add-entity

add-entity is a skill for Claude Code from SSWConsulting/SSW.VerticalSliceArchitecture. It costs 116 tokens per session (1,740 once invoked), scanned A, original, MIT.

A workflow for adding a persisted domain entity—an important business object stored by the application—to a Vertical Slice Architecture project. It includes the related identifier, database mapping, registration, and migration.

In plain words
What is it for?
Use it when adding an entity or aggregate to the project's domain model. It helps create its ID, errors, database configuration, database set, converter registration, and migration.
Why use it?
In this project, an entity requires changes in several places, and missing one can cause build or startup failures. The workflow helps keep those pieces together.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

Good fit Use it when adding an entity or aggregate to the project's domain model. It helps create its ID, errors, database configuration, database set, converter registration, and migration.

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Install with agentmods
npx agentmods add skills/sswconsulting/ssw.verticalslicearchitecture/add-entity
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 SSWConsulting/SSW.VerticalSliceArchitecture --skill add-entity
Clone the repo
git clone --depth 1 https://github.com/SSWConsulting/SSW.VerticalSliceArchitecture

Made for: Claude Code.

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 add-entity

README.md
[![agentmods](https://agentmods.dev/badge/skills/sswconsulting/ssw.verticalslicearchitecture/add-entity.svg)](https://agentmods.dev/skills/sswconsulting/ssw.verticalslicearchitecture/add-entity)
Your own site
<a href="https://agentmods.dev/skills/sswconsulting/ssw.verticalslicearchitecture/add-entity"><img src="https://agentmods.dev/badge/skills/sswconsulting/ssw.verticalslicearchitecture/add-entity.svg" alt="Measured on agentmods" height="20"></a>
Per session 116 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,740 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Agent Snooping · line 81
    Skill reads from agent configuration directories (.claude/, .codex/, .gemini/). These directories may contain API keys, personal settings, and other credentials that the skill has no legitimate need to access.
    Fix: Remove all code or instructions that access agent configuration directories (.claude/, .codex/, .gemini/). If configuration values are needed, pass them explicitly as parameters or environment variabl
How audits are shown
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 $0.00116 $0.01740
Opus 5 $0.00058 $0.00870
Sonnet 5 $0.00023 $0.00348
Haiku 4.5 $0.00012 $0.00174

Measured 8d ago against content hash 8453e148cd2a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

add-entity 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 8d 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.

.claude/skills/add-entity/SKILL.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Add an Entity

A new persisted domain type in this template is never one file. It's a domain object, a strongly typed ID, an EF configuration, a DbSet, a converter registration, and a migration — spread across two folders. Miss one and you get anything from a compile error to an app that won't start.

The trap this skill exists to close

Every strongly typed ID must be registered in src/WebApi/Common/Persistence/VogenEfCoreConverters.cs.

Forget it and nothing complains at compile time. dotnet build is green, the architecture tests are green, and the app throws on startup when EF Core tries to map a HeroId it has no converter for. That is the single most expensive thing to forget in this repo, so step 5 below is not optional and the verification step checks for it explicitly.

Read the live reference first

Before generating anything, read the canonical aggregate and its persistence wiring:

  • src/WebApi/Common/Domain/Heroes/Hero.cs — aggregate root, Vogen ID, field-keyword setter guards
  • src/WebApi/Common/Domain/Teams/Team.cs — an aggregate that returns ErrorOr<Success> from behaviour
  • src/WebApi/Common/Persistence/Heroes/HeroConfiguration.cs — EF configuration
  • src/WebApi/Common/Persistence/VogenEfCoreConverters.cs — the registration list

The templates in references/ follow these files, but the repo is the source of truth. If the two disagree, the repo wins — follow it and update the template (see Keeping this skill honest at the bottom).

One deliberate divergence: the aggregate template gives properties a private set plus a named mutator, following Team.cs. Hero.cs uses a public set instead, so UpdateHeroEndpoint can assign hero.Name directly. Both keep the guard in the setter, which is the part that matters; prefer the Team.cs shape for new work, because it keeps the aggregate in charge of how it changes.

What you need to know before scaffolding

Ask the user for anything not already stated:

Input Notes
Entity name Singular, PascalCase (Hero, Mission). The folder and pluralised DbSet derive from it.
Aggregate or child entity? Aggregate root if it's the transactional boundary or raises domain events. Child entity if it only ever lives inside another aggregate (Mission inside Team).
Owning aggregate For a child entity — which aggregate holds it, and via what collection.
Properties Name, type, required/optional, and a max length for every string.
Behaviour The methods that mutate it. Guards go in the property setter, business rules go in the method.
Domain events Does any mutation need to trigger work elsewhere? Aggregate roots only.

Read the full file on GitHub · 94 lines

Files

What ships with it

2 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.

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. 8d ago First seen · 94 lines · 116 tokens per session scan A 8453e148cd2a

Subscribe to this mod's changes

add-entity is a skill published in the GitHub repository SSWConsulting/SSW.VerticalSliceArchitecture (398 stars, last pushed 1mo ago), licensed MIT. It adds 116 tokens to every session and 1,740 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 2026-08-30.

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