npm i -g hotcell vs PenguinHarness

Self-hostable sandbox SDK inspired by Cloudflare Sandbox SDK. works on any device (Mac, Linux, bare metal). super easy to use (both by human engineers and agents). you get full control over capacity/token spent per sandbox, you can default-deny egress but still allow access to LLM providers, and API keys never directly enter each sandbox (it creates per-sandbox tokens instead that die when the sandbox stops). npm i -g hotcell

PenguinHarness is an open-source, local-first multi-agent development and recursive auto-tuning platform created by the engineering minds behind LlamaFactory. While traditional frameworks like LangChain or AutoGen require developers to manually construct prompts, state machines, and tools step-by-step, PenguinHarness shifts to an autonomous meta-agent architecture. With simple natural-language directives, the platform enables AI agents to design, scaffold, test, and deploy entire secondary agent applications—such as turnkey RAG systems—at a tiny fraction of conventional compute expense (often around $0.02 using models like DeepSeek). At the core of the framework lies its closed-loop self-evolution engine governed by a strict safety manifesto ('CONTRACT.md'). In this loop, an Optimizer orchestrates multiple parallel Evaluators to benchmark the target agent across real execution traces, isolate failure points, and iteratively refine the agent's prompts and skills from version N to version N+1. Available as both a standalone desktop application and a CLI/SDK supporting over 1,000 models, PenguinHarness provides an end-to-end mission control deck featuring multi-session streaming chat, token cost tracking, skill repositories, and one-click rollback snapshotting.