# Arch

> Use when the user wants architecture-first product and system design with explicit stack rationale, boundaries, tradeoffs, data model choices, and phased delivery planning.

- Skill: `justinedevs/arch` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add justinedevs/arch`
- Raw SKILL.md: https://api.skillmd.com/api/skills/justinedevs/arch/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: JustineDevs (https://skillmd.com/u/justinedevs)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/justinedevs/arch

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# Arch

Use this skill inside Codex to turn a product idea into a concrete architecture brief.

## Output

Produce:
- problem framing
- `decision`, `status`, `evidence`, `blockers`, `next_allowed_triggers`
- user and workload assumptions
- system architecture and subsystem boundaries
- stack recommendation with tradeoffs
- rejected alternatives with rationale
- data model and storage choices
- auth, security, and operational concerns
- phased delivery plan
- top risks and open questions
- exact next trigger, usually `$sage`

## Rules

- Ask only for constraints that materially change the architecture.
- Keep the design biased toward the simplest system that can satisfy the stated requirements.
- Be explicit about tradeoffs, failure modes, and what should stay out of the first version.