Set OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT to true in local development

[JamesNK]

Description

MEAI will automatically enable sensitive content (aka messages) when this env var is set: dotnet/extensions#6790

Setting this env var in Aspire by default so GenAI telemetry Just Works(tm)*

*when updated MEAI version is released and we update to use it

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:

curl -fsSL https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 11304

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 11304"

[Copilot]

Pull Request Overview

This PR enables detailed GenAI telemetry capture in local development environments by setting the OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT environment variable to true. This allows GenAI libraries to automatically capture sensitive content (messages) when running in development mode.

• Sets the OpenTelemetry GenAI instrumentation environment variable for development environments
• Updates test assertions to verify the new environment variable is properly configured

Reviewed Changes

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

File	Description
src/Aspire.Hosting/ProjectResourceBuilderExtensions.cs	Adds the OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT environment variable configuration for development mode
tests/Aspire.Hosting.Tests/ProjectResourceTests.cs	Updates test to verify the new GenAI telemetry environment variable is set correctly