Custom Copilot agents, IDE arenas, and terminal control planes
AI agent tooling for developers is maturing with customizable Copilot skills, IDE-based model comparisons, and terminal-first control planes, while new research warns multi-agent setups often hurt results. GitHub now documents how to tailor the Copilot CLI and coding agent with project-specific instructions, hooks, and skills, enabling targeted automation for repo chores, build/test flows, and shell tasks directly from your terminal or VS Code Insiders agent mode ([customize Copilot CLI](https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot), [create agent skills](https://docs.github.com/copilot/how-tos/use-copilot-agents/coding-agent/create-skills)). In parallel, IDE workflows are adding native model evaluation and task skills: Windsurf’s terminal and test-generation capabilities are backed by docs and guides, and its recent “Arena Mode” for side-by-side model comparisons surfaced in industry coverage ([terminal guide](https://docs.windsurf.ai/features/terminal), [AI command assistance](https://docs.windsurf.ai/cascade/terminal), [test generation](https://docs.windsurf.ai/features/test-generation), [InfoQ LLMs page](https://www.infoq.com/llms/news/)). Agent orchestration is shifting to the command line as well: Cline CLI 2.0 positions the terminal as an AI agent control plane for multi-file refactors and scripted operations ([DevOps.com](https://devops.com/cline-cli-2-0-turns-your-terminal-into-an-ai-agent-control-plane/)). But a new Google Research study summarized by InfoQ reports that scaling to multiple cooperating agents does not reliably improve outcomes and can reduce performance, so start with single-agent flows and measure before adding complexity ([InfoQ LLMs page](https://www.infoq.com/llms/news/)). Early experiments like xAI’s Grok Build with parallel agents and arena-style evaluation point to where this is heading, but details remain in flux ([TestingCatalog](https://www.testingcatalog.com/xai-tests-parralel-agents-and-arena-mode-for-grok-build/)).