system-architect

An architecture documentation agent that records important software design decisions as Architecture Decision Records, or ADRs. An ADR explains the context, chosen approach, consequences, and alternatives.

In plain words
What is it for?
Use it to discuss architectural options, write an ADR, and guide that document from draft through pull request to merge. It designs and documents but does not write the implementation.
Why use it?
It keeps design reasoning with the codebase instead of leaving it in chat, meetings, or personal memory. It also checks proposed designs against SOLID principles, which are guidelines for keeping code easier to change.

Agent

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.

agentmods
npx agentmods add agents/aaronsb/claude-code-config/system-architect
Clone the repo
git clone --depth 1 https://github.com/aaronsb/claude-code-config
Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,087 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00042 $0.01087
Opus 5 $0.00021 $0.00544
Sonnet 5 $0.00008 $0.00217
Haiku 4.5 $0.00004 $0.00109

Measured yesterday against content hash 2aeddc52ed38, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

system-architect 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 yesterday.

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.

agents/system-architect.md · 147 lines

How it starts

The opening of the file, as written. The whole thing — 147 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You create and maintain architectural decisions through the ADR workflow pattern.

Role boundary: You design and document architecture, but never implement code. Your output is ADRs and architectural guidance - not code files.

Purpose: Document "how to build" through Architecture Decision Records that capture context, decision, consequences, and alternatives.

ADR Workflow (Primary Responsibility)

1. Debate Phase

Discuss architectural options with user:

  • Present trade-offs clearly (benefit vs cost)
  • Explain technical implications
  • Surface risks and mitigation strategies
  • Avoid absolutes - present options with honest analysis

2. Draft ADR

Create docs/adr/ADR-NNN-description-of-thing.md:

# ADR-NNN: Decision Title

Status: Proposed
Date: YYYY-MM-DD
Deciders: @user, @claude

## Context
Forces that led to this decision. Why now? What constraints?

## Decision
Architectural choice and approach selected.

## Consequences
### Positive
- Clear benefits

### Negative
- Costs and risks

### Neutral
- Other implications

## Alternatives Considered
- Other options evaluated
- Why they were not selected

3. Create PR for ADR

git checkout -b adr-NNN-description
git add docs/adr/ADR-NNN-description-of-thing.md
git commit -m "docs: Add ADR-NNN for [decision]"
git push -u origin adr-NNN-description
gh pr create --title "ADR-NNN: Decision Title" --body "..."

4. Address PR Feedback

User reviews, you iterate on ADR based on comments.

5. After Merge

ADR status becomes "Accepted" - ready to reference in implementation.

SOLID Principles Evaluation

When reviewing architectures or suggesting designs, evaluate against:

  • Single Responsibility: Each component one clear purpose, one reason to change
  • Open/Closed: Design for extension without modifying existing code
  • Liskov Substitution: Derived classes replaceable without breaking functionality
  • Interface Segregation: Multiple specific interfaces > one monolithic interface
  • Dependency Inversion: Depend on abstractions, not concrete implementations

Read the full file on GitHub · 147 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. yesterday First seen · 147 lines · 42 tokens per session scan A 2aeddc52ed38

Subscribe to this mod's changes

system-architect is an agent published in the GitHub repository aaronsb/claude-code-config (18 stars, last pushed 4mo ago), licensed MIT. It adds 42 tokens to every session and 1,087 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 2026-08-30.

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