Manage distribution board components

docs/spec/09-distribution-board-components-and-protection-groups.md

@@ -740,8 +740,8 @@ Acceptance:
 ### E. Editor Projection and Editing
 
 Status: In progress. The complete tree read model E1, pure structural
-projection E2a and read-only grid rendering E2b are complete. Editing remains
-pending.
+projection E2a, grid rendering E2b and mutable component editing E3a are
+complete. Group management and circuit-protection editing remain pending.
 
 - render fixed header components
 - render group components and circuit blocks
@@ -750,7 +750,7 @@ pending.
 - add type-dependent protection editing
 - keep spreadsheet selection, keyboard and drag behavior coherent
 
-Implemented in E1/E2a/E2b:
+Implemented in E1/E2a/E2b/E3a:
 
 - the tree response exposes fixed header, group and auxiliary footer
   components plus both one-to-one protection layers
@@ -764,6 +764,12 @@ Implemented in E1/E2a/E2b:
   components as read-only full-width rows
 - structural component rows are excluded from spreadsheet cell navigation,
   insertion and deletion commands until their dedicated editing controls exist
+- group headings offer at most one optional upstream protection device and one
+  optional group RCD; the agreed group-RCD default is applied only when it is
+  created
+- mutable group protection and auxiliary footer components use labeled modals,
+  type-dependent protection fields and persistent project commands
+- fixed main-switch and surge-protection header components remain read-only
 
 Acceptance: