DeerFlow is ByteDance's open-source Super Agent Harness built on Python 3.12 + LangGraph. It orchestrates long-running tasks through sandboxes, long-term memory, sub-agents, skills, and a messaging gateway. It hit #1 on GitHub Trending in February 2026, now surpassing 63,000 stars, with support for Telegram/Slack/Feishu, Claude Code integration, and multiple search backends.
"OpenClaw is a Gateway shell around Pi" is obsolete. The docs now say the built-in runtime id is openclaw, that pi is a legacy alias which normalizes to it, and that no external agent framework packages remain. The only Pi-related third-party dependency left is a terminal component toolkit.
AI Agent is not a single technology -- it is an entire architecture system. This article is a systematic navigation: starting from the Agent Three Pillars (Context/Cognition/Action), through the three-stage evolution of AI engineering (Prompt -> Context -> Harness), to eight Multi-Agent design patterns and production-grade Harness infrastructure. Each topic links to a dedicated deep-dive article.