.NET: [Bug]: Aspire DevUI does not work for the agent server with HttpsRedirection

[Kumima]

Description

When the agent server has HttpsRedirection configured. The Aspire DevUI does not work. And the UI error is misleading like:

I did take some investigation on source. The endpoint resolving is hard coded as http. So when the agent has https redirection, since the proxy client is configured as AllowAutoRedirect = false. That redirect response is directly sent back to the browser. The browser will take control the request, but that request is raw without handling the agent name prefix. 👈That's the reason why the UI error still has the prefix.

Then the things break. Is that AllowAutoRedirect = false intended? Or do we need to check https endpoint?

Code Sample

Error Messages / Stack Traces

Package Versions

Aspire.Hosting.AgentFramework.DevUI:1.11.1-preview.260625.1

.NET Version

.NET 10

Additional Context

No response

[github-actions]

🤖 Automated triage reproduction notes (agent-authored — trust but verify)

Agent analysis

Repro: DevUIAggregatorHostedService.ResolveBackends() in dotnet/src/Aspire.Hosting.AgentFramework.DevUI/DevUIAggregatorHostedService.cs:301 hardcodes rwe.GetEndpoint("http") and never checks for "https" endpoints; combined with AllowAutoRedirect = false on the proxy HttpClient (line 67), any backend with HTTPS redirection returns a 301/302 that CopyResponseAsync (line 755) forwards verbatim to the browser, bypassing the DevUI prefix routing. Fix should prefer "https" endpoint when available (falling back to "http") and/or handle redirect responses in the proxy layer rather than forwarding them.

• Failing test: none
• Files examined: dotnet/src/Aspire.Hosting.AgentFramework.DevUI/DevUIAggregatorHostedService.cs, dotnet/tests/Aspire.Hosting.AgentFramework.DevUI.UnitTests/DevUIAggregatorHostedServiceTests.cs, dotnet/src/Aspire.Hosting.AgentFramework.DevUI/Aspire.Hosting.AgentFramework.DevUI.csproj
• Tests run: none
• Reported version: 1.11.1-preview.260625.1
• Current version: 1.11.1