Plugin agents not registered in interactive sessions when plugin is enabled via repo enabledPlugins #5329

Describe the bug

When a plugin is enabled through the repository settings (enabledPlugins in .github/copilot/settings.json), an interactive session does not register the plugin's custom agents with the task tool. Delegating to one fails with:

Unknown agent_type: my-plugin:<agent-name>

The plugin's skills load normally. The same plugin's agents work in non-interactive mode (-p) and in interactive mode when the plugin is enabled by a user install or --plugin-dir instead of the repo setting.

Affected version

GitHub Copilot CLI 1.0.105

Steps to reproduce the behavior

1. Create a plugin my-plugin in a git-based marketplace my-marketplace that ships custom agents (agents/*.agent.md) and skills.
2. In a repository, add .github/copilot/settings.json:

   {
     "extraKnownMarketplaces": {
       "my-marketplace": { "source": { "source": "git", "url": "<marketplace-git-url>" } }
     },
     "enabledPlugins": { "my-plugin@my-marketplace": true }
   }

3. Start an interactive session in that repository (copilot or copilot -i "...").
4. Ask the agent to delegate a task to my-plugin:<agent-name> via the task tool.
5. See Unknown agent_type: my-plugin:<agent-name>.

Expected behavior

The plugin's agents are available as my-plugin:<agent-name> in interactive sessions, the same as in -p mode or when the plugin is user-installed.

Additional context

• Works: copilot -p ... with the same repo settings.
• Works: removing enabledPlugins from the repo settings and enabling the plugin via copilot plugin install my-plugin@my-marketplace (or --plugin-dir).
• Same result whether the plugin is loaded via --plugin-dir or from the marketplace; waiting or pre-installing the plugin does not help.
• copilot plugin disable is refused while the repo setting controls the plugin.
• OS: Windows 11, x86_64, PowerShell 7