# Plan Architecture

> Plan an implementation structure; hand durable architecture decisions to FIRST. Use when the user types /plan-architecture.

- Skill: `blockmatic/plan-architecture` (Agent Skill)
- Install (CLI): `npx skillmds@latest add blockmatic/plan-architecture`
- Raw SKILL.md: https://api.skillmd.com/api/skills/blockmatic/plan-architecture/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: blockmatic (https://skillmd.com/u/blockmatic)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/blockmatic/plan-architecture

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## Purpose and inputs

Produce an implementation-structure plan for the user's question. Durable system decomposition and ADRs belong to `/f-architecture` and `ARCHITECTURE.md`. Do not mint a second ADR tree.

## Steps

1. Load FIRST and read the architecture overlay plus matching technical MDX. If the change is a durable boundary, stop and use `/f-architecture`.
2. State implementation goals vs nice-to-haves. Stay inside the existing architecture unless the user already authorized a station decision.
3. List constraints, trade-offs, and alternatives that affect this change. Flag high-risk items for a human.
4. Add Mermaid only when structure or flow is otherwise unclear.
5. Save only if the user gave a path; otherwise return in chat. Include assumptions and References. Do not create a branch.

## Verification

- [ ] The plan does not replace `ARCHITECTURE.md` or invent an ADR location.
- [ ] Assumptions and deferrals are explicit.
- [ ] Commands and generated-source owners come from inspected docs.

## Handoff

Return the plan location or chat body and whether `/f-architecture` is still required.