Read Copilot CLI user-installed plugins from `~/.copilot/installed-plugins/`

[digitarald]

Plugins installed via Copilot CLI (stored in ~/.copilot/installed-plugins/_direct/) are not automatically discovered by VS Code. Users expect a single plugin to work across both Copilot CLI and VS Code without a separate installation step.

Steps to Reproduce:

1. Install a plugin via Copilot CLI (e.g., github/moda-linter) — it appears under ~/.copilot/installed-plugins/_direct/github--moda-linter--copilot-plugin/
2. Open VS Code and check Chat Customizations or use Chat: Configure Skills
3. The CLI-installed plugin does not appear

Expected Behavior:
VS Code should discover and list plugins installed by Copilot CLI from the shared ~/.copilot/installed-plugins/ directory, or provide a clear path for users to use the same plugin across both surfaces.

Current Workarounds:

• Use Chat: Install Plugin From Source to install the same plugin separately in VS Code
• Add the plugin path to the chat.plugins.paths setting manually

[zacharymuehlich]

This is a meaningful pain point for plugin marketplace developers. As someone maintaining extensions that need to work across VS Code, VS Code Insiders, VS Code Agents Insiders, and Copilot CLI, the current model requires users to install the same plugin separately in each environment which creates real friction at the point of onboarding as well as keeping each installation location on the same version for experience parity.

The ideal outcome here would be for all VS Code surfaces to treat the Copilot CLI plugin directory (~/.copilot/installed-plugins/) as an additional, automatically-resolved source alongside existing install locations — not a replacement for them. Users who install plugins through VS Code's own interface today would be unaffected but this would extend discovery to include plugins already present from a Copilot CLI install.

Given that Microsoft owns both the VS Code and Copilot CLI ecosystems, a unified plugin resolution strategy seems like a natural fit and would meaningfully reduce the install surface that marketplace developers have to document and support.