Merge master into feat/project-lock

Conflicts: the lock dialog and the recovery dialog both kept in
qetdiagrameditor.cpp; the lock and previous-versions settings both kept.
The spacer in the General settings page moves to row 9, below the lock
checkbox, which the merge had left on the same row.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MgPFANhWgD66V3v9KVKV58

cmake/qet_compilation_vars.cmake

@@ -942,7 +942,10 @@ set(QET_SRC_FILES
   ${QET_DIR}/sources/utils/qetsettings.cpp
   ${QET_DIR}/sources/utils/qetsettings.h
   ${QET_DIR}/sources/utils/qetutils.cpp
+  ${QET_DIR}/sources/utils/previousversions.cpp
+  ${QET_DIR}/sources/utils/previousversions.h
   ${QET_DIR}/sources/utils/qetutils.h
+  ${QET_DIR}/sources/utils/syncfolder.h
 
   ${QET_DIR}/sources/materiallist/materialentrydialog.cpp
   ${QET_DIR}/sources/materiallist/materialentrydialog.h

sources/cli_export.cpp

@@ -29,6 +29,7 @@
 #include "dxfexport.h"
 #include "exportproperties.h"
 #include "pdf_links.h"
+#include "container/qetcontainer.h"
 #include "qetgraphicsitem/conductor.h"
 #include "qetgraphicsitem/diagramimageitem.h"
 #include "qetgraphicsitem/element.h"
@@ -86,6 +87,7 @@ const QHash<QString, QString> &exportFlags()
 		{"--info", "info"},
 		{"--check-elements", "check"},
 		{"--resave", "resave"},
+		{"--recover", "recover"},
 		{"--set-titleblock", "settb"},
 	};
 	return flags;
@@ -871,6 +873,42 @@ int exportLinks(QETProject &project, const QString &output)
 
 /// Round-trip: load the project and write its XML back out, so an external
 /// diff can reveal markup QET silently normalises (tolerated-but-invalid XML).
+/// What can be read of the damaged .qetz @p input, written to the .qet
+/// @p output, and what was left out (QetContainer::recover()).
+int recoverProject(const QString &input, const QString &output)
+{
+	QFile file(input);
+	if (!file.open(QIODevice::ReadOnly)) {
+		err << "Cannot read '" << input << "': " << file.errorString() << "\n";
+		return 2;
+	}
+	const QByteArray content = file.readAll();
+	if (!QetContainer::isZip(content)) {
+		err << "'" << input << "' is not a .qetz project; a .qet opens as it is, or can be fixed in a text editor\n";
+		return 2;
+	}
+	QDomDocument document;
+	QStringList lost;
+	QString error;
+	if (!QetContainer::recover(content, &document, &lost, &error)) {
+		err << "Nothing can be recovered from '" << input << "': " << error << "\n";
+		return 1;
+	}
+	if (!QET::writeXmlFile(document, output, &error)) {
+		err << "Cannot write '" << output << "': " << error << "\n";
+		return 1;
+	}
+	out << "Recovered " << input << " -> " << output << "\n";
+	if (lost.isEmpty()) {
+		out << "Nothing was left out.\n";
+	} else {
+		out << "Left out:\n";
+		for (const QString &item : std::as_const(lost))
+			out << "  " << item << "\n";
+	}
+	return 0;
+}
+
 int resaveProject(QETProject &project, const QString &output)
 {
 	if (QETProject::isContainerPath(output)) {
@@ -886,14 +924,13 @@ int resaveProject(QETProject &project, const QString &output)
 		//what building them would write (QETProject::toXml())
 	QHash<int, QByteArray> kept_folios;
 	const QDomDocument doc = project.toXml(&kept_folios);
-	QFile file(output);
-	if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
-		err << "Cannot open '" << output << "' for writing.\n";
+		//Through a temporary file, as the GUI saves: a run stopped
+		//part-way leaves the previous file
+	QString error;
+	if (!QET::writeXmlText(QETProject::spliceKeptFolios(doc.toString(4), kept_folios), output, &error)) {
+		err << "Cannot write '" << output << "': " << error << "\n";
 		return 1;
 	}
-	QTextStream fout(&file);
-	fout << QETProject::spliceKeptFolios(doc.toString(4), kept_folios);
-	file.close();
 	out << "Re-saved project -> " << output << "\n";
 	return 0;
 }
@@ -981,14 +1018,11 @@ int setTitleBlock(QETProject &project, const QString &output,
 			//is what building them would write (QETProject::toXml())
 		QHash<int, QByteArray> kept_folios;
 		const QDomDocument doc = project.toXml(&kept_folios);
-		QFile file(output);
-		if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
-			err << "Cannot open '" << output << "' for writing.\n";
+		QString error;
+		if (!QET::writeXmlText(QETProject::spliceKeptFolios(doc.toString(4), kept_folios), output, &error)) {
+			err << "Cannot write '" << output << "': " << error << "\n";
 			return 1;
 		}
-		QTextStream fout(&file);
-		fout << QETProject::spliceKeptFolios(doc.toString(4), kept_folios);
-		file.close();
 	}
 	out << "Stamped " << fields.size() << " field(s) on "
 		<< folios << " folio(s) -> " << output << "\n";
@@ -1044,6 +1078,16 @@ int run(const QStringList &args)
 		return checkElements(rest.at(0));
 	}
 
+	// --recover reads what it can of a damaged .qetz, which a project
+	// cannot be opened from.
+	if (format == "recover") {
+		if (rest.size() < 2) {
+			err << "Usage: qelectrotech --recover <damaged.qetz> <output.qet>\n";
+			return 2;
+		}
+		return recoverProject(rest.at(0), rest.at(1));
+	}
+
 	const QString input = rest.value(0);
 	if (input.isEmpty()) {
 		err << "Usage: qelectrotech " << flag << " <project.qet> <output>\n";

sources/cli_export.h

@@ -55,6 +55,7 @@ namespace CLIExport {
 		  qelectrotech --info           <project.qet> [output.json]
 		  qelectrotech --check-elements <element.elmt | directory>
 		  qelectrotech --resave         <project.qet> <output.qet>
+		  qelectrotech --recover        <damaged.qetz> <output.qet>
 		  qelectrotech --set-titleblock <project.qet> <output.qet> key=value...
 
 		PDF: one multi-page document (one diagram per page).

sources/container/qetcontainer.cpp

@@ -184,11 +184,37 @@ bool QetContainer::readDocument(const QByteArray &content, QDomDocument *documen
 			&& join(entries, document, error, nullptr, pictures, format);
 }
 
+/**
+	@brief QetContainer::recover
+	What can be read of the .qetz @p content, a damaged one, into @p project:
+	a folio file, a picture or an entry that cannot be read is left out,
+	symbols and wires that do not match the database lose what it held, and
+	a database that cannot be read loses it all (wires, whose ends it holds,
+	go too). Each thing left out is said in @p lost.
+	@return false, with @p error, when nothing can be read: not a zip, no
+	project.xml, or a later format
+*/
+bool QetContainer::recover(const QByteArray &content, QDomDocument *project, QStringList *lost, QString *error)
+{
+	QStringList none;
+	if (!lost) lost = &none;
+	QList<QetZip::Entry> entries;
+	return QetZip::fromBytes(content, &entries, error, lost)
+			&& join(entries, project, error, nullptr, nullptr, nullptr, lost);
+}
+
 QString QetContainer::pictureFile(const QDomElement &image)
 {
 	return image.attribute(ImageFileAttribute);
 }
 
+void QetContainer::inlinePicture(QDomElement image, const QByteArray &bytes)
+{
+	image.removeAttribute(ImageFileAttribute);
+	image.insertBefore(image.ownerDocument().createTextNode(QString::fromLatin1(bytes.toBase64())),
+					   image.firstChild());
+}
+
 /**
 	@brief QetContainer::ownUuids
 	@return true if every folio, symbol and wire of @p project has a uuid
@@ -421,23 +447,35 @@ QList<QetZip::Entry> QetContainer::split(const QDomDocument &project, const QStr
 	for a later one this may read (its min-reader allows it).
 */
 bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *project, QString *error,
-						QStringList *folio_files, Pictures *pictures, int *format)
+						QStringList *folio_files, Pictures *pictures, int *format, QStringList *lost)
 {
+		//Recovering a damaged project (recover()): what is missing or
+		//damaged is noted in lost and left out, instead of refusing it all
+	const auto noted = [error, lost](const QString &problem) {
+		if (lost) {
+			lost->append(problem);
+			return true;
+		}
+		setError(error, problem);
+		return false;
+	};
 	QHash<QString, QByteArray> files;
 	for (const QetZip::Entry &entry : entries)
 		files.insert(entry.name, entry.data);
 
 	const QByteArray mimetype = files.value(QStringLiteral("mimetype"));
-	if (mimetype != QByteArray(MimeType) && mimetype != QByteArray(OldMimeType)) {
-		setError(error, QStringLiteral("not a QElectroTech project (.qetz)"));
+	if (mimetype != QByteArray(MimeType) && mimetype != QByteArray(OldMimeType)
+			&& !noted(QStringLiteral("not a QElectroTech project (.qetz)")))
 		return false;
-	}
 	QDomDocument manifest;
-	if (!parse(files.value(QStringLiteral("manifest.xml")), &manifest, error))
+	QString manifest_error;
+	const bool has_manifest = parse(files.value(QStringLiteral("manifest.xml")), &manifest, &manifest_error);
+	if (!has_manifest && !noted(manifest_error))
 		return false;
 	bool ok = false;
 	const int min_reader = manifest.documentElement().attribute(QStringLiteral("min-reader")).toInt(&ok);
-	if (!ok || min_reader > Format) {
+		//A later format is not damage: refused all the same
+	if (has_manifest && (!ok || min_reader > Format)) {
 		setError(error, QStringLiteral("made by a later QElectroTech (format %1, this one reads up to %2)")
 				 .arg(manifest.documentElement().attribute(QStringLiteral("format")))
 				 .arg(Format));
@@ -460,29 +498,33 @@ bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *proje
 				&& file.startsWith(QLatin1String("folios/")))
 			folio_files->append(file);
 		if (!files.contains(file)) {
-			setError(error, QStringLiteral("part \"%1\" is missing").arg(file));
-			return false;
+			if (!noted(QStringLiteral("part \"%1\" is missing").arg(file))) return false;
+			part.parentNode().removeChild(part);
+			continue;
 		}
 		QDomDocument document;
 		QString part_error;
 		if (!parse(files.value(file), &document, &part_error)) {
-			setError(error, QStringLiteral("%1: %2").arg(file, part_error));
-			return false;
+			if (!noted(QStringLiteral("%1: %2").arg(file, part_error))) return false;
+			part.parentNode().removeChild(part);
+			continue;
 		}
 		part.parentNode().replaceChild(project->importNode(document.documentElement(), true), part);
 	}
 
 		//Pictures back to base64, as the image's first child, or into
 		//pictures
-	const QDomNodeList images = project->elementsByTagName(QStringLiteral("image"));
-	for (int i = 0 ; i < images.size() ; ++i)
+	const QDomNodeList image_list = project->elementsByTagName(QStringLiteral("image"));
+	QList<QDomElement> images;
+	for (int i = 0 ; i < image_list.size() ; ++i) images << image_list.at(i).toElement();
+	for (QDomElement image : images)
 	{
-		QDomElement image = images.at(i).toElement();
 		if (!image.hasAttribute(ImageFileAttribute)) continue;
 		const QString file = image.attribute(ImageFileAttribute);
 		if (!files.contains(file)) {
-			setError(error, QStringLiteral("picture \"%1\" is missing").arg(file));
-			return false;
+			if (!noted(QStringLiteral("picture \"%1\" is missing").arg(file))) return false;
+			image.parentNode().removeChild(image);
+			continue;
 		}
 		if (pictures) {
 			pictures->insert(file, files.value(file));
@@ -496,7 +538,12 @@ bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *proje
 		//The engineering data back from project.sqlite (format 2 on)
 	if (files.contains(QStringLiteral("project.sqlite"))
 		&& !QetContainerDb::restore(project->documentElement(),
-									files.value(QStringLiteral("project.sqlite")), error))
+									files.value(QStringLiteral("project.sqlite")), error, lost))
 		return false;
+	if (lost) {
+		if (!files.contains(QStringLiteral("project.sqlite")))
+			lost->append(QStringLiteral("project.sqlite is missing"));
+		QetContainerDb::dropLeftovers(project->documentElement(), lost);
+	}
 	return true;
 }

sources/container/qetcontainer.h

@@ -77,9 +77,16 @@ namespace QetContainer
 							   const QHash<QString, QByteArray> &kept_from = QHash<QString, QByteArray>());
 	bool join(const QList<QetZip::Entry> &entries, QDomDocument *project,
 			  QString *error = nullptr, QStringList *folio_files = nullptr,
-			  Pictures *pictures = nullptr, int *format = nullptr);
+			  Pictures *pictures = nullptr, int *format = nullptr,
+			  QStringList *lost = nullptr);
+		/// What can be read of a damaged .qetz, and in @p lost what could not
+	bool recover(const QByteArray &content, QDomDocument *project, QStringList *lost,
+				 QString *error = nullptr);
 		/// The file join() left the picture of @p image in, or an empty string
 	QString pictureFile(const QDomElement &image);
+		/// @p image, which names its picture's file (pictureFile()), given
+		/// the picture itself, @p bytes, as a document read whole has it
+	void inlinePicture(QDomElement image, const QByteArray &bytes);
 
 		/// Take what QElectroTech computes out of a folio (format 4)
 	void dropComputed(QDomElement diagram, bool terminal_lists);

sources/container/qetcontainerdb.cpp

@@ -570,6 +570,32 @@ bool plainTables(sqlite3 *db)
 	return ok && run(QStringLiteral("VACUUM"));
 }
 
+	//What SQLite advises for a database read from a file
+	//(https://www.sqlite.org/security.html): nothing in its schema runs, no
+	//trigger or view either, the defensive mode, no value longer than any
+	//project holds, and the size of each cell checked as its page is read.
+	//The database @p schema of @p db ("main", or an attached one) is then
+	//checked whole, so that damage is said as such before anything reads
+	//it, instead of showing as a missing row or not at all.
+bool readAsUntrusted(Database &db, const QString &schema, QString *error)
+{
+	sqlite3_db_config(db.m_db, SQLITE_DBCONFIG_DEFENSIVE, 1, nullptr);
+	sqlite3_db_config(db.m_db, SQLITE_DBCONFIG_ENABLE_TRIGGER, 0, nullptr);
+#ifdef SQLITE_DBCONFIG_ENABLE_VIEW
+	sqlite3_db_config(db.m_db, SQLITE_DBCONFIG_ENABLE_VIEW, 0, nullptr);
+#endif
+	db.exec(QStringLiteral("PRAGMA trusted_schema = OFF"));
+	db.exec(QStringLiteral("PRAGMA cell_size_check = ON"));
+	sqlite3_limit(db.m_db, SQLITE_LIMIT_LENGTH, 256 * 1024 * 1024);
+	Statement check(db, QStringLiteral("PRAGMA %1.quick_check(1)").arg(schema));
+	const QString result = check.next() ? check.value(0).toString() : db.error();
+	if (result != QLatin1String("ok")) {
+		setError(error, QStringLiteral("the project database is damaged: %1").arg(result));
+		return false;
+	}
+	return true;
+}
+
 	//@p database opened in @p db, its tables checked to be plain tables and
 	//its format one this reads: a file is untrusted
 bool openDatabase(Database &db, const QByteArray &database, QString *error)
@@ -587,9 +613,10 @@ bool openDatabase(Database &db, const QByteArray &database, QString *error)
 		setError(error, QStringLiteral("the project database cannot be read"));
 		return false;
 	}
-		//A file is untrusted: nothing in its schema may run, and every name
-		//read must be a plain table.
-	db.exec(QStringLiteral("PRAGMA trusted_schema = OFF"));
+		//A file is untrusted (readAsUntrusted()), and every name read must
+		//be a plain table.
+	if (!readAsUntrusted(db, QStringLiteral("main"), error))
+		return false;
 	for (const QString &table : DocTables) {
 		Statement kind(db, QStringLiteral("SELECT type FROM sqlite_master WHERE name = ?"));
 		kind.bind({table});
@@ -749,8 +776,22 @@ struct UsedRows
 	}
 };
 
-	//The engineering data of the folio @p d back from @p db
-bool restoreDiagram(Database &db, QDomElement d, UsedRows &used, QString *error)
+	//A database that does not match its folios: refused, or, with @p lost
+	//(a damaged project recovered, QetContainer::recover()), @p problem
+	//noted and gone past. @return true to go on
+bool noted(QString *error, QStringList *lost, const QString &problem)
+{
+	if (lost) {
+		lost->append(problem);
+		return true;
+	}
+	setError(error, problem);
+	return false;
+}
+
+	//The engineering data of the folio @p d back from @p db; with @p lost,
+	//what does not match is noted and left out (noted())
+bool restoreDiagram(Database &db, QDomElement d, UsedRows &used, QString *error, QStringList *lost)
 {
 	QDomDocument document = d.ownerDocument();
 	auto entry = [&document](const QVariant &name_attr, const QString &name, const QVariant &value,
@@ -759,10 +800,11 @@ bool restoreDiagram(Database &db, QDomElement d, UsedRows &used, QString *error)
 	};
 	const QString id = keyOf(d, FolioAttribute);
 	if (id.isEmpty()) return true;
-	if (!used.use(used.folios, id, QStringLiteral("folio"), error)) return false;
+	QString problem;
+	if (!used.use(used.folios, id, QStringLiteral("folio"), &problem)) return noted(error, lost, problem);
 	Statement f(db, QStringLiteral("SELECT %1, props_attrs FROM folio WHERE uuid = ?").arg(quoted(FolioData)));
 	f.bind({id});
-	if (!f.next()) { setError(error, QStringLiteral("folio %1 is not in the database").arg(id)); return false; }
+	if (!f.next()) return noted(error, lost, QStringLiteral("folio %1 is not in the database").arg(id));
 	QVariantList values;
 	for (int i = 0 ; i < FolioData.size() + 1 ; ++i) values << f.value(i);
 	put(d, FolioData, values, 0);
@@ -777,24 +819,30 @@ bool restoreDiagram(Database &db, QDomElement d, UsedRows &used, QString *error)
 			props.appendChild(entry(p.value(0), QStringLiteral("name"), p.value(1), p.value(2),
 									QStringLiteral("property"), p.value(3)));
 		restoreWhitespace(props, values.at(FolioData.size()));
-		if (!replaceMarker(d, props)) {
-			setError(error, QStringLiteral("folio %1's properties have no place").arg(id));
+		if (!replaceMarker(d, props)
+				&& !noted(error, lost, QStringLiteral("folio %1's properties have no place").arg(id)))
 			return false;
-		}
 	}
 
 	for (const QDomElement &list : children(d, QStringLiteral("elements"))) {
 		for (QDomElement e : children(list, QStringLiteral("element"))) {
 			const QString key = keyOf(e, KeyAttribute);
 			if (key.isEmpty()) continue;
-			if (!used.use(used.elements, key, QStringLiteral("symbol"), error)) return false;
+			if (!used.use(used.elements, key, QStringLiteral("symbol"), &problem)) {
+				if (!noted(error, lost, problem)) return false;
+				continue;
+			}
 			Statement s(db, QStringLiteral("SELECT %1, info_attrs, links_attrs, folio_uuid FROM element WHERE uuid = ?")
 						.arg(quoted(ElementData)));
 			s.bind({key});
-			if (!s.next()) { setError(error, QStringLiteral("symbol %1 is not in the database").arg(key)); return false; }
+			if (!s.next()) {
+				if (!noted(error, lost, QStringLiteral("symbol %1 is not in the database").arg(key))) return false;
+				continue;
+			}
 			if (s.value(ElementData.size() + 2).toString() != id) {
-				setError(error, QStringLiteral("symbol %1 is on folio %2, the database says another").arg(key, id));
-				return false;
+				if (!noted(error, lost, QStringLiteral("symbol %1 is on folio %2, the database says another").arg(key, id)))
+					return false;
+				continue;
 			}
 			QVariantList v;
 			for (int i = 0 ; i < ElementData.size() + 2 ; ++i) v << s.value(i);
@@ -821,25 +869,31 @@ bool restoreDiagram(Database &db, QDomElement d, UsedRows &used, QString *error)
 											QStringLiteral("link_uuid")));
 				restoreWhitespace(links, v.at(n + 1));
 			}
-			if ((!info.isNull() && !replaceMarker(e, info))
-				|| (!links.isNull() && !replaceMarker(e, links))) {
-				setError(error, QStringLiteral("symbol %1's information has no place").arg(key));
+			if (((!info.isNull() && !replaceMarker(e, info))
+				 || (!links.isNull() && !replaceMarker(e, links)))
+					&& !noted(error, lost, QStringLiteral("symbol %1's information has no place").arg(key)))
 				return false;
-			}
 		}
 	}
 	for (const QDomElement &list : children(d, QStringLiteral("conductors"))) {
 		for (QDomElement c : children(list, QStringLiteral("conductor"))) {
 			const QString key = keyOf(c, KeyAttribute);
 			if (key.isEmpty()) continue;
-			if (!used.use(used.conductors, key, QStringLiteral("wire"), error)) return false;
+			if (!used.use(used.conductors, key, QStringLiteral("wire"), &problem)) {
+				if (!noted(error, lost, problem)) return false;
+				continue;
+			}
 			Statement s(db, QStringLiteral("SELECT %1, folio_uuid FROM conductor WHERE uuid = ?")
 						.arg(quoted(ConductorData)));
 			s.bind({key});
-			if (!s.next()) { setError(error, QStringLiteral("wire %1 is not in the database").arg(key)); return false; }
+			if (!s.next()) {
+				if (!noted(error, lost, QStringLiteral("wire %1 is not in the database").arg(key))) return false;
+				continue;
+			}
 			if (s.value(ConductorData.size()).toString() != id) {
-				setError(error, QStringLiteral("wire %1 is on folio %2, the database says another").arg(key, id));
-				return false;
+				if (!noted(error, lost, QStringLiteral("wire %1 is on folio %2, the database says another").arg(key, id)))
+					return false;
+				continue;
 			}
 			QVariantList v;
 			for (int i = 0 ; i < ConductorData.size() ; ++i) v << s.value(i);
@@ -902,7 +956,8 @@ QByteArray QetContainerDb::extract(QDomElement project, QString *error, const QB
 			setError(error, QStringLiteral("cannot read the database the kept folios come from"));
 			return {};
 		}
-		db.exec(QStringLiteral("PRAGMA trusted_schema = OFF"));
+		if (!readAsUntrusted(db, QStringLiteral("old"), error))
+			return {};
 		for (const QString &table : DocTables) {
 			Statement kind(db, QStringLiteral("SELECT type FROM old.sqlite_master WHERE name = ?"));
 			kind.bind({table});
@@ -1135,12 +1190,14 @@ QByteArray QetContainerDb::extract(QDomElement project, QString *error, const QB
 	Put the engineering data in @p database back into @p project (the
 	<project> element, its folios joined back already).
 */
-bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QString *error)
+bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QString *error,
+							 QStringList *lost)
 {
 	QDomDocument document = project.ownerDocument();
 	Database db;
-	if (!openDatabase(db, database, error) || !readyToRead(db, project, error))
-		return false;
+	QString problem;
+	if (!openDatabase(db, database, &problem) || !readyToRead(db, project, &problem))
+		return noted(error, lost, problem);
 
 		//Project properties
 	QHash<QString, QVariant> meta;
@@ -1156,10 +1213,9 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 			props.appendChild(entryElement(document, s.value(0), QStringLiteral("name"), s.value(1), s.value(2),
 										   QStringLiteral("property"), s.value(3)));
 		restoreWhitespace(props, meta.value(QStringLiteral("props_attrs")));
-		if (!replaceMarker(project, props)) {
-			setError(error, QStringLiteral("the project's properties have no place"));
+		if (!replaceMarker(project, props)
+				&& !noted(error, lost, QStringLiteral("the project's properties have no place")))
 			return false;
-		}
 	}
 
 	if (meta.contains(QStringLiteral("terminal_strips"))) {
@@ -1176,17 +1232,53 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 		read(QStringLiteral("SELECT * FROM strip_terminal ORDER BY strip_uuid, pos, level"), 4, &rows.terminals);
 		read(QStringLiteral("SELECT * FROM strip_bridge ORDER BY ord"), 4, &rows.bridges);
 		read(QStringLiteral("SELECT * FROM strip_bridge_terminal ORDER BY bridge_uuid, ord"), 3, &rows.bridge_terminals);
-		if (!replaceMarker(project, stripsXml(document, rows))) {
-			setError(error, QStringLiteral("the terminal strips have no place"));
+		if (!replaceMarker(project, stripsXml(document, rows))
+				&& !noted(error, lost, QStringLiteral("the terminal strips have no place")))
 			return false;
-		}
 	}
 
 	UsedRows used;
 	for (QDomElement d : children(project, QStringLiteral("diagram")))
-		if (!restoreDiagram(db, d, used, error))
+		if (!restoreDiagram(db, d, used, error, lost))
 			return false;
-	return noRowLeft(db, used, error);
+	if (!noRowLeft(db, used, &problem))
+		return noted(error, lost, problem);
+	return true;
+}
+
+/**
+	@brief QetContainerDb::dropLeftovers
+	After restore() of a damaged project (with lost): take out of
+	@p project what only the database could have filled -- the markers of
+	blocks it held, the keys of rows -- and the wires whose ends it held,
+	which cannot be drawn without them. Each kind left out is said in @p lost.
+*/
+void QetContainerDb::dropLeftovers(QDomElement project, QStringList *lost)
+{
+	QList<QDomElement> markers, wires;
+	QList<QDomElement> all{project};
+	for (int i = 0 ; i < all.size() ; ++i) {
+		QDomElement e = all.at(i);
+		for (QDomElement c = e.firstChildElement() ; !c.isNull() ; c = c.nextSiblingElement())
+			all << c;
+		if (e.tagName() == MarkerTag) markers << e;
+		e.removeAttribute(KeyAttribute);
+		e.removeAttribute(FolioAttribute);
+		e.removeAttribute(KeptPartAttribute);
+		if (e.tagName() == QLatin1String("conductor") && e.parentNode().nodeName() == QLatin1String("conductors")
+				//Every format names a wire's ends by terminal (older files
+				//by terminal only), and a .qetz holds them in the database
+				&& (!e.hasAttribute(QStringLiteral("terminal1")) || !e.hasAttribute(QStringLiteral("terminal2"))))
+			wires << e;
+	}
+	for (QDomElement m : std::as_const(markers))
+		m.parentNode().removeChild(m);
+	for (QDomElement w : std::as_const(wires))
+		w.parentNode().removeChild(w);
+	if (lost && !markers.isEmpty())
+		lost->append(QStringLiteral("%1 blocks of information the database held").arg(markers.size()));
+	if (lost && !wires.isEmpty())
+		lost->append(QStringLiteral("%1 wires, whose ends the database held").arg(wires.size()));
 }
 
 /**

sources/container/qetcontainerdb.h

@@ -20,6 +20,7 @@
 
 #include <QByteArray>
 #include <QDomElement>
+#include <QStringList>
 
 /**
 	@brief The QetContainerDb namespace
@@ -41,7 +42,13 @@ namespace QetContainerDb
 {
 	QByteArray extract(QDomElement project, QString *error = nullptr,
 					   const QByteArray &kept_from = QByteArray());
-	bool restore(QDomElement project, const QByteArray &database, QString *error = nullptr);
+		/// With @p lost, a damaged project being recovered: what does not
+		/// match is noted there and left out, instead of refusing it all
+	bool restore(QDomElement project, const QByteArray &database, QString *error = nullptr,
+				 QStringList *lost = nullptr);
+		/// What only the database could fill, left in @p project after a
+		/// restore() with lost, taken out; said in @p lost
+	void dropLeftovers(QDomElement project, QStringList *lost);
 		/// true if @p database is of the format this writes
 	bool currentFormat(const QByteArray &database);
 }

sources/container/qetzip.cpp

@@ -18,6 +18,7 @@
 #include "qetzip.h"
 
 #include "miniz/miniz.h"
+#include "../utils/syncfolder.h"
 
 #include <QFile>
 #include <QSaveFile>
@@ -152,6 +153,7 @@ bool QetZip::write(const QString &path, const QList<Entry> &entries, QString *er
 		setError(error, file.errorString());
 		return false;
 	}
+	QET::syncFolderOf(path);
 	return true;
 }
 
@@ -160,9 +162,12 @@ bool QetZip::write(const QString &path, const QList<Entry> &entries, QString *er
 	Read every file entry of the zip @p zip into @p entries, in archive
 	order. Folders are skipped. An encrypted entry, an unsafe or repeated
 	name, a method miniz cannot read, or more than MaxEntries entries or
-	MaxUncompressedSize bytes refuse the whole archive.
+	MaxUncompressedSize bytes refuse the whole archive. With @p skipped (a
+	damaged project recovered), an entry that cannot be read is named
+	there and left out instead; the size limits still refuse it all.
 */
-bool QetZip::fromBytes(const QByteArray &zip_bytes, QList<Entry> *entries, QString *error)
+bool QetZip::fromBytes(const QByteArray &zip_bytes, QList<Entry> *entries, QString *error,
+					   QStringList *skipped)
 {
 	if (!entries) return false;
 	entries->clear();
@@ -188,6 +193,10 @@ bool QetZip::fromBytes(const QByteArray &zip_bytes, QList<Entry> *entries, QStri
 	{
 		mz_zip_archive_file_stat stat;
 		if (!mz_zip_reader_file_stat(&zip, i, &stat)) {
+			if (skipped) {
+				skipped->append(QStringLiteral("unreadable entry %1").arg(i));
+				continue;
+			}
 			setError(error, QStringLiteral("unreadable entry %1").arg(i));
 			mz_zip_reader_end(&zip);
 			return false;
@@ -197,6 +206,10 @@ bool QetZip::fromBytes(const QByteArray &zip_bytes, QList<Entry> *entries, QStri
 		const QString name = QString::fromUtf8(stat.m_filename);
 		if (stat.m_is_encrypted || !stat.m_is_supported || !safeName(name)
 			|| names.contains(name)) {
+			if (skipped) {
+				skipped->append(QStringLiteral("entry \"%1\" cannot be read").arg(name));
+				continue;
+			}
 			setError(error, QStringLiteral("entry \"%1\" cannot be read").arg(name));
 			mz_zip_reader_end(&zip);
 			return false;
@@ -211,8 +224,13 @@ bool QetZip::fromBytes(const QByteArray &zip_bytes, QList<Entry> *entries, QStri
 		size_t size = 0;
 		void *data = mz_zip_reader_extract_to_heap(&zip, i, &size, 0);
 		if (!data) {
-			setError(error, QStringLiteral("cannot unpack \"%1\": %2")
-					 .arg(name, QString::fromLatin1(mz_zip_get_error_string(mz_zip_get_last_error(&zip)))));
+			const QString problem = QStringLiteral("cannot unpack \"%1\": %2")
+					.arg(name, QString::fromLatin1(mz_zip_get_error_string(mz_zip_get_last_error(&zip))));
+			if (skipped) {
+				skipped->append(problem);
+				continue;
+			}
+			setError(error, problem);
 			mz_zip_reader_end(&zip);
 			return false;
 		}

sources/container/qetzip.h

@@ -21,6 +21,7 @@
 #include <QByteArray>
 #include <QList>
 #include <QString>
+#include <QStringList>
 
 /**
 	@brief The QetZip namespace
@@ -49,7 +50,8 @@ namespace QetZip
 	bool write(const QString &path, const QList<Entry> &entries, QString *error = nullptr);
 	QByteArray toBytes(const QList<Entry> &entries, QString *error = nullptr);
 	bool read(const QString &path, QList<Entry> *entries, QString *error = nullptr);
-	bool fromBytes(const QByteArray &zip, QList<Entry> *entries, QString *error = nullptr);
+	bool fromBytes(const QByteArray &zip, QList<Entry> *entries, QString *error = nullptr,
+				   QStringList *skipped = nullptr);
 }
 
 #endif // QETZIP_H

sources/diagram.cpp

@@ -881,6 +881,17 @@ QDomElement Diagram::deferredXmlWithHeader(QDomDocument &document)
 	for (QDomElement child = items.firstChildElement() ; !child.isNull() ; child = child.nextSiblingElement())
 		if (!header_children.contains(child.tagName()))
 			folio.appendChild(document.importNode(child, true));
+		//Its pictures written in, as building it writes them. A folio read
+		//from a .qetz names its pictures' files instead, which the next
+		//.qetz written from this document would leave out: that project
+		//then refused to open, "picture ... is missing" (F118).
+	for (QDomElement image : QET::findInDomElement(folio, QStringLiteral("images"), QStringLiteral("image"))) {
+		const QString file = QetContainer::pictureFile(image);
+		if (file.isEmpty() || !m_project) continue;
+		const QByteArray bytes = m_project->containerPicture(file);
+		if (!bytes.isEmpty())
+			QetContainer::inlinePicture(image, bytes);
+	}
 	return folio;
 }
 

sources/qet.cpp

@@ -19,6 +19,7 @@
 #include "qetapp.h"
 #include "qeticons.h"
 #include "shortcutmanager.h"
+#include "utils/syncfolder.h"
 
 #include <cmath>
 #include <limits>
@@ -809,6 +810,7 @@ bool QET::writeXmlText(const QString &text, const QString &filepath, QString *er
 
 		return false;
 	}
+	syncFolderOf(filepath);
 
 	return(true);
 }

sources/qetdiagrameditor.cpp

@@ -16,6 +16,9 @@
 	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
 */
 #include "qetdiagrameditor.h"
+#include "container/qetcontainer.h"
+#include "container/qetzip.h"
+#include "utils/previousversions.h"
 #include "shownkinds.h"
 #ifdef QET_HAS_SCRIPTING
 #include "scripting/qetscripting.h"
@@ -25,6 +28,8 @@
 #include "scripting/macrorecorder.h"
 #include "scripting/assistantinfo.h"
 #endif
+#include <QDomDocument>
+#include <QTemporaryDir>
 #include <QCoreApplication>
 #include <QToolButton>
 #include <QWidgetAction>
@@ -1933,6 +1938,115 @@ QETDiagramEditor::LockChoice QETDiagramEditor::askAboutLock(
 	return LockChoice::Cancel;
 }
 
+/**
+	@brief QETDiagramEditor::offerToRecover
+	@p filepath could not be read (@p reason): say why, and offer its newest
+	previous version (PreviousVersions) and, for a .qetz, what can be read
+	of it (QetContainer::recover()). Either opens as a new project,
+	"<name> (recovered)"; @p filepath is never moved or written.
+	@return true if a project was opened
+*/
+bool QETDiagramEditor::offerToRecover(const QString &filepath, const QString &reason)
+{
+	const QFileInfo info(filepath);
+	QFile file(filepath);
+	const bool zip = file.open(QIODevice::ReadOnly) && QetContainer::isZip(file.peek(4));
+	file.close();
+	const QStringList versions = PreviousVersions::kept(filepath);
+
+	QMessageBox box(QMessageBox::Warning, tr("Cannot open %1").arg(info.fileName()),
+					reason.isEmpty()
+					? tr("The file %1 cannot be read as a QElectroTech project.").arg(info.fileName())
+					: tr("The project file is damaged:\n%1").arg(reason),
+					QMessageBox::Cancel, this);
+	QAbstractButton *previous = nullptr, *recover = nullptr;
+	if (!versions.isEmpty()) {
+		const QDateTime saved = QFileInfo(versions.first()).lastModified();
+		previous = box.addButton(tr("Open the version saved %1")
+								 .arg(QLocale().toString(saved, QLocale::ShortFormat)),
+								 QMessageBox::AcceptRole);
+	}
+	if (zip)
+		recover = box.addButton(tr("Recover what can be read"), QMessageBox::AcceptRole);
+	if (previous || recover)
+		box.setInformativeText(tr("Either opens as a new project, \"%1\"; %2 is left as it is.")
+							   .arg(recoveredPath(filepath, info.suffix()).section(QLatin1Char('/'), -1),
+									info.fileName()));
+	box.exec();
+
+	if (previous && box.clickedButton() == previous)
+		return openAsRecovered(versions.first(), filepath);
+	if (recover && box.clickedButton() == recover) {
+		file.open(QIODevice::ReadOnly);
+		QDomDocument document;
+		QStringList lost;
+		QString error;
+		if (!QetContainer::recover(file.readAll(), &document, &lost, &error)) {
+			QET::QetMessageBox::warning(this, tr("Cannot open %1").arg(info.fileName()),
+										tr("Nothing can be recovered from it:\n%1").arg(error));
+			return false;
+		}
+			//Opened from a .qetz written of it, as the project it replaces
+		QTemporaryDir dir;
+		const QString read = dir.filePath(info.completeBaseName() + QStringLiteral(".qetz"));
+		const QList<QetZip::Entry> parts = QetContainer::split(document, QString(), &error);
+		if (!dir.isValid() || parts.isEmpty() || !QetZip::write(read, parts, &error)
+				|| !openAsRecovered(read, filepath)) {
+			if (!error.isEmpty())
+				QET::QetMessageBox::warning(this, tr("Cannot open %1").arg(info.fileName()), error);
+			return false;
+		}
+		if (!lost.isEmpty()) {
+			QMessageBox done(QMessageBox::Information, tr("Project recovered"),
+							 tr("What could be read of %1 is open as a new project. "
+								"Some parts could not be read and were left out: see the details.")
+							 .arg(info.fileName()),
+							 QMessageBox::Ok, this);
+			done.setDetailedText(lost.join(QLatin1Char('\n')));
+			done.exec();
+		}
+		return true;
+	}
+	return false;
+}
+
+/**
+	@brief QETDiagramEditor::recoveredPath
+	@return where a project recovered from @p filepath is saved: beside it,
+	"<name> (recovered).<suffix>", numbered if that is taken
+*/
+QString QETDiagramEditor::recoveredPath(const QString &filepath, const QString &suffix)
+{
+	const QFileInfo info(filepath);
+	QString path = info.absoluteDir().filePath(tr("%1 (recovered)").arg(info.completeBaseName())
+											   + QLatin1Char('.') + suffix);
+	for (int n = 2 ; QFileInfo::exists(path) ; ++n)
+		path = info.absoluteDir().filePath(tr("%1 (recovered %2)").arg(info.completeBaseName()).arg(n)
+										   + QLatin1Char('.') + suffix);
+	return path;
+}
+
+/**
+	@brief QETDiagramEditor::openAsRecovered
+	Open @p source as a new project saved beside @p original, of its type
+	(recoveredPath()), not saved yet.
+	@return true if it opened
+*/
+bool QETDiagramEditor::openAsRecovered(const QString &source, const QString &original)
+{
+	QETProject *project = new QETProject(source);
+	if (project->state() != QETProject::Ok) {
+		QET::QetMessageBox::warning(this, tr("Cannot open %1").arg(QFileInfo(source).fileName()),
+									project->openError());
+		delete project;
+		return false;
+	}
+	project->setFilePath(recoveredPath(original, QFileInfo(original).suffix()));
+	project->setModified(true);
+	addProject(project);
+	return true;
+}
+
 /**
 	Ouvre un projet depuis un fichier et l'ajoute a cet editeur
 	@param filepath Chemin du projet a ouvrir
@@ -2058,7 +2172,17 @@ bool QETDiagramEditor::openAndAddProject(
 	QETProject *project = new QETProject(filepath);
 	if (project -> state() != QETProject::Ok)
 	{
-		if (interactive && project -> state() != QETProject::FileOpenDiscard)
+			//A damaged project: its previous version or what can be read
+			//of it, as a new project; the file itself is left as it is
+		if (interactive && project->state() == QETProject::XmlParsingFailed
+				&& offerToRecover(filepath, project->openError()))
+		{
+			delete project;
+			DialogWaiting::dropInstance();
+			return(true);
+		}
+		if (interactive && project -> state() != QETProject::FileOpenDiscard
+				&& project -> state() != QETProject::XmlParsingFailed)
 		{
 			QET::QetMessageBox::warning(
 				this,

sources/qetdiagrameditor.h

@@ -89,6 +89,9 @@ class QETDiagramEditor : public QETMainWindow
 	  protected:
 		bool event(QEvent *) override;
 	private:
+		bool offerToRecover(const QString &filepath, const QString &reason);
+		bool openAsRecovered(const QString &source, const QString &original);
+		static QString recoveredPath(const QString &filepath, const QString &suffix);
 		// Declared first so it is initialised before any member whose
 		// constructor may dispatch a Qt event calling event() (e.g. the
 		// QActionGroup members below trigger QObject::setParent events).

sources/qetgraphicsitem/dynamicelementtextitem.cpp

@@ -1098,6 +1098,19 @@ void DynamicElementTextItem::handlerMouseReleaseEvent(QetGraphicsHandlerItem *ha
 
 void DynamicElementTextItem::elementInfoChanged()
 {
+		//A folio report's label shows where its partner is
+		//(updateReportText()); the label in its information is only where
+		//the partner was when last saved, and changing any other
+		//information wrote that stale position back (F116)
+	if (m_text_from == ElementInfo && m_info_name == QLatin1String("label")
+			&& m_parent_element && (m_parent_element.data()->linkType() & Element::AllReport)
+			&& m_other_report) {
+		setupFormulaConnection();
+		updateReportText();
+		emit plainTextChanged();
+		return;
+	}
+
 	DiagramContext dc;
 	Element *element = elementUseForInfo();
 	if(element) {

sources/qetproject.cpp

@@ -48,6 +48,7 @@
 #include "qetinformation.h"
 #include "qetversion.h"
 #include "undocommand/adddiagramcommand.h"
+#include "utils/previousversions.h"
 
 #include <QCryptographicHash>
 #include <QElapsedTimer>
@@ -514,6 +515,7 @@ QETProject::ProjectState QETProject::openFile(QFile *file)
 	if (!read)
 	{
 		qWarning().noquote() << "Unable to read" << fi.fileName() << ":" << read_error;
+		m_open_error = read_error;
 		m_container_pictures.clear();
 		m_folio_parts.clear();
 		if(opened_here) {
@@ -602,6 +604,16 @@ QETProject::ProjectState QETProject::state() const
 	return(m_state);
 }
 
+/**
+	@brief QETProject::openError
+	@return why the file could not be read, when state() is
+	XmlParsingFailed: "picture ... is missing", say; empty otherwise
+*/
+QString QETProject::openError() const
+{
+	return m_open_error;
+}
+
 /**
 	@return la liste des schemas de ce projet
 */
@@ -2763,6 +2775,13 @@ QETResult QETProject::write()
 			return(QString("the file %1 was opened read-only and thus will not be written").arg(m_file_path));
 	}
 
+		//The file as it was goes among its previous versions first
+		//(Settings > General > Projects); a copy that fails does not stop
+		//the save
+	QString backup_error;
+	if (!PreviousVersions::keep(m_file_path, PreviousVersions::count(), &backup_error))
+		qWarning().noquote() << "Previous version of" << m_file_path << "not kept:" << backup_error;
+
 	QString error_message;
 	if (isContainerPath(m_file_path))
 	{

sources/qetproject.h

@@ -124,6 +124,7 @@ class QETProject : public QObject
 		QUuid derivedItemUuid(const QString &kind, const QString &key);
 		QByteArray containerPicture(const QString &file) const;
 		ProjectState state() const;
+		QString openError() const;
 		QList<Diagram *> diagrams() const;
 			//The folios whether their items are built or not
 			//(lazy folios); diagrams() builds them
@@ -594,6 +595,8 @@ class QETProject : public QObject
 		QFuture<bool> m_backup_future;
 			/// Crash-recovery snapshots, written in turn by writeBackup()
 		std::array<KAutoSaveFile, BackupGenerations> m_backup_files;
+			/// Why the file could not be read, see openError()
+		QString m_open_error;
 		int m_next_backup_slot = 0;
 		QUuid m_uuid = QUuid::createUuid();
 		QHash<QString, int> m_derived_uuid_keys;

sources/ui/configpage/generalconfigurationpage.cpp

@@ -26,6 +26,7 @@
 #include "../../cablelist/cabletypelist.h"
 #include "../../utils/qetsettings.h"
 #include "../../utils/qetutils.h"
+#include "../../utils/previousversions.h"
 #include "../../qetmessagebox.h"
 #include "../../textgrid.h"
 #include "../../wiringrules.h"
@@ -191,6 +192,7 @@ GeneralConfigurationPage::GeneralConfigurationPage(QWidget *parent) :
 	ui->m_border_0->setChecked(settings.value("border-columns_0", false).toBool());
 	ui->m_autosave_sb->setValue(settings.value("diagrameditor/autosave-interval", 0).toInt());
 	ui->m_project_lock->setChecked(settings.value("projectlock/enabled", true).toBool());
+	ui->m_previous_versions_sb->setValue(PreviousVersions::count());
 	
 	QString fontInfos = settings.value("diagramitemfont", "Liberation Sans").toString() + " " +
 			settings.value("diagramitemsize", "9").toString() + " (" +
@@ -419,6 +421,7 @@ void GeneralConfigurationPage::applyConf()
 	}
 	settings.setValue("diagrameditor/autosave-interval", ui->m_autosave_sb->value());
 	settings.setValue("projectlock/enabled", ui->m_project_lock->isChecked());
+	PreviousVersions::setCount(ui->m_previous_versions_sb->value());
 
 	settings.setValue("diagrameditor/grid_display_startup", ui->grid_startup_cb->isChecked());
 	settings.setValue("diagrameditor/guides_display_startup", ui->guides_startup_cb->isChecked());

sources/ui/configpage/generalconfigurationpage.ui

@@ -375,6 +375,29 @@
         </widget>
        </item>
        <item row="7" column="0">
+        <widget class="QLabel" name="m_previous_versions_label">
+         <property name="text">
+          <string>Previous versions kept when saving a project</string>
+         </property>
+         <property name="toolTip">
+          <string>Before a project is saved, the file as it was is copied to a folder beside it, named after the project with "-backups". Only the newest are kept.</string>
+         </property>
+        </widget>
+       </item>
+       <item row="7" column="2">
+        <widget class="QSpinBox" name="m_previous_versions_sb">
+         <property name="toolTip">
+          <string>Before a project is saved, the file as it was is copied to a folder beside it, named after the project with "-backups". Only the newest are kept.</string>
+         </property>
+         <property name="specialValueText">
+          <string>None</string>
+         </property>
+         <property name="maximum">
+          <number>100</number>
+         </property>
+        </widget>
+       </item>
+       <item row="9" column="0">
         <spacer name="verticalSpacer_2">
          <property name="orientation">
           <enum>Qt::Vertical</enum>
@@ -1545,6 +1568,7 @@
   <tabstop>m_use_folio_label</tabstop>
   <tabstop>m_border_0</tabstop>
   <tabstop>m_autosave_sb</tabstop>
+  <tabstop>m_previous_versions_sb</tabstop>
   <tabstop>m_common_elmt_path_cb</tabstop>
   <tabstop>m_custom_elmt_path_cb</tabstop>
   <tabstop>m_custom_tbt_path_cb</tabstop>

sources/utils/previousversions.cpp

@@ -0,0 +1,113 @@
+/*
+	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 "previousversions.h"
+
+#include <QCryptographicHash>
+#include <QDateTime>
+#include <QDir>
+#include <QFile>
+#include <QFileInfo>
+#include <QSettings>
+
+namespace {
+const QString CountKey = QStringLiteral("diagrameditor/previous-versions");
+constexpr int DefaultCount = 5;
+
+	//What a version of @p info is named, without the extension: its base
+	//name and a time
+QString versionPrefix(const QFileInfo &info)
+{
+	return info.completeBaseName() + QLatin1Char(' ');
+}
+
+QByteArray digest(const QString &path)
+{
+	QFile file(path);
+	if (!file.open(QIODevice::ReadOnly)) return {};
+	QCryptographicHash hash(QCryptographicHash::Sha256);
+	hash.addData(&file);
+	return hash.result();
+}
+}
+
+int PreviousVersions::count()
+{
+	return qMax(0, QSettings().value(CountKey, DefaultCount).toInt());
+}
+
+void PreviousVersions::setCount(int count)
+{
+	QSettings().setValue(CountKey, qMax(0, count));
+}
+
+QString PreviousVersions::folder(const QString &file_path)
+{
+	const QFileInfo info(file_path);
+	return info.absoluteDir().filePath(info.completeBaseName() + QStringLiteral("-backups"));
+}
+
+QStringList PreviousVersions::kept(const QString &file_path)
+{
+	const QFileInfo info(file_path);
+	const QDir dir(folder(file_path));
+		//Each copy has the time its version was saved (keep()); a .qet and
+		//a .qetz of the same project are versions of it alike
+	QStringList names = dir.entryList({versionPrefix(info) + QStringLiteral("????-??-?? ??-??-??*.qet"),
+									   versionPrefix(info) + QStringLiteral("????-??-?? ??-??-??*.qetz")},
+									  QDir::Files, QDir::Time);
+	QStringList paths;
+	for (const QString &name : std::as_const(names))
+		paths << dir.filePath(name);
+	return paths;
+}
+
+bool PreviousVersions::keep(const QString &file_path, int count, QString *error)
+{
+	const QFileInfo info(file_path);
+	if (count <= 0 || !info.isFile()) return true;
+
+	const QStringList versions = kept(file_path);
+	if (!versions.isEmpty() && QFileInfo(versions.first()).size() == info.size()
+			&& digest(versions.first()) == digest(file_path))
+		return true;
+
+	QDir dir(folder(file_path));
+	if (!dir.exists() && !QDir().mkpath(dir.path())) {
+		if (error) *error = QStringLiteral("cannot create the folder %1").arg(dir.path());
+		return false;
+	}
+		//Named by the time this version was saved, made unique if another
+		//was saved the same second
+	const QDateTime saved = info.lastModified();
+	const QString stem = versionPrefix(info) + saved.toString(QStringLiteral("yyyy-MM-dd HH-mm-ss"));
+	QString target = dir.filePath(stem + QLatin1Char('.') + info.suffix());
+	for (int n = 2 ; QFileInfo::exists(target) ; ++n)
+		target = dir.filePath(stem + QStringLiteral(" (%1).").arg(n) + info.suffix());
+	if (!QFile::copy(file_path, target)) {
+		if (error) *error = QStringLiteral("cannot copy %1 to %2").arg(file_path, target);
+		return false;
+	}
+	QFile copy(target);
+	if (copy.open(QIODevice::ReadWrite))
+		copy.setFileTime(saved, QFileDevice::FileModificationTime);
+
+	const QStringList all = kept(file_path);
+	for (int i = count ; i < all.size() ; ++i)
+		QFile::remove(all.at(i));
+	return true;
+}

sources/utils/previousversions.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 PREVIOUSVERSIONS_H
+#define PREVIOUSVERSIONS_H
+
+#include <QString>
+#include <QStringList>
+
+/**
+	@brief The PreviousVersions namespace
+	The versions of a project file kept before it is saved over, as KiCad
+	and AutoCAD keep theirs: a copy of the file as it was goes in a folder
+	beside it, "<name>-backups", named by the time that version was saved
+	("industrial 2026-10-16 08-30-12.qetz"), and only the newest are kept.
+	The file is copied, never moved: a save that fails leaves it in place.
+*/
+namespace PreviousVersions
+{
+		/// How many versions to keep (Settings > General > Projects); 0 keeps none
+	int count();
+	void setCount(int count);
+		/// The folder the versions of @p file_path go in
+	QString folder(const QString &file_path);
+		/// The versions kept of @p file_path, newest first
+	QStringList kept(const QString &file_path);
+		/// Copy @p file_path, about to be saved over, among its versions and
+		/// keep only the @p count newest. Nothing is copied when the file does
+		/// not exist, when @p count is 0, or when the newest version kept
+		/// holds the same bytes. @return false, with @p error, when the copy
+		/// could not be made: the save goes on all the same.
+	bool keep(const QString &file_path, int count, QString *error = nullptr);
+}
+
+#endif // PREVIOUSVERSIONS_H

sources/utils/syncfolder.h

@@ -0,0 +1,54 @@
+/*
+	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 SYNCFOLDER_H
+#define SYNCFOLDER_H
+
+#include <QFile>
+#include <QFileInfo>
+#include <QString>
+
+#ifndef Q_OS_WIN
+#include <fcntl.h>
+#include <unistd.h>
+#endif
+
+namespace QET {
+	/**
+		Force to disk the folder holding @p file_path, once
+		QSaveFile::commit() renamed a new file into it. QSaveFile syncs the
+		file it wrote but not the folder, and on some file systems (ext4,
+		XFS) a power cut soon after can then lose the rename: the previous
+		file comes back, or none. Does nothing on Windows, where a folder
+		cannot be synced this way.
+	*/
+	inline void syncFolderOf(const QString &file_path)
+	{
+#ifndef Q_OS_WIN
+		const QByteArray folder = QFile::encodeName(QFileInfo(file_path).absolutePath());
+		const int fd = ::open(folder.constData(), O_RDONLY | O_DIRECTORY | O_CLOEXEC);
+		if (fd >= 0) {
+			::fsync(fd);
+			::close(fd);
+		}
+#else
+		Q_UNUSED(file_path)
+#endif
+	}
+}
+
+#endif // SYNCFOLDER_H

tests/qttest/CMakeLists.txt

@@ -942,6 +942,30 @@ if(QET_HAS_SCRIPTING)
     "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\""
     "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\"")
 
+  # A folio report keeps showing where its partner is when another of its
+  # information changes (F116), on examples/iso_sfc_example.qet.
+  add_executable(
+    tst_reporttextafterinfo
+    tst_reporttextafterinfo.cpp)
+  add_test(NAME tst_reporttextafterinfo COMMAND tst_reporttextafterinfo)
+  add_dependencies(tst_reporttextafterinfo qelectrotech)
+  target_link_libraries(tst_reporttextafterinfo PRIVATE Qt::Test Qt::Xml)
+  target_compile_definitions(tst_reporttextafterinfo PRIVATE
+    "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\""
+    "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\"")
+
+  # A .qetz folio whose title only changed keeps its pictures when saved
+  # with folios built when needed (F118), on examples/grafcet.qet.
+  add_executable(
+    tst_qetzheaderpictures
+    tst_qetzheaderpictures.cpp)
+  add_test(NAME tst_qetzheaderpictures COMMAND tst_qetzheaderpictures)
+  add_dependencies(tst_qetzheaderpictures qelectrotech)
+  target_link_libraries(tst_qetzheaderpictures PRIVATE Qt::Test)
+  target_compile_definitions(tst_qetzheaderpictures PRIVATE
+    "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\""
+    "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\"")
+
   # qet.elementTerminals() lists each terminal's uuid and qet.terminalIndex()
   # turns element uuid + terminal uuid back into the index the conductor
   # calls take, on examples/perceuse.qet (two terminals at one point).
@@ -1275,6 +1299,17 @@ if(Qt6_VERSION VERSION_LESS 6.5.0)
   endforeach()
 endif()
 
+# The versions of a project kept before it is saved over: the newest
+# kept, same bytes not kept twice, a failed copy said
+# (sources/utils/previousversions.*).
+add_executable(
+  tst_previousversions
+  tst_previousversions.cpp
+  ${QET_DIR}/sources/utils/previousversions.cpp)
+add_test(NAME tst_previousversions COMMAND tst_previousversions)
+target_include_directories(tst_previousversions PRIVATE ${QET_DIR}/sources)
+target_link_libraries(tst_previousversions PRIVATE Qt::Test)
+
 # The zip a .qetz project is stored in: round trip, same bytes twice,
 # unsafe entry names refused (sources/container/qetzip.*, bundled miniz).
 add_executable(

tests/qttest/tst_previousversions.cpp

@@ -0,0 +1,127 @@
+/*
+	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 <QtTest>
+
+#include <QDateTime>
+#include <QFile>
+#include <QTemporaryDir>
+
+#include "utils/previousversions.h"
+
+// The versions of a project kept before it is saved over
+// (sources/utils/previousversions.*)
+class tst_previousversions : public QObject
+{
+	Q_OBJECT
+
+	QTemporaryDir m_dir;
+
+		// @p path holding @p text, saved at @p when
+	static void write(const QString &path, const QByteArray &text, const QDateTime &when)
+	{
+		QFile file(path);
+		QVERIFY(file.open(QIODevice::WriteOnly | QIODevice::Truncate));
+		file.write(text);
+		file.flush();	//else closing writes, and sets the time to now
+		QVERIFY(file.setFileTime(when, QFileDevice::FileModificationTime));
+	}
+
+	static QByteArray read(const QString &path)
+	{
+		QFile file(path);
+		return file.open(QIODevice::ReadOnly) ? file.readAll() : QByteArray();
+	}
+
+private slots:
+	void initTestCase() { QVERIFY(m_dir.isValid()); }
+
+	// Each save keeps the file as it was, newest first, named by the time
+	// that version was saved, in "<name>-backups" beside it; only the
+	// newest are kept
+	void keepsTheNewest()
+	{
+		const QString project = m_dir.filePath(QStringLiteral("plant.qetz"));
+		const QDateTime start(QDate(2026, 10, 16), QTime(8, 0, 0));
+		for (int i = 0 ; i < 7 ; ++i) {
+			write(project, "version " + QByteArray::number(i), start.addSecs(60 * i));
+			QVERIFY(PreviousVersions::keep(project, 3));
+		}
+		const QStringList kept = PreviousVersions::kept(project);
+		QCOMPARE(kept.size(), 3);
+		QCOMPARE(read(kept.at(0)), QByteArray("version 6"));
+		QCOMPARE(read(kept.at(2)), QByteArray("version 4"));
+		QCOMPARE(QFileInfo(kept.at(0)).fileName(), QStringLiteral("plant 2026-10-16 08-06-00.qetz"));
+		QCOMPARE(QFileInfo(kept.at(0)).absolutePath(), m_dir.filePath(QStringLiteral("plant-backups")));
+			// The project itself is untouched
+		QCOMPARE(read(project), QByteArray("version 6"));
+	}
+
+	// Saving the same bytes again keeps no second copy
+	void sameBytesNotKeptTwice()
+	{
+		const QString project = m_dir.filePath(QStringLiteral("same.qet"));
+		const QDateTime when(QDate(2026, 10, 16), QTime(9, 0, 0));
+		write(project, "unchanged", when);
+		QVERIFY(PreviousVersions::keep(project, 5));
+		write(project, "unchanged", when.addSecs(30));
+		QVERIFY(PreviousVersions::keep(project, 5));
+		QCOMPARE(PreviousVersions::kept(project).size(), 1);
+	}
+
+	// Two versions saved the same second both kept
+	void sameSecond()
+	{
+		const QString project = m_dir.filePath(QStringLiteral("fast.qetz"));
+		const QDateTime when(QDate(2026, 10, 16), QTime(10, 0, 0));
+		write(project, "first", when);
+		QVERIFY(PreviousVersions::keep(project, 5));
+		write(project, "second", when);
+		QVERIFY(PreviousVersions::keep(project, 5));
+		QCOMPARE(PreviousVersions::kept(project).size(), 2);
+	}
+
+	// Nothing kept for a new file, or when the count is 0; another
+	// project's versions in the same folder are not counted
+	void nothingToKeep()
+	{
+		const QString project = m_dir.filePath(QStringLiteral("new.qetz"));
+		QVERIFY(PreviousVersions::keep(project, 5));
+		QVERIFY(!QFileInfo::exists(PreviousVersions::folder(project)));
+		write(project, "x", QDateTime(QDate(2026, 10, 16), QTime(11, 0, 0)));
+		QVERIFY(PreviousVersions::keep(project, 0));
+		QVERIFY(!QFileInfo::exists(PreviousVersions::folder(project)));
+		QVERIFY(PreviousVersions::kept(m_dir.filePath(QStringLiteral("other.qetz"))).isEmpty());
+	}
+
+	// A copy that cannot be made says so, and leaves the project as it is
+	void copyFails()
+	{
+		const QString project = m_dir.filePath(QStringLiteral("blocked.qetz"));
+		write(project, "data", QDateTime(QDate(2026, 10, 16), QTime(12, 0, 0)));
+			// A file where the folder should be
+		write(PreviousVersions::folder(project), "", QDateTime::currentDateTime());
+		QString error;
+		QVERIFY(!PreviousVersions::keep(project, 5, &error));
+		QVERIFY(!error.isEmpty());
+		QCOMPARE(read(project), QByteArray("data"));
+	}
+};
+
+QTEST_GUILESS_MAIN(tst_previousversions)
+
+#include "tst_previousversions.moc"

tests/qttest/tst_qetcontainer.cpp

@@ -3,6 +3,7 @@
 
 #include <QDir>
 #include <QFile>
+#include <QtEndian>
 
 #include <functional>
 
@@ -533,6 +534,38 @@ private slots:
 		QVERIFY(!error.isEmpty());
 	}
 
+	// A page of the database overwritten, as a bad disk or a broken copy
+	// would: refused, and said to be damaged (quick_check on opening),
+	// whichever table the page held
+	void damagedDatabaseRefused_data()
+	{
+		QTest::addColumn<double>("where");
+		QTest::newRow("second page") << 0.0;
+		QTest::newRow("middle page") << 0.5;
+		QTest::newRow("last page") << 1.0;
+	}
+	void damagedDatabaseRefused()
+	{
+		QFETCH(double, where);
+		QDomDocument original;
+		QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		bool damaged = false;
+		for (QetZip::Entry &entry : entries) {
+			if (entry.name != QLatin1String("project.sqlite")) continue;
+			const int page_size = qFromBigEndian<quint16>(entry.data.constData() + 16);
+			const int pages = int(entry.data.size() / page_size);
+			QVERIFY(pages > 3);
+			const int page = 1 + int(where * (pages - 2));
+			entry.data.replace(page * page_size, page_size, QByteArray(page_size, char(0xff)));
+			damaged = true;
+		}
+		QVERIFY(damaged);
+		QDomDocument back;
+		QString error;
+		QVERIFY(!QetContainer::join(entries, &back, &error));
+		QVERIFY2(error.contains(QStringLiteral("damaged")), qPrintable(error));
+	}
+
 	// project.sqlite changed by @p sql in @p entries
 	static void alterDatabase(QList<QetZip::Entry> &entries, const char *sql)
 	{
@@ -764,6 +797,119 @@ private slots:
 		QString error;
 		QVERIFY(!QetContainer::join({{QStringLiteral("mimetype"), "application/zip", false}}, &back, &error));
 	}
+
+	// recover() reads what it can of a damaged .qetz: each kind of damage
+	// costs what it held and nothing else, and is said
+	void recoverLeavesOutOnlyTheDamage_data()
+	{
+		QTest::addColumn<QString>("damage");
+		QTest::addColumn<QString>("said");
+		QTest::addColumn<int>("folios");
+		QTest::addColumn<int>("wires");
+		QTest::newRow("nothing") << QString() << QString() << 0 << 0;
+		QTest::newRow("folio file missing") << QStringLiteral("folio") << QStringLiteral("is missing") << -1 << 0;
+		QTest::newRow("wire row deleted") << QStringLiteral("row") << QStringLiteral("not in the database") << 0 << -1;
+		QTest::newRow("database page overwritten") << QStringLiteral("page") << QStringLiteral("cannot be read") << 0 << -1000;
+	}
+	void recoverLeavesOutOnlyTheDamage()
+	{
+		QFETCH(QString, damage);
+		QFETCH(QString, said);
+		QFETCH(int, folios);
+		QFETCH(int, wires);
+		QDomDocument original;
+		QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		QVERIFY(!entries.isEmpty());
+		auto count = [](const QDomDocument &d, const QString &tag) {
+			return int(d.documentElement().elementsByTagName(tag).size());
+		};
+		const int folios_before = count(original, QStringLiteral("diagram"));
+		const int wires_before = count(original, QStringLiteral("conductor"));
+		if (damage == QLatin1String("folio")) {
+			for (int i = 0 ; i < entries.size() ; ++i)
+				if (entries.at(i).name.startsWith(QStringLiteral("folios/"))) { entries.removeAt(i); break; }
+		} else if (damage == QLatin1String("row")) {
+			alterDatabase(entries, "DELETE FROM conductor WHERE rowid = (SELECT min(rowid) FROM conductor)");
+		} else if (damage == QLatin1String("page")) {
+			for (QetZip::Entry &entry : entries) {
+				if (entry.name != QLatin1String("project.sqlite")) continue;
+				const int page_size = qFromBigEndian<quint16>(entry.data.constData() + 16);
+				const int page = int(entry.data.size() / page_size / 2);
+				entry.data.replace(page * page_size, page_size, QByteArray(page_size, char(0xff)));
+			}
+		}
+		QByteArray zip;
+		QString error;
+		QVERIFY2(QetZip::toBytes(entries, &error).size() > 0, qPrintable(error));
+		zip = QetZip::toBytes(entries, &error);
+
+		QDomDocument back;
+		QStringList lost;
+		QVERIFY2(QetContainer::recover(zip, &back, &lost, &error), qPrintable(error));
+		if (said.isEmpty()) {
+			QVERIFY2(lost.isEmpty(), qPrintable(lost.join(QLatin1Char('\n'))));
+		} else {
+			QVERIFY2(lost.join(QLatin1Char('\n')).contains(said), qPrintable(lost.join(QLatin1Char('\n'))));
+				// Strict reading refuses it
+			QDomDocument strict;
+			QVERIFY(!QetContainer::join(entries, &strict));
+		}
+		QCOMPARE(count(back, QStringLiteral("diagram")), folios_before + folios);
+		if (wires == -1000)
+			QCOMPARE(count(back, QStringLiteral("conductor")), 0);
+		else
+			QCOMPARE(count(back, QStringLiteral("conductor")), wires_before + wires);
+			// Nothing of the container's own left in the document
+		QVERIFY(!back.toString().contains(QStringLiteral("qetz-")));
+	}
+
+	// A picture's file missing (F118 wrote such projects): the picture is
+	// left out, the rest read
+	void recoverMissingPicture()
+	{
+		QList<QetZip::Entry> entries;
+		QString error;
+		QVERIFY2(QetZip::fromBytes(read(QStringLiteral(QET_FIXTURES_DIR "/qetz_format2.qetz")), &entries, &error),
+				 qPrintable(error));
+		QDomDocument document;
+		QVERIFY2(QetContainer::join(entries, &document, &error), qPrintable(error));
+			// A picture on the first folio, then saved and its file dropped
+		QDomElement folio = document.documentElement().firstChildElement(QStringLiteral("diagram"));
+		QDomElement images = folio.firstChildElement(QStringLiteral("images"));
+		if (images.isNull()) images = folio.appendChild(document.createElement(QStringLiteral("images"))).toElement();
+		QDomElement image = document.createElement(QStringLiteral("image"));
+		image.setAttribute(QStringLiteral("type"), QStringLiteral("png"));
+		image.appendChild(document.createTextNode(QStringLiteral(
+			"iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg==")));
+		images.appendChild(image);
+		QList<QetZip::Entry> saved = QetContainer::split(document, QString(), &error);
+		QVERIFY2(!saved.isEmpty(), qPrintable(error));
+		bool dropped = false;
+		for (int i = 0 ; i < saved.size() ; ++i)
+			if (saved.at(i).name.startsWith(QStringLiteral("images/"))) { saved.removeAt(i); dropped = true; break; }
+		QVERIFY(dropped);
+		QDomDocument strict;
+		QVERIFY(!QetContainer::join(saved, &strict, &error));
+		QVERIFY(error.contains(QStringLiteral("picture")));
+
+		QDomDocument back;
+		QStringList lost;
+		QVERIFY2(QetContainer::recover(QetZip::toBytes(saved), &back, &lost, &error), qPrintable(error));
+		QCOMPARE(lost.size(), 1);
+		QVERIFY(lost.first().contains(QStringLiteral("picture")));
+		QCOMPARE(int(back.documentElement().elementsByTagName(QStringLiteral("image")).size()), 0);
+		QVERIFY(back.toString().contains(QStringLiteral("<elementInformation ")));
+	}
+
+	// What cannot be read as a zip at all is still refused
+	void recoverNotAZipRefused()
+	{
+		QDomDocument back;
+		QStringList lost;
+		QString error;
+		QVERIFY(!QetContainer::recover(QByteArray("not a zip").repeated(10), &back, &lost, &error));
+		QVERIFY(!error.isEmpty());
+	}
 };
 
 QTEST_APPLESS_MAIN(tst_qetcontainer)

tests/qttest/tst_qetzheaderpictures.cpp

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <QtTest>
+
+#include <QDir>
+#include <QFile>
+#include <QProcess>
+#include <QProcessEnvironment>
+#include <QTemporaryDir>
+
+// A folio of a .qetz whose title only changed is saved from its items as
+// read, not built (Diagram::deferredXmlWithHeader()). Those items name
+// their pictures' files in the .qetz, which the new .qetz left out: the
+// project saved then refused to open, 'picture "images/..." is missing'
+// (FINDINGS F118). Runs scripts through the real binary's --run on a copy
+// of examples/grafcet.qet given a picture on its second folio.
+class tst_qetzheaderpictures : public QObject
+{
+	Q_OBJECT
+
+	QTemporaryDir m_dir;
+
+		// Run @p script on @p project; its output
+	QString run(const QString &script, const QString &project, bool every_folio_built)
+	{
+		const QString path = m_dir.filePath(QStringLiteral("script.js"));
+		QFile f(path);
+		if (!f.open(QIODevice::WriteOnly | QIODevice::Truncate)) return QString();
+		f.write(script.toUtf8());
+		f.close();
+		const QString home = m_dir.filePath(QStringLiteral("home"));
+		QDir().mkpath(home);
+		QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+		env.insert(QStringLiteral("QT_QPA_PLATFORM"), QStringLiteral("offscreen"));
+		env.insert(QStringLiteral("QET_ENABLE_SCRIPTING"), QStringLiteral("1"));
+		env.insert(QStringLiteral("HOME"), home);
+		env.insert(QStringLiteral("XDG_CONFIG_HOME"), home + QStringLiteral("/config"));
+		env.insert(QStringLiteral("XDG_DATA_HOME"), home + QStringLiteral("/data"));
+		env.insert(QStringLiteral("TMPDIR"), m_dir.path());
+		if (every_folio_built)
+			env.insert(QStringLiteral("QET_EAGER_FOLIOS"), QStringLiteral("1"));
+		else
+			env.remove(QStringLiteral("QET_EAGER_FOLIOS"));
+		QProcess proc;
+		proc.setProcessEnvironment(env);
+		proc.start(QStringLiteral(QET_TEST_BINARY_PATH), {QStringLiteral("--run"), path, project});
+		proc.waitForFinished(120000);
+		return QString::fromUtf8(proc.readAllStandardOutput() + proc.readAllStandardError());
+	}
+
+private slots:
+	void initTestCase()
+	{
+		QVERIFY(m_dir.isValid());
+		QVERIFY(QFile::exists(QStringLiteral(QET_TEST_BINARY_PATH)));
+	}
+
+	void titleChangeKeepsPictures()
+	{
+			// A 1x1 PNG
+		const QString png = m_dir.filePath(QStringLiteral("dot.png"));
+		QFile p(png);
+		QVERIFY(p.open(QIODevice::WriteOnly));
+		p.write(QByteArray::fromBase64("iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg=="));
+		p.close();
+		const QString with_picture = m_dir.filePath(QStringLiteral("picture.qetz"));
+		const QString titled = m_dir.filePath(QStringLiteral("titled.qetz"));
+		QString out = run(QStringLiteral("qet.log('ADDED ' + qet.addImage(1, '%1', 100, 100));"
+										 "qet.save('%2');").arg(png, with_picture),
+						  QStringLiteral(QET_EXAMPLES_DIR "/grafcet.qet"), true);
+		QVERIFY2(out.contains(QStringLiteral("ADDED 0")), qPrintable(out));
+		QVERIFY(QFile::exists(with_picture));
+
+			// Only the title of the folio with the picture, folios built
+			// when needed
+		out = run(QStringLiteral("qet.log('SET ' + qet.setFolioProperty(1, 'title', 'Edited'));"
+								 "qet.save('%1');").arg(titled), with_picture, false);
+		QVERIFY2(out.contains(QStringLiteral("SET true")), qPrintable(out));
+		QVERIFY(QFile::exists(titled));
+
+			// Opens, with its picture and the new title
+		out = run(QStringLiteral("qet.log('PICTURES ' + qet.images(1).length);"
+								 "qet.log('TITLE ' + qet.folioTitle(1));"), titled, true);
+		QVERIFY2(out.contains(QStringLiteral("PICTURES 1")), qPrintable(out));
+		QVERIFY2(out.contains(QStringLiteral("TITLE Edited")), qPrintable(out));
+	}
+};
+
+QTEST_APPLESS_MAIN(tst_qetzheaderpictures)
+
+#include "tst_qetzheaderpictures.moc"

tests/qttest/tst_reporttextafterinfo.cpp

@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <QtTest>
+
+#include <QDir>
+#include <QDomDocument>
+#include <QFile>
+#include <QProcess>
+#include <QProcessEnvironment>
+#include <QTemporaryDir>
+
+// A folio report shows where its partner is. Changing any other
+// information of the report wrote back the label stored in its
+// information, the partner's position when the file was last saved, so
+// the report pointed at the wrong place until the partner moved again
+// (FINDINGS F116). Runs a script through the real binary's --run on
+// examples/iso_sfc_example.qet: the "jump to" of folio 1 moves from
+// column 4 to column 9, then the "jump from" on folio 2 gets a comment.
+class tst_reporttextafterinfo : public QObject
+{
+	Q_OBJECT
+
+	QTemporaryDir m_dir;
+
+		// The text a symbol @p uuid of @p saved shows for its label
+	static QString labelText(const QString &saved, const QString &uuid)
+	{
+		QFile file(saved);
+		if (!file.open(QIODevice::ReadOnly)) return QStringLiteral("(not saved)");
+		QDomDocument doc;
+		if (!doc.setContent(&file)) return QStringLiteral("(not read)");
+		const QDomNodeList elements = doc.elementsByTagName(QStringLiteral("element"));
+		for (int i = 0 ; i < elements.size() ; ++i) {
+			const QDomElement e = elements.at(i).toElement();
+			if (e.attribute(QStringLiteral("uuid")) != uuid) continue;
+			const QDomNodeList texts = e.elementsByTagName(QStringLiteral("dynamic_elmt_text"));
+			for (int j = 0 ; j < texts.size() ; ++j) {
+				const QDomElement t = texts.at(j).toElement();
+				if (t.firstChildElement(QStringLiteral("info_name")).text() == QLatin1String("label"))
+					return t.firstChildElement(QStringLiteral("text")).text();
+			}
+		}
+		return QStringLiteral("(no such text)");
+	}
+
+private slots:
+	void initTestCase()
+	{
+		QVERIFY(m_dir.isValid());
+		QVERIFY(QFile::exists(QStringLiteral(QET_TEST_BINARY_PATH)));
+	}
+
+	void reportFollowsItsPartner_data()
+	{
+		QTest::addColumn<bool>("every_folio_built");
+		QTest::newRow("folios built when needed") << false;
+		QTest::newRow("every folio built") << true;
+	}
+	void reportFollowsItsPartner()
+	{
+		QFETCH(bool, every_folio_built);
+		const QString tag = every_folio_built ? QStringLiteral("eager") : QStringLiteral("lazy");
+		const QString saved = m_dir.filePath(tag + QStringLiteral(".qet"));
+		const QString script = m_dir.filePath(tag + QStringLiteral(".js"));
+		QFile f(script);
+		QVERIFY(f.open(QIODevice::WriteOnly));
+		f.write("qet.moveElement(0, '{bcf3d2e9-7190-48ed-bbb5-57bcc9ba8cfa}', 300, 0);\n"
+				"qet.setElementInfo(1, '{016d0266-33ac-4255-8fe2-4d9629a12d86}', 'comment', 'edited');\n"
+				"qet.save('" + saved.toUtf8() + "');\n");
+		f.close();
+
+			// Columns numbered from 1, as QElectroTech's settings page
+			// shows by default
+		const QString home = m_dir.filePath(tag + QStringLiteral("-home"));
+		QVERIFY(QDir().mkpath(home + QStringLiteral("/config/QElectroTech")));
+		QFile conf(home + QStringLiteral("/config/QElectroTech/QElectroTech.conf"));
+		QVERIFY(conf.open(QIODevice::WriteOnly));
+		conf.write("[General]\nborder-columns_0=false\n");
+		conf.close();
+
+		QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+		env.insert(QStringLiteral("QT_QPA_PLATFORM"), QStringLiteral("offscreen"));
+		env.insert(QStringLiteral("QET_ENABLE_SCRIPTING"), QStringLiteral("1"));
+		env.insert(QStringLiteral("HOME"), home);
+		env.insert(QStringLiteral("XDG_CONFIG_HOME"), home + QStringLiteral("/config"));
+		env.insert(QStringLiteral("XDG_DATA_HOME"), home + QStringLiteral("/data"));
+		env.insert(QStringLiteral("TMPDIR"), m_dir.path());
+		if (every_folio_built)
+			env.insert(QStringLiteral("QET_EAGER_FOLIOS"), QStringLiteral("1"));
+		else
+			env.remove(QStringLiteral("QET_EAGER_FOLIOS"));
+		QProcess proc;
+		proc.setProcessEnvironment(env);
+		proc.start(QStringLiteral(QET_TEST_BINARY_PATH),
+				   {QStringLiteral("--run"), script,
+					QStringLiteral(QET_EXAMPLES_DIR "/iso_sfc_example.qet")});
+		QVERIFY(proc.waitForFinished(120000));
+
+			// The partner, moved, and the report that shows where it is
+		QCOMPARE(labelText(saved, QStringLiteral("{016d0266-33ac-4255-8fe2-4d9629a12d86}")),
+				 QStringLiteral("1-C9"));
+	}
+};
+
+QTEST_APPLESS_MAIN(tst_reporttextafterinfo)
+
+#include "tst_reporttextafterinfo.moc"