Y Combinator Open-Sources QM, the AI Agent Harness It Uses to Run Itself

Y Combinator announced Friday it has open-sourced QM, the internal agent harness the accelerator uses to manage fleets of AI agents across Slack and the web. The repository is live under the yc-software organization on GitHub and is licensed under MIT, allowing commercial use and modification without a waitlist. The GitHub README describes QM as a multiplayer agent harness designed for work environments. It provides each person and room with scoped memory, files, a keychain view, permissions, crons, web apps, and a durable sandbox. YC said it previously ran more than 50 Hermes agents for individual employees but found managing that fleet difficult, prompting the development of QM, short for quartermaster. The core runs on TypeScript with Node and Fastify, stores session history and memory in Postgres, and offers Slack as an optional in-process plugin. YC said it did not tie QM to a single model; the README notes that Pi, OpenCode, Codex, and Claude Code can all drive the same core. The project page states YC wanted a system it could own and host itself with control over credentials, logs, permissions, and the cloud account. The security section says QM follows the pattern of local coding agents where the agent acts using the person's credentials while actions are audited. It offers security postures ranging from strict human approval to a mode labeled dangerous with no pauses between tool calls. The code is available at github.com/yc-software/qm.