Module layout 

Functions

handle_layout_clear 🔒

handle_layout_delete_node 🔒

handle_layout_insert_node 🔒

handle_layout_set_tree 🔒

handle_set_focused_node 🔒

Phase E.4 (Option A) — set the focused layout-node id on a tab. Errors (non-fatal) if the tab is unknown to the reducer; no-op short-circuit when the value is already current. Empty node_id clears the field. Bumps the version only on real changes so a burst of identical sets doesn’t churn the event stream.

handle_set_magnified_node 🔒

Phase E.4 (Option A) — set the magnified layout-node id on a tab. Same shape as handle_set_focused_node. Empty node_id is the toggle-off / clear case.