diff --git a/tools/chatgui/src/avatars/avatarcrop.cpp b/tools/chatgui/src/avatars/avatarcrop.cpp
index 5c5bfc19..437fac66 100644
--- a/tools/chatgui/src/avatars/avatarcrop.cpp
+++ b/tools/chatgui/src/avatars/avatarcrop.cpp
@@ -11,10 +11,12 @@
 #include <QPainterPath>
 #include <QPointer>
 #include <QPushButton>
+#include <QScopeGuard>
 #include <QRunnable>
 #include <QThreadPool>
 #include <QVBoxLayout>
 #include <QWheelEvent>
+#include <cmath>
 extern "C" {
 #include "debug_config.h"
 }
@@ -29,10 +31,13 @@ public:
     double scale() const { return qMax(frame().width()/originalSize.width(), frame().height()/originalSize.height()) * zoom; }
     void clamp() {
         if (image.isNull()) return;
-        const double s = scale(), mx = (originalSize.width()*s-frame().width())/2, my = (originalSize.height()*s-frame().height())/2;
+        const double s = scale();
+        const double mx = qMax(0.0, (originalSize.width()*s-frame().width())/2);
+        const double my = qMax(0.0, (originalSize.height()*s-frame().height())/2);
         offset = {qBound(-mx, offset.x(), mx), qBound(-my, offset.y(), my)};
     }
-    QRectF selection() const {
+    QRectF selection() {
+        clamp();
         const double s = scale();
         const QPointF top = QPointF(width()/2.0,height()/2.0) + offset - QPointF(originalSize.width()*s/2, originalSize.height()*s/2);
         const QRectF f = frame();
@@ -45,56 +50,91 @@ protected:
         clamp(); const double s = scale(); const QSizeF size(originalSize.width()*s, originalSize.height()*s);
         p.setRenderHint(QPainter::SmoothPixmapTransform);
         p.setRenderHint(QPainter::Antialiasing);
-        p.drawImage(QRectF(QPointF(width()/2.0,height()/2.0)+offset-QPointF(size.width()/2,size.height()/2), size), image);
+        const QRectF photo(QPointF(width()/2.0,height()/2.0)+offset-QPointF(size.width()/2,size.height()/2), size);
+        const QRectF visible = photo.intersected(rect());
+        const QRectF sample((visible.x()-photo.x())/photo.width()*image.width(), (visible.y()-photo.y())/photo.height()*image.height(),
+                            visible.width()/photo.width()*image.width(), visible.height()/photo.height()*image.height());
+        p.drawImage(visible, image, sample);
         QPainterPath mask; mask.addRect(rect()); mask.addEllipse(frame()); p.fillPath(mask, QColor(0,0,0,150));
         p.setPen(QPen(Qt::white, 2)); p.drawEllipse(frame());
     }
     void wheelEvent(QWheelEvent* e) override {
-        if (image.isNull()) return;
-        const double previous = zoom; zoom = qBound(1.0, zoom * (e->angleDelta().y()>0 ? 1.15 : 1/1.15), 16.0);
+        const int delta = e->angleDelta().y() ? e->angleDelta().y() : e->pixelDelta().y();
+        if (image.isNull() || !delta) { e->ignore(); return; }
+        const double previous = zoom;
+        const double maximum = qMin(16.0, double(qMin(originalSize.width(), originalSize.height())));
+        zoom = qBound(1.0, zoom * (delta > 0 ? 1.15 : 1/1.15), maximum);
         offset *= zoom/previous; clamp(); update(); e->accept();
     }
-    void mousePressEvent(QMouseEvent* e) override { if (e->button()==Qt::LeftButton) { last=e->pos(); dragging=true; } }
-    void mouseMoveEvent(QMouseEvent* e) override { if (dragging) { offset+=e->pos()-last; last=e->pos(); clamp(); update(); } }
-    void mouseReleaseEvent(QMouseEvent*) override { dragging=false; }
+    void mousePressEvent(QMouseEvent* e) override {
+        if (e->button() == Qt::LeftButton && !image.isNull()) { last = e->pos(); dragging = true; setCursor(Qt::ClosedHandCursor); }
+    }
+    void mouseMoveEvent(QMouseEvent* e) override {
+        if (!(e->buttons() & Qt::LeftButton)) { dragging = false; setCursor(Qt::OpenHandCursor); }
+        if (dragging) { offset += e->pos()-last; last = e->pos(); clamp(); update(); }
+    }
+    void mouseReleaseEvent(QMouseEvent* e) override {
+        if (e->button() == Qt::LeftButton) { dragging = false; setCursor(Qt::OpenHandCursor); }
+    }
 private:
     double zoom = 1; QPointF offset; QPoint last; bool dragging = false;
 };
 }
 
 bool selectAvatarCrop(const QString& source, QRectF& crop, QWidget* parent) {
-    QDialog dialog(parent); dialog.setWindowTitle(QCoreApplication::translate("ChatGui", "Crop avatar")); dialog.resize(620,650);
-    auto* layout = new QVBoxLayout(&dialog); auto* view = new CropView(&dialog); layout->addWidget(view, 1);
+    QPointer<QDialog> dialog = new QDialog(parent);
+    auto release = qScopeGuard([&] { delete dialog.data(); });
+    dialog->setWindowTitle(QCoreApplication::translate("ChatGui", "Crop avatar")); dialog->resize(620,650);
+    auto* layout = new QVBoxLayout(dialog); auto* view = new CropView(dialog); layout->addWidget(view, 1);
     view->setObjectName("avatarCropView");
-    auto* status = new QLabel(QCoreApplication::translate("ChatGui", "Drag photo and use the wheel to fit the circle"), &dialog);
-    layout->addWidget(status); auto* buttons = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, &dialog);
+    auto* status = new QLabel(QCoreApplication::translate("ChatGui", "Drag photo and use the wheel to fit the circle"), dialog);
+    layout->addWidget(status); auto* buttons = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, dialog);
     buttons->button(QDialogButtonBox::Ok)->setText(QCoreApplication::translate("ChatGui", "Upload avatar"));
     buttons->button(QDialogButtonBox::Ok)->setObjectName("avatarCropUpload");
     buttons->button(QDialogButtonBox::Ok)->setEnabled(false); layout->addWidget(buttons);
-    QObject::connect(buttons, &QDialogButtonBox::accepted, &dialog, &QDialog::accept);
-    QObject::connect(buttons, &QDialogButtonBox::rejected, &dialog, &QDialog::reject);
+    QObject::connect(buttons, &QDialogButtonBox::accepted, dialog, &QDialog::accept);
+    QObject::connect(buttons, &QDialogButtonBox::rejected, dialog, &QDialog::reject);
+    // Получатель живёт до завершения worker, независимо от уничтожения окна/parent.
+    QObject completion;
     QThreadPool pool; pool.setMaxThreadCount(1);
-    pool.start(QRunnable::create([source, &dialog, view, status, buttons] {
+    pool.start(QRunnable::create([source, &completion, dialog, view, status, buttons] {
         QImageReader reader(source); reader.setAutoTransform(true); const QSize size = reader.size(); QImage image;
+        QString error;
         QSize orientedSize=size;
         if (reader.transformation() & QImageIOHandler::TransformationRotate90) orientedSize.transpose();
-        if (QFileInfo(source).size() <= AvatarCache::OriginalMaxBytes && size.isValid() &&
+        if (QFileInfo(source).size() > 0 && QFileInfo(source).size() <= AvatarCache::OriginalMaxBytes && size.width() > 0 && size.height() > 0 &&
             qint64(size.width())*size.height() <= 16*1024*1024 &&
             (reader.format()=="jpeg" || reader.format()=="png" || reader.format()=="webp")) {
-            reader.setScaledSize(size.scaled(1600,1600,Qt::KeepAspectRatio)); image = reader.read();
-        }
-        QMetaObject::invokeMethod(&dialog, [view, image, orientedSize, status, buttons] {
+            if (qMax(size.width(), size.height()) > 1600) {
+                const QSize preview = size.scaled(1600, 1600, Qt::KeepAspectRatio);
+                reader.setScaledSize({qMax(1, preview.width()), qMax(1, preview.height())});
+            }
+            image = reader.read(); if (image.isNull()) error = reader.errorString();
+        } else error = QStringLiteral("source is unreadable, exceeds 32 MiB/16 MP, or has an unsupported format");
+        if (image.isNull()) DEBUG_WARN(DEBUG_CATEGORY_MEDIA, "avatar: editor decode failed source=%s reason=%s", qPrintable(source), qPrintable(error));
+        if (!QMetaObject::invokeMethod(&completion, [dialog, view, image, orientedSize, status, buttons] {
+            if (!dialog) return;
             if (image.isNull()) {
-                DEBUG_WARN(DEBUG_CATEGORY_MEDIA, "avatar: editor cannot decode selected source");
                 status->setText(QCoreApplication::translate("ChatGui", "Cannot load avatar image")); return;
             }
             view->image=image; view->originalSize=orientedSize; view->update(); buttons->button(QDialogButtonBox::Ok)->setEnabled(true);
             DEBUG_DEBUG(DEBUG_CATEGORY_MEDIA, "avatar: editor loaded original=%dx%d preview=%dx%d mask=circle",
                 orientedSize.width(), orientedSize.height(), image.width(), image.height());
-        }, Qt::QueuedConnection);
+        }, Qt::QueuedConnection)) DEBUG_ERROR(DEBUG_CATEGORY_MEDIA, "avatar: cannot queue editor preview source=%s", qPrintable(source));
     }));
-    const int result=dialog.exec(); pool.waitForDone();
-    if (result!=QDialog::Accepted) { DEBUG_DEBUG(DEBUG_CATEGORY_MEDIA, "avatar: crop cancelled"); return false; }
-    crop=view->selection(); DEBUG_INFO(DEBUG_CATEGORY_MEDIA, "avatar: crop selected x=%.5f y=%.5f w=%.5f h=%.5f",
+    const int result = dialog->exec(); pool.waitForDone();
+    if (!dialog || result != QDialog::Accepted) { DEBUG_DEBUG(DEBUG_CATEGORY_MEDIA, "avatar: crop cancelled owner_gone=%d", !dialog); return false; }
+    if (view->image.isNull() || view->originalSize.width() <= 0 || view->originalSize.height() <= 0) {
+        DEBUG_WARN(DEBUG_CATEGORY_MEDIA, "avatar: crop acceptance rejected before preview loaded source=%s", qPrintable(source)); return false;
+    }
+    const QRectF selected = view->selection().intersected(QRectF(0, 0, 1, 1));
+    if (!selected.isValid() || !std::isfinite(selected.x()) || !std::isfinite(selected.y())
+        || !std::isfinite(selected.width()) || !std::isfinite(selected.height())
+        || selected.width()*view->originalSize.width() < 1-1e-6
+        || qAbs(selected.width()*view->originalSize.width()-selected.height()*view->originalSize.height()) > 1e-6) {
+        DEBUG_ERROR(DEBUG_CATEGORY_MEDIA, "avatar: invalid editor selection original=%dx%d x=%g y=%g w=%g h=%g",
+                    view->originalSize.width(), view->originalSize.height(), selected.x(), selected.y(), selected.width(), selected.height()); return false;
+    }
+    crop = selected; DEBUG_INFO(DEBUG_CATEGORY_MEDIA, "avatar: crop selected x=%.5f y=%.5f w=%.5f h=%.5f",
         crop.x(), crop.y(), crop.width(), crop.height()); return true;
 }
diff --git a/tools/chatgui/src/avatars/avatarcrop.h b/tools/chatgui/src/avatars/avatarcrop.h
index 6d0b9786..d78907fc 100644
--- a/tools/chatgui/src/avatars/avatarcrop.h
+++ b/tools/chatgui/src/avatars/avatarcrop.h
@@ -1,6 +1,13 @@
-/* Выбор области аватара: круглая рамка неподвижна, фото перемещается и масштабируется. */
+/* Модальный выбор квадрата аватара в GUI-потоке: неподвижная круглая рамка, фото перемещается ЛКМ.
+ * Вертикальное колесо (angle/pixel delta) меняет zoom в 1.15 раза, диапазон 1..min(16, меньшая сторона оригинала).
+ * JPEG/PNG/WebP читается в локальном worker: файл <=32 MiB, <=16 MP; preview <=1600px, без увеличения исходника.
+ * Функция ждёт worker перед возвратом; уничтожение parent безопасно отменяет выбор, queued preview не обращается к удалённому окну. */
 #pragma once
 #include <QRectF>
 #include <QString>
 class QWidget;
+/* source — локальный файл; parent — необязательный заимствованный владелец окна.
+ * true: crop заменён нормализованным QRectF в [0,1] после EXIF, квадратным в пикселях оригинала (не меньше1px).
+ * false: Cancel/уничтожение parent/ошибка загрузки или выделения, crop не меняется.
+ * Только выбирает координаты: не создаёт кеш/файлы и не публикует аватар; передать crop в AvatarCache::prepare. */
 bool selectAvatarCrop(const QString& source, QRectF& crop, QWidget* parent);