LangChain Publishes Practical Guide to Building Custom Agent Harnesses
hwchase17 · x · 2026-09-14
LangChain engineer Sydney Runkle published a practical guide to building domain-specific agent harnesses. Key ideas: an agent is model + harness, where the harness is scaffolding that feeds the model the right context at every step; createagent is LangChain's primitive for custom harnesses with custom prompting, business logic and guardrails, complementing pre-assembled harnesses like Deep Agents and Claude Agent SDK that ship opinionated middleware (memory, context management, sandboxing). Includes runnable code examples, amplified by Garry Tan's quip: 'either you die a system of record or you live long enough to become a domain-specific harness.'
Related event: LangChain Publishes Guide to Building Domain-Specific Agent Harnesses(2 posts)→
More from coding & agent
- Anthropic quietly ships server-side rule banning game rewrites in Claude Code — petrusenko_max · 2026-10-31
- Bootstrapping competitive edge with frontier tokens — curious_vii · 2026-10-31
- Element Forge: open-source editable AI VFX for real footage in ComfyUI — zitroffell · 2026-10-30
- Gym-Anything Adds Audit Agents That Try to Break Simulations With Legal Robot Actions — wellecks · 2026-10-30
- durable-object-migrator: zero-downtime exports for Cloudflare Durable Objects — samgoodwin89 · 2026-10-30
- This 5-question interview prompt makes Grok design your first two custom bots in minutes — nateliason · 2026-10-30