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 OKHP3/skillz --skill ddd-best-practicesgit clone --depth 1 https://github.com/OKHP3/skillzWrote 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/okhp3/skillz/ddd-best-practices)<a href="https://agentmods.dev/skills/okhp3/skillz/ddd-best-practices"><img src="https://agentmods.dev/badge/skills/okhp3/skillz/ddd-best-practices/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/okhp3/skillz/ddd-best-practices"><img src="https://agentmods.dev/badge/skills/okhp3/skillz/ddd-best-practices.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 | $0.00114 | $0.02066 |
| Opus 5 | $0.00057 | $0.01033 |
| Sonnet 5 | $0.00023 | $0.00413 |
| Haiku 4.5 | $0.00011 | $0.00207 |
Grade A, and why
ddd-best-practices 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.
DDD Best Practices
Use this skill when the main question is how to model a domain, where to draw boundaries, or how to structure collaboration between subdomains.
Working Style
- Start from the domain problem, not from technical constructs.
- Build a Ubiquitous Language before writing any code.
- Keep Aggregates small — consistency boundary, not convenience grouping.
- Prefer Value Objects when a domain concept has value semantics, not as a blanket wrapper for every primitive.
- Let Domain Events tell the story of what happened, not what to do next.
- Never let infrastructure concerns leak into the domain model.
Design Workflow
-
Discover the domain.
- Who are the domain experts? What language do they use?
- What are the core subdomains (Core, Supporting, Generic)?
- Where does the most complex business logic live?
-
Draw Bounded Contexts.
- One model per context — resist the urge to share models across contexts.
- Name each context after a team or capability, not a technical layer.
- Define context relationships explicitly (Partnership, Customer-Supplier, Anti-Corruption Layer, etc.).
-
Design Aggregates.
- Start from one business command and state the invariants it must preserve.
- Include only state that must commit or reject atomically.
- Each Aggregate has one root Entity that controls access.
- Reference other Aggregates by identity and make eventual consistency explicit.
- Check lifecycle, cardinality, contention, and concurrency; table count does not define the boundary.
-
Model with tactical patterns.
- Entity: has identity that persists over time.
- Value Object: defined by its attributes; value equality; immutable by default; no identity.
- Domain Service: stateless logic that doesn't belong to any single Entity.
- Domain Event: records that something significant happened.
- Repository: collection-like access to Aggregates.
- Factory: encapsulates complex construction.
What ships with it
13 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/aggregates.md 12 KB
- references/context-mapping.md 18 KB
- references/cqrs-and-events.md 23 KB
- references/ddd-in-practice.md 38 KB
- references/domain-errors.md 9.1 KB
- references/domain-events.md 7.7 KB
- references/go-ddd-examples.md 11 KB
- references/hexagonal-architecture.md 33 KB
- references/read-models.md 17 KB
- references/repositories.md 11 KB
- references/strategic-design.md 15 KB
- references/tactical-patterns.md 31 KB
- references/typescript-ddd-examples.md 26 KB
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.
- 6d ago First seen · 135 lines · 114 tokens per session scan A e59838a5d904
ddd-best-practices is a skill published in the GitHub repository OKHP3/skillz (3 stars, last pushed yesterday), licensed MIT. It adds 114 tokens to every session and 2,066 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 2026-09-03.
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