Agent skill

Add Feature

by fullstackhero in fullstackhero/dotnet-starter-kit

Add a vertical-slice feature (command/query + handler + validator + endpoint) to an existing FSH module.

MITAuto-check passedDevelopment

Install Add Feature

skills CLI

$ npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install fullstackhero/dotnet-starter-kit add-feature --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/fullstackhero/dotnet-starter-kit.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/add-feature .claude/skills/add-feature && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "add-feature" agent skill from https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature into .claude/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install fullstackhero/dotnet-starter-kit add-feature --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/fullstackhero/dotnet-starter-kit.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/add-feature .agents/skills/add-feature && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "add-feature" agent skill from https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature into .agents/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install fullstackhero/dotnet-starter-kit add-feature --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/fullstackhero/dotnet-starter-kit.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/add-feature .cursor/skills/add-feature && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "add-feature" agent skill from https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature into .cursor/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/fullstackhero/dotnet-starter-kit.git --path .agents/skills/add-feature

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install fullstackhero/dotnet-starter-kit add-feature --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/fullstackhero/dotnet-starter-kit.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/add-feature .gemini/skills/add-feature && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "add-feature" agent skill from https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature into .gemini/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install fullstackhero/dotnet-starter-kit add-feature

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/fullstackhero/dotnet-starter-kit.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/add-feature .github/skills/add-feature && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "add-feature" agent skill from https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature into .github/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install fullstackhero/dotnet-starter-kit add-feature --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/fullstackhero/dotnet-starter-kit.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/add-feature .opencode/skills/add-feature && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "add-feature" agent skill from https://github.com/fullstackhero/dotnet-starter-kit/tree/main/.agents/skills/add-feature into .opencode/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: add-feature
GitHub stars: 6.8k
Token cost: ~1.1k tokens
SKILL.md length: 191 words
Files: 1
Skills in repo: 11
Repo updated: Sep 30, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Add a vertical-slice feature (command/query + handler + validator + endpoint) to an existing FSH module.

Works in 6 steps: Command/Query (Contracts project) → Handler (runtime Features/) — inject the… → Validator (required; same folder) → …
Adding an API endpoint
SKILL.md covers Layout (real), Step 1 — Command/Query…, Step 2 — Handler (runtime… and Step 3 — Validator (required;…, plus 4 more sections
Calls dotnet

What it does

Add Feature is an agent skill from fullstackhero/dotnet-starter-kit. Add a vertical-slice feature (command/query + handler + validator + endpoint) to an existing FSH module. Use when adding an API endpoint or business operation to a module that already exists.

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering REST APIs, Operations and SOPs and Project scaffolding. The repository describes itself as: Production Grade Cloud-Ready .NET 10 Starter Kit (Web API + React Client) with Multitenancy Support, and Clean/Modular Architecture that saves roughly 200+ Development Hours! All… The licence is MIT.

When your agent uses it

Adding an API endpoint
Business operation to a module that already exists

Example prompts

“/add-feature”

Workflow steps

6 steps, taken from the step headings in SKILL.md.

Command/Query (Contracts project)
Handler (runtime Features/) — inject the DbContext, NOT a repository
Validator (required; same folder)
Endpoint (same folder)
Wire it in {X}Module.MapEndpoints
Verify

What it can do on your machine

Read from SKILL.md and the folder at commit 0bd98e3. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- dotnet
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Add Feature loads about 1.1k tokens when it runs. Until then it costs about 51 tokens; SKILL.md has 191 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~51
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from fullstackhero/dotnet-starter-kit at commit 0bd98e3, republished under its MIT licence (© fullstackhero). 191 words, ~1,132 tokens.

Download SKILL.mdSave it as .claude/skills/add-feature/SKILL.md (or your agent's skills folder).

name: add-feature
description: Add a vertical-slice feature (command/query + handler + validator + endpoint) to an existing FSH module. Use when adding an API endpoint or business operation to a module that already exists.
argument-hint: [ModuleName] [Area] [FeatureName]

Add Feature

A feature is a vertical slice split across two projects: the request/response types live in the module's .Contracts project (public API); the handler, validator, and endpoint live in the runtime project. Full conventions: .agents/rules/api-conventions.md.

Layout (real)

src/Modules/{X}/Modules.{X}.Contracts/v1/{Area}/{Feature}Command.cs   # ICommand<T>/IQuery<T>
src/Modules/{X}/Modules.{X}.Contracts/Dtos/{Entity}Dto.cs             # response DTOs (if any)
src/Modules/{X}/Modules.{X}/Features/v1/{Area}/{Feature}/
├── {Feature}CommandHandler.cs    # public sealed, injects the DbContext directly
├── {Feature}CommandValidator.cs  # required for commands + paginated queries
└── {Feature}Endpoint.cs          # internal static extension

Step 1 — Command/Query (Contracts project)

Mediator interfaces (using Mediator;). Records. A create command can return the raw Guid.

csharp

namespace FSH.Modules.{X}.Contracts.v1.{Area};

public sealed record Create{Entity}Command(string Name, decimal PriceAmount, string PriceCurrency)
    : ICommand<Guid>;

Read/list DTOs go in Modules.{X}.Contracts/Dtos/. Paginated queries return PagedResponse<T> (FSH.Framework.Shared.Persistence) — see query-patterns.

Step 2 — Handler (runtime `Features/`) — inject the DbContext, NOT a repository

There is no generic IRepository<T>. Inject the module's {X}DbContext. public sealed, primary ctor, ValueTask<T>, .ConfigureAwait(false), guard first. Tenant/audit fields are auto-stamped — only inject ICurrentUser if you need the acting user (GetUserId() / GetTenant()).

csharp

public sealed class Create{Entity}CommandHandler(CatalogDbContext dbContext)
    : ICommandHandler<Create{Entity}Command, Guid>
{
    public async ValueTask<Guid> Handle(Create{Entity}Command command, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(command);

        var entity = {Entity}.Create(command.Name, new Money(command.PriceAmount, command.PriceCurrency));
        dbContext.{Entities}.Add(entity);
        await dbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        return entity.Id;
    }
}

Throw NotFoundException / CustomException(msg, errors, HttpStatusCode) (FSH.Framework.Core.Exceptions) — the global handler maps them to ProblemDetails.

Step 3 — Validator (required; same folder)

csharp

public sealed class Create{Entity}CommandValidator : AbstractValidator<Create{Entity}Command>
{
    public Create{Entity}CommandValidator()
    {
        RuleFor(x => x.Name).NotEmpty().MaximumLength(200);
        RuleFor(x => x.PriceCurrency).NotEmpty().Length(3);
    }
}

Architecture.Tests fails the build if a command/paginated-query handler has no {Name}Validator.

Step 4 — Endpoint (same folder)

csharp

public static class Create{Entity}Endpoint
{
    internal static RouteHandlerBuilder MapCreate{Entity}Endpoint(this IEndpointRouteBuilder endpoints) =>
        endpoints.MapPost("/{entities}",
                async (Create{Entity}Command command, IMediator mediator, CancellationToken ct) =>
                    Results.Ok(await mediator.Send(command, ct)))
            .WithName("Create{Entity}")
            .WithSummary("Create a {entity}")
            .RequirePermission({X}Permissions.{Entities}.Create)
            .WithIdempotency();   // on replay-safe POSTs
}

Step 5 — Wire it in `{X}Module.MapEndpoints`

csharp

group.MapCreate{Entity}Endpoint();   // group = endpoints.MapGroup("api/v{version:apiVersion}/{x}") …

Step 6 — Verify

bash

dotnet build src/FSH.Starter.slnx          # 0 warnings (TreatWarningsAsErrors)
dotnet test src/Tests/{X}.Tests            # + add a handler/validator test (see testing-guide)

Checklist

Command/Query in the Contracts project (using Mediator;), DTOs in Contracts/Dtos/
Handler public sealed, injects {X}DbContext (no repository), ValueTask<T> + .ConfigureAwait(false)
{Name}Validator exists
Endpoint internal static …Map{Feature}Endpoint, .RequirePermission(...), .WithName/.WithSummary
Wired in {X}Module.MapEndpoints
Build 0 warnings; test added

Files

Just SKILL.md in .agents/skills/add-feature of fullstackhero/dotnet-starter-kit.

Open the folder on GitHubat commit 0bd98e3

Compare with similar skills

Add Feature next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Add Feature compared with similar skills
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Create Datadriven Aspnetcoredotnet/skills	5.6k	1 repos	~3.2k	Automated safety check: Pass	MIT	today
Strands Reviewstrands-agents/harness-sdk	8.7k	—	~3.2k	Automated safety check: Pass	Apache-2.0	yesterday
Systematic Testingadam-s/intercept	189	—	~1.4k	Automated safety check: Pass	MIT	2 mo ago
Foundry Agent Syncgithub/awesome-copilot	40k	1 repos	~2.1k	Automated safety check: Pass	MIT	today
Project GeneratorLeoYeAI/openclaw-master-skills	2.2k	—	~4.5k	Automated safety check: Pass	MIT	2 mo ago

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Questions about Add Feature

What does Add Feature do?

Add a vertical-slice feature (command/query + handler + validator + endpoint) to an existing FSH module. Add Feature is an agent skill from fullstackhero/dotnet-starter-kit. Add a vertical-slice feature (command/query + handler + validator + endpoint) to an existing FSH module.

When should I use Add Feature?

Add Feature fits situations like: adding an API endpoint; business operation to a module that already exists.

How do I install Add Feature in Claude Code?

Run `npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a claude-code`. Or copy the skill folder (.agents/skills/add-feature in fullstackhero/dotnet-starter-kit) into .claude/skills/add-feature in your project. Claude Code loads it when a task matches its description.

How do I install Add Feature in Codex?

Run `npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a codex`. Or copy the skill folder (.agents/skills/add-feature in fullstackhero/dotnet-starter-kit) into .agents/skills/add-feature in your project. Codex loads it when a task matches its description.

Can I use Add Feature in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add fullstackhero/dotnet-starter-kit --skill add-feature -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/add-feature, .gemini/skills/add-feature, .github/skills/add-feature and .opencode/skills/add-feature in your project.

What does Add Feature need to run?

Going by SKILL.md and its folder, Add Feature needs the command-line tools its instructions call (dotnet).

Does Add Feature access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Add Feature safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Add Feature use?

Add Feature is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Add Feature use?

About 1.1k tokens (SKILL.md is roughly 4.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Add Feature?

Skills that share tags, products or a category with Add Feature: Create Datadriven Aspnetcore (dotnet/skills, 5.6k stars), Strands Review (strands-agents/harness-sdk, 8.7k stars), Systematic Testing (adam-s/intercept, 189 stars) and Foundry Agent Sync (github/awesome-copilot, 40k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Add Feature?

fullstackhero (a GitHub organization) maintains it in fullstackhero/dotnet-starter-kit, which has 6,813 GitHub stars. The repository holds 11 skills in this directory. The repository was last updated on September 30, 2026.

Source: fullstackhero/dotnet-starter-kit on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Add Feature

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Add Feature

Layout (real)

Step 1 — Command/Query (Contracts project)

Step 2 — Handler (runtime Features/) — inject the DbContext, NOT a repository

Step 3 — Validator (required; same folder)

Step 4 — Endpoint (same folder)

Step 5 — Wire it in {X}Module.MapEndpoints

Step 6 — Verify

Checklist

Files

Compare with similar skills

Similar skills

More from fullstackhero/dotnet-starter-kit

Related

Questions about Add Feature

Step 2 — Handler (runtime `Features/`) — inject the DbContext, NOT a repository

Step 5 — Wire it in `{X}Module.MapEndpoints`