Multi select in the editor

DECISIONS.md

@@ -858,3 +858,28 @@ Rotation cuts across rendering, picking, collision, bounds, serialization, inspe
 - The next viewport transform tool after move should be scale.
 - Rotation remains planned but deliberately later.
 - Any future rotation work should start by documenting what rotates visually only and what rotates physically.
+
+---
+
+## Defer grouped inspector edit actions
+
+### Decision
+
+Implement basic group support for move and delete, but defer grouped inspector/property edits.
+
+### Why
+
+Grouped editor commands are now supported for multi-selection move and delete, because those actions need to undo and redo atomically as a single user action.
+
+Grouped inspector/property edits are intentionally deferred. Changing size, colour, sprite, flags, labels, or scene-specific properties across multiple selected objects introduces additional UI and command-history complexity:
+
+mixed values need clear inspector behaviour
+partial edits need explicit rules
+command history must describe the grouped edit accurately
+undo/redo must restore all affected objects as one atomic command
+
+For now, the inspector continues to edit the active selected object only. Multi-object mutation is limited to viewport movement and deletion.
+
+### Revisit when
+
+Tools are stable enough and we have irnoned out any issues with the multi-selection and the command history model. Then we can start to explore grouped inspector edits with a clear understanding of how the editor behaves and what the user expects.

NOTES.md

@@ -67,10 +67,10 @@ Add normal editor actions once command history exists.
 
 Initial scope:
 
-- Delete selected authored object
-- Duplicate selected authored object
-- Select the duplicated object
-- Offset duplicates slightly so the result is visible
+- [x] Delete selected authored object
+- [x] Duplicate selected authored object
+- [x] Select the duplicated object
+- [x] Offset duplicates slightly so the result is visible
 
 This gives undo/redo useful behaviour to prove.
 
@@ -80,12 +80,18 @@ Add multi-select after the single-object command path is stable.
 
 Initial scope:
 
-- Selection set instead of one selected id
-- Shift-click to add/remove from the selection set
-- Clear selection on empty viewport click
-- Outliner multi-select support - only if it stays small
-
-The first implementation should not include grouping.
+- [x] Selection set instead of one selected id
+- [x] Shift-click to add/remove from the selection set
+- [x] Clear selection on empty viewport click
+- [x] Outliner multi-select support
+- [x] Visible outline for every selected object
+- [x] Combined selection bounds in the viewport
+- [x] Multi-selection drag handle on the selection bounds
+- [x] Selection count in editor UI
+- [x] Move selected objects as one editor command
+- [x] Delete selected deletable objects as one editor command
+
+Multi-select now supports grouped viewport move and grouped delete. Grouped inspector/property edits remain deferred because they need more specific UX and command labels.
 
 ### 5. Tool mode state
 

src/prune/editor/editor_command.cpp

@@ -103,6 +103,10 @@ namespace prune {
             return "Change sprite";
         case EditorCommandType::MoveViewport:
             return "Move viewport";
+        case EditorCommandType::MoveObjects:
+            return "Move objects";
+        case EditorCommandType::DeleteObjects:
+            return "Delete objects";
         }
 
         return "Unknown editor command";
@@ -120,6 +124,7 @@ namespace prune {
         command.label = std::string(label);
         command.detail = std::string(detail);
         command.object_id = after.identity.id;
+        command.object_ids.push_back(after.identity.id);
         command.before_object = before;
         command.after_object = after;
 
@@ -135,6 +140,7 @@ namespace prune {
         command.label = editor_command_type_label(EditorCommandType::CreateObject);
         command.detail = std::string(detail);
         command.object_id = created.identity.id;
+        command.object_ids.push_back(created.identity.id);
         command.after_object = created;
 
         return command;
@@ -149,11 +155,52 @@ namespace prune {
         command.label = editor_command_type_label(EditorCommandType::DeleteObject);
         command.detail = std::string(detail);
         command.object_id = deleted.identity.id;
+        command.object_ids.push_back(deleted.identity.id);
         command.before_object = deleted;
 
         return command;
     }
 
+    EditorCommand make_multi_object_command(
+        EditorCommandType type,
+        std::string_view label,
+        std::span<const GameObject> before,
+        std::span<const GameObject> after,
+        std::string_view detail
+    ) {
+        EditorCommand command{};
+        command.type = type;
+        command.label = std::string(label);
+        command.detail = std::string(detail);
+        command.before_objects.assign(before.begin(), before.end());
+        command.after_objects.assign(after.begin(), after.end());
+
+        command.object_ids.reserve(command.after_objects.size());
+        for (const GameObject& object : command.after_objects) {
+            command.object_ids.push_back(object.identity.id);
+        }
+
+        return command;
+    }
+
+    EditorCommand make_multi_delete_object_command(
+        std::span<const GameObject> deleted,
+        std::string_view detail
+    ) {
+        EditorCommand command{};
+        command.type = EditorCommandType::DeleteObjects;
+        command.label = editor_command_type_label(EditorCommandType::DeleteObjects);
+        command.detail = std::string(detail);
+        command.before_objects.assign(deleted.begin(), deleted.end());
+
+        command.object_ids.reserve(command.before_objects.size());
+        for (const GameObject& object : command.before_objects) {
+            command.object_ids.push_back(object.identity.id);
+        }
+
+        return command;
+    }
+
     EditorCommand make_viewport_command(
         std::string_view label,
         const Camera& before,

src/prune/editor/editor_command.hpp

@@ -2,6 +2,7 @@
 
 #include <cstddef>
 #include <optional>
+#include <span>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -22,7 +23,9 @@ namespace prune {
         ChangeObjectColour,
         ChangeObjectFlag,
         ChangeSprite,
-        MoveViewport
+        MoveViewport,
+        MoveObjects,
+        DeleteObjects
     };
 
     struct EditorCommand {
@@ -33,6 +36,9 @@ namespace prune {
 
         std::optional<GameObject> before_object;
         std::optional<GameObject> after_object;
+        std::vector<GameObject> before_objects;
+        std::vector<GameObject> after_objects;
+        std::vector<GameObjectId> object_ids;
 
         std::optional<Camera> before_camera;
         std::optional<Camera> after_camera;
@@ -80,6 +86,19 @@ namespace prune {
         std::string_view detail = {}
     );
 
+    [[nodiscard]] EditorCommand make_multi_object_command(
+        EditorCommandType type,
+        std::string_view label,
+        std::span<const GameObject> before,
+        std::span<const GameObject> after,
+        std::string_view detail = {}
+    );
+
+    [[nodiscard]] EditorCommand make_multi_delete_object_command(
+        std::span<const GameObject> deleted,
+        std::string_view detail = {}
+    );
+
     [[nodiscard]] EditorCommand make_viewport_command(
         std::string_view label,
         const Camera& before,