feat(templates): add Orleans application templates

[ReubenBond]

Problem

Orleans documents the core APIs and project setup, but it has no Microsoft-maintained dotnet new templates for the common application layouts requested in #7184. Developers must reproduce a multi-project solution or co-hosted web setup manually, which makes the first successful application harder to repeat consistently.

Solution

Add the Microsoft.Orleans.Templates package with two maintained templates:

• orleans creates separate grain contracts, grain implementations, silo, and external client projects
• orleans-web creates an ASP.NET Core application which co-hosts an Orleans silo and calls a grain from an HTTP endpoint

Both templates support .NET 10 and .NET 8, centralize Orleans package versions, expose an Orleans version option, restore generated projects, and start with localhost clustering for development. The first-application and client guides now provide concrete template-driven recipes and link production configuration guidance.

Rationale

Keeping templates in this repository lets the solution build and release them with Orleans while keeping generated code aligned with maintained documentation. The documentation changes complement the how-to index in #10554 without duplicating or modifying its navigation scope.

Fixes #7184
Fixes #7479

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull request overview

This PR adds a new Microsoft.Orleans.Templates NuGet package to the Orleans repo, providing Microsoft-maintained dotnet new templates for common Orleans application layouts, and updates the docs to reference these templates as an on-ramp for new apps.

Changes:

• Add the orleans multi-project solution template (contracts, grains, silo, external client) with centralized package versions and restore post-actions.
• Add the orleans-web ASP.NET Core co-hosted silo template with a minimal HTTP endpoint calling a grain.
• Update quickstart/client documentation to include template-based commands alongside existing manual setup guidance.

Show a summary per file

File	Description
templates/Microsoft.Orleans.Templates/templates/orleans/README.md	Usage/readme for the multi-project orleans template.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.slnx	Solution template grouping the generated projects.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Silo/Program.cs	Minimal silo host using localhost clustering.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Silo/OrleansApp.Silo.csproj	Silo project definition and dependencies.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Grains/OrleansApp.Grains.csproj	Grains project definition and dependencies.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Grains/HelloGrain.cs	Example grain implementation.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Contracts/OrleansApp.Contracts.csproj	Contracts project definition and dependencies.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Contracts/IHelloGrain.cs	Example grain interface.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Client/Program.cs	Minimal external client which calls the grain.
templates/Microsoft.Orleans.Templates/templates/orleans/OrleansApp.Client/OrleansApp.Client.csproj	Client project definition and dependencies.
templates/Microsoft.Orleans.Templates/templates/orleans/Directory.Packages.props	Central package management for the orleans template.
templates/Microsoft.Orleans.Templates/templates/orleans/.template.config/template.json	Template metadata and parameters (framework, Orleans version, restore).
templates/Microsoft.Orleans.Templates/templates/orleans/.template.config/dotnetcli.host.json	CLI parameter mapping for the orleans template.
templates/Microsoft.Orleans.Templates/templates/orleans-web/README.md	Usage/readme for the orleans-web template.
templates/Microsoft.Orleans.Templates/templates/orleans-web/Properties/launchSettings.json	Launch profile for consistent local URL.
templates/Microsoft.Orleans.Templates/templates/orleans-web/Program.cs	Minimal ASP.NET Core app co-hosting a silo and exposing /hello/{name}.
templates/Microsoft.Orleans.Templates/templates/orleans-web/OrleansWebApp.csproj	Web project definition and dependencies.
templates/Microsoft.Orleans.Templates/templates/orleans-web/IHelloGrain.cs	Example grain interface for the web template.
templates/Microsoft.Orleans.Templates/templates/orleans-web/HelloGrain.cs	Example grain implementation for the web template.
templates/Microsoft.Orleans.Templates/templates/orleans-web/Directory.Packages.props	Central package management for the orleans-web template.
templates/Microsoft.Orleans.Templates/templates/orleans-web/.template.config/template.json	Template metadata and parameters (framework, Orleans version, restore).
templates/Microsoft.Orleans.Templates/templates/orleans-web/.template.config/dotnetcli.host.json	CLI parameter mapping for the orleans-web template.
templates/Microsoft.Orleans.Templates/README.md	Package-level README describing installation and template usage.
templates/Microsoft.Orleans.Templates/Microsoft.Orleans.Templates.csproj	Packable template NuGet project configuration and content inclusion.
Orleans.slnx	Adds the templates project to the main solution.
docs/site/src/content/docs/quickstarts/build-your-first-orleans-app.md	Adds template-driven “fast path” commands to the first-app tutorial.
docs/site/src/content/docs/host/client.md	Adds a template-driven ASP.NET Core co-hosted client example.

Review details

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• Files reviewed: 27/27 changed files
• Comments generated: 2
• Review effort level: Lite

[Copilot]

Review details

• Files reviewed: 27/27 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

Review details

• Files reviewed: 30/30 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (2)

Previously missed (2) — in code that hasn't changed since the last review.

docs/site/src/content/docs/quickstarts/build-your-first-orleans-app.md:42

• The quickstart states that the tutorial uses localhost clustering and omits durable storage, but this new template callout describes the orleans template using Azurite-backed Azure Storage resources (and it also requires a container runtime). This can confuse readers who expect the template to match the tutorial’s “localhost/no durable storage” setup. Consider explicitly calling out that difference here.

The `Microsoft.Orleans.Templates` package creates this layout and adds an Aspire AppHost that orchestrates the silo, client, and Azurite-backed Azure Storage resources:

```dotnetcli
dotnet new install Microsoft.Orleans.Templates
dotnet new orleans --name OrleansHelloWorld --output OrleansHelloWorld

templates/Microsoft.Orleans.Templates/README.md:35

• The package README mentions that the orleans template uses Azurite-backed Azure Storage, but it doesn’t mention that running the generated AppHost requires a container runtime so Aspire can start Azurite (as noted in the per-template README). Adding that requirement here would help avoid a confusing first-run failure.

The `orleans` template uses the Aspire Orleans integration to orchestrate the silo, client, and Azurite-backed Azure Table clustering and Azure Blob grain storage. The `orleans-web` template uses localhost clustering for a one-node local development host. See the [Orleans hosting documentation](https://dotnet.github.io/orleans/docs/host/configuration-guide/) for production configuration guidance.

• Files reviewed: 30/30 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

templates/Microsoft.Orleans.Templates/templates/orleans/Directory.Packages.props:15

• The template supports --framework net8.0 (see .template.config/template.json), but Directory.Packages.props hard-pins Microsoft.Extensions.Hosting to 10.0.9. That makes the generated output’s package graph independent of the selected target framework and can break restores/compatibility when targeting .NET 8.

Consider pinning Microsoft.Extensions.Hosting to an 8.x version which is compatible with both net8.0 and net10.0 (as used elsewhere in this repo), or making the version conditional on the framework template parameter.

    <PackageVersion Include="Aspire.Hosting.Azure.Storage" Version="$(AspireVersion)" />
    <PackageVersion Include="Aspire.Hosting.Orleans" Version="$(AspireVersion)" />
    <PackageVersion Include="Microsoft.Extensions.Hosting" Version="10.0.9" />
    <PackageVersion Include="Microsoft.Orleans.Client" Version="$(OrleansVersion)" />

• Files reviewed: 30/30 changed files
• Comments generated: 0 new
• Review effort level: Lite