Extract history UI operation planning

docs/modernization/roadmap.md

@@ -503,6 +503,9 @@ callbacks before legacy `Brush` mutation and resource loading continue.
 pick/load/reload/clear, lightmap render capability/limit checks, and heightmap
 commit used by the live grid panel before legacy image loading, OpenGL texture
 updates, nanort lightmap baking, and `Canvas::draw_objects` execution continue.
+`pano_cli plan-history-operation` exposes app-core planning for undo, redo, and
+clear-history availability used by toolbar buttons and canvas shortcuts before
+legacy `ActionManager` stack execution continues.
 `pano_cli plan-quick-operation` exposes app-core planning for quick brush/color
 slot selection versus popup opening, plus quick mini-state restore/reset
 validation used by the live quick panel before legacy `Brush`, color picker,
@@ -1155,6 +1158,14 @@ Results:
   `pano_cli_plan_grid_operation_rejects_empty_reload`, and
   `pano_cli_plan_grid_operation_rejects_bad_samples` passed and expose live
   grid/heightmap/lightmap planning as JSON automation.
+- `pp_app_core_history_ui_tests` passed, covering undo/redo availability,
+  no-op history commands, clear-history stack/memory state, memory-only clear,
+  and negative metric rejection.
+- `pano_cli_plan_history_operation_undo_smoke`,
+  `pano_cli_plan_history_operation_redo_empty_smoke`,
+  `pano_cli_plan_history_operation_clear_smoke`, and
+  `pano_cli_plan_history_operation_rejects_negative_count` passed and expose
+  toolbar/canvas history planning as JSON automation.
 - `pp_app_core_quick_ui_tests` passed, covering quick brush/color slot
   selection, active-slot popup decisions, invalid slot rejection, restore-state
   validation, and reset-state validation.