SDK Marketplace plugin install completes but card reports stale inventory #340931

Testing #340922

• VS Code Insiders: 1.142.0-insider, commit dab4f45f6cbfbd55ff3de3ac3a328fb7d6d2f642
• OS: macOS arm64
• Session Target: Copilot
• Profile and COPILOT_HOME: disposable and isolated

Steps to reproduce

1. Enable:

   "chat.customizations.marketplace.enabled": true,
   "chat.customizations.marketplace.sources.publicFeed.enabled": true

2. Start a new chat and select Copilot in Session Target.

3. Run Chat: Open Customizations > Discover.

4. Select Install on Security Best Practices and accept the marketplace trust prompt.

Expected

The card changes from Installing... to Uninstall after the SDK-owned plugin inventory publishes the installation.

Actual

The Plugins count increases and the plugin is installed on disk, but Discover reports:

Could not install Security Best Practices. The SDK completed the plugin operation, but its installation inventory did not update.

The card changes to Retry Install instead of Uninstall.

The isolated Copilot state confirms:

• config.json contains enabled security-best-practices@awesome-copilot version 1.0.0 with a cache_path.
• The cache_path exists and contains plugin.json and the plugin files.
• Agent Host later publishes session/customizationsChanged containing the installed plugin.

The operation therefore succeeds, but the workbench/provider synchronization misses or times out before recognizing the authoritative inventory update.