/template-comparison

name: template-comparison
description: >
  Compares two or more dotnet new templates side by side to help users choose between
  them based on parameters, feature support, frameworks, and classifications.
  USE FOR: deciding between similar templates (webapi vs webapp, blazor vs
  blazorwasm, console vs worker), producing a side-by-side comparison of parameters and
  feature support, understanding how templates differ before creating a project.
  DO NOT USE FOR: creating a project from a template (use template-instantiation),
  authoring or validating custom templates (use template-authoring and template-validation),
  general single-template discovery (use template-discovery).
license: MIT

Template Comparison

This skill helps an agent compare 2+ `dotnet new` templates side by side so the user can pick the right one. It inspects each template's parameters and feature support and renders a comparison table.

When to Use

• User is deciding between similar templates (e.g., `webapi` vs `webapp`, `blazor` vs `blazorwasm`)
• User asks "which template should I use for X?"
• User wants to understand how two or more templates differ before creating a project

When Not to Use

• User wants to create a project — route to `template-instantiation`
• User wants to author or validate a custom template — route to `template-authoring` or `template-validation`
• User just needs to find or inspect a single template — route to `template-discovery`

Inputs

| Input | Required | Description | |-------|----------|-------------| | Template short names | Yes | Two or more template short names to compare (e.g., `webapi`, `webapp`) | | Comparison focus | No | Optional aspect to emphasize (auth, AOT, frameworks, interactivity) |

Workflow

**Evidence contract:** a side-by-side table is useful only when every option claim is grounded in the currently installed templates. Run each `--help` command sequentially, capture the same requested dimensions for each template, and label an unavailable option as `Not exposed` rather than guessing or borrowing a flag from another template.

**Decision contract:** optimize the comparison for the user's stated decision, not table size. Cover every requested dimension, omit unrelated option rows, give a scenario-specific reason, and include one safe `--dry-run` command for the recommended starting point when it would make the recommendation actionable.

Step 1: Inspect each template

Run `dotnet new <template> --help` for each template being compared to collect its parameters (names, types, defaults, choices) and supported frameworks:

dotnet new webapi --help
dotnet new webapp --help

If a template is not installed, search for its provider and report the missing prerequisite. Install it only when the user asked you to modify the environment or approved the install.

> **Run `--help` calls sequentially.** The template engine uses a global mutex, so running > several `dotnet new <template> --help` commands concurrently can fail with a transient > "mutex"/"persistence" error and empty output. Inspect templates one at a time; if a call > fails, retry it once before moving on, and still produce the comparison from whatever > parameter knowledge you have rather than ending with no answer.

Step 2: Build the comparison table

Produce a side-by-side table covering:

• **Parameters** — name, type, default, choices
• **Feature support** — auth, AOT, Docker, controllers, interactivity
• **Available frameworks** — e.g., net8.0, net9.0, net10.0
• **Classifications** — categories the template advertises (Web, API, Blazor, etc.)

Use one row per requested decision dimension and cite the observed option name in the cell. Do not fill a requested row with general framework knowledge when it is specifically about what the template generates or exposes.

When the user asks about **generated dependencies** without allowing project creation, inspect the installed template package's source `.csproj` files. `--help` and `--dry-run` do not reveal package references. Do not create temporary projects merely to inspect them, and do not guess current package IDs or test-platform defaults.

Example shape:

| Aspect | `webapi` | `webapp` | |--------|----------|----------| | Auth (`--auth`) | None, Individual, SingleOrg, Windows | None, Individual, SingleOrg, ... | | AOT (`--aot` flag) | present if `dotnet new webapi --help` lists `--aot` | present if `dotnet new webapp --help` lists `--aot` | | Controllers (`--use-controllers`) | Yes | n/a | | Interactivity | n/a | n/a | | Frameworks | net8.0 / net9.0 / net10.0 | net8.0 / net9.0 / net10.0 | | Classifications | Web, WebAPI | Web, Razor Pages |

Step 3: Recommend

End with a decisive **Recommendation** line — never leave the user with just a table. Format:

> **Recommendation: `<template>`** — one sentence tying the choice to the user's stated scenario. (Pick the other if `<condition>`.)

Then link to `template-instantiation` to create it. A comparison that ends without naming a winner (or a clear "it depends on X") is incomplete — that indecision is what makes this skill tie with a plain answer.

Decision shortcuts for common pairs

Use these only for the recommendation, not as evidence of current parameter support. Still inspect with `--help` before filling the comparison table:

| Pair | Default pick | Because | |------|-------------|---------| | `webapi` vs `webapp` | **`webapi`** for a JSON/REST backend; `webapp` for server-rendered HTML/Razor Pages | webapi ships controllers/minimal APIs + OpenAPI, no UI | | `blazor` vs `blazorwasm` | **`blazorwasm`** when offline / no server is required; `blazor` (Web App) for flexible server + client interactivity | Standalone WASM runs fully client-side, works offline | | `worker` vs `console` | **`worker`** for long-lived/queue/background processing | Generic Host: DI, logging, config, graceful shutdown, `IHostedService` lifecycle | | `mvc` vs `webapp` | **`webapp`**