Reason Machines is shipping a desktop app for engineers who want named AI teammates running coding work beside their own files. In the app, a Reason is a teammate with its own instructions, and a session is the run where that teammate takes a task through a repository and returns changes you can review. The desktop build is available for macOS and Linux, and the same sessions also open on the web and in the CLI, including on Windows. The launch is aimed at people already paying for ChatGPT, Claude, GitHub Copilot, Grok, or their own API keys, whose plans hit usage caps mid-task. You connect those accounts in the app, and when one limit is hit the work rolls to the next connected account instead of stopping. Reason Machines builds the harness that decides how a model inspects a repository, edits files, and runs tests, and on its Y Combinator page it reports the same performance as Codex at 22% lower cost. Cofounders Adi Singh and Sven Myhre, both EECS graduates of UC Berkeley, are a two-person team in San Francisco. On the desktop, a session can use a local checkout, installed tools, and development ports when you grant access, and the same conversation remains available on the web if you leave the machine.