harness-engineering

Design the harness — the 8-layer scaffolding around the LLM loop that makes agents reliable. Covers the agent loop itself (gather/act/verify), context management, durable execution, guardrails, human-in-the-loop, evals, observability, and the cross-cutting security & identity layer. In production agents, the harness is 98% of the code. Use whenever the user is structuring code around an agent loop, asks "how do I make this reliable / production-ready," is implementing verification, retry logic, sub-agent delegation, permission systems, approval gates, or wants to understand what makes Claude Code / Codex / Devin work beyond the model.