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harness-engineering-playbook

harness-engineering-playbook is a skill for Codex from broomva/harness-engineering. It costs 81 tokens per session (1,187 once invoked), scanned A, original, MIT.

A set of practices and tools for making a repository easier and safer for coding agents to use. It covers documentation, repeatable checks, architecture rules, and data contracts.

In plain words
What is it for?
Use it to assess a repository, create or improve AGENTS.md and PLANS.md, define smoke tests, linting, type checks, and other repeatable checks.
Why use it?
It reduces setup confusion, inconsistent workflows, flaky tests, and unclear project boundaries when agents work on the code.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions AGENTS.md.

not rated 25repo 2mo ago A scan Socket: warnSnyk: pass 81 tokens original MIT

Good fit Use it to assess a repository, create or improve AGENTS.md and PLANS.md, define smoke tests, linting, type checks, and other repeatable checks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/broomva/harness-engineering/harness-engineering-playbook
View source ↗ broomva/harness-engineering
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add broomva/harness-engineering --skill harness-engineering-playbook
Clone the repo
git clone --depth 1 https://github.com/broomva/harness-engineering

Made for: Codex.

Wrote 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.

agentmods badge for harness-engineering-playbook

README.md
[![agentmods](https://agentmods.dev/badge/skills/broomva/harness-engineering/harness-engineering-playbook.svg)](https://agentmods.dev/skills/broomva/harness-engineering/harness-engineering-playbook)
Your own site
<a href="https://agentmods.dev/skills/broomva/harness-engineering/harness-engineering-playbook"><img src="https://agentmods.dev/badge/skills/broomva/harness-engineering/harness-engineering-playbook.svg" alt="Measured on agentmods" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,187 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket warn 7 Jul 2026
  • Snyk pass 7 Jul 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00081 $0.01187
Opus 5 $0.00041 $0.00593
Sonnet 5 $0.00016 $0.00237
Haiku 4.5 $0.00008 $0.00119

Measured 8d ago against content hash 66b53db02096, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

harness-engineering-playbook 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 8d ago.

The scan reads SKILL.md. This mod also ships 9 executable files (assets/templates/scripts/audit_harness.sh, assets/templates/scripts/harness/entropy_check.sh, assets/templates/scripts/harness/lint.sh, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.skills/harness-engineering-playbook/SKILL.md · 157 lines

How it starts

The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Harness Engineering Playbook

Use this skill to operationalize the practices from OpenAI's Harness Engineering guide in a repo that agents can run against repeatedly and safely.

What To Load

  • Use references/openai-harness-practices.md for the full practice-to-artifact mapping.
  • Use references/rollout-checklist.md for phased adoption in active repos.
  • Use references/wizard-cli.md for Typer wizard command flows.
  • Use assets/templates/ when creating or updating harness files.

Inputs

  • Target repository path.
  • Existing command surface (make, npm, cargo, pytest, etc.).
  • Existing CI workflows and branch protections.

Workflow

  1. Baseline the repo and detect existing workflows.
  2. Bootstrap harness artifacts and templates.
  3. Apply all nine Harness Engineering practices.
  4. Run harness audit checks and repair gaps.
  5. Iterate after real agent runs.

Step 1: Baseline The Repo

  • Identify language/toolchain and canonical entrypoints.
  • Inventory existing checks, scripts, and CI jobs.
  • Record current pain points for agent runs: setup drift, unclear docs, flaky tests, missing trace IDs, slow loops.

Use a short baseline note inside PLANS.md so decisions remain durable.

Step 2: Bootstrap Harness Artifacts

Preferred entrypoint:

python3 scripts/harness_wizard.py init <repo-path> --profile control

Profiles:

  • baseline: only core harness artifacts.
  • control: baseline + control-system primitives.
  • full: control + entropy controls (nightly audit + entropy checks).

Direct shell fallback:

Run:

./scripts/bootstrap_harness.sh <repo-path>

This script installs safe defaults from assets/templates/:

  • AGENTS.md
  • PLANS.md
  • docs/ARCHITECTURE.md
  • docs/OBSERVABILITY.md
  • Makefile.harness (+ -include Makefile.harness in Makefile)
  • scripts/audit_harness.sh
  • scripts/harness/{smoke,test,lint,typecheck}.sh
  • .github/workflows/harness.yml

By default, existing files are not overwritten. Pass --force to replace template-managed files.

Read the full file on GitHub · 157 lines

Files

What ships with it

29 files 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.

Changes

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.

  1. 8d ago First seen · 157 lines · 81 tokens per session scan A 66b53db02096

Subscribe to this mod's changes

harness-engineering-playbook is a skill published in the GitHub repository broomva/harness-engineering (25 stars, last pushed 2mo ago), licensed MIT. It adds 81 tokens to every session and 1,187 once invoked, about $0.0004 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.

Autonomous AgentsBuilding agentsagent-skillsbstack-foundationharness-engineeringopenai-codexskills-sh
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