fix: external images now load + list pane can shrink to compact mode

Bug 1 - 'Cargar imágenes' did nothing: QTextBrowser cannot fetch http(s)
images itself, so re-rendering with m_allowExternalImages=true changed
nothing. Add ReaderView::processImages() which downloads each external
image via QNetworkAccessManager (sync QEventLoop, 8s timeout) and replaces
the src with a data: URI that QTextBrowser renders. Add a second button
'Mostrar siempre imágenes de este remitente' that persists the sender in
QSettings (ReaderView/trustedSenders); sanitizeHtml auto-loads images for
trusted senders.

Bug 2 - list pane could not shrink (compact mode never appeared): fixed-width
combos (pivot 140 / display 120) + 'Agrupar:' label + search inflated the
layout minimumSizeHint, so the QSplitter would not reduce the list below the
650px compact threshold. Fix: layout->setSizeConstraint(SetNoConstraint) on
the root layout + combos use MaximumWidth/Preferred instead of Fixed.

Verified: compiles, app runs clean, no crashes.

src/ui/maillistview.cpp

@@ -32,6 +32,9 @@ void MailListView::setupUI()
     QVBoxLayout *layout = new QVBoxLayout(this);
     layout->setContentsMargins(0, 0, 0, 0);
     layout->setSpacing(0);
+    // Let the view shrink freely (esp. to trigger compact mode); the filter/search
+    // controls must not inflate the minimum width of the enclosing splitter pane.
+    layout->setSizeConstraint(QLayout::SetNoConstraint);
 
     // Search bar
     QWidget *searchBar = new QWidget();
@@ -103,8 +106,8 @@ void MailListView::setupUI()
     m_pivotCombo = new QComboBox();
     m_pivotCombo->addItem("Principal");  // Focused
     m_pivotCombo->addItem("Otros");      // Other
-    m_pivotCombo->setFixedWidth(140);
+    m_pivotCombo->setMaximumWidth(140);
-    m_pivotCombo->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    m_pivotCombo->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
     m_pivotCombo->setStyleSheet(
         "QComboBox { border: 1px solid #d1d1d6; border-radius: 4px; padding: 4px 8px; "
         "background: white; min-height: 20px; }"
@@ -121,8 +124,8 @@ void MailListView::setupUI()
     m_displayModeCombo->addItem("Compacto");
     m_displayModeCombo->addItem("Medio");
     m_displayModeCombo->addItem("Espacioso");
-    m_displayModeCombo->setFixedWidth(120);
+    m_displayModeCombo->setMaximumWidth(120);
-    m_displayModeCombo->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    m_displayModeCombo->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
     m_displayModeCombo->setStyleSheet(
         "QComboBox { border: 1px solid #d1d1d6; border-radius: 4px; padding: 4px 8px; "
         "background: white; min-height: 20px; }"

src/ui/readerview.cpp

@@ -24,11 +24,17 @@
 #include <QFileDialog>
 #include <QFile>
 #include <QDir>
+#include <QNetworkReply>
+#include <QNetworkRequest>
+#include <QEventLoop>
+#include <QTimer>
 #include <functional>
 #include <QGraphicsDropShadowEffect>
 #include "db/dao/mailitemdao.h"
 
 ReaderView::ReaderView(QWidget *parent) : QWidget(parent) {
+    m_network = new QNetworkAccessManager(this);
+    loadTrustedSenders();
     setupUI();
     applyEmailCss();
 }
@@ -114,6 +120,37 @@ void ReaderView::setupUI() {
         refreshCurrentMail();
     });
 
+    // "Always show images from this sender" button (persists the choice)
+    m_alwaysLoadImagesButton = new QToolButton();
+    m_alwaysLoadImagesButton->setText("🙂 Mostrar siempre imágenes de este remitente");
+    m_alwaysLoadImagesButton->setToolTip("Confiar en este remitente: sus imágenes externas se cargarán automáticamente en el futuro");
+    m_alwaysLoadImagesButton->setFixedHeight(28);
+    m_alwaysLoadImagesButton->setVisible(false);
+    m_alwaysLoadImagesButton->setStyleSheet(
+        "QToolButton {"
+        "   background: #e8f5e9;"
+        "   border: 1px solid #2e7d32;"
+        "   border-radius: 4px;"
+        "   padding: 4px 10px;"
+        "   font-size: 11px;"
+        "   color: #2e7d32;"
+        "   font-weight: 500;"
+        "}"
+        "QToolButton:hover {"
+        "   background: #c8e6c9;"
+        "}"
+    );
+    connect(m_alwaysLoadImagesButton, &QToolButton::clicked, [this]() {
+        if (!m_currentSender.isEmpty()) {
+            m_trustedSenders.insert(trustKey(m_currentSender));
+            saveTrustedSenders();
+        }
+        m_allowExternalImages = true;
+        m_alwaysLoadImagesButton->setVisible(false);
+        m_loadImagesButton->setVisible(false);
+        refreshCurrentMail();
+    });
+
     m_zoomOutButton = new QToolButton();
     m_zoomOutButton->setText("−");
     m_zoomOutButton->setFixedSize(28, 28);
@@ -147,6 +184,7 @@ void ReaderView::setupUI() {
     });
 
     toolbarLayout->addWidget(m_loadImagesButton);
+    toolbarLayout->addWidget(m_alwaysLoadImagesButton);
     toolbarLayout->addStretch();
     toolbarLayout->addWidget(m_zoomOutButton);
     toolbarLayout->addWidget(m_zoomLabel);
@@ -599,6 +637,89 @@ void ReaderView::updateZoom() {
     // The font scaling above handles it
 }
 
+void ReaderView::loadTrustedSenders()
+{
+    m_trustedSenders.clear();
+    QSettings s;
+    s.beginGroup("ReaderView");
+    const QStringList list = s.value("trustedSenders").toStringList();
+    for (const QString &key : list) m_trustedSenders.insert(key.trimmed().toLower());
+    s.endGroup();
+}
+
+void ReaderView::saveTrustedSenders()
+{
+    QSettings s;
+    s.beginGroup("ReaderView");
+    QStringList list = m_trustedSenders.values();
+    QStringList cleaned;
+    for (const QString &k : list) if (!k.isEmpty()) cleaned << k;
+    s.setValue("trustedSenders", cleaned);
+    s.endGroup();
+    s.sync();
+}
+
+QString ReaderView::processImages(QString html, bool allow)
+{
+    if (!allow) return html;
+
+    // Find all external (http/https) image URLs in the html.
+    QRegularExpression re("(?i)<img\\b([^>]*\\bsrc\\s*=\\s*[\"'])(https?://[^\"'>\\s]+)([\"'][^>]*)>");
+    QStringList urls;
+    auto mit = re.globalMatch(html);
+    while (mit.hasNext()) {
+        auto m = mit.next();
+        urls << m.captured(2);
+    }
+
+    if (urls.isEmpty()) return html;
+
+    // Download each unique URL and substitute with a data: URI (QTextBrowser
+    // cannot fetch http images itself). Synchronous within reason; a short
+    // per-request timeout keeps the UI responsive.
+    QStringList done;
+    for (const QString &url : urls) {
+        if (done.contains(url)) continue;
+        done << url;
+        QUrl u(url);
+        if (!u.isValid() || (u.scheme() != "http" && u.scheme() != "https")) continue;
+
+        QNetworkRequest req(u);
+        req.setTransferTimeout(8000);
+        QNetworkReply *reply = m_network->get(req);
+        QEventLoop loop;
+        QTimer timer; timer.setSingleShot(true);
+        connect(&timer, &QTimer::timeout, &loop, &QEventLoop::quit);
+        connect(reply, &QNetworkReply::finished, &loop, &QEventLoop::quit);
+        timer.start(8000);
+        loop.exec();
+
+        QString replacement;
+        if (reply->error() == QNetworkReply::NoError) {
+            const QByteArray data = reply->readAll();
+            if (!data.isEmpty()) {
+                const QByteArray mime = reply->header(QNetworkRequest::ContentTypeHeader)
+                                            .toByteArray().split(';').first().trimmed();
+                const QByteArray b64 = data.toBase64();
+                replacement = QString("data:%1;base64,%2").arg(QString::fromLatin1(mime.isEmpty() ? "image/png" : mime),
+                                                               QString::fromLatin1(b64));
+            }
+        } else {
+            qDebug() << "[ReaderView] image load failed:" << url << reply->errorString();
+        }
+        reply->deleteLater();
+
+        if (!replacement.isEmpty()) {
+            // Replace this exact src URL (the first occurrence only risk is fine here because
+            // we iterate unique URLs and each appears verbatim).
+            html.replace(QUrl::fromPercentEncoding(url.toUtf8()), replacement);
+            // Also try replacing the raw-encoded form if slightly different.
+            html.replace(url, replacement);
+        }
+    }
+    return html;
+}
+
 QString ReaderView::sanitizeHtml(const QString &html) {
     if (html.isEmpty()) return "<div class='email-body'><i style='color:#999'>(Mensaje vacío)</i></div>";
     
@@ -617,7 +738,10 @@ QString ReaderView::sanitizeHtml(const QString &html) {
     result.remove(QRegularExpression("(?is)\\s(on\\w+)\\s*=\\s*\\w+"));
     
     // Block external images (tracking pixels, etc.) - replace with placeholder, unless allowed
-    if (!m_allowExternalImages) {
+    // An image is "allowed" if the user clicked "Cargar imágenes", or if this sender is trusted
+    // ("Mostrar siempre imágenes de este remitente" persisted choice).
+    const bool trusted = !m_currentSender.isEmpty() && isSenderTrusted(m_currentSender);
+    if (!m_allowExternalImages && !trusted) {
         // Match images with http/https/data URLs in src attribute
         QRegularExpression extImgRegex("(?i)<img([^>]*src\\s*=\\s*[\"'](?:https?|data):[^\"']*[\"'][^>]*)>");
         int beforeCount = result.count("data-blocked=\"true\"");
@@ -625,12 +749,18 @@ QString ReaderView::sanitizeHtml(const QString &html) {
             "<img\\1 style=\"max-width:100%;height:auto;\" data-blocked=\"true\" title=\"Imagen externa bloqueada por privacidad\">");
         int afterCount = result.count("data-blocked=\"true\"");
         
-        qDebug() << "[ReaderView] External images blocked:" << (afterCount - beforeCount);
+        qDebug() << "[ReaderView] External images blocked count:" << (afterCount - beforeCount);
         
-        // Show load images button if there were blocked images
+        // Show the two buttons if there were blocked images.
-        if (m_loadImagesButton && result.contains("data-blocked=\"true\"")) {
+        bool hasBlocked = result.contains("data-blocked=\"true\"");
-            m_loadImagesButton->setVisible(true);
+        if (m_loadImagesButton) m_loadImagesButton->setVisible(hasBlocked);
-        }
+        if (m_alwaysLoadImagesButton) m_alwaysLoadImagesButton->setVisible(hasBlocked);
+    } else {
+        // Images are allowed for this view: hide both buttons and download+render
+        // the external images as data: URIs (QTextBrowser cannot fetch http itself).
+        if (m_loadImagesButton) m_loadImagesButton->setVisible(false);
+        if (m_alwaysLoadImagesButton) m_alwaysLoadImagesButton->setVisible(false);
+        result = processImages(result, true);
     }
     
     // Add dark mode class if needed
@@ -755,8 +885,10 @@ void ReaderView::showAttachmentContextMenu(const QPoint &pos, const QString &pat
 void ReaderView::setMailItem(const MailItem* item) {
     if (!item) {
         m_currentMailId = -1;
+        m_currentSender.clear();
         m_allowExternalImages = false;
         m_loadImagesButton->setVisible(false);
+        if (m_alwaysLoadImagesButton) m_alwaysLoadImagesButton->setVisible(false);
         m_subjectLabel->setText("(Sin asunto)");
         m_avatarLabel->setText("?");
         m_fromLabel->setText("Remitente: —");
@@ -769,8 +901,10 @@ void ReaderView::setMailItem(const MailItem* item) {
     }
     
     m_currentMailId = item->id();
+    m_currentSender = item->sender().trimmed();
     m_allowExternalImages = false;
     m_loadImagesButton->setVisible(false);
+    if (m_alwaysLoadImagesButton) m_alwaysLoadImagesButton->setVisible(false);
     
     // Subject
     m_subjectLabel->setText(item->subject().isEmpty() ? "(Sin asunto)" : item->subject());

src/ui/readerview.h

@@ -12,6 +12,9 @@
 #include <QScrollArea>
 #include <QFrame>
 #include <QMenu>
+#include <QNetworkAccessManager>
+#include <QSet>
+#include <QSettings>
 #include "core/mailitem.h"
 
 class ReaderView : public QWidget {
@@ -101,4 +104,17 @@ private:
     QString m_baseCss;
     bool m_allowExternalImages = false;
     QToolButton *m_loadImagesButton = nullptr;
+    QToolButton *m_alwaysLoadImagesButton = nullptr;
+    QString m_currentSender;                    // sender of the currently shown mail
+    QSet<QString> m_trustedSenders;             // senders whose images load automatically (persisted)
+    QNetworkAccessManager *m_network = nullptr; // downloads external images when allowed
+
+    // Image loading
+    bool isSenderTrusted(const QString &sender) const { return m_trustedSenders.contains(trustKey(sender)); }
+    static QString trustKey(const QString &sender) { return sender.trimmed().toLower(); }
+    void loadTrustedSenders();
+    void saveTrustedSenders();
+    /// Post-process html: if images allowed (via button or trusted sender), replace
+    /// external http(s) image src with downloaded data: URIs so QTextBrowser shows them.
+    QString processImages(QString html, bool allow);
 };