domain-modeling

domain-modeling is a skill for Claude Code from camilooscargbaptista/cto-toolkit. It costs 24 tokens per session (1,346 once invoked), scanned A, original, MIT.

A practical guide to domain-driven design, a way to organise software around real business concepts. It covers Event Storming, service boundaries, and rules for grouping related data and behaviour.

In plain words
What is it for?
Use it to map business events and commands, define bounded contexts and aggregates, design new modules or services, and prepare a system for microservices decomposition.
Why use it?
It helps teams decide where business logic belongs and avoid unclear boundaries as a system grows or is split into services.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cto-toolkit plugin — 54 skills, 6 agents, 3 hooks shipped together

Good fit Use it to map business events and commands, define bounded contexts and aggregates, design new modules or services, and prepare a system for microservices decomposition.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/camilooscargbaptista/cto-toolkit/domain-modeling
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.

Any agent
npx skills add camilooscargbaptista/cto-toolkit --skill domain-modeling
Clone the repo
git clone --depth 1 https://github.com/camilooscargbaptista/cto-toolkit

Made for: Claude Code.

Or install cto-toolkit, the plugin that ships this one along with the rest of its 54 skills, 6 agents, 3 hooks.

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 domain-modeling

README.md
[![agentmods](https://agentmods.dev/badge/skills/camilooscargbaptista/cto-toolkit/domain-modeling/github.svg)](https://agentmods.dev/skills/camilooscargbaptista/cto-toolkit/domain-modeling)
Your own site
<a href="https://agentmods.dev/skills/camilooscargbaptista/cto-toolkit/domain-modeling"><img src="https://agentmods.dev/badge/skills/camilooscargbaptista/cto-toolkit/domain-modeling/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 domain-modeling

Your own site · 80×15
<a href="https://agentmods.dev/skills/camilooscargbaptista/cto-toolkit/domain-modeling"><img src="https://agentmods.dev/badge/skills/camilooscargbaptista/cto-toolkit/domain-modeling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,346 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 $0.00024 $0.01346
Opus 5 $0.00012 $0.00673
Sonnet 5 $0.00005 $0.00269
Haiku 4.5 $0.00002 $0.00135

Measured 9d ago against content hash 09abd96ab992, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

domain-modeling 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 9d 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.

domain-modeling/SKILL.md · 201 lines

How it starts

The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Domain Modeling (DDD Practical)

When to Use

  • Starting a new module/service and need to define boundaries
  • Complex business logic that doesn't fit in simple CRUD
  • Team struggling with "where does this logic go?"
  • Preparing for microservices decomposition

Event Storming (Discovery)

The Process

1. Invite: developers + domain experts + product
2. Orange stickies: Domain Events (past tense)
   "Abastecimento Validado", "Ciclo de Faturamento Fechado"
3. Blue stickies: Commands (what triggers events)
   "Validar Abastecimento", "Fechar Ciclo"
4. Yellow stickies: Aggregates (who handles commands)
   "Abastecimento", "CicloFaturamento"
5. Pink stickies: External Systems
   "Gateway Pagamento", "Emissor NF-e"
6. Group into Bounded Contexts

Example — ZECA Domain

┌─── Refueling Context ──────────────────────────┐
│ Events:                                         │
│   RefeuelingCodeGenerated                       │
│   RefuelingValidated                            │
│   RefuelingCancelled                            │
│ Aggregates:                                     │
│   RefuelingCode, Refueling                      │
│ Commands:                                       │
│   GenerateCode, ValidateRefueling, CancelCode   │
└─────────────────────────────────────────────────┘

┌─── Billing Context ────────────────────────────┐
│ Events:                                         │
│   BillingCycleOpened                            │
│   FeeCalculated                                 │
│   CycleClosed                                   │
│   InvoiceGenerated                              │
│ Aggregates:                                     │
│   BillingCycle, Invoice                         │
│ Commands:                                       │
│   CalculateFee, CloseCycle, GenerateInvoice     │
└─────────────────────────────────────────────────┘

Bounded Contexts

Rules:
1. Each context owns its data (no shared database tables)
2. Same word can mean different things in different contexts
   "User" in Auth = credentials + session
   "User" in Billing = payment info + billing address
3. Communication between contexts via events or APIs
4. One team per context (ideally)

Read the full file on GitHub · 201 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. 9d ago First seen · 201 lines · 24 tokens per session scan A 09abd96ab992

Subscribe to this mod's changes

domain-modeling is a skill published in the GitHub repository camilooscargbaptista/cto-toolkit (7 stars, last pushed 5mo ago), licensed MIT. It adds 24 tokens to every session and 1,346 once invoked, about $0.0001 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 2026-08-31.

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