Panel Layout Backup & Restore

Plasma's panel/desktop layout lives primarily in:

• ~/.config/plasma-org.kde.plasma.desktop-appletsrc — panels, containments, applets, their positions and config.
• ~/.config/plasmashellrc — plasmashell preferences.
• ~/.config/plasmarc — global Plasma settings.
• ~/.config/kwinrc — window manager config (often paired with layout changes).

Backup

Snapshot to the plugin data dir, timestamped: