Pi
earendil-works/pi
A minimal, steerable coding agent and toolkit.
Pi is a deliberately small agent toolkit — unified LLM API, agent loop, TUI and a coding-agent CLI — designed to be easy to reason about and extend. It runs across a dozen-plus providers in four modes (interactive, JSON, RPC, SDK) and became the reference 'minimal harness' that enterprises inspect and fork.
In the news
Best of Agent Harnesses tracks 167 harnesses — and their graveyard
The Best of Agent Harnesses list ranks 167 agent harnesses weekly by capability, autonomy and recovery, ships an MCP server so agents can pick their own harness, and maintains a graveyard that flagged a 268k-star repo for suspected star manipulation. Curation itself becomes harness infrastructure.
HarnessTax: harness choice swings agent cost more than model choice
Arena.ai's HarnessTax study tests 21 model–harness combinations across Claude Code, Codex CLI and Pi, finding harness choice can significantly change cost even at similar task success rates. Weeks earlier, SWE-bench Pro analysis showed swapping harnesses moved pass@1 more than model upgrades (23%→52% on GLM-5.2) — and that harness rankings barely transfer across models.
Anthropic blocks third-party use of Claude Code subscriptions
Anthropic began enforcing its terms against third-party clients using Claude Code subscriptions, forcing alternative harnesses like opencode to rework authentication (its issue thread became the debate's ground zero). A defining platform-risk moment for the open-harness ecosystem: the model provider owns the login, the harness does not.
Anthropic moves MCP toward open foundation governance
Anthropic announces plans to donate MCP to a neutral foundation, with new registry, auth and sandbox specs — cementing MCP as vendor-neutral infrastructure for the entire agent ecosystem.
Related projects
OpenClaw
openclaw/openclaw
The viral open-source personal AI assistant that really does things.
OpenClaw (born as Clawdbot in late 2025) is a self-hosted personal agent that connects your chats, email, browser and terminal into one always-on assistant. Its explosive growth — hundreds of thousands of stars within months — made 'personal agent harness' a mainstream category.
superpowers
obra/superpowers
An agentic skills framework and software methodology that works.
superpowers is the most-adopted skills pack in harness engineering: skills, instincts, memory, security and research-first workflows for Claude Code and 13 other harnesses (Codex, Cursor, opencode, Gemini CLI and more). Treats harness engineering itself as the discipline.
DeepSeek Harness
deepseek-ai/deepseek-harness
Everything is a Plugin — DeepSeek's open agent harness.
DeepSeek Harness is the breakout open-source harness of 2026: an architecture where everything — tools, subagents, even the loop itself — is a plugin. A Desktop app for macOS and Windows followed in October 2026, and the project passed 240k stars in under three months.