Copilot Cowork engineers share lessons from agent-assisted development and a live Rust migration
Microsoft’s Copilot Cowork engineering team published six practices for agent-assisted software development with explicit human control.
The account describes written specifications, narrowly scoped agents, checks that are deliberately tested for failure, repository-based engineering rules, modular code and bounded automated improvement loops.
The team reports merging 1,211 pull requests on October 21 while retaining human review for critical changes and production deployment decisions. A Python-to-Rust runtime migration used recorded behavior fixtures and reversible cluster-by-cluster rollout.
The article details both improvements and failures, including unrecorded event-ordering behavior; its pull-request volume describes this team’s experience.
Partner briefing
- What it is
An engineering account of Copilot Cowork development and its live Python-to-Rust migration.
- What’s changing
Documents six development practices and behavior-fixture testing with staged, reversible traffic migration.
- Why it matters
Explains the testing and human decision boundaries used as agent-generated changes increased.
- Who it affects
Engineering teams building agentic products and running agent-assisted development workflows.