Module ExtensionInstall 

extensions:install IPC handler - local VSIX only. Gallery installs are declined (Land has no marketplace backend) and return null.

Sequence:

1. Resolve the VSIX path from Arguments[0] (string or UriComponents).
2. Reject non-.vsix files.
3. Unpack into the user-scope extension directory via VsixInstaller::InstallVsix.
4. Register with ScannedExtensions so GetExtensions() reflects the install on the next read.
5. Fire-and-forget $deltaExtensions + $activateByEvent to Cocoon so the extension activates without a workbench reload.
6. Emit sky://extensions/installed so Wind refreshes the sidebar.
7. Return an ILocalExtension envelope shaped for VS Code’s ExtensionEnablementService sidebar merge path.

Functions

ExtensionInstall