Claude Code Harness is a development workflow for coding agents that organizes work into planning, implementation, review, synchronization, and release stages. It helps developers keep specifications, tests, independent reviews, and release evidence connected while using tools such as Claude Code, Codex CLI, Cursor, or Grok.
Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/Chachamaru127/claude-code-harnessnpx agentmods add skills/chachamaru127/claude-code-harness/harness-plan-briefWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/chachamaru127/claude-code-harness/harness-plan-brief)<a href="https://agentmods.dev/skills/chachamaru127/claude-code-harness/harness-plan-brief"><img src="https://agentmods.dev/badge/skills/chachamaru127/claude-code-harness/harness-plan-brief.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00114 | $0.03428 |
| Opus 5 | $0.00057 | $0.01714 |
| Sonnet 5 | $0.00023 | $0.00686 |
| Haiku 4.5 | $0.00011 | $0.00343 |
Grade A, and why
harness-plan-brief scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 241 lines — stays where its author put it; the contents beside it link to each section on GitHub.
harness-plan-brief
非エンジニアの発注者・プロデューサー職向けに、Claude が着手しようとしている計画を HTML 1 枚 で提示するスキル。 発注者の認知負荷ピーク (1) 計画理解の段階で使う。
Quick Reference
- 「Plan Brief を作って」 → このスキル
- 「実装前にざっくり整理」 → このスキル
- 「非エンジニア向けに計画を見せて」 → このスキル
責任境界
| 範囲 | このスキルの責務 |
|---|---|
| 検索 | 現プロジェクトのみ (project: <current>, strict_project: true を必ず指定) |
| クロスプロジェクト | やらない (Phase 65.3 以降で --cross-project-group <name> flag で opt-in 解放) |
| 書き込み | やらない (Plan Brief 承認後の memory write は plan-brief-record-decision.sh の責務) |
| plan_readiness 算出 | scripts/plan-brief-compile.sh に委譲。互換フィールド名 confidence は残すが、意味は DoD 明確度 + 依存解決率に限定 |
入力
引数 [task-description] にユーザーの request を渡す。
引数なしの場合は、会話の原依頼と選択済み計画から回収する。複数の候補が残って判断を変える場合だけ確認する。
計画の目的、担当範囲、未決事項と合格条件を示し、計画概要の作成依頼から実装を始めない。
出力
| 出力 | パス | 形式 |
|---|---|---|
| Plan Brief HTML | .claude/state/views/plan-brief-<timestamp>.html |
単独で開ける HTML (no server, no JS framework) |
| Plan Brief context JSON | .claude/state/views/plan-brief-<timestamp>.context.json |
plan-brief-context.v1 schema |
Schema: plan-brief-context.v1
{
"schema": "plan-brief-context.v1",
"user_request": "string (ユーザーの request 原文)",
"my_understanding": "string (Claude の理解を 1-3 段落で)",
"options": [
{ "name": "string", "summary": "string", "pros": ["string"], "cons": ["string"] }
],
"risks": [
{ "kind": "string", "severity": "info|warn|critical", "description": "string", "mitigation": "string" }
],
"acceptance_criteria": [
{ "id": "string", "description": "string", "verifiable_by": "string" }
],
"tdd_required": "yes|no|skip:<reason>",
"confidence": 0,
"confidence_evidence": ["string (plan_readiness evidence: DoD clarity + dependency resolution only)"],
"related_decisions": [
{ "id": "string", "title": "string", "relevance": "string" }
],
"similar_past_plans": [
{ "archive_path": "string", "phase": "string", "outcome": "cc:完了|cc:WIP|cc:TODO|skipped", "relevance": "string" }
],
"project": "string",
"generated_at": "ISO8601"
}
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago Changed · +1 lines 1437aff64cc3
- 9d ago First seen · 240 lines · 114 tokens per session scan A 65f72036af60
harness-plan-brief is a skill published in the GitHub repository Chachamaru127/claude-code-harness (3,098 stars, last pushed yesterday), licensed MIT. It adds 114 tokens to every session and 3,428 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
local-ai-agents
Build local-first AI agents that run entirely on a developer workstation with Microsoft Foundry Local and Qwen function-calling models. Covers Small Language Models (SLMs), the OpenAI-compatible local endpoint, sandboxed local tools, local RAG with Chroma, local MCP servers, hybrid cloud/local routing, and the…
next-cache-components-adoption
Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…
next-cache-components-optimizer
Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…
next-partial-prefetching-adoption
Turn on Partial Prefetching in a Next.js app and work through the insights it surfaces. Use when the user wants to enable or adopt Partial Prefetching, flip the partialPrefetching flag, opt routes in with export const prefetch = 'partial', audit Link prefetch={true} behavior, preserve existing prefetched UI with…
chronicle
Analyze Copilot session history for standup reports, usage tips, session search, and session reindexing. Use when the user asks for a standup, daily summary, usage tips, workflow recommendations, wants to search or find past sessions by keyword/file/PR, wants to reindex their session store, or asks about deleting…