Add undo/redo support for folio add, delete, and reorder (#575)

Three new QUndoCommand subclasses (AddDiagramCommand, RemoveDiagramCommand,
MoveDiagramCommand) pushed onto the project's existing (already
project-scoped) undo stack, so folio structure edits are undoable
alongside every item-level edit already on that stack.

- QETProject::addDiagram()/detachDiagram() are the shared attach/detach
  primitives: they mutate the diagram list, connect/disconnect the two
  per-diagram signals set up at add time, and emit diagramAdded/
  diagramRemoved. AddDiagramCommand and RemoveDiagramCommand call these
  (via friend access) for both redo and undo, so a removed diagram is
  parked rather than destroyed -- it's only actually deleted if the
  command itself falls out of undo history while still detached.
- ProjectView reacts to diagramRemoved the same way it already reacted to
  diagramAdded (tearing down/rebuilding the tab), so both directions of
  both commands go through the same reactive path every other diagram
  listener (project database, cross-references, generic panel) already
  relies on.
- MoveDiagramCommand wraps a new ProjectView::setDiagramPosition(), which
  performs the tab move and the project's diagramOrderChanged() list
  reorder synchronously in one step, instead of relying on the queued
  tabMoved connection (needed for interactive drag-and-drop) to catch up
  later -- avoiding a second, redundant reorder from that queued call.
- Multi-folio delete and multi-folio move (QETDiagramEditor::removeDiagrams()
  and the moveDiagram*(QList<Diagram*>) batch slots) wrap their per-diagram
  loop in QUndoStack::beginMacro()/endMacro(), so a multi-select action is
  one undo step, matching current UX.
- Softened the delete confirmation's "this change is irreversible" wording
  now that it no longer is.

Verified headlessly (Xvfb + xdotool + scrot): add/undo/redo, delete/undo/
redo (single and multi-select, single undo step for the batch), and
move/undo/redo all behave correctly against a 7-folio project.

cmake/qet_compilation_vars.cmake

@@ -735,6 +735,8 @@ set(QET_SRC_FILES
 
   ${QET_DIR}/sources/undocommand/addelementtextcommand.cpp
   ${QET_DIR}/sources/undocommand/addelementtextcommand.h
+  ${QET_DIR}/sources/undocommand/adddiagramcommand.cpp
+  ${QET_DIR}/sources/undocommand/adddiagramcommand.h
   ${QET_DIR}/sources/undocommand/addgraphicsobjectcommand.cpp
   ${QET_DIR}/sources/undocommand/addgraphicsobjectcommand.h
   ${QET_DIR}/sources/undocommand/changeelementdatacommand.cpp
@@ -749,6 +751,10 @@ set(QET_SRC_FILES
   ${QET_DIR}/sources/undocommand/itemmodelcommand.h
   ${QET_DIR}/sources/undocommand/linkelementcommand.cpp
   ${QET_DIR}/sources/undocommand/linkelementcommand.h
+  ${QET_DIR}/sources/undocommand/movediagramcommand.cpp
+  ${QET_DIR}/sources/undocommand/movediagramcommand.h
+  ${QET_DIR}/sources/undocommand/removediagramcommand.cpp
+  ${QET_DIR}/sources/undocommand/removediagramcommand.h
   ${QET_DIR}/sources/undocommand/rotateselectioncommand.cpp
   ${QET_DIR}/sources/undocommand/rotateselectioncommand.h
   ${QET_DIR}/sources/undocommand/rotatetextscommand.cpp

sources/projectview.cpp

@@ -33,6 +33,8 @@
 #include "ui/dialogwaiting.h"
 #include "ui/projectpropertiesdialog.h"
 #include "ui/titleblockpropertieswidget.h"
+#include "undocommand/movediagramcommand.h"
+#include "undocommand/removediagramcommand.h"
 
 /**
 	Constructeur
@@ -87,6 +89,10 @@ void ProjectView::setProject(QETProject *project)
 			Q_UNUSED(project)
 			this->diagramAdded(diagram);
 		});
+		connect(m_project, &QETProject::diagramRemoved, [this](QETProject *project, Diagram *diagram) {
+			Q_UNUSED(project)
+			this->diagramRemoved(diagram);
+		});
 
 		adjustReadOnlyState();
 		loadDiagrams();
@@ -383,7 +389,7 @@ void ProjectView::removeDiagram(DiagramView *diagram_view, bool silent)
 		int answer = QET::QetMessageBox::question(
 			this,
 			tr("Supprimer le folio ?", "message box title"),
-												  tr("Êtes-vous sûr de vouloir supprimer ce folio du projet ? Ce changement est irréversible.", "message box content"),
+												  tr("Êtes-vous sûr de vouloir supprimer ce folio du projet ?", "message box content"),
 												  QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel,
 											QMessageBox::No
 		);
@@ -392,16 +398,33 @@ void ProjectView::removeDiagram(DiagramView *diagram_view, bool silent)
 		}
 	}
 
-	//Remove the diagram view of the tabs widget
+	m_project->undoStack()->push(new RemoveDiagramCommand(m_project, diagram_view->diagram()));
+}
+
+/**
+	@brief ProjectView::diagramRemoved
+	Slot called when the project emits diagramRemoved (either from a direct,
+	non-undoable QETProject::removeDiagram() call, or -- the normal UI path
+	-- from a RemoveDiagramCommand's redo()/undo()). Tears down the tab and
+	DiagramView for the given diagram; the diagram itself is left untouched,
+	since by this point it has already been detached (and possibly parked
+	for undo) by the caller.
+	@param diagram
+*/
+void ProjectView::diagramRemoved(Diagram *diagram)
+{
+	DiagramView *diagram_view = findDiagram(diagram);
+	if (!diagram_view)
+		return;
+
 	int index_to_remove = m_diagram_ids.key(diagram_view);
 	m_tab->removeTab(index_to_remove);
 	m_diagram_view_list.removeAll(diagram_view);
 	rebuildDiagramsMap();
 
-	m_project -> removeDiagram(diagram_view -> diagram());
+	emit(diagramRemoved(diagram_view));
 	delete diagram_view;
 
-	emit(diagramRemoved(diagram_view));
 	updateAllTabsTitle();
 	m_project -> setModified(true);
 }
@@ -485,7 +508,7 @@ void ProjectView::moveDiagramUp(DiagramView *diagram_view) {
 		// le schema est le premier du projet
 		return;
 	}
-	m_tab -> tabBar() -> moveTab(diagram_view_position, diagram_view_position - 1);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), diagram_view_position - 1));
 }
 
 /**
@@ -506,7 +529,7 @@ void ProjectView::moveDiagramDown(DiagramView *diagram_view) {
 		// le schema est le dernier du projet
 		return;
 	}
-	m_tab -> tabBar() -> moveTab(diagram_view_position, diagram_view_position + 1);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), diagram_view_position + 1));
 }
 
 /**
@@ -528,7 +551,7 @@ void ProjectView::moveDiagramUpTop(DiagramView *diagram_view)
 		// le schema est le premier du projet
 		return;
 	}
-	m_tab->tabBar()->moveTab(diagram_view_position, 0);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), 0));
 }
 
 /*
@@ -550,7 +573,7 @@ void ProjectView::moveDiagramUpx10(DiagramView *diagram_view) {
 		// le schema est le premier du projet
 		return;
 	}
-	m_tab -> tabBar() -> moveTab(diagram_view_position, diagram_view_position - 10);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), diagram_view_position - 10));
 }
 
 /**
@@ -573,7 +596,7 @@ void ProjectView::moveDiagramUpx100(DiagramView *diagram_view) {
 		// The diagram is the first of the project
 		return;
 	}
-	m_tab->tabBar()->moveTab(diagram_view_position, diagram_view_position - 100);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), diagram_view_position - 100));
 }
 
 /**
@@ -598,7 +621,7 @@ void ProjectView::moveDiagramDownx100(DiagramView *diagram_view) {
 		// The diagram is the last of the project
 		return;
 	}
-	m_tab->tabBar()->moveTab(diagram_view_position, diagram_view_position + 100);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), diagram_view_position + 100));
 }
 
 /**
@@ -621,7 +644,7 @@ void ProjectView::moveDiagramDownx10(DiagramView *diagram_view) {
 		// le schema est le dernier du projet
 		return;
 	}
-	m_tab -> tabBar() -> moveTab(diagram_view_position, diagram_view_position + 10);
+	m_project->undoStack()->push(new MoveDiagramCommand(this, diagram_view->diagram(), diagram_view_position + 10));
 }
 
 /**
@@ -1052,10 +1075,10 @@ void ProjectView::tabMoved(int from, int to)
 {
 	if (!m_project)
 		return;
-	
+
 	m_project->diagramOrderChanged(from, to);
 	rebuildDiagramsMap();
-	
+
 		//Rebuild the title of each diagram in range from - to
 	for (int i= qMin(from,to) ; i< qMax(from,to)+1 ; ++i)
 	{
@@ -1064,6 +1087,52 @@ void ProjectView::tabMoved(int from, int to)
 	}
 }
 
+/**
+	@brief ProjectView::setDiagramPosition
+	Move \p diagram's tab to \p new_position (out-of-range values are
+	clamped by the underlying tab bar, same as a direct QTabBar::moveTab()
+	call). Used by MoveDiagramCommand for both redo and undo.
+
+	tabMoved() -- the slot that normally keeps the project's diagram list in
+	sync with the tab bar -- is connected with Qt::QueuedConnection (needed
+	so interactive drag-and-drop reordering settles before the model
+	updates). That queued call would run a second, redundant
+	diagramOrderChanged() after this method already performed it
+	synchronously, so that one connection is temporarily dropped around the
+	move (blocking all of the tab bar's signals instead would also suppress
+	QTabWidget's own internal tabMoved connection, which is what keeps its
+	page stack in the same order as the tab bar -- breaking the move
+	visually).
+	@param diagram
+	@param new_position
+*/
+void ProjectView::setDiagramPosition(Diagram *diagram, int new_position)
+{
+	if (!m_project)
+		return;
+
+	DiagramView *diagram_view = findDiagram(diagram);
+	if (!diagram_view)
+		return;
+
+	int current_position = m_diagram_ids.key(diagram_view, -1);
+	if (current_position < 0)
+		return;
+
+	disconnect(m_tab->tabBar(), SIGNAL(tabMoved(int,int)), this, SLOT(tabMoved(int,int)));
+	m_tab->tabBar()->moveTab(current_position, new_position);
+	connect(m_tab->tabBar(), SIGNAL(tabMoved(int,int)), this, SLOT(tabMoved(int,int)), Qt::QueuedConnection);
+
+	rebuildDiagramsMap();
+
+	int actual_new_position = m_tab->indexOf(diagram_view);
+	if (actual_new_position != current_position)
+		m_project->diagramOrderChanged(current_position, actual_new_position);
+
+	for (int i = qMin(current_position, actual_new_position); i <= qMax(current_position, actual_new_position); ++i)
+		updateTabTitle(m_diagram_ids.value(i));
+}
+
 /**
 	@param diagram Schema a trouver
 	@return le DiagramView correspondant au schema passe en parametre, ou 0 si

sources/projectview.h

@@ -102,6 +102,7 @@ class ProjectView : public QWidget
 		void changeTabDown();
 		void changeFirstTab();
 		void changeLastTab();
+		void setDiagramPosition(Diagram *diagram, int new_position);
 
 	public slots:
 		void removeDiagram(DiagramView *diagram_view, bool silent = false);
@@ -168,6 +169,7 @@ class ProjectView : public QWidget
 		void setDisplayFallbackWidget(bool);
 		void adjustReadOnlyState();
 		void diagramAdded(Diagram *diagram);
+		void diagramRemoved(Diagram *diagram);
 
 		// attributes
 	private:

sources/qetdiagrameditor.cpp

@@ -2249,17 +2249,26 @@ void QETDiagramEditor::removeDiagrams(const QList<Diagram *> &diagrams)
 	}
 
 	ProjectView *project_view = nullptr;
-	if (QETProject *diagram_project = diagrams.first()->project()) {
+	QETProject *project = diagrams.first()->project();
-		project_view = findProject(diagram_project);
+	if (project) {
+		project_view = findProject(project);
 	}
 
 	if (project_view) project_view->setUpdatesEnabled(false);
 	if (pa) pa->setUpdatesEnabled(false);
 
+	if (project) {
+		project->undoStack()->beginMacro(diagrams.count() == 1
+			? tr("Supprimer le folio")
+			: tr("Supprimer %1 folios").arg(diagrams.count()));
+	}
+
 	foreach (Diagram *diagram, diagrams) {
 		removeDiagramSilent(diagram);
 	}
 
+	if (project) project->undoStack()->endMacro();
+
 	if (pa) pa->setUpdatesEnabled(true);
 	if (project_view) project_view->setUpdatesEnabled(true);
 
@@ -2289,10 +2298,12 @@ void QETDiagramEditor::moveDiagramUp(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Forward loop for moving up
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = 0; i < safeDiagrams.size(); ++i) {
 					project_view->moveDiagramUp(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}
@@ -2305,10 +2316,12 @@ void QETDiagramEditor::moveDiagramDown(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Backward loop for moving down
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = safeDiagrams.size() - 1; i >= 0; --i) {
 					project_view->moveDiagramDown(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}
@@ -2321,10 +2334,12 @@ void QETDiagramEditor::moveDiagramUpTop(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Backward loop to preserve relative order of the selected items when moving to top
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = safeDiagrams.size() - 1; i >= 0; --i) {
 					project_view->moveDiagramUpTop(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}
@@ -2337,10 +2352,12 @@ void QETDiagramEditor::moveDiagramUpx10(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Forward loop for moving up
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = 0; i < safeDiagrams.size(); ++i) {
 					project_view->moveDiagramUpx10(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}
@@ -2353,10 +2370,12 @@ void QETDiagramEditor::moveDiagramDownx10(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Backward loop for moving down
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = safeDiagrams.size() - 1; i >= 0; --i) {
 					project_view->moveDiagramDownx10(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}
@@ -2369,10 +2388,12 @@ void QETDiagramEditor::moveDiagramUpx100(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Forward loop for moving up
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = 0; i < safeDiagrams.size(); ++i) {
 					project_view->moveDiagramUpx100(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}
@@ -2385,10 +2406,12 @@ void QETDiagramEditor::moveDiagramDownx100(const QList<Diagram *> &diagrams) {
 		if (!diagram_project->isReadOnly()) {
 			if (ProjectView *project_view = findProject(diagram_project)) {
 				// Backward loop for moving down
+				diagram_project->undoStack()->beginMacro(tr("Déplacer les folios"));
 				for (int i = safeDiagrams.size() - 1; i >= 0; --i) {
 					project_view->moveDiagramDownx100(safeDiagrams.at(i));
 					QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 				}
+				diagram_project->undoStack()->endMacro();
 			}
 		}
 	}

sources/qetproject.cpp

@@ -34,6 +34,7 @@
 #include "TerminalStrip/terminalstrip.h"
 #include "qetxml.h"
 #include "qetversion.h"
+#include "undocommand/adddiagramcommand.h"
 
 #include <QElapsedTimer>
 #include <QHash>
@@ -1348,6 +1349,8 @@ bool QETProject::usesTitleBlockTemplate(const TitleBlockTemplateLocation &locati
 /**
 	@brief QETProject::addNewDiagram
 	Add a new diagram in project at position pos.
+	This is pushed as an undoable AddDiagramCommand: use undoStack()->undo()
+	to remove it again.
 	@param pos
 	@return the new created diagram
 */
@@ -1363,14 +1366,15 @@ Diagram *QETProject::addNewDiagram(int pos)
 	diagram->border_and_titleblock.importTitleBlock(defaultTitleBlockProperties());
 	diagram->defaultConductorProperties = defaultConductorProperties();
 
-	addDiagram(diagram, pos);
+	m_undo_stack->push(new AddDiagramCommand(this, diagram, pos));
-	emit diagramAdded(this, diagram);
 	return(diagram);
 }
 
 /**
 	@brief QETProject::removeDiagram
-	Remove diagram from project
+	Remove diagram from project immediately (not undoable). UI code should
+	generally go through ProjectView::removeDiagram() instead, which pushes
+	an undoable RemoveDiagramCommand.
 	@param diagram
 */
 void QETProject::removeDiagram(Diagram *diagram)
@@ -1380,13 +1384,8 @@ void QETProject::removeDiagram(Diagram *diagram)
 		return;
 	}
 
-	if (m_diagrams_list.removeAll(diagram))
+	detachDiagram(diagram);
-	{
+	diagram->deleteLater();
-		emit diagramRemoved(this, diagram);
-		diagram->deleteLater();
-	}
-
-	updateDiagramsFolioData();
 }
 
 /**
@@ -1930,6 +1929,33 @@ void QETProject::addDiagram(Diagram *diagram, int pos)
 	}
 
 	updateDiagramsFolioData();
+	emit diagramAdded(this, diagram);
+}
+
+/**
+	@brief QETProject::detachDiagram
+	Inverse of addDiagram(): removes \p diagram from this project's diagram
+	list and disconnects the signals set up by addDiagram(), without
+	destroying it. Used by RemoveDiagramCommand (and removeDiagram()) so a
+	removed diagram can be parked and later reinserted by undo.
+	@param diagram
+*/
+void QETProject::detachDiagram(Diagram *diagram)
+{
+	if (!diagram || !m_diagrams_list.contains(diagram)) {
+		return;
+	}
+
+	disconnect(&diagram->border_and_titleblock,
+		&BorderTitleBlock::needFolioData,
+		this,
+		&QETProject::updateDiagramsFolioData);
+	disconnect(diagram, &Diagram::usedTitleBlockTemplateChanged,
+		this, &QETProject::usedTitleBlockTemplateChanged);
+
+	m_diagrams_list.removeAll(diagram);
+	updateDiagramsFolioData();
+	emit diagramRemoved(this, diagram);
 }
 
 /**

sources/qetproject.h

@@ -75,6 +75,8 @@ struct GuideProperties {
 */
 class QETProject : public QObject
 {
+		friend class AddDiagramCommand;
+		friend class RemoveDiagramCommand;
 		Q_OBJECT
 	public :
 		//This enum lists possible states for a particular project.
@@ -257,6 +259,7 @@ class QETProject : public QObject
 		void writeDefaultPropertiesXml(QDomElement &);
 		void writeUsageXml(QDomElement &);
 		void addDiagram(Diagram *diagram, int pos = -1);
+		void detachDiagram(Diagram *diagram);
 		void writeBackup();
 		void init();
 		ProjectState openFile(QFile *file);

sources/undocommand/adddiagramcommand.cpp

@@ -0,0 +1,68 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "adddiagramcommand.h"
+
+#include "../qetproject.h"
+#include "../diagram.h"
+
+/**
+	@brief AddDiagramCommand::AddDiagramCommand
+	@param project : project the diagram is added to
+	@param diagram : the already constructed diagram to add (not yet part of any project's diagram list)
+	@param pos : position to insert the diagram at, -1 to append at the end
+	@param parent
+*/
+AddDiagramCommand::AddDiagramCommand(QETProject *project, Diagram *diagram, int pos, QUndoCommand *parent) :
+	QUndoCommand(parent),
+	m_project(project),
+	m_diagram(diagram),
+	m_position(pos)
+{
+	setText(QObject::tr("Ajouter un folio", "undo command text"));
+}
+
+/**
+	@brief AddDiagramCommand::~AddDiagramCommand
+	Destroy the diagram only if it is currently detached from the project
+	(i.e. this add was undone) -- otherwise the project owns it and will
+	destroy it itself.
+*/
+AddDiagramCommand::~AddDiagramCommand()
+{
+	if (m_owns_diagram && m_diagram) {
+		m_diagram->deleteLater();
+	}
+}
+
+void AddDiagramCommand::redo()
+{
+	if (!m_project || !m_diagram) {
+		return;
+	}
+	m_project->addDiagram(m_diagram, m_position);
+	m_owns_diagram = false;
+}
+
+void AddDiagramCommand::undo()
+{
+	if (!m_project || !m_diagram) {
+		return;
+	}
+	m_project->detachDiagram(m_diagram);
+	m_owns_diagram = true;
+}

sources/undocommand/adddiagramcommand.h

@@ -0,0 +1,52 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef ADDDIAGRAMCOMMAND_H
+#define ADDDIAGRAMCOMMAND_H
+
+#include <QUndoCommand>
+#include <QPointer>
+
+class QETProject;
+class Diagram;
+
+/**
+	@brief The AddDiagramCommand class
+	Undo/redo support for adding a new folio (diagram) to a project.
+	Takes ownership of the (already constructed, not yet inserted) diagram:
+	redo() inserts it into the project, undo() detaches it again without
+	destroying it. The diagram is only actually destroyed when this command
+	itself is destroyed while the diagram is detached (i.e. while undone).
+*/
+class AddDiagramCommand : public QUndoCommand
+{
+	public:
+		AddDiagramCommand(QETProject *project, Diagram *diagram, int pos = -1, QUndoCommand *parent = nullptr);
+		~AddDiagramCommand() override;
+
+		void undo() override;
+		void redo() override;
+
+	private:
+		QPointer<QETProject> m_project;
+		Diagram *m_diagram;
+		int m_position;
+		/// true while the diagram is detached from the project (not currently in its diagram list)
+		bool m_owns_diagram = true;
+};
+
+#endif // ADDDIAGRAMCOMMAND_H

sources/undocommand/movediagramcommand.cpp

@@ -0,0 +1,56 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "movediagramcommand.h"
+
+#include "../projectview.h"
+#include "../qetproject.h"
+
+/**
+	@brief MoveDiagramCommand::MoveDiagramCommand
+	@param project_view : project view the diagram's tab belongs to
+	@param diagram : the diagram to move
+	@param new_position : target position (may be out of range, e.g. for a
+	x10/x100 move near either end -- ProjectView::setDiagramPosition() clamps
+	it the same way the underlying tab bar always has)
+	@param parent
+*/
+MoveDiagramCommand::MoveDiagramCommand(ProjectView *project_view, Diagram *diagram, int new_position, QUndoCommand *parent) :
+	QUndoCommand(parent),
+	m_project_view(project_view),
+	m_diagram(diagram),
+	m_old_position(project_view ? project_view->project()->folioIndex(diagram) : -1),
+	m_new_position(new_position)
+{
+	setText(QObject::tr("Déplacer un folio", "undo command text"));
+}
+
+void MoveDiagramCommand::redo()
+{
+	if (!m_project_view) {
+		return;
+	}
+	m_project_view->setDiagramPosition(m_diagram, m_new_position);
+}
+
+void MoveDiagramCommand::undo()
+{
+	if (!m_project_view) {
+		return;
+	}
+	m_project_view->setDiagramPosition(m_diagram, m_old_position);
+}

sources/undocommand/movediagramcommand.h

@@ -0,0 +1,49 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef MOVEDIAGRAMCOMMAND_H
+#define MOVEDIAGRAMCOMMAND_H
+
+#include <QUndoCommand>
+#include <QPointer>
+
+class ProjectView;
+class Diagram;
+
+/**
+	@brief The MoveDiagramCommand class
+	Undo/redo support for reordering a folio (diagram) within a project's
+	tabs. Wraps ProjectView::setDiagramPosition(), which performs the tab
+	move and the matching (synchronous) project diagram-list reorder in one
+	step.
+*/
+class MoveDiagramCommand : public QUndoCommand
+{
+	public:
+		MoveDiagramCommand(ProjectView *project_view, Diagram *diagram, int new_position, QUndoCommand *parent = nullptr);
+
+		void undo() override;
+		void redo() override;
+
+	private:
+		QPointer<ProjectView> m_project_view;
+		Diagram *m_diagram;
+		int m_old_position;
+		int m_new_position;
+};
+
+#endif // MOVEDIAGRAMCOMMAND_H

sources/undocommand/removediagramcommand.cpp

@@ -0,0 +1,67 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "removediagramcommand.h"
+
+#include "../qetproject.h"
+#include "../diagram.h"
+
+/**
+	@brief RemoveDiagramCommand::RemoveDiagramCommand
+	@param project : project the diagram is removed from
+	@param diagram : the diagram to remove, currently part of \p project
+	@param parent
+*/
+RemoveDiagramCommand::RemoveDiagramCommand(QETProject *project, Diagram *diagram, QUndoCommand *parent) :
+	QUndoCommand(parent),
+	m_project(project),
+	m_diagram(diagram),
+	m_position(project ? project->folioIndex(diagram) : -1)
+{
+	setText(QObject::tr("Supprimer un folio", "undo command text"));
+}
+
+/**
+	@brief RemoveDiagramCommand::~RemoveDiagramCommand
+	Destroy the diagram only if it is currently detached from the project
+	(i.e. the removal is currently in effect) -- otherwise the project owns
+	it and will destroy it itself.
+*/
+RemoveDiagramCommand::~RemoveDiagramCommand()
+{
+	if (m_owns_diagram && m_diagram) {
+		m_diagram->deleteLater();
+	}
+}
+
+void RemoveDiagramCommand::redo()
+{
+	if (!m_project || !m_diagram) {
+		return;
+	}
+	m_project->detachDiagram(m_diagram);
+	m_owns_diagram = true;
+}
+
+void RemoveDiagramCommand::undo()
+{
+	if (!m_project || !m_diagram) {
+		return;
+	}
+	m_project->addDiagram(m_diagram, m_position);
+	m_owns_diagram = false;
+}

sources/undocommand/removediagramcommand.h

@@ -0,0 +1,53 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef REMOVEDIAGRAMCOMMAND_H
+#define REMOVEDIAGRAMCOMMAND_H
+
+#include <QUndoCommand>
+#include <QPointer>
+
+class QETProject;
+class Diagram;
+
+/**
+	@brief The RemoveDiagramCommand class
+	Undo/redo support for removing a folio (diagram) from a project.
+	redo() detaches the diagram from the project (and, reactively, its
+	ProjectView tab) without destroying it; undo() reinserts it at its
+	original position. The diagram is only actually destroyed when this
+	command itself is destroyed while the diagram is detached (i.e. while
+	the removal is still in effect).
+*/
+class RemoveDiagramCommand : public QUndoCommand
+{
+	public:
+		RemoveDiagramCommand(QETProject *project, Diagram *diagram, QUndoCommand *parent = nullptr);
+		~RemoveDiagramCommand() override;
+
+		void undo() override;
+		void redo() override;
+
+	private:
+		QPointer<QETProject> m_project;
+		Diagram *m_diagram;
+		int m_position;
+		/// true while the diagram is detached from the project (i.e. the removal is in effect)
+		bool m_owns_diagram = false;
+};
+
+#endif // REMOVEDIAGRAMCOMMAND_H