Yangtian Zi
Author directory2026
AgentPack: A Dataset of Code Changes, Co-Authored by Agents and Humans
Yangtian Zi | Zixuan Wu | Aleksander Boruch-Gruszecki | Jonathan Bell | Arjun Guha
Findings of the Association for Computational Linguistics: EMNLP 2026
Yangtian Zi | Zixuan Wu | Aleksander Boruch-Gruszecki | Jonathan Bell | Arjun Guha
Findings of the Association for Computational Linguistics: EMNLP 2026
Fine-tuning large language models for code editing has typically relied on mining commits and pull requests. The working hypothesis has been that commit messages describe human intent in natural language, and patches to code describe the changes that implement that intent. However, much of the previously collected data is noisy: commit messages are terse, human-written commits commingle several unrelated edits, and many historical commits come from simple, rule-based bots.
The recent adoption of software engineering agents changes this landscape. Code changes co-authored by humans and agents are often accompanied by substantially more explicit natural-language descriptions of intent and rationale. Moreover, changes in public repositories may have passed through human selection and review, and we treat this potential human filtering as an indirect signal of data quality.
We present AgentPack, a corpus of 1.8M code edits co-authored by Claude Code, OpenAI Codex, and Cursor Agent across public GitHub projects up to early October 2025. We describe the identification and curation pipeline, quantify adoption trends of these agents, and analyze the structural properties of the edits. Finally, we show that models fine-tuned on AgentPack outperform models trained on prior human-only commit corpora, highlighting the potential of using public data from software engineering agents to train future code-editing models.
The recent adoption of software engineering agents changes this landscape. Code changes co-authored by humans and agents are often accompanied by substantially more explicit natural-language descriptions of intent and rationale. Moreover, changes in public repositories may have passed through human selection and review, and we treat this potential human filtering as an indirect signal of data quality.
We present AgentPack, a corpus of 1.8M code edits co-authored by Claude Code, OpenAI Codex, and Cursor Agent across public GitHub projects up to early October 2025. We describe the identification and curation pipeline, quantify adoption trends of these agents, and analyze the structural properties of the edits. Finally, we show that models fine-tuned on AgentPack outperform models trained on prior human-only commit corpora, highlighting the potential of using public data from software engineering agents to train future code-editing models.
2025
More Than a Score: Probing the Impact of Prompt Specificity on LLM Code Generation
Yangtian Zi | Harshitha Menon | Arjun Guha
Proceedings of the 14th International Joint Conference on Natural Language Processing and the 4th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics
Yangtian Zi | Harshitha Menon | Arjun Guha
Proceedings of the 14th International Joint Conference on Natural Language Processing and the 4th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics
State-of-the-art Large Language Models (LLMs) achieve high pass@1 on general benchmarks like HumanEval (Chen et al., 2021) but underperform on specialized suites such as ParEval (Nichols et al., 2024). Is this due to LLMs missing domain knowledge or insufficient prompt detail is given? To answer this, we introduce PartialOrderEval, which augments any code generation benchmark with a partial order of prompts from minimal to maximally detailed. Applying it to HumanEval and both serial and OpenMP subsets of ParEval, we measure how pass@1 scales with prompt specificity. Our experiments with Llama-3.x and Qwen2.5-Coder demonstrate varying degrees of prompt sensitivity across different tasks, and a qualitative analysis highlights explicit I/O specifications, edge-case handling, and stepwise breakdowns as the key drivers of prompt detail improvement.
2024
StudentEval: A Benchmark of Student-Written Prompts for Large Language Models of Code
Hannah McLean Babe | Sydney Nguyen | Yangtian Zi | Arjun Guha | Molly Q Feldman | Carolyn Jane Anderson
Findings of the Association for Computational Linguistics: ACL 2024
Hannah McLean Babe | Sydney Nguyen | Yangtian Zi | Arjun Guha | Molly Q Feldman | Carolyn Jane Anderson
Findings of the Association for Computational Linguistics: ACL 2024
Code LLMs have the potential to make it easier for non-experts to understand and write code. However, current CodeLLM benchmarks rely on a single expert-written prompt per problem, making it hard to generalize their success to non-expert users. In this paper, we present a new natural-language-to-code benchmark of prompts written by a key population of non-experts: beginning programmers. StudentEval contains 1,749 prompts written by 80 students who have only completed one introductory Python course. StudentEval contains numerous non-expert prompts describing the same problem, enabling exploration of key factors in prompt success. We use StudentEval to evaluate 12 Code LLMs and find that StudentEval is a better discriminator of model performance than existing benchmarks. Our analysis of student prompting strategies reveals that nondeterministic LLM sampling can mislead students about the quality of their descriptions, a finding with key implications for Code LLMs in education.