Plugin-contributed agents, skills, and MCP servers load inconsistently across sessions

Short summary

Agents, skills, and MCP servers contributed by installed plugins load inconsistently in the Copilot desktop app. Some sessions load all plugin components, while others do not load them at all; in some sessions they initially appear and then disappear. Directly installed agents and skills remain reliable.

Affected version or release

v1.1.15

Installation context

GitHub Copilot desktop app for Windows with installed plugins that contribute agents, skills, and MCP servers

What happened?

Plugin-contributed components are loaded inconsistently across Copilot desktop app sessions:

• Some sessions load all agents, skills, and MCP servers contributed by installed plugins.
• Other sessions do not load the plugin-contributed components.
• In some sessions, the plugin components are present when the session starts but disappear later while the session is still open.
• Agents and skills installed directly under .copilot/agents and .copilot/skills load consistently and do not exhibit this behavior.
• The easiest visible way to detect the problem is through the Agents dropdown: plugin-contributed agents are present in some sessions and absent in others.
• Plugin-contributed skills and MCP servers appear to follow the same inconsistent loading behavior.

At present, plugin components load successfully in approximately 50% of sessions. The behavior varies between sessions without any intentional configuration changes.

Steps to reproduce

1. Install and enable one or more Copilot plugins that contribute agents, skills, and MCP servers.
2. Open the GitHub Copilot desktop app and create a new session.
3. Open the Agents dropdown and check whether the plugin-contributed agents are listed.
4. Check whether the plugin-contributed skills and MCP servers are available in the session.
5. Create additional sessions and repeat the checks.
6. Observe that some sessions load all plugin components while other sessions omit them.
7. Leave a session open after the plugin components initially load.
8. Observe that, in some cases, the plugin-contributed components later disappear from the active session.
9. Compare with agents and skills installed directly in .copilot/agents and .copilot/skills; those continue to load consistently.

The current observed success rate is approximately 50%.

Expected behavior

Enabled plugin-contributed agents, skills, and MCP servers should load deterministically in every session and remain available for the lifetime of that session. Their availability should not vary between otherwise equivalent sessions or disappear after initially loading.

Directly installed and plugin-contributed components should follow equally reliable discovery and lifecycle behavior. If a plugin component fails to load, the app should surface a clear diagnostic identifying the affected plugin and the reason for the failure.

Additional context

• Platform: Windows
• App version: v1.1.15
• Approximate reproduction rate: 50%
• Most obvious indicator: plugin-contributed agents intermittently missing from the Agents dropdown
• Also affected: plugin-contributed skills and MCP servers
• Not affected: agents and skills installed directly in .copilot/agents and .copilot/skills
• The issue can occur at session startup or after plugin components initially loaded successfully and were available in the session.

Reproduce the behavior across new and existing sessions using the Agents dropdown, then compare plugin-contributed components with directly installed files under .copilot/agents and .copilot/skills. Trace plugin discovery and session lifecycle behavior for agents, skills, and MCP servers; done means enabled components load consistently, remain available, and failures provide a clear diagnostic.