SSW.VerticalSliceArchitecture: Instructions file for Claude Code

CLAUDE.md

SSW.VerticalSliceArchitecture CLAUDE.md is an instructions file for Claude Code from SSWConsulting/SSW.VerticalSliceArchitecture. It costs 1,020 tokens per session, scanned A, original, MIT.

Project instructions for a .NET template using Vertical Slice Architecture, where each use case keeps its related code in one feature folder. They describe its web API, database, local orchestration, validation, and testing tools.

In plain words
What is it for?
Adding web-API features, organizing domain and infrastructure code, defining endpoints and validation, and running integration tests against a real SQL Server.
Why use it?
They explain the project’s architectural rules and technology choices so changes fit the intended feature-folder structure and testing setup.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: reads .claude/ paths; mentions Claude Code.

This is SSWConsulting/SSW.VerticalSliceArchitecture's own configuration. It tells Claude Code how to work on SSW.VerticalSliceArchitecture itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything SSW.VerticalSliceArchitecture configures →

Reuse

Borrowing it

Nothing to install: this file belongs to SSWConsulting/SSW.VerticalSliceArchitecture. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/SSWConsulting/SSW.VerticalSliceArchitecture/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/SSWConsulting/SSW.VerticalSliceArchitecture

Made for: Claude Code.

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Origin original No closer match found in the catalogue.
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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 $0.01020 $0.01020
Opus 5 $0.00510 $0.00510
Sonnet 5 $0.00204 $0.00204
Haiku 4.5 $0.00102 $0.00102

Measured 8d ago against content hash 4bc12b6e0cb9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

SSW.VerticalSliceArchitecture CLAUDE.md 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.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SSW Vertical Slice Architecture — Agent Instructions

Project Overview

A template for .NET 10 + Vertical Slice Architecture + Aspire. Each use case is a self-contained vertical slice in its own folder under src/WebApi/Features/{Feature}/, shared domain types sit in src/WebApi/Common/Domain/, and infrastructure (EF Core, middleware, services) lives in src/WebApi/Common/. Terms are defined in CONTEXT.md.

Technology Stack

  • .NET 10, ASP.NET Core, EF Core (SQL Server)
  • FastEndpoints — HTTP endpoints with strongly-typed request/response
  • Aspire — local orchestration, observability, service discovery
  • Vogen — strongly typed IDs
  • Ardalis.Specification — query specs
  • ErrorOr + FluentValidation — result & input handling
  • Bogus — dev seed data
  • xUnit + Testcontainers + Respawn — integration tests against a real SQL Server

Rules

Detailed conventions are in .claude/rules/ (auto-loaded by Claude Code when matching files are in scope):

File Covers
architecture.md VSA slice layout, FastEndpoints conventions, groups, error handling
domain.md entities, aggregates, value objects, specs, strongly typed IDs, domain events
database.md adding entities, migration commands, seeding
testing.md unit, integration, and architecture test projects
dependencies.md NuGet audit (NU1903) failures, transitive pinning, verifying pins
verification.md what "done" means: Debug + Release builds, all test projects, Aspire boot + health, REST smoke checks

Skills

The rules describe the conventions; the skills in .claude/skills/ run them. Invoke one by name in Claude Code (/add-slice) or read its SKILL.md directly — the references/ folder beside each holds the code templates.

Skill Does
add-entity Domain object, strongly typed ID, errors, spec, EF configuration, DbSet, the VogenEfCoreConverters registration, and the migration
add-slice One use case in its own folder — endpoint, request, response, validator, summary — plus the Feature and Group when it's the first slice, and its tests
add-adr An Architectural Decision Record in docs/adr/ following the repo's Log4brains conventions
aspire Operating the AppHost through the Aspire CLI — start, wait, inspect resources, read logs and traces
bump-version Cuts a template release by bumping the version in VerticalSliceArchitecture.nuspec

Read the full file on GitHub · 80 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. 8d ago First seen · 80 lines · 1,020 tokens per session scan A 4bc12b6e0cb9

Subscribe to this mod's changes

SSW.VerticalSliceArchitecture CLAUDE.md is an instructions file published in the GitHub repository SSWConsulting/SSW.VerticalSliceArchitecture (398 stars, last pushed 1mo ago), licensed MIT. It adds 1,020 tokens to every session, about $0.0051 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.