androidZzT

Harness Engineering Practice — Development skill for Claude Code

Development community

Harness Engineering — a practical guide to the platform layer of coding agents (Claude Code & Codex): skills, hooks, config, permissions, reasoning effort.

How to install Harness Engineering Practice

This entry records only its repository, not the path inside it, so there is no exact command to give. Open androidZzT/harness-engineering-practice and copy the folder into ~/.claude/skills/, or the file into ~/.claude/agents/.

What Harness Engineering Practice does

Harness Engineering — a practical guide to the platform layer of coding agents (Claude Code & Codex): skills, hooks, config, permissions, reasoning effort. EN / 한국어 / 日本語 / 中文.

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README

**English** ∙ [한국어](README.ko.md) ∙ [日本語](README.ja.md) ∙ [中文](README.zh-CN.md)

Harness Engineering

**A practical guide to the platform layer of coding agents — Claude Code & Codex.**

What is Harness Engineering?

When you build with a coding agent like **Claude Code** or **Codex**, your code is only half the story. The other half is the *harness* — the runtime around the model that manages context, memory, tool calls, sub-agents, skills, hooks, and the loop that holds it all together.

*"the full environment of scaffolding, constraints, and feedback loops that surrounds the agent."* — OpenAI, [Harness engineering](https://openai.com/index/harness-engineering/)

**Harness Engineering** is the discipline of building *on top of* that layer instead of fighting it. The central claim of this series is a boundary:

**The harness is the coding agent's platform layer. Your business engineering is a set of specs built on top of it — and you should not rewrite the harness itself.**

Get that boundary right and a lot of agent pain disappears: context windows stop overflowing, sub-agents stop leaking across phases, and every platform upgrade is a free upgrade instead of a three-hour compatibility audit.

This is a hands-on, source-grounded series comparing how the two harnesses most engineers actually use — **Claude Code (Anthropic)** and **Codex (OpenAI)** — solve the same problems: skills, configuration directories, hooks, permissions, and reasoning effort.

Who is this for

Engineers building serious workflows on Claude Code, Codex, Cursor, or any agentic coding tool.
Anyone who has felt the urge to "just patch the agent" and wants to know when not to.
Readers interested in agentic engineering, context engineering, and spec-driven development (SDD) as practical disciplines rather than buzzwords.

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