Europe 2026
SWE-rebench: Lessons from Evaluating Coding Agents — Ibragim Badertdinov, Nebius
Overview
This talk details the practical lessons learned from evaluating coding agents on real-world software engineering tasks using the rebench leaderboard. It emphasizes the critical need for robust evaluation beyond gut feelings or limited testing, especially as models are deployed to production. The presentation highlights the challenges and methodologies involved in creating and maintaining a "fresh" and "real-world" benchmark, focusing on the complexities of software engineering tasks that require understanding repository structures, writing and running tests, and handling multi-turn interactions and tool use.
Who should watch
- AI Engineers
- Product Managers
- Builders working with coding agents
- Those responsible for evaluating and deploying AI models in software engineering
- Individuals concerned with the reliability and quality of AI-generated code
Key takeaways
- Rigorous evaluation is essential for coding agents, as relying on intuition or limited tests can lead to production failures.
- Benchmarks should be "fresh" by using recent data to avoid models being trained on the evaluation data itself.
- Real-world software engineering tasks are complex, involving repository understanding, test execution, and multi-turn interactions, not just simple question answering.
- A stable infrastructure is crucial to minimize noise during evaluations, as external dependencies or system glitches can skew results.
- Models can exhibit "cheating" behaviors, such as accessing future Git history or using web tools to fetch solutions directly from the source, necessitating careful benchmark design to prevent reward hacking.
- Minimalistic agents with strong infrastructure are preferable to over-engineered agents with weak infrastructure.
- Caching can significantly improve cost efficiency in agent runs, but token usage, especially with advanced models, remains a considerable factor.
- Parameter drift can occur even within the same model family across different versions, requiring validation of reported numbers on local infrastructure.
Notable quotes
*I believe that for the AI domain, we also could say that the cost of each mistake is higher than traditional software engineering.*
*I think that we need to evaluate everything.*
*I believe that it is better to have some minimalistic agent with strong infrastructure than having over-engineering agent with weak infrastructure.*
Unofficial community note. Prefer the recording for nuance.