From Issue to Reviewable Patch: Build a Sandboxed Coding Agent With Deep Agents and Automated Tests

A coding agent becomes useful to an engineering team only when its output is more than plausible source code. The real unit of work is a reviewable patch: a small, inspectable diff tied to an issue, accompanied by a regression test, validated in an isolated environment, and rejected automatically when deterministic checks fail. Deep Agents fits this workflow because its agent harness exposes filesystem operations and subagent delegation, while a sandbox backend adds shell execution without giving the model direct access to the host filesystem.