Metaview says all of its agents now run on one shared harness, and a new agent takes under two hours to stand up

Metaview builds recruiting agents. Mond writes that its earliest agent ran on AWS Step Functions and later ones used LangGraph, the OpenAI Responses API and hand-rolled loops. They now share one harness built after Ramp's Inspect background agent: a Cloudflare Durable Object per session for state and streaming, a Modal Sandbox running OpenCode as the loop, and a broker on AWS Lambda that holds the credentials. The sandbox holds none, and the agent calls the broker with a short-lived session token. Mond says a new agent is now a prompt, some skills and a small config, down from several days to under two hours.

Two choices cut against common advice. The agent loop runs inside the sandbox, which Mond says goes against the popular approach of keeping the loop outside, and most tools ship as scripts the agent can chain and edit. Metaview also decided against a hosted agent platform, citing lock-in to one lab's models and limits on customizing the loop; the model is a config value, and the post names a one-line switch between Opus 5.5 and GPT-6.1 Sol. Evals judge outputs only: an orchestration agent drives real sessions, and one Sourcing prompt change was checked against over 1,000 real requests.

Why it matters: This is a worked answer to where credentials live when the loop runs next to the code it executes: in a broker, not the sandbox. It is a company's description of its own system. The post gives no public code and no measured results beyond setup time and the request count above.