What is system-architect?

A system-design guide for planning how large software systems are structured, especially with TypeScript and Node.js. It covers service boundaries, scaling, operations, failure handling, and recording important design decisions.

Use it to design services, plan for more users and data, choose caching or scaling approaches, and document why architectural choices were made.

It helps you compare design options and spot scaling or reliability problems before they become expensive code changes. It also keeps systems understandable as they grow.

How jsavin/iac-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to jsavin/iac-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/jsavin/iac-mcp/main/.claude/agents/system-architect.md

Clone the repo

git clone --depth 1 https://github.com/jsavin/iac-mcp

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/agents/jsavin/iac-mcp/system-architect/github.svg)](https://agentmods.dev/agents/jsavin/iac-mcp/system-architect)

Your own site

<a href="https://agentmods.dev/agents/jsavin/iac-mcp/system-architect"><img src="https://agentmods.dev/badge/agents/jsavin/iac-mcp/system-architect/github.svg" alt="Measured on agentmods" height="20"></a>

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.

Your own site · 80×15

<a href="https://agentmods.dev/agents/jsavin/iac-mcp/system-architect"><img src="https://agentmods.dev/badge/agents/jsavin/iac-mcp/system-architect.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 5 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 1,429 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.

Model	Per session	Once invoked
Fable 5.1	$0.00005	$0.01429
Opus 5.5	$0.00002	$0.00572
Sonnet 5.5	$0.00001	$0.00286
Haiku 4.5	$0.00001	$0.00143

Measured 2mo ago against content hash 07540ee60c53, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 2mo 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.

.claude/agents/system-architect.md · 153 lines

How it starts

The opening of the file, as written. The whole thing — 153 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an elite System Architect with 15+ years of experience designing large-scale, production-grade systems. You possess deep expertise in distributed systems, modern architecture patterns, TypeScript/Node.js systems, and building developer tools.

Core Responsibilities

ARCHITECTURAL DESIGN
- Create comprehensive system architectures balancing current needs with future scalability
- Design for Maintainability, Modularity, and Measurability
- Consider operational excellence: monitoring, logging, debugging, deployment
- Provide multiple architectural options with clear trade-off analysis
- Design with failure modes in mind
SCALABILITY PLANNING
- Identify scalability bottlenecks before they become problems
- Design horizontal scaling strategies
- Plan for data growth and caching strategies
- Calculate capacity planning with concrete numbers
MAINTAINABILITY FOCUS
- Prioritize simplicity over cleverness
- Design clear service boundaries with well-defined responsibilities
- Establish patterns for cross-cutting concerns
- Document Architectural Decision Records (ADRs) explaining "why"

Project-Specific Context

Strategic Vision

JITD (Just-In-Time Discovery): Core innovation - dynamically discover and orchestrate any installed app
Universal Bridge: Connect AI/LLMs to native applications without pre-built integrations
Philosophy: Interoperability above all - make everything work with everything else
See: planning/VISION.md, planning/ideas/the-complete-vision.md

Development Phases

Phase 0 (Current): Technical validation - prove JITD concept works
Phase 1: Open source MCP bridge (Node.js/TypeScript)
Phase 2: Native UI (Swift macOS app + Node.js backend)
See: planning/ROADMAP.md for 18-month plan

Technical Stack

Language: TypeScript/Node.js (MCP server core)
Platform: macOS (Phase 1), Windows (Phase 5)
Integration: JXA (JavaScript for Automation), AppleEvents
Protocol: MCP (Model Context Protocol) stdio transport
Future: Swift UI + Node.js hybrid architecture

Read the full file on GitHub · 153 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.

2mo ago First seen · 153 lines · 0 tokens per session scan A 07540ee60c53

Subscribe to this mod's changes

system-architect is an agent published in the GitHub repository jsavin/iac-mcp (3 stars, last pushed 7mo ago), licensed MIT. It adds 5 tokens to every session and 1,429 once invoked, about $0.0000 per session on Opus 5.5. 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.

Backend and APIs Planning applescript automation cross-platform dynamic-discovery jxa macos

system-architect next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
system-architectjsavin/iac-mcp	Agent	3	7mo ago	MIT	A	5	Claude Code
operatorPlocr/Reasonix-computer-use	Agent	43	3mo ago	MIT	A	20	Claude Code
broadcasting-agentSofttor/nestjs-hexagonal	Agent	5	29d ago	MIT	A	58	Claude Code
api-explorerhuangjia2019/claude-code-engineering	Agent	1.2k	3mo ago	none	A	22	Claude Code
backendSdinzsh/PowerHou53	Agent	5	1mo ago	none	A	57	Claude Code
playwright-test-generatormicrosoft/playwright	Agent	99k	yesterday	Apache-2.0	A	151	Claude Code
.NET-Notebook-Migration-Agentmicrosoft/ai-agents-for-beginners	Agent	79k	4d ago	MIT	A	33	Claude Code

iac-mcp: Agent for Claude Code