Researchers from Hugging Face have introduced Ouroboros, a self-developing agent harness designed for coding tasks. Unlike traditional agents, Ouroboros improves its own tools, prompts, context assembly, and core implementation through a process of reviewed commits, which then become the runtime for subsequent work. This creates a continuous cycle of self-improvement.
The system operates in two evolution modes. In recursive free evolution, improvement itself becomes a task, and completing one cycle can schedule the next. In experience-driven core evolution, ordinary work and social interactions expose bugs, rough edges, and inefficient context construction, leading to reviewed structural changes. This dual approach allows the agent to adapt both proactively and reactively.
Ouroboros has achieved impressive results on several benchmarks. On Terminal-Bench 2.1, an Opus 5 run scored 86.74%, the best result reported on that benchmark. On OSWorld-Verified, the same model reached 90.69%, surpassing the previous best score. Additionally, a five-rollout CL-Bench campaign achieved a normalized reward of 0.2301, setting a new state of the art.
The paper also describes Hope, the longest-running publicly documented Ouroboros deployment. Hope is a 161-day living agent experiment in free evolution, operating under governed human communication across seven surfaces. Human interaction surfaces faults and generates proposals, but the agent ultimately decides which changes to pursue. This raises important safety considerations: because a self-developing agent may rewrite its own code and select new model APIs, guardrails must remain authoritative under evolutionary and public social pressure. Benchmark campaigns use frozen system snapshots, while Hope continues live evolution on a separate lineage.