macOS Tahoe Breaks Safari MCP's Focus Protection

Safari MCP's carefully engineered focus guard mechanism failed on macOS Tahoe due to undocumented OS behavior changes that cause AppleScript operations and system commands to implicitly activate Safari windows. This exposes the fundamental vulnerability of background automation tools relying on OS-level assumptions, especially when platforms evolve without advance notice. The failure—traced to multiple race conditions in the focus restoration pipeline—underscores why automation safety requires redundant protections.