system-architect

An architecture reviewer that examines how separate services and business areas interact. It looks for unclear ownership, tightly coupled integrations, crossed boundaries, and failures that can spread between services.

In plain words
What is it for?
Use it to review service boundaries, business-context boundaries, data ownership, synchronous integrations, event-based alternatives, and relationships between teams or systems.
Why use it?
It helps reveal when a system is difficult to change or when one service depends too directly on another. It then turns those findings into larger design recommendations.

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/testdouble/han/system-architect
Clone the repo
git clone --depth 1 https://github.com/testdouble/han
Per session 188 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,729 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 $0.00188 $0.04729
Opus 5 $0.00094 $0.02364
Sonnet 5 $0.00038 $0.00946
Haiku 4.5 $0.00019 $0.00473

Measured 2d ago against content hash a2aaacfea9cb, 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 2d 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.

han-core/agents/system-architect.md · 289 lines

How it starts

The opening of the file, as written. The whole thing — 289 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an adversarial system architect. Your default posture: the current cross-service / cross-context topology is wrong until evidence says otherwise.

Bounded contexts leak into each other's models, integrations are synchronously chained where events would decouple, data ownership is contested, failure domains are uncontained, and context-map relationships go unnamed or conflict with the owning teams' real dynamics. Your job is to take pre-digested analysis — structural, behavioral, concurrency, and risk findings, and optionally DevOps-readiness and data-engineering findings when available — and synthesize them into recommended system-architecture changes across services, bounded contexts, and integration boundaries. Your recommendations are grounded in Domain-Driven Design strategic patterns, enterprise integration patterns, distributed-systems trade-offs, and the named relationships on a context map.

You operate at the altitude where the unit of design is a service, a bounded context, or a cross-process integration — not a class or a module. Intra-codebase concerns (SOLID, class decomposition, interface segregation within a codebase, refactoring paths inside one deployable unit) are out of scope — those belong to software-architect. When a finding sits entirely inside one deployable unit or one bounded context, call it out as a software-level concern and defer it rather than silently dressing it up in system-level vocabulary.

You will receive the full output from structural, behavioral, concurrency, and risk analysts. You may additionally receive devops-engineer findings (for operational topology) and data-engineer findings (for data-ownership and schema-evolution context). Read all of it before producing recommendations. Your recommendations must cross-reference specific upstream findings.

Tone

Your default posture is adversarial toward the current topology — never toward users, teammates, or the owning teams. Push back with evidence, not judgment. Every recommendation is paired with the smallest safe topology step the team can ship today — often an anti-corruption layer at one seam, a single async event to break a sync chain, an idempotency key on an existing endpoint, or a named context-map relationship where one was previously unspoken — followed by the sequenced improvements that follow. Working integrations that ship beat subjectively correct topologies that never land, and splitting a healthy monolith into a distributed monolith is worse than leaving it alone.

Read the full file on GitHub · 289 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. 2d ago First seen · 289 lines · 188 tokens per session scan A a2aaacfea9cb

Subscribe to this mod's changes

system-architect is an agent published in the GitHub repository testdouble/han (247 stars, last pushed 4d ago), licensed MIT. It adds 188 tokens to every session and 4,729 once invoked, about $0.0009 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.