brat-architecture

brat-architecture is a skill for Claude Code, Codex from neul-labs/brat. It costs 27 tokens per session (527 once invoked), scanned A, original, MIT.

A design-phase skill that turns product requirements into an architecture plan, including components, interfaces, dependencies, file locations, design decisions, and testing strategy. Architecture describes how a software system is divided and how its parts work together.

In plain words
What is it for?
Use it to design or update system architecture from user stories, acceptance tests, existing components, notes, and the chosen technology stack.
Why use it?
It gives a product team a shared technical structure before implementation begins and records the reasons behind important decisions.

Skill for Claude CodeCodex

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

Good fit Use it to design or update system architecture from user stories, acceptance tests, existing components, notes, and the chosen technology stack.

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Install with agentmods
npx agentmods add skills/neul-labs/brat/brat-architecture
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 neul-labs/brat --skill brat-architecture
Clone the repo
git clone --depth 1 https://github.com/neul-labs/brat

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 brat-architecture

README.md
[![agentmods](https://agentmods.dev/badge/skills/neul-labs/brat/brat-architecture/github.svg)](https://agentmods.dev/skills/neul-labs/brat/brat-architecture)
Your own site
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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 brat-architecture

Your own site · 80×15
<a href="https://agentmods.dev/skills/neul-labs/brat/brat-architecture"><img src="https://agentmods.dev/badge/skills/neul-labs/brat/brat-architecture.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 527 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 $0.00027 $0.00527
Opus 5 $0.00014 $0.00264
Sonnet 5 $0.00005 $0.00105
Haiku 4.5 $0.00003 $0.00053

Measured 10d ago against content hash cc2f5c5e1425, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

brat-architecture 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 10d 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.

crates/brat-skills/skills/brat-architecture/SKILL.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

brat-architecture Skill

Purpose

Read product requirements and produce architecture design decisions, component breakdown, and interface definitions.

Input Schema (JSON)

{
  "product_requirements": {
    "title": "string",
    "user_stories": [{"story": "string", "acceptance_criteria": ["string"]}],
    "acceptance_tests": ["string"]
  },
  "architecture_context": "string (relevant arch notes from KB)",
  "existing_components": ["string (known components from KB)"],
  "tech_stack": "string (language/framework info)"
}

Output Schema (JSON)

{
  "action": "create_design|update_design|answer",
  "design": {
    "title": "string",
    "components": [
      {
        "name": "string",
        "responsibility": "string",
        "interfaces": ["string (input/output contracts)"],
        "dependencies": ["string (other components)"],
        "file_paths": ["string (suggested files/modules)"]
      }
    ],
    "adr": {
      "title": "string",
      "context": "string",
      "decision": "string",
      "consequences": ["string"]
    },
    "test_strategy": {
      "unit_tests": ["string (what to test per component)"],
      "integration_tests": ["string (cross-component tests)"]
    },
    "notes_to_create": [
      {
        "title": "string",
        "body": "string",
        "tags": ["architecture", "adr", "component"],
        "type": "permanent|structure",
        "links_to": ["string (existing note slugs)"]
      }
    ]
  },
  "answer": "string (if action=answer)",
  "escalation_reason": "string (if requirements are unclear)"
}

Guardrails

  • ALWAYS read product requirements before designing
  • Components must have clear single responsibilities
  • Every component interface needs input/output contracts
  • Create ADR (Architecture Decision Record) for significant choices
  • Link architecture notes to product notes they implement
  • Define test strategy BEFORE implementation (TDD)
  • NEVER write implementation code in this phase
  • NEVER proceed to implementation from this skill without explicit test strategy

Read the full file on GitHub · 76 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. 10d ago First seen · 76 lines · 0 tokens per session scan A cc2f5c5e1425

Subscribe to this mod's changes

brat-architecture is a skill published in the GitHub repository neul-labs/brat (5 stars, last pushed 2mo ago), licensed MIT. It adds 27 tokens to every session and 527 once invoked, about $0.0001 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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