attachments: preview bar + combined send (Android + desktop)

Android: file picker → pending preview bar (name+size+X) →
         combined send with text; cache copy, save dialog for downloads

Desktop: attach stores pending, preview bar before send,
         combined with text in onSendClicked

C: attachment_sender.c — include filename in msg data for display

tools/chatgui/src/inputbar.cpp

@@ -45,6 +45,16 @@ static QWidget *wrapBottomBtn(QPushButton *btn, int pad) {
     return w;
 }
 
+QString InputBar::formatFileSize(qint64 bytes) {
+    if (bytes < 1024) return QString("%1B").arg(bytes);
+    double kb = bytes / 1024.0;
+    if (kb < 1024.0) return QString("%1KB").arg(kb, 0, 'f', kb < 10.0 ? 1 : 0);
+    double mb = kb / 1024.0;
+    if (mb < 1024.0) return QString("%1MB").arg(mb, 0, 'f', mb < 10.0 ? 1 : 0);
+    double gb = mb / 1024.0;
+    return QString("%1GB").arg(gb, 0, 'f', 1);
+}
+
 InputBar::InputBar(EmojiPanel *emojiPanel, AudioRecorder *recorder, QWidget *parent)
     : QWidget(parent)
     , m_input(new QTextEdit(this))
@@ -53,8 +63,29 @@ InputBar::InputBar(EmojiPanel *emojiPanel, AudioRecorder *recorder, QWidget *par
     , m_emojiPanel(emojiPanel)
     , m_recorder(recorder)
 {
-    auto *layout = new QHBoxLayout(this);
-    layout->setContentsMargins(8, 4, 8, 4);
+    auto *mainLayout = new QVBoxLayout(this);
+    mainLayout->setContentsMargins(8, 4, 8, 0);
+    mainLayout->setSpacing(2);
+
+    /* Attachment preview bar (hidden until file selected) */
+    m_attachPreview = new QWidget(this);
+    auto *prevLay = new QHBoxLayout(m_attachPreview);
+    prevLay->setContentsMargins(0, 2, 0, 2);
+    prevLay->setSpacing(4);
+    m_attachPreviewLabel = new QLabel(m_attachPreview);
+    m_attachPreviewLabel->setStyleSheet("background: palette(light); border-radius: 6px; padding: 2px 8px;");
+    prevLay->addWidget(m_attachPreviewLabel, 1);
+    m_attachClearBtn = new QPushButton(QString::fromUtf8("\xE2\x9C\x95"), m_attachPreview);
+    m_attachClearBtn->setFixedSize(20, 20);
+    m_attachClearBtn->setCursor(Qt::PointingHandCursor);
+    m_attachClearBtn->setStyleSheet("QPushButton { border: none; background: transparent; color: palette(text); }"
+                                     "QPushButton:hover { color: #e74c3c; }");
+    connect(m_attachClearBtn, &QPushButton::clicked, this, &InputBar::clearPendingAttachment);
+    prevLay->addWidget(m_attachClearBtn);
+    m_attachPreview->hide();
+    mainLayout->addWidget(m_attachPreview);
+
+    auto *layout = new QHBoxLayout();
     layout->setSpacing(4);
 
     m_attachBtn = makeIconBtn(QIcon(":/icons/attach.png"),
@@ -144,6 +175,8 @@ InputBar::InputBar(EmojiPanel *emojiPanel, AudioRecorder *recorder, QWidget *par
         connect(recorder, &AudioRecorder::recordingStopped, this, [this](int) { hideRecordOverlay(); });
         connect(recorder, &AudioRecorder::durationChanged, this, &InputBar::updateRecordingUI);
     }
+
+    mainLayout->addLayout(layout);
 }
 
 bool InputBar::eventFilter(QObject *obj, QEvent *event) {
@@ -185,15 +218,29 @@ void InputBar::adjustInputHeight() {
 
 void InputBar::onSendClicked() {
     QString text = m_input->toPlainText();
-    GUI_INFO("send: len=%d hasLF=%d text='%s'",
-             text.length(), text.contains('\n'), qPrintable(text));
     while (!text.isEmpty() && (text.back() == ' ' || text.back() == '\t'))
         text.chop(1);
-    if (text.isEmpty()) return;
-    emit sendMessage(text);
-    m_input->clear();
-    if (m_emojiPanel) m_emojiPanel->hide();
-    m_input->setFocus();
+
+    bool hasAttach = !m_pendingAttachSrc.isEmpty();
+    if (!hasAttach && text.isEmpty()) return;
+
+    if (hasAttach) {
+        GUI_INFO("send: file=%s name=%s", qPrintable(m_pendingAttachSrc), qPrintable(m_pendingAttachName));
+        emit sendFileAttachment(m_pendingAttachSrc, m_pendingAttachDest, m_pendingAttachName);
+        m_pendingAttachSrc.clear();
+        m_pendingAttachDest.clear();
+        m_pendingAttachName.clear();
+        m_pendingAttachSize = 0;
+        m_attachPreview->hide();
+    }
+    if (!text.isEmpty()) {
+        GUI_INFO("send: len=%d hasLF=%d text='%s'",
+                 text.length(), text.contains('\n'), qPrintable(text));
+        emit sendMessage(text);
+        m_input->clear();
+        if (m_emojiPanel) m_emojiPanel->hide();
+        m_input->setFocus();
+    }
 }
 
 void InputBar::setRecordingContext(const QString& mediaDirBase, const QString& channelId) {
@@ -284,9 +331,26 @@ void InputBar::onAttachClicked() {
     QString destPath = QString("%1/%2_%3_%4.%5")
         .arg(mediaPath, ts).arg(fi.completeBaseName()).arg(rnd, 4, 16, QChar('0')).arg(fi.suffix().isEmpty() ? "bin" : fi.suffix());
 
-    GUI_INFO("InputBar::onAttachClicked: src=%s dest=%s",
-             qPrintable(srcPath), qPrintable(destPath));
-    emit sendFileAttachment(srcPath, destPath, fi.fileName());
+    m_pendingAttachSrc  = srcPath;
+    m_pendingAttachDest = destPath;
+    m_pendingAttachName = fi.fileName();
+    m_pendingAttachSize = fi.size();
+
+    QString labelText = QString::fromUtf8("\xF0\x9F\x93\x8E %1 (%2)")
+        .arg(fi.fileName(), formatFileSize(fi.size()));
+    m_attachPreviewLabel->setText(labelText);
+    m_attachPreview->show();
+
+    GUI_INFO("InputBar::onAttachClicked: pending %s size=%lld",
+             qPrintable(srcPath), (long long)fi.size());
+}
+
+void InputBar::clearPendingAttachment() {
+    m_pendingAttachSrc.clear();
+    m_pendingAttachDest.clear();
+    m_pendingAttachName.clear();
+    m_pendingAttachSize = 0;
+    m_attachPreview->hide();
 }
 
 void InputBar::resizeEvent(QResizeEvent* event) {