Template Instantiation Agent Skill

Template Instantiation

This skill creates .NET projects from templates using dotnet new CLI commands, with guidance for parameter validation, Central Package Management adaptation, and multi-project composition.

> Match the workspace, then stop. The highest-value move is aligning the new project with the repo it lands in: detect CPM (Directory.Packages.props) and the target framework used by neighbouring .csproj files, and mirror both. Treat the discovered target framework as an explicit choice — pass it as --framework so template-smart-defaults won't override it; deviate only when it's incompatible with a requested feature (then flag the conflict). Do this in as few steps as possible — a --dry-run, the create, and one dotnet build to confirm is usually enough. Extra exploratory turns add cost without improving the result.

When to Use

• User asks to create a new .NET project, app, or service
• User needs a solution with multiple projects (API + tests + library)
• User wants to create a project that respects existing Directory.Packages.props
• User needs to install or manage template packages

When Not to Use

• User is searching for templates — route to template-discovery skill; for a detailed side-by-side comparison — route to template-comparison skill
• User wants to author a custom template — route to template-authoring skill
• User wants to add packages to an existing project — use dotnet add package directly

Inputs

| Input | Required | Description |

|-------|----------|-------------|

| Template name or intent | Yes | Template short name (e.g., webapi) or natural-language description |

| Project name | Yes | Name for the created project |

| Output path | Recommended | Directory where the project should be created |

| Parameters | No | Template-specific parameters (e.g., --framework, --auth, --aot) |

Workflow

Step 1: Resolve template and parameters

If the user provides a natural-language description, map it to a template short name (see the keyword table in the template-discovery skill). If they provide a template name, proceed directly.

Use dotnet new <template> --help to review available parameters, defaults, and types for any parameters the user did not specify.

When a parameter the user chose implies a value for an unset *related* parameter, invoke the template-smart-defaults skill to resolve the gap before assembling the command line — e.g., native AOT implies a recent AOT-capable target framework, a non-None --auth choice means HTTPS must stay enabled (don't add --no-https), and --use-controllers excludes the minimal-API option. Smart defaults only fill gaps; never let them override a value the user set explicitly. The workspace framework discovered in Step 2 counts as such an explicit value — pass it to smart-defaults as the chosen --framework so it isn't treated as an unset gap; deviate only if it is incompatible with the requested feature/template (then surface the conflict to the user).

Step 2: Analyze the workspace

Check the existing solution structure before creating:

• Is Central Package Management (CPM) enabled? Look for Directory.Packages.props
• What target frameworks are in use? Check existing .csproj files
• Is there a global.json pinning the SDK?

This ensures the new project is consistent with the workspace.

Step 3: Preview the creation

Use dotnet new <template> --dry-run to show the user what files would be created. Confirm before proceeding.

dotnet new webapi --name MyApi --framework net10.0 --dry-run

Step 4: Create the project

Use dotnet new with the template name and all parameters:

dotnet new webapi --name MyApi --output ./src/MyApi --framework net10.0 --auth Individual

Common parameter combinations

| Template | Parameters | Example |

|----------|-----------|---------|

| webapi | --auth (None, Individual, SingleOrg, Windows), --aot (native AOT) | dotnet new webapi -n MyApi --auth Individual --aot |

| webapi | --use-controllers (use controllers vs minimal APIs) | dotnet new webapi -n MyApi --use-controllers |

| blazor | --interactivity (None, Server, WebAssembly, Auto), --auth | dotnet new blazor -n MyApp --interactivity Server |

| grpc | --aot (native AOT) | dotnet new grpc -n MyService --aot |

| worker | --aot (native AOT) | dotnet new worker -n MyWorker --aot |

Note: Use dotnet new <template> --help to see all available parameters for any template.

After creation, adapt the project to Central Package Management and refresh stale versions:

• Detect CPM — walk up the directory tree from the new project looking for a Directory.Packages.props.
• Strip inline versions — if found, for each <PackageReference Include="X" Version="Y" /> the template generated, remove the Version attribute from the .csproj (leaving <PackageReference Include="X" />).
• Centralize the version — add or merge a <PackageVersion Include="X" Version="Y" /> entry in Directory.Packages.props.
• Optionally refresh stale template-default versions — templates often hardcode old versions. Keep the template's versions by default (safest for reproducibility and controlled upgrades). Only refresh when the user asks, and when you do:
• Prefer a tooling-driven flow: run dotnet list package --outdated and confirm the proposed bumps with the user before changing anything.
• Constrain upgrades to the same major (or major/minor) version unless the user explicitly opts into larger upgrades, since cross-major bumps can introduce breaking changes.
• When checking the latest stable version of a package conceptually, the NuGet V3 flat-container index.json endpoint for that package ID lists published versions; never select a prerelease unless requested.
• Build — run dotnet build to confirm the centralized/refreshed versions resolve.

Step 5: Multi-project composition (optional)

For complex structures, create each project sequentially and wire them together:

dotnet new webapi --name MyApi --output ./src/MyApi
dotnet new xunit --name MyApi.Tests --output ./tests/MyApi.Tests
dotnet add ./tests/MyApi.Tests reference ./src/MyApi
dotnet sln add ./src/MyApi ./tests/MyApi.Tests

Step 6: Template package management

Install or uninstall template packages:

dotnet new install Microsoft.DotNet.Web.ProjectTemplates.10.0
dotnet new uninstall Microsoft.DotNet.Web.ProjectTemplates.10.0

Step 7: Post-creation verification

• Verify the project builds: dotnet build
• If added to a solution, verify dotnet build at the solution level
• If CPM was adapted, verify Directory.Packages.props has the new entries

Validation

• [ ] Project was created successfully with the expected files
• [ ] Project builds cleanly with dotnet build
• [ ] If CPM is active, .csproj has no version attributes and Directory.Packages.props has matching entries
• [ ] Package versions in the project are current (not stale template defaults)
• [ ] If multi-project, all projects build and reference each other correctly

Common Pitfalls

| Pitfall | Solution |

|---------|----------|

| Not checking for CPM before creating a project | If Directory.Packages.props exists, dotnet new creates projects with inline versions that conflict. After creation, move versions to Directory.Packages.props and remove them from .csproj. |

| Creating projects without specifying the framework | Always specify --framework when the template supports multiple TFMs to avoid defaulting to an older version. |

| Not adding the project to the solution | After creation, run dotnet sln add to include the project in the solution. |

| Not verifying the project builds | Always run dotnet build after creation to catch missing dependencies or parameter issues early. |

More Info

• Central Package Management — CPM documentation
• dotnet new — CLI reference