[Richard Markiewicz (thenextman)]

The tray app can now check whether dynamic virtual channels work in the current remote session.
A hidden menu item (Ctrl+right-click, "Test virtual channels...") opens the built-in ECHO channel, the Devolutions::Now::Agent channel and a name no client registers, then shows each outcome next to the expected one.

Support can use it to tell a host where virtual channels fail for every program from one where only the Now channel fails.
The Now channel is skipped while Devolutions Session runs in the session, because opening it again would replace the live channel.

[Richard Markiewicz (thenextman)]

Lines changed

Category	Added	Removed
Production code (dotnet/DesktopAgent)	326	1
Tests	0	0
Other files	0	0

There is no test project for DesktopAgent, so none was added.
The files typecheck for net48 with warnings as errors; the full project does not build on macOS because of its image resources, so the dialog layout and the Windows call are unexercised until CI produces an artifact.

UNTESTED: properties

• ChannelProbe.ProbeNow must never open Devolutions::Now::Agent while Devolutions Session runs in the same session.
  A second open offers the client another channel, which replaces the live one.
  The running-process check is the only guard; when changing it, check that the open stays gated on it.

Note

Human-tuned, LLM-assisted content.

[github-actions]

Let maintainers know that an action is required on their side

• Add the label release-required Please cut a new release (Devolutions Gateway, Devolutions Agent, Jetsocat, PowerShell module) when you request a maintainer to cut a new release (Devolutions Gateway, Devolutions Agent, Jetsocat, PowerShell module)

• Add the label release-blocker Follow-up is required before cutting a new release if a follow-up is required before cutting a new release

• Add the label publish-required Please publish libraries (`Devolutions.Gateway.Utils`, OpenAPI clients, etc) when you request a maintainer to publish libraries (Devolutions.Gateway.Utils, OpenAPI clients, etc.)

• Add the label publish-blocker Follow-up is required before publishing libraries if a follow-up is required before publishing libraries

[Copilot]

🟡 Changes recommended

The Now probe lacks exclusive channel ownership and can disrupt a live session during a concurrent host launch, while RemoteFX RDP sessions can be misclassified and skip diagnostics.

2 open issues

• Diagnostic probe can replace a live session-host channel · New
• SM_REMOTESESSION can misclassify RemoteFX RDP sessions as console · New

What changed in this PR

Adds virtual-channel diagnostics to the Agent tray app so support can distinguish general channel failures from problems specific to the Now channel.

Changes:

• Adds a hidden Ctrl+right-click menu action to launch diagnostics.
• Probes ECHO, Devolutions::Now::Agent, and an unregistered channel, reporting actual versus expected outcomes.
• Provides rerun and copy controls, logs results, and checks for a running session host before probing Now.

File	Description
dotnet/​DesktopAgent/​Program.cs	Adds the hidden diagnostics menu action.
dotnet/​DesktopAgent/​Diagnostics/​ChannelProbeForm.cs	Adds the report window with background execution, rerun, and copy controls.
dotnet/​DesktopAgent/​Diagnostics/​ChannelProbe.cs	Implements channel probes, session-host detection, and diagnostic reporting.

_{Review effort: Balanced}