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.
npx skills add ronmkr/PromptBook --skill hexagonal-architecturegit clone --depth 1 https://github.com/ronmkr/PromptBookWrote 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.
[](https://agentmods.dev/skills/ronmkr/promptbook/hexagonal-architecture)<a href="https://agentmods.dev/skills/ronmkr/promptbook/hexagonal-architecture"><img src="https://agentmods.dev/badge/skills/ronmkr/promptbook/hexagonal-architecture/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.
<a href="https://agentmods.dev/skills/ronmkr/promptbook/hexagonal-architecture"><img src="https://agentmods.dev/badge/skills/ronmkr/promptbook/hexagonal-architecture.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00044 | $0.02375 |
| Opus 5 | $0.00022 | $0.01188 |
| Sonnet 5 | $0.00009 | $0.00475 |
| Haiku 4.5 | $0.00004 | $0.00237 |
Grade A, and why
hexagonal-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 5d 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.
This is a copy
97% identical to hexagonal-architecture — 28 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 277 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Hexagonal Architecture
Hexagonal architecture (Ports and Adapters) keeps business logic independent from frameworks, transport, and persistence details. The core app depends on abstract ports, and adapters implement those ports at the edges.
When to Use
- Building new features where long-term maintainability and testability matter.
- Refactoring layered or framework-heavy code where domain logic is mixed with I/O concerns.
- Supporting multiple interfaces for the same use case (HTTP, CLI, queue workers, cron jobs).
- Replacing infrastructure (database, external APIs, message bus) without rewriting business rules.
Use this skill when the request involves boundaries, domain-centric design, refactoring tightly coupled services, or decoupling application logic from specific libraries.
Core Concepts
- Domain model: Business rules and entities/value objects. No framework imports.
- Use cases (application layer): Orchestrate domain behavior and workflow steps.
- Inbound ports: Contracts describing what the application can do (commands/queries/use-case interfaces).
- Outbound ports: Contracts for dependencies the application needs (repositories, gateways, event publishers, clock, UUID, etc.).
- Adapters: Infrastructure and delivery implementations of ports (HTTP controllers, DB repositories, queue consumers, SDK wrappers).
- Composition root: Single wiring location where concrete adapters are bound to use cases.
Outbound port interfaces usually live in the application layer (or in domain only when the abstraction is truly domain-level), while infrastructure adapters implement them.
Dependency direction is always inward:
- Adapters -> application/domain
- Application -> port interfaces (inbound/outbound contracts)
- Domain -> domain-only abstractions (no framework or infrastructure dependencies)
- Domain -> nothing external
How It Works
Step 1: Model a use case boundary
Define a single use case with a clear input and output DTO. Keep transport details (Express req, GraphQL context, job payload wrappers) outside this boundary.
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.
- 5d ago First seen · 277 lines · 44 tokens per session scan A 81a81ee6d1bc
hexagonal-architecture is a skill published in the GitHub repository ronmkr/PromptBook (2 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 44 tokens to every session and 2,375 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 97% identical to hexagonal-architecture, differing in 28 lines, and is treated as a copy.
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