init

A setup procedure for scaffolding a project's agent harness, including AGENTS.md, hooks, and guardrails.

In plain words
What is it for?
Use it when starting a project or hardening an existing one. It checks for jq and Python, then assesses existing harness files against the provided templates.
Why use it?
It checks required tools and existing setup before making changes, helping avoid overwriting a project's current or customized configuration.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/sliday/harn/init
Any agent
npx skills add sliday/harn --skill init
Clone the repo
git clone --depth 1 https://github.com/sliday/harn

Made for: Claude Code, Codex.

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,949 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 2 findings. Scan, not verified.
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 $0.00059 $0.02949
Opus 5 $0.00030 $0.01474
Sonnet 5 $0.00012 $0.00590
Haiku 4.5 $0.00006 $0.00295

Measured yesterday against content hash 37df72a747cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

init scanned grade A with 2 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 yesterday.

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.

Unrestricted tool accesslowExcessive agency

A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.

> These are opt-in. Run any command to add it.

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

r"curl\s+.*\|\s*(?:sudo\s+)?(?:bash|sh)",
skills/init/SKILL.md · 379 lines

How it starts

The opening of the file, as written. The whole thing — 379 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Harness Init v2.0 — Full Project Scaffold

You are scaffolding a complete harness for the current project. Follow these steps exactly.

Step 0: Pre-flight Checks

Before anything:

  1. Verify core dependencies are available:

    • jq — run command -v jq
    • python3 — run command -v python3 If either is missing, tell the user to install them first and stop.
  2. Check if AGENTS.md, scripts/harness/, or .claude/settings.json already exist in the project root.

  3. If ANY exist, assess each file against the templates in this skill:

    • Read each existing file
    • Compare to the template version (Steps 2-6)
    • Classify each as: up-to-date, outdated (missing sections/patterns), or customized (user modifications beyond template)
  4. Present a summary table and recommendation:

    Existing harness assessment:
    | File                    | Status      | Action       |
    |-------------------------|-------------|--------------|
    | AGENTS.md               | up-to-date  | skip         |
    | security_guard.py       | outdated    | update       |
    | quality_gate.sh         | customized  | skip (manual)|
    | trace_logger.sh         | missing     | create       |
    | .claude/settings.json   | up-to-date  | skip         |
    
    Recommendation: Update 1 file, create 1 file. 2 files unchanged.
    Proceed?
    
    • up-to-date → skip (no changes needed)
    • outdated → recommend update (template has improvements)
    • customized → skip and flag for manual review (don't overwrite user work)
    • missing → create

    Wait for user confirmation before proceeding. Only touch files marked for update/create.

  5. If NO harness files exist, proceed directly to Step 1 (fresh scaffold).

Step 1: Detect Tech Stack

Read the project root to identify the stack:

  • package.json → Node.js/TypeScript (check for typescript dep → TS)
  • Cargo.toml → Rust
  • go.mod → Go
  • pyproject.toml or requirements.txt → Python
  • Gemfile → Ruby

Read the full file on GitHub · 379 lines

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. yesterday First seen · 379 lines · 59 tokens per session scan A 37df72a747cd

Subscribe to this mod's changes

init is a skill published in the GitHub repository sliday/harn (5 stars, last pushed 4mo ago), licensed MIT. It adds 59 tokens to every session and 2,949 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 2 findings (unrestricted tool access, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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