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design-child-contract

design-child-contract is a skill for Claude Code, Codex from siarhei-belavus/agent-public. It costs 38 tokens per session (332 once invoked), scanned A, original, MIT.

A design-process skill for choosing an unclear interface between a child project and the rest of a system. An interface is the agreed shape of an API, configuration, stored data, or module connection.

In plain words
What is it for?
Use it to compare two or three contract options, choose one using stated criteria, and record the decision in the project files before planning implementation.
Why use it?
It prevents teams from carrying several competing designs forward or making an important contract decision implicitly in conversation.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

not rated 2repo 3mo ago A scan 38 tokens original MIT

Good fit Use it to compare two or three contract options, choose one using stated criteria, and record the decision in the project files before planning implementation.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/siarhei-belavus/agent-public/design-child-contract
View source ↗ siarhei-belavus/agent-public
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 siarhei-belavus/agent-public --skill design-child-contract
Clone the repo
git clone --depth 1 https://github.com/siarhei-belavus/agent-public

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 design-child-contract

README.md
[![agentmods](https://agentmods.dev/badge/skills/siarhei-belavus/agent-public/design-child-contract/github.svg)](https://agentmods.dev/skills/siarhei-belavus/agent-public/design-child-contract)
Your own site
<a href="https://agentmods.dev/skills/siarhei-belavus/agent-public/design-child-contract"><img src="https://agentmods.dev/badge/skills/siarhei-belavus/agent-public/design-child-contract/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 design-child-contract

Your own site · 80×15
<a href="https://agentmods.dev/skills/siarhei-belavus/agent-public/design-child-contract"><img src="https://agentmods.dev/badge/skills/siarhei-belavus/agent-public/design-child-contract.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 332 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 $0.00038 $0.00332
Opus 5 $0.00019 $0.00166
Sonnet 5 $0.00008 $0.00066
Haiku 4.5 $0.00004 $0.00033

Measured 11d ago against content hash 7de933315743, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

design-child-contract 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 11d 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.

skills/atelier-workflow/design-child-contract/SKILL.md · 35 lines

What it actually says

design-child-contract

Use only when the child owns an ambiguous API/config/storage/hook/module contract.

Read first

  • ../references/task-packet-contract.md
  • ../references/final-state-authoring-policy.md
  • child INDEX.md, BRIEF.md, PLAN.md, AMENDMENTS.md, ARTIFACT_CANDIDATES.md
  • relevant parent initiative files referenced by the child brief
  • ../../references/communication-mode.md

Workflow

  1. Generate 2-3 materially different contract shapes.
  2. Compare them on simplicity, coupling, flexibility, validation fit, and misuse risk.
  3. Choose one direction explicitly.
  4. Write CONTRACT_DECISION.md with the chosen direction, rejected alternatives, and rationale.
  5. Update child INDEX.md to Packet phase: contract_decided.

Writing rule

Write the chosen contract as the current local design decision. Do not preserve competing contract vocabularies inside the canonical child packet after the decision is made.

Do not

  • write implementation code
  • leave the contract decision implicit in chat only
  • create contract churn when the packet already has a clear contract surface

Communication

Honor active caveman mode for user-facing replies per ../../references/communication-mode.md. Keep durable artifacts normal unless the human asks otherwise. Drop caveman for safety/clarity when needed, then resume.

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. 11d ago First seen · 35 lines · 38 tokens per session scan A 7de933315743

Subscribe to this mod's changes

design-child-contract is a skill published in the GitHub repository siarhei-belavus/agent-public (2 stars, last pushed 3mo ago), licensed MIT. It adds 38 tokens to every session and 332 once invoked, about $0.0002 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.

Planning
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