What
When Claude Code extracts a plugin's files to disk to load it, it now records identifying details of that directory (its device, inode, and creation time) beforehand and checks them again afterward. If the directory was removed or replaced with something else during loading, Claude Code now throws an error saying the plugin directory "was removed before it could be loaded" or "was replaced while it was being loaded," instead of silently continuing.
Why
This guards against a plugin's files being tampered with or swapped out during the brief window while it's being loaded, so Claude Code doesn't end up loading unexpected content without noticing.