risk Capabilities group as a full-time engineer. On the research side, I co-develop ReCAP, a recursive reasoning and planning framework for large language models.

During my undergraduate studies in Game Design and Computer Science at NYU, I founded Kromo Games, a student-led studio where I led the development of Mikrocosmos, a multiplayer game with over 25,000 downloads on Steam. To support its growth, I built MikroFramework, a modular game framework inspired by MVC principles that emphasized scalability and extensibility. This early experience in systems and framework design continues to influence how I approach engineering challenges today.

I am motivated by problems at the intersection of systems and intelligent systems, and I enjoy building infrastructure and platforms that enable breakthroughs in AI and data-driven applications.

Selected work

Recent research, infrastructure, and shipped software.

Research / LLM Agents
ReCAP recursive planning diagram showing task, plan, copied blocks, observations, context injection, and a sliding context window across recursion depths.
ReCAP local reasoning subtree diagram showing a current task, just-finished subtask, first remaining subtask, injected old reasoning, new reasoning, and refined subtasks.

ReCAP: Recursive Context-Aware Reasoning and Planning for Large Language Model Agents

Zhenyu Zhang, Tianyi Chen, Weiran Xu, Alex Pentland, Jiaxin Pei

Co-developed a hierarchical framework for long-horizon LLM agents that plans ahead, executes the first subtask, recursively decomposes composite work, and re-injects the parent plan on return to keep multi-level context coherent.

  • Combines plan-ahead decomposition, structured parent-plan re-injection, and bounded active prompts.
  • Evaluated under strict pass@1 on Robotouille, ALFWorld, FEVER, and SWE-bench.
Infrastructure / Stripe

Rules infrastructure performance

Optimized a core database interaction by adding a pre-check that reduced daily write transactions by over 85%, then drove a synchronous execution refactor that increased throughput under load.

Write-path optimization / execution architecture / production-safe rollout

Mikrocosmos Steam capsule artwork
Earlier systems / game tech

Mikrocosmos

Led a 6-person team building an online multiplayer strategy-action game with Unity, Mirror networking, PlayFab/Azure backend services, and hot-update driven content systems.

Research

Planning, graphs, and grounded models.

My research work sits near the boundary between model capability and the systems that make those capabilities usable in longer tasks.

2025

ReCAP: Recursive Context-Aware Reasoning and Planning for Large Language Model Agents

Zhenyu Zhang, Tianyi Chen, Weiran Xu, Alex Pentland, Jiaxin Pei

Designed core inference architecture for recursive, context-aware agent execution: plan-ahead decomposition, structured parent-plan re-injection during backtracking, bounded context management, and benchmark evaluation across embodied, fact-checking, and coding tasks.

2024

Water Quality Analysis and Prediction in Unmonitored Networks with RGCNs

Built a Transformer-enhanced relational graph convolutional model to capture temporal and spatial dependencies in unmonitored water networks, improving over GCN and RGCN baselines.

PyTorch PyG Graph ML
2023-24

Cataract surgery simulator

Developed a Unity-based haptic simulator with surgical-step replication, educational tools, and 3D Systems Touch device integration; awarded NYU Dean's Undergraduate Research Fund.

Unity Haptics Simulation

Experience

Research depth, production pressure, shipped software.

Sep 2025 - Present

Stanford University Computer Science Department

Course Assistant for CS224W and CS246 / Research Assistant

Core contributor to large-scale graph ML and data mining courses under Prof. Jure Leskovec, including assignments, exams, office hours, and course design, while researching LLM-based reasoning systems with Jiaxin Pei and Alex Pentland.

Jun 2025 - Sep 2025

Stripe

Returning Full-time Engineer, Risk Capabilities / Engineer Intern, Rules Infrastructure

Returning to Stripe's Risk Capabilities group full time after reducing database write load, simplifying execution architecture, and validating production changes with feature flags and monitoring during the internship.

Jun 2023 - Sep 2023

Johnson & Johnson

Backend Development Intern

Built logistics prediction systems and improved a complex table query/pagination flow by 60% using TypeScript, NestJS, SQL Server, and TypeORM.

Mar 2022 - May 2024

Kromo Games

Co-founder, Lead Game Developer

Led a small team shipping Mikrocosmos, integrating multiplayer networking, PlayFab/Azure services, rapid feedback cycles, and extensible game systems.

Project archive

Selected research, infrastructure, and shipped projects.

AI Research

ReCAP: Recursive Context-Aware Reasoning and Planning for Large Language Model Agents

NeurIPS 2025 framework for recursive planning, bounded context management, and parent-plan re-injection in long-horizon LLM agents.

Unity Framework

MikroFramework

MVC-oriented Unity framework with event systems, code generation, IOC, pools, hot-update, and resource management.

GitHub
Steam Game

Mikrocosmos

Multiplayer trading-and-combat party game with networking and backend service integration.

Steam
NYU Capstone / itch.io Game

To Oasis

Earlier indie game project published on itch.io, part of the undergraduate game-development period that led into systems tooling work.

itch.io
Undergraduate Archive

Game Projects Archive

Legacy collection from my earlier personal site, covering game-design projects and prototypes from my NYU period.

Old game projects page

Toolkit

What I reach for.

Programming Languages

Python, C++, C#, TypeScript, JavaScript, Java, SQL

AI & Data

PyTorch, PyG, Triton, Hugging Face Transformers, scikit-learn, Pandas, NumPy, NetworkX, OpenCV

Backend & Infra

Node.js, NestJS, SQL Server, Spark, Kafka, Docker, AWS, GCP, Azure, Grafana, Splunk, CI/CD

Game & Simulation

Unity, Mirror, PlayFab, MVC architecture, hot-update systems, shaders, haptics

Contact

Open to research conversations, systems work, and ambitious technical projects.