Display help text for GenAI sensitive data when no messages

[JamesNK]

Description

MEAI changed how it writes telemetry in the latest version. If sensitive data isn't enabled then MEAI telemetry doesn't output any messages. Unfortunatly the help text only displays if there are messages with no content, but not when there are no messages at all.

PR changes that logic to display help text when there are no messages:

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

[Copilot]

Pull Request Overview

This PR fixes the display logic for GenAI help text in the Aspire Dashboard. Previously, help text for sensitive data was only shown when messages existed but had no content. Now it also displays when no messages are present at all, which occurs when Microsoft.Extensions.AI doesn't output message telemetry due to disabled sensitive data settings.

• Updates the AllMessagesHaveNoContent method to return true when there are no messages
• Adds comprehensive test coverage for the no-messages scenario

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/Aspire.Dashboard/Model/GenAI/GenAIVisualizerDialogViewModel.cs	Modified logic to show help text when no messages are present
tests/Aspire.Dashboard.Tests/Model/GenAIVisualizerDialogViewModelTests.cs	Added test case to verify help text displays when no messages exist

[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 -- 11656

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 11656"

[adamint]

@JamesNK this is not getting backported right?

[JamesNK]

/backport to 9.5

[github-actions]

Started backporting to 9.5: https://github.com/dotnet/aspire/actions/runs/18027514307

[github-actions]

@JamesNK an error occurred while backporting to "9.5", please check the run log for details!

The process '/usr/bin/git' failed with exit code 1

[JamesNK]

/backport to release/9.5

[github-actions]

Started backporting to release/9.5: https://github.com/dotnet/aspire/actions/runs/18027523371