arch-design

arch-design is a skill for Claude Code from heliohq/ship. It costs 109 tokens per session (1,806 once invoked), scanned A, original, MIT.

A system-design guide for thinking through goals, boundaries, components, interfaces, failures, security, operations, trade-offs, and rough numbers before writing code or documentation.

In plain words
What is it for?
Designing services, command-line tools, frontends, data pipelines, agent runtimes, APIs, and data models.
Why use it?
It exposes important design decisions and risks before implementation makes them expensive to change.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the ship plugin — 11 skills, 3 hooks, 1 MCP server shipped together

Good fit Designing services, command-line tools, frontends, data pipelines, agent runtimes, APIs, and data models.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/heliohq/ship/arch-design
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 heliohq/ship --skill arch-design
Clone the repo
git clone --depth 1 https://github.com/heliohq/ship

Made for: Claude Code.

Or install ship, the plugin that ships this one along with the rest of its 11 skills, 3 hooks, 1 MCP server.

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 arch-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/heliohq/ship/arch-design.svg)](https://agentmods.dev/skills/heliohq/ship/arch-design)
Your own site
<a href="https://agentmods.dev/skills/heliohq/ship/arch-design"><img src="https://agentmods.dev/badge/skills/heliohq/ship/arch-design.svg" alt="Measured on agentmods" height="20"></a>
Per session 109 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,806 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
  • NVIDIA SkillSpector pass 7 Sept 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 $0.00109 $0.01806
Opus 5 $0.00055 $0.00903
Sonnet 5 $0.00022 $0.00361
Haiku 4.5 $0.00011 $0.00181

Measured 8d ago against content hash adb095d8007b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

arch-design 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.

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/arch-design/SKILL.md · 167 lines

How it starts

The opening of the file, as written. The whole thing — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ship: Architecture Design

Think the design through before anything is written or built. The lenses below apply to any system: a service, a CLI, a frontend, a data pipeline, an agent runtime. Scale the depth to the decision — a single component with clear constraints needs the frame, a contract sketch, and trade-offs; a new system with unknowns needs every lens. Skipping a lens is a judgment call you record with its reason ("no trust boundary crossed — internal tool, single user"), never a silent omission.

Path note: ../shared/*.md references resolve against this skill's base directory (announced as "Base directory for this skill" when the skill loaded), not your working directory.

The quality bar for every lens: statements someone could prove wrong — named numbers, named failure behaviors, named rejected alternatives. Virtue words ("scalable", "robust", "flexible") with no test attached are filler.

Red Flag

Never:

  • Jump to a solution before the frame (goals, non-goals, numbers) exists
  • Present a design with zero numbers and zero rejected alternatives — that's a description, not a design
  • Resolve a question from memory when the codebase can answer it
  • Interrogate the user question-by-question — self-interview instead; user-owned calls become recorded assumptions
  • Open many design branches at once — resolve dependencies in order
  • Skip a lens silently — skip with a recorded reason, or don't skip

Method — Walk the Lenses as a Self-Interview

Interview yourself relentlessly about every aspect of the design until no unresolved question remains — the lenses below are the branches of the tree. Take questions one at a time, in dependency order: resolve a decision before opening the ones that build on it (storage before schema, contract before internals) — an answer stacked on an unresolved dependency is a guess, and opening many branches at once produces shallow parallel guesses. For each question, state your recommended answer, then resolve it with the strongest means available:

Read the full file on GitHub · 167 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. 8d ago First seen · 167 lines · 109 tokens per session scan A adb095d8007b

Subscribe to this mod's changes

arch-design is a skill published in the GitHub repository heliohq/ship (92 stars, last pushed 2mo ago), licensed MIT. It adds 109 tokens to every session and 1,806 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 2026-08-30.

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