speckit.ddd

speckit.ddd is a skill for Claude Code, Codex from wedabro/bro-skills. It costs 33 tokens per session (601 once invoked), scanned A, original, MIT.

A specialist guide for Domain-Driven Design (DDD), a way to model software around complex business rules and the language used by domain experts. It covers business boundaries, aggregates, rules, events, and ownership.

In plain words
What is it for?
Use it to discover business terms and boundaries, define subdomains and bounded contexts, and model aggregates, invariants, events, and integration contracts when the domain is complex.
Why use it?
It helps teams avoid mixing different meanings or responsibilities and prevents complex patterns from being added to simple CRUD work.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it to discover business terms and boundaries, define subdomains and bounded contexts, and model aggregates, invariants, events, and integration contracts when the domain is complex.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/wedabro/bro-skills/speckit.ddd
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 wedabro/bro-skills --skill speckit.ddd
Clone the repo
git clone --depth 1 https://github.com/wedabro/bro-skills

Made for: Claude Code, Codex.

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 speckit.ddd

README.md
[![agentmods](https://agentmods.dev/badge/skills/wedabro/bro-skills/speckit.ddd/github.svg)](https://agentmods.dev/skills/wedabro/bro-skills/speckit.ddd)
Your own site
<a href="https://agentmods.dev/skills/wedabro/bro-skills/speckit.ddd"><img src="https://agentmods.dev/badge/skills/wedabro/bro-skills/speckit.ddd/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 speckit.ddd

Your own site · 80×15
<a href="https://agentmods.dev/skills/wedabro/bro-skills/speckit.ddd"><img src="https://agentmods.dev/badge/skills/wedabro/bro-skills/speckit.ddd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 601 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 $0.00033 $0.00601
Opus 5 $0.00016 $0.00300
Sonnet 5 $0.00007 $0.00120
Haiku 4.5 $0.00003 $0.00060

Measured 10d ago against content hash 64a6d12a36eb, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

speckit.ddd 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/skills/speckit.ddd/SKILL.md · 65 lines

How it starts

The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Mission

Use DDD only where domain complexity justifies it. Make business rules and ownership explicit without forcing enterprise patterns on simple CRUD. Pair with speckit.architecture for system decisions and speckit.backend for delivery.

Protocol

0. Suitability and Discovery

  • Confirm the problem has complex, evolving rules, competing meanings, or coordination costs. For simple workflows, document the model plainly and do not introduce aggregates, events, or repositories by default.
  • Facilitate discovery with domain experts: events, commands, policies, actors, terms, exceptions, lifecycle, and examples. Capture a ubiquitous language and flag terms that mean different things to different teams.

1. Strategic Design

  • Identify subdomains and classify core, supporting, and generic work. Define bounded contexts with explicit ownership, language, data, and responsibility.
  • Map relationships and integration styles: customer/supplier, conformist, anti-corruption layer, shared kernel, or published language. Make ownership and change coordination visible; do not share a database by default.
  • Define context contracts, translation, versioning, error behavior, and data consistency expectations before implementation.

2. Tactical Model

  • Model entities by identity, value objects by immutable meaning, aggregates by transactional consistency boundary, and domain services only for behavior that belongs to no entity/value object.
  • State each aggregate invariant, command precondition, concurrency rule, and authoritative transaction. Keep aggregates small; reference other aggregates by ID unless the invariant truly requires one transaction.
  • Publish domain events only after durable state change. Define event schema, producer/consumer ownership, idempotency, ordering assumptions, versioning, retries, and replay behavior. Use an outbox when database and event delivery must remain consistent.

3. Delivery and Validation

Read the full file on GitHub · 65 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 · 65 lines · 33 tokens per session scan A 64a6d12a36eb

Subscribe to this mod's changes

speckit.ddd is a skill published in the GitHub repository wedabro/bro-skills (2 stars, last pushed 14d ago), licensed MIT. It adds 33 tokens to every session and 601 once invoked, about $0.0002 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.