/template-authoring

name: template-authoring
description: >
  Guides creation and validation of custom dotnet new templates from existing projects.
  Generates a .template.config/template.json that preserves the source project's conventions.
  USE FOR: creating a reusable dotnet new template from an existing project, bootstrapping
  .template.config/template.json with correct identity, shortName, parameters, and
  post-actions, adding parameters or conditional content to a template you are authoring,
  validating the template.json you are authoring before publishing,
  packaging templates as NuGet packages for distribution.
  DO NOT USE FOR: validating an existing template.json as a standalone task (use
  template-validation), finding or using existing templates (use template-discovery and
  template-instantiation), MSBuild project file issues unrelated to template authoring,
  NuGet package publishing (only template packaging structure).
license: MIT

Template Authoring

This skill helps an agent create and validate custom `dotnet new` templates. It guides bootstrapping templates from existing projects and validates `template.json` files for authoring issues before publishing.

When to Use

• User wants to create a reusable template from an existing .csproj
• User wants to validate a template.json they are authoring before publishing
• User is setting up `.template.config/template.json` from scratch
• User wants to package a template for NuGet distribution

When Not to Use

• User wants to find or use existing templates — route to `template-discovery` or `template-instantiation`
• User has MSBuild issues unrelated to template authoring — route to `dotnet-msbuild` plugin

Inputs

| Input | Required | Description | |-------|----------|-------------| | Source project path | For creation | Path to the .csproj to use as template source | | template.json path | For validation | Path to an existing template.json to validate | | Template name | For creation | Human-readable name for the template | | Short name | Recommended | Short name for `dotnet new <shortname>` usage |

Workflow

Step 1: Bootstrap from existing project

Analyze the source `.csproj` and create a `.template.config/template.json`:

1. Create `.template.config` directory next to the project 2. Generate `template.json` with `identity` (reverse-DNS), `name`, `shortName`, `sourceName` (project name for replacement), `classifications`, and `tags` 3. Preserve from source — generic `dotnet new` templates frequently get these wrong, so verify each is carried over from the original `.csproj`: 1. **SDK type** — `Microsoft.NET.Sdk`, `Microsoft.NET.Sdk.Web`, `Microsoft.NET.Sdk.Worker`, etc. 2. **Analyzer/package reference metadata** — `PrivateAssets`, `IncludeAssets`, `ExcludeAssets` 3. **`OutputType` and other key properties** — `TreatWarningsAsErrors`, `Nullable`, `LangVersion` 4. **CPM participation** — no inline `Version` attributes when a `Directory.Packages.props` is present 5. **Custom build props/targets** and `Directory.Build.props` conventions 6. **Repo conventions** — folder layout, naming, `global.json` SDK pin

Minimal example:

{
  "$schema": "http://json.schemastore.org/template",
  "author": "MyOrg",
  "classifications": ["Library"],
  "identity": "MyOrg.Templates.MyLib",
  "name": "My Library Template",
  "shortName": "mylib",
  "sourceName": "MyLib",
  "tags": { "language": "C#", "type": "project" }
}

**Required output — do not stop at a minimal stub.** Write the *complete* `.template.config/template.json` for the actual source project, then emit a short **conventions-preserved** confirmation so the user can see nothing was silently dropped. This carry-over is the whole value of the skill; a generic `dotnet new` template that loses these is why authoring ties with a hand-written stub.

| Source `.csproj` setting | Carried over? | How | |--------------------------|---------------|-----| | SDK (`Microsoft.NET.Sdk.*`) | ✅ | template content `.csproj` uses same SDK | | `TreatWarningsAsErrors` / `Nullable` / `LangVersion` | ✅ | preserved verbatim in template `.csproj` | | PackageReference `PrivateAssets` / `IncludeAssets` / `ExcludeAssets` | ✅ | metadata kept on each reference | | CPM (`Directory.Packages.props` present) | ✅ | no inline `Version` attributes emitted |

Mark any row you intentionally omitted as ⚠️ with a reason — never leave it implicit.

Step 2: Validate template.json

Validate the generated `template.json` using the **template-validation** skill (it owns the full rule set — required fields, identity format, reserved shortName conflicts, parameter datatypes, post-actions, constraints, and tags).

Quick summary of what gets checked:

• **Required fields** — `identity`, `name`, and `shortName` must be present.
• **ShortName conflicts** — avoid names that collide with `dotnet new` subcommands. Read the authoritative set from the `Commands:` section of `dotnet new --help` for the installed SDK and do not hardcode it (it can change between versions); illustrative examples from current SDKs are `install`, `uninstall`, `update`, `list`, `search`, `details`, `create`. A conflict happens because `dotnet new <name>` would be parsed as the subcommand of the same name. Top-level `dotnet` verbs like `build`, `run`, `test`, and `publish` do NOT conflict. Run `dotnet new list` to confirm the name is not already taken.
• **Parameters, post-actions, tags** — see template-validation for the complete rules, including the valid datatype list.

Step 3: Refine the template

Based on validation results and user requirements:

1. **Add parameters** with appropriate types (string, bool, choice), defaults, and descriptions 2. **Add conditional content** using `#if` preprocessor directives for optional features 3. **Configure post-actions** for solution add, restore, or custom scripts 4. **Set constraints** to restrict which SDKs or workloads the template supports 5. **Add classifications** and