Fix generating random MCP endpoint URL in templates

[JamesNK]

Description

ASPIRE_DASHBOARD_MCP_ENDPOINT_URL values had previously been added to template's launchSettings.json. However config wasn't added to templates to generate a random value for the endpoint when a template was created.

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue (consider using one of the following templates):
      • New (or update) doc-idea template
      • New breaking-change template
      • New diagnostic template
  • No

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 12558

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 12558"

[Copilot]

Pull Request Overview

This PR adds MCP (Model Context Protocol) endpoint configuration to Aspire project templates. MCP endpoints are configured similarly to existing OTLP endpoints with both HTTP and HTTPS variants.

• Adds port configuration parameters for MCP HTTP (18000) and HTTPS (23000) endpoints across all templates
• Updates template configuration files to support user-specified or auto-generated MCP ports
• Adds MCP endpoint environment variables to launch settings

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Aspire.ProjectTemplates/templates/aspire-starter/.template.config/template.json	Adds MCP HTTP/HTTPS port parameters with generation and coalescing logic
src/Aspire.ProjectTemplates/templates/aspire-starter/.template.config/dotnetcli.host.json	Hides MCP port parameters from CLI interface
src/Aspire.ProjectTemplates/templates/aspire-py-starter/13.0/apphost.run.json	Adds MCP endpoint environment variable configuration
src/Aspire.ProjectTemplates/templates/aspire-py-starter/.template.config/template.json	Adds MCP HTTP/HTTPS port parameters with generation and coalescing logic
src/Aspire.ProjectTemplates/templates/aspire-empty/.template.config/template.json	Adds MCP HTTP/HTTPS port parameters with generation and coalescing logic
src/Aspire.ProjectTemplates/templates/aspire-empty/.template.config/dotnetcli.host.json	Hides MCP port parameters from CLI interface
src/Aspire.ProjectTemplates/templates/aspire-apphost/.template.config/template.json	Adds MCP HTTP/HTTPS port parameters with generation and coalescing logic
src/Aspire.ProjectTemplates/templates/aspire-apphost/.template.config/dotnetcli.host.json	Hides MCP port parameters from CLI interface
src/Aspire.ProjectTemplates/templates/aspire-apphost-singlefile/.template.config/template.json	Adds MCP HTTP/HTTPS port parameters with generation and coalescing logic
src/Aspire.ProjectTemplates/templates/aspire-apphost-singlefile/.template.config/dotnetcli.host.json	Hides MCP port parameters from CLI interface

[davidfowl]

/backport to release/13.0

[github-actions]

Started backporting to release/13.0: https://github.com/dotnet/aspire/actions/runs/18986770305

[JamesNK]

I made this PR at the end of the day and didn't test it before signing off.

Does it work?

[davidfowl]

I did, yes it does.