A curated, verified, cross-vendor directory of AI agent harnesses — the runtime scaffolding that turns a model into an agent.
◆ 74 harnesses profiled · 9-axis capability schema · last verified 2026-07-08
High-performance Rust editor (GPL, hit 1.0 in 2026) whose Agent Panel offers a native agent with profiles/tool-permissions and MCP, but whose real differentiator is the open Agent Client Protocol (ACP) that lets external agents (Claude Code, Codex CLI, Gemini CLI, OpenCode — which bring their own skills support) render diffs natively in-editor, plus first-in-class native Parallel Agents (April 2026).
Copilot's agent mode inside VS Code (extension itself MIT open-sourced; backend service proprietary) iterates on errors, runs tools/terminal, and applies multi-file edits, distinguished by deep GitHub-ecosystem reach: MCP support, SKILL.md Agent Skills (added April 2026), custom .agent.md agents, a multi-vendor model picker with Ollama BYOK, and a cloud 'coding agent' that works issues into PRs on GitHub Actions.