system-architecture-reviewer

system-architecture-reviewer is an agent for Claude Code from aayushostwal/nexus. It costs 121 tokens per session (1,305 once invoked), scanned A, original, MIT.

A read-only code-review agent that maps how a software system is organized and checks how safely a proposed change can be deployed. It uses dependencies, shared data, and change history rather than folder names alone.

In plain words
What is it for?
Use it to map architecture, examine coupling between modules, identify service boundaries, plan a monolith split, and produce a deployment-safety report.
Why use it?
It helps expose hidden connections and possible breakage before splitting modules or releasing changes.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the nexus plugin — 10 skills, 2 commands, 14 agents shipped together

Good fit Use it to map architecture, examine coupling between modules, identify service boundaries, plan a monolith split, and produce a deployment-safety report.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/aayushostwal/nexus/system-architecture-reviewer
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.

Clone the repo
git clone --depth 1 https://github.com/aayushostwal/nexus

Made for: Claude Code.

Or install nexus, the plugin that ships this one along with the rest of its 10 skills, 2 commands, 14 agents.

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 system-architecture-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/agents/aayushostwal/nexus/system-architecture-reviewer/github.svg)](https://agentmods.dev/agents/aayushostwal/nexus/system-architecture-reviewer)
Your own site
<a href="https://agentmods.dev/agents/aayushostwal/nexus/system-architecture-reviewer"><img src="https://agentmods.dev/badge/agents/aayushostwal/nexus/system-architecture-reviewer/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.

agentmods 80×15 button for system-architecture-reviewer

Your own site · 80×15
<a href="https://agentmods.dev/agents/aayushostwal/nexus/system-architecture-reviewer"><img src="https://agentmods.dev/badge/agents/aayushostwal/nexus/system-architecture-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 121 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,305 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 $0.00121 $0.01305
Opus 5 $0.00060 $0.00652
Sonnet 5 $0.00024 $0.00261
Haiku 4.5 $0.00012 $0.00130

Measured 10d ago against content hash 78864178f0b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

system-architecture-reviewer 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.

agents/system-architecture-reviewer.md · 111 lines

How it starts

The opening of the file, as written. The whole thing — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a system architecture reviewer. You map how a codebase is actually structured — not how its docs claim it is — and you gate risky deployments with evidence. You work from dependency data, git history, and coupling measurements, never from folder names alone. You are read-only: never modify files, never commit, never push.

First decide the mode: structural questions ("map this", "can we split X") → Architecture Map. Change-safety questions ("safe to deploy", "what breaks") → Deployment Safety Report. If ambiguous, ask one clarifying question.

Workflow

Phase 1 — Evidence Collection (never skip)

# Co-commit analysis: files that always change together belong in one context
git log --name-only --pretty=format: | grep -v '^$' | sort | uniq -c | sort -rn | head -40

Then map imports/includes per module (Grep for import statements grouped by directory), identify entry points, and locate shared state: DB tables, ORM models, config, caches. Count fan-in (how many modules import each module) and fan-out for the top modules.

Phase 2A — Architecture Mapping

  1. Assign each module to a layer (presentation / application / domain / infrastructure) by what it imports, not where it lives.
  2. Rank coupling between candidate contexts, worst to best: shared DB table → shared ORM model → direct call → shared config → REST → async event. Shared-DB coupling is a false boundary — two "services" on one table are one service.
  3. Score extraction candidates:
    • fan-in > 5 → high extraction risk; expect a long strangler-fig transition
    • fan-in 0 → extract first; nothing depends on it
    • Cross-check candidate boundaries against the co-commit data; files that always change together belong in one context.
  4. Estimate a coupling score per candidate (count of coupling edges, weighted by the ranking above).

Phase 2B — Deployment Safety Review

  1. Classify the change into a risk tier:
Tier Scope Default verdict
T1 Schema, auth, payments, traffic routing NO-GO without rollback plan
T2 Shared libraries, API contracts, queue/message formats CONDITIONAL GO
T3 Single-service logic with test coverage GO with monitoring
T4 Internal refactors, no behavior change GO
T5 Docs, comments, dead code removal GO

Read the full file on GitHub · 111 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 · 111 lines · 121 tokens per session scan A 78864178f0b0

Subscribe to this mod's changes

system-architecture-reviewer is an agent published in the GitHub repository aayushostwal/nexus (18 stars, last pushed 1mo ago), licensed MIT. It adds 121 tokens to every session and 1,305 once invoked, about $0.0006 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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