midas-harness: Skill for Claude Code

.agents/skills/midas-sandbox/SKILL.md

midas-sandbox is a skill for Claude Code, Codex from okuzpe/midas-harness. It costs 93 tokens per session (2,621 once invoked), scanned A, original, Apache-2.0.

A safe test environment for checking changes to Midas skills and rules against a small example project.

In plain words
What is it for?
Use it before committing skill or rule changes to run a real skill in an isolated example, record decisions and traces, and save findings for review.
Why use it?
It shows how a skill behaves without editing the real harness source or using a potentially dirty product installation.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents; installed under .agents/ (shared by several agents); mentions AGENTS.md.

This is okuzpe/midas-harness's own configuration. It tells Claude Code and Codex how to work on midas-harness itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything midas-harness configures →

Reuse

Borrowing it

Nothing to install: this file belongs to okuzpe/midas-harness. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/okuzpe/midas-harness/main/.agents/skills/midas-sandbox/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/okuzpe/midas-harness

Made for: Claude Code, 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 midas-sandbox

README.md
[![agentmods](https://agentmods.dev/badge/skills/okuzpe/midas-harness/midas-sandbox/github.svg)](https://agentmods.dev/skills/okuzpe/midas-harness/midas-sandbox)
Your own site
<a href="https://agentmods.dev/skills/okuzpe/midas-harness/midas-sandbox"><img src="https://agentmods.dev/badge/skills/okuzpe/midas-harness/midas-sandbox/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for midas-sandbox

Your own site · 80×15
<a href="https://agentmods.dev/skills/okuzpe/midas-harness/midas-sandbox"><img src="https://agentmods.dev/badge/skills/okuzpe/midas-harness/midas-sandbox.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 93 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,621 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.
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 $0.00093 $0.02621
Opus 5 $0.00046 $0.01311
Sonnet 5 $0.00019 $0.00524
Haiku 4.5 $0.00009 $0.00262

Measured 5d ago against content hash fda99853096a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

midas-sandbox 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 5d 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.

.agents/skills/midas-sandbox/SKILL.md · 160 lines

How it starts

The opening of the file, as written. The whole thing — 160 lines — stays where its author put it; the contents beside it link to each section on GitHub.

midas-sandbox — real skill dry-run lab (engine only)

Guard + state: <paths.engine>/templates/skill-state-ritual.md (+ AGENTS.md § Safety / Path resolution). Engine-only. Isolation + cost: sandbox/README.md. Runner: node scripts/sandbox-run.mjs. Tally: <paths.engine>/templates/audit-checklists.md § Parseable tally lines.

Dispatches a real Midas skill (unmodified, from harness/skills/) against sandbox/example-product/, on a Task subagent pinned to composer-2.5 (never composer-2.5-fast). Findings are proposals; nothing under harness/skills/ or harness/rules/ is edited here.

Does / Does not

Does Does not
Abort unless cwd is midas-harness engine Run on product installs / template trees
Always reset then require env exit 0 before any Task Trust a dirty example-product/ or engine harness/state.yaml
Run the target skill in the composer-2.5 Task Spawn nested Task / midas-builder on another model
Log [SANDBOX AUTO-DECISION] for every substituted AskQuestion Auto-apply findings to harness source
Write sandbox/findings/<date>-<mode>.md + MIDAS_SANDBOX_RESULT: Advance real engine stage / gates
Run sandbox-run grade (disk oracles) after the Task Let composer grade its own homework

Feedback loop (touch → detect → classify → re-smoke)

When the diff touches harness/skills/** or harness/rules/**, the default lab is --skill / --smoke, not --all. Findings stay proposals (no writes under harness/skills / harness/rules until a later turn after human OK). After a harness-gap patch, re-run --smoke until grade passes. Skip --smoke only when the fixture cannot exercise the change (docs-only prose, engine-only skill itself). Adapters / VERSION → /midas-align.

Engine guard (hard)

  1. Confirm engine: package.json"name": "midas-harness" and scripts/test.mjs exists.
  2. Otherwise print: ABORT — /midas-sandbox is engine-only; use /midas-verifySTOP.

Read the full file on GitHub · 160 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. 5d ago Changed · +23 lines fda99853096a
  2. 10d ago First seen · 137 lines · 93 tokens per session scan A 0a5e9d2931a0

Subscribe to this mod's changes

midas-sandbox is a skill published in the GitHub repository okuzpe/midas-harness (2 stars, last pushed 6d ago), licensed Apache-2.0. It adds 93 tokens to every session and 2,621 once invoked, about $0.0005 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 2026-08-31.

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