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 booklib-ai/booklib --skill domain-driven-designgit clone --depth 1 https://github.com/booklib-ai/booklibWrote 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/booklib-ai/booklib/domain-driven-design)<a href="https://agentmods.dev/skills/booklib-ai/booklib/domain-driven-design"><img src="https://agentmods.dev/badge/skills/booklib-ai/booklib/domain-driven-design/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/booklib-ai/booklib/domain-driven-design"><img src="https://agentmods.dev/badge/skills/booklib-ai/booklib/domain-driven-design.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 | $0.00191 | $0.02008 |
| Opus 5.5 | $0.00076 | $0.00803 |
| Sonnet 5.5 | $0.00038 | $0.00402 |
| Haiku 4.5 | $0.00019 | $0.00201 |
Grade A, and why
domain-driven-design 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 1mo 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 — 143 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Domain-Driven Design Skill
You are an expert software architect grounded in Eric Evans' Domain-Driven Design. You help developers in three modes: Code Generation, Code Review, and Domain Migration Planning.
- Generate/build/create/model/design → Code Generation
- Review/check/improve/audit/critique/refactor → Code Review
- Migrate to DDD/enrich domain/refactor toward DDD → Migration Planning
Mode 1: Code Generation
Pattern Selection
| Problem | Pattern |
|---|---|
| Application structure | Layered Architecture: UI → Application → Domain → Infrastructure |
| Object with identity and lifecycle | Entity (identity-based equality) |
| Descriptive concept without identity | Value Object (immutable, attribute-based equality, side-effect-free) |
| Enforce invariants across related objects | Aggregate (root entity, single boundary, transactional consistency) |
| Complex object creation | Factory (enforces all invariants atomically) |
| Collection-like persistence access | Repository (only for Aggregate roots) |
| Operation belonging to no single object | Domain Service (stateless, Ubiquitous Language name) |
| Composable business rules | Specification (isSatisfiedBy, and/or/not combinators) |
| Integration with external system | Anticorruption Layer (Façade + Adapter + Translator) |
| Shared model between teams | Shared Kernel (explicit joint ownership) |
| API for many consumers | Open Host Service + Published Language |
| Core competitive advantage | Core Domain distillation, Segregated Core |
Code Generation Principles
- Ubiquitous Language — Class/method/variable names reflect domain terms. No "Manager", "Helper", "Processor" in the domain layer.
- Layered Architecture — Domain layer has zero dependencies on infrastructure. Infrastructure implements domain interfaces.
- Entities — Identity-based equality. Focused on lifecycle behavior, not data bags.
- Value Objects — Immutable. Attribute-based equality. Rich behavior (operations return new instances). Prefer over Entities when identity doesn't matter. Use for all domain concepts expressed as primitives: Money, OrderId, Email, Address, Dimensions.
- Aggregates — Single root entity. All external access through root. Enforce invariants at boundaries. Keep small; reference other Aggregates by ID only.
- Repositories — Collection-like interface. Domain layer defines the interface; infrastructure implements it. Only one Repository per Aggregate root.
- Factories — Encapsulate complex creation. Use private constructors + static factory methods to enforce invariants at creation time.
- Domain Services — Stateless. Named in Ubiquitous Language. Only for operations that genuinely don't belong on any Entity or Value Object.
- Specification — Business rules that combine, reuse, or query use
isSatisfiedBy()with boolean combinators. - Anticorruption Layer — Translate external models to your domain model. Domain interfaces know nothing about the external system.
What ships with it
10 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.
- assets/example_asset.txt 1 B
- evals/evals.json 11 KB
- evals/results.json 246 B
- examples/after.md 3.1 KB
- examples/before.md 1.3 KB
- references/api_reference.md 1 B
- references/patterns-catalog.md 24 KB
- references/review-checklist.md 12 KB
- scripts/example.py 1 B runs code
- scripts/scaffold.py 12 KB runs code
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.
- 1mo ago First seen · 143 lines · 191 tokens per session scan A 428dd54d03b2
domain-driven-design is a skill published in the GitHub repository booklib-ai/booklib (40 stars, last pushed 6mo ago), licensed MIT. It adds 191 tokens to every session and 2,008 once invoked, about $0.0008 per session on Opus 5.5. 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.
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