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 nWave-ai/nWave --skill nw-fp-domain-modelinggit clone --depth 1 https://github.com/nWave-ai/nWaveWrote 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/nwave-ai/nwave/nw-fp-domain-modeling)<a href="https://agentmods.dev/skills/nwave-ai/nwave/nw-fp-domain-modeling"><img src="https://agentmods.dev/badge/skills/nwave-ai/nwave/nw-fp-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.
<a href="https://agentmods.dev/skills/nwave-ai/nwave/nw-fp-domain-modeling"><img src="https://agentmods.dev/badge/skills/nwave-ai/nwave/nw-fp-domain-modeling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00023 | $0.02057 |
| Opus 5 | $0.00012 | $0.01028 |
| Sonnet 5 | $0.00005 | $0.00411 |
| Haiku 4.5 | $0.00002 | $0.00206 |
Grade A, and why
nw-fp-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 7d 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 — 267 lines — stays where its author put it; the contents beside it link to each section on GitHub.
FP Domain Modeling
Domain modeling with types. Make illegal states unrepresentable, workflows as pipelines, error handling at the type level.
Cross-references: fp-principles | fp-hexagonal-architecture | fp-algebra-driven-design
1. The Two Building Blocks
[STARTER]
All domain types compose from two operations:
- AND (Record Types): Value has ALL of these fields. Order requires CustomerInfo AND ShippingAddress AND OrderLines.
- OR (Choice Types): Value is ONE OF these alternatives. ProductCode is either WidgetCode OR GizmoCode.
Combined recursively, these express virtually any domain structure.
2. Domain Wrappers for Primitives
[STARTER]
Never use primitives directly in the domain model. Each domain concept gets its own wrapper type.
What: Wrap primitives so the compiler distinguishes CustomerId from OrderId. When: Every primitive with domain meaning. Why: Prevents accidental mixing (compiler rejects comparing CustomerId with OrderId). Each wrapper carries its own validation rules. The type name IS the documentation.
3. Validated Construction (Smart Constructors)
[STARTER]
Raw constructor is private. A create function validates input and returns a Result type, making validation failure explicit.
Pattern: UnitQuantity must be between 1 and 1000. Its create function rejects values outside that range. A companion value function provides read access to the inner primitive.
When: Every domain wrapper with validation rules. Why: Once constructed, a value is guaranteed valid. No defensive checks deeper in the code.
4. Making Illegal States Unrepresentable
[STARTER]
The central design guideline. Instead of flags and runtime checks, model the domain so invalid states cannot be constructed.
Replace Flags with Distinct Types
Instead of { EmailAddress; IsVerified: bool }, create separate VerifiedEmailAddress and UnverifiedEmailAddress types. Functions requiring verification take VerifiedEmailAddress, making misuse a compile error.
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.
- 7d ago First seen · 267 lines · 23 tokens per session scan A 10f78944b4f9
nw-fp-domain-modeling is a skill published in the GitHub repository nWave-ai/nWave (610 stars, last pushed 5d ago), licensed MIT. It adds 23 tokens to every session and 2,057 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 2026-09-03.
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