AI-agentic developer tools like Claude Code or GitHub Copilot CLI have emerged as a primary way to develop software over the last few months. However, agentic engineering has been a solo story so far - one developer with a dozen agents, moving forward at warp speed. But coding without thoughtful planning, understanding of the problems, and team alignment is just a waste of time and tokens. When everyone on a team is directing agents alone in their personal CLI tools with no shared context, you get duplicate work, conflicting changes, poorly-designed solutions, surprise features nobody else agreed to build, and everyone pulling in different directions.

At the same time, serious software development is a collaborative problem-solving - you need multiple perspectives, types of expertise and various backgrounds to build great things together. We need agentic environments that enable this, where people can plan together and share the same context with AI agents driven by the team, rather than by individual developers.

In this talk, I'll demo how we've addressed these design challenges in Ace, a multiplayer agent environment from GitHub Next that enables real-time collaboration, proactive agents, and sandboxed micro VMs for rapid prototyping and exploration, fostering a more engaging teamwork experience.