Plugin updates fail with Access is denied when other Copilot CLI or VS Code sessions are open

Description

Plugin updates fail when multiple Copilot CLI sessions or VS Code windows are open, even when the plugin is not actively invoked or being used by those sessions. The update appears to be blocked by file locks held by unrelated processes or sessions.

Impact

Updating a plugin currently requires closing and reopening every Copilot CLI shell and VS Code window. This is disruptive and can prevent urgent plugin updates from being applied promptly.

Observed error

Installing plugin "Agentic-Workflows@CalOps-Hub"...
Failed to install plugin: Failed to install plugin: Access is denied. (os error 5)

Expected behavior

Plugin updates should succeed when the plugin is not actively in use. If a file lock makes an immediate update impossible, Copilot CLI should identify the process or session holding the lock and provide targeted remediation, or support a deferred or atomic update without requiring all Copilot CLI and VS Code sessions to be closed.

Actual behavior

The update fails with a generic Access is denied (os error 5) message while other Copilot CLI sessions or VS Code windows are open, without identifying the locking process or offering a recovery mechanism.

Screenshot

No source file or test is named. Start by reproducing the update with multiple Copilot CLI sessions and VS Code windows open, then trace the plugin update entry point and the source of the Windows “Access is denied” error. Done means updates succeed when the plugin is unused, or the locking process and a recovery or deferred-update path are clearly reported.