Composer 2 Technical Report Targets Long-Horizon Agentic Coding Workflows

A new paper on arXiv is putting software engineering agents in the center of model design. The Composer 2 Technical Report says the model is built for long-horizon coding work, not just short interactive prompts.

The paper was published on March 25, 2026 and updated on March 26, 2026 as version 2. It describes a two-phase training recipe: continued pretraining first, then large-scale reinforcement learning to improve end-to-end coding behavior.

One detail worth tracking is the evaluation setup. The report says the team trained and evaluated in a harness aligned with real software engineering tool use, and introduced a benchmark based on real-world coding problems with increasing difficulty.

If you are comparing coding models for production workflows, this publication is useful because it emphasizes execution quality over single-turn answer quality. That distinction often decides whether an agent helps or stalls inside a real repository.

Read the technical report on arXiv here. Internal reading: Research topic page and Developer Tools topic page.