Template Authoring

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

Workflow

Rules that change the answer

Use these structures exactly; do not invent fields from other template features.

Deliver the requested artifact. When the user says "show", "write", or "give me the content", put the complete JSON/XML in the final response even if you also wrote it to disk. Never edit this skill's SKILL.md or plugin documentation as a substitute for authoring the user's template. Only create or modify template files when the user requested file changes and the target template/project is present.

Step 1: Bootstrap from existing project

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

1. Copy the source project into a dedicated template-source directory by default, preserving the original project untouched. Modify the original in place only when the user explicitly asks for that layout.
2. Create .template.config inside the template-source directory.
3. Generate template.json with identity (reverse-DNS), name, shortName, sourceName (project name for replacement), classifications, and tags
4. 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.

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.