Function move_tab 

pub(crate) async fn move_tab(
    state: &AppState,
    cmd: CommandPaneMoveTabData,
) -> Result<(), String>

Core pane.moveTab logic — reorder cmd.block_id within its own pane, or move it into a different pane (Command::LayoutStackMove). Queues a stackmove layout action so any OTHER window/tab viewing the same db_layout sees the change (mirrors stack_onto_block_id’s stackpush queue above); the calling frontend applies its own optimistic local edit directly and does not wait on the queue for itself. SPEC_PANE_TAB_DRAG_AND_DROP_2026_09_19.md §4.1, Phase 3.