refactor: throttle markdown conversion and add force‑update flag

* Added a `QElapsedTimer` in `MarkdownLabel` to limit markdown
conversions to ~30 fps.
* Introduced a guard that restarts the timer after each conversion and
an `invalidate()` method to reset it for forced updates.
* Updated `ChatMessage::renderMarkdown` to take a `forceUpdate` boolean
(default `false`).
* Updated all callers (`ChatEditor::onMessageAppended`,
`ChatMessage::buildUI`, `ChatMessage::messageCompleted`) to pass `true`
when a new message is appended or finished, ensuring the UI is refreshed
immediately.
* Adjusted header declarations and added comments for clarity.

This change prevents UI freezes caused by rapid markdown re‑rendering
while still allowing explicit updates when a message changes.

Author: cristianadam

llamachateditor.cpp

@@ -434,7 +434,7 @@ void ChatEditor::onMessageAppended(const Message &msg, qint64 pendingId)
         w->setSiblingIdx(siblingIdx);
         w->setSiblingLeafIds(siblings);
 
-        w->renderMarkdown(msg.content);
+        w->renderMarkdown(msg.content, true);
         w->messageCompleted(true);
     }
 

llamachatmessage.cpp

@@ -73,7 +73,7 @@ void ChatMessage::buildUI()
         connect(m_thoughtToggle, &QPushButton::toggled, this, &ChatMessage::onThoughtToggle);
         onThoughtToggle(false);
     } else {
-        renderMarkdown(m_msg.content);
+        renderMarkdown(m_msg.content, true);
     }
 
     m_markdownLabel->setObjectName(m_isUser ? "BubbleUser" : "BubbleAssistant");
@@ -247,8 +247,11 @@ bool ChatMessage::eventFilter(QObject *obj, QEvent *event)
     return QWidget::eventFilter(obj, event);
 }
 
-void ChatMessage::renderMarkdown(const QString &text)
+void ChatMessage::renderMarkdown(const QString &text, bool forceUpdate)
 {
+    if (forceUpdate)
+        m_markdownLabel->invalidate();
+
     if (m_thoughtToggle) {
         auto [thinking, message] = ThinkingSectionParser::parseThinkingSection(text);
         if (m_thoughtToggle->isChecked()) {
@@ -278,7 +281,7 @@ void ChatMessage::messageCompleted(bool completed)
         m_regenButton->setVisible(completed);
         m_copyButton->setVisible(completed);
 
-        renderMarkdown(m_msg.content);
+        renderMarkdown(m_msg.content, completed);
     }
 }
 

llamachatmessage.h

@@ -23,7 +23,7 @@ class ChatMessage : public QWidget
                          QWidget *parent = nullptr);
 
     Message &message() { return m_msg; }
-    void renderMarkdown(const QString &text);
+    void renderMarkdown(const QString &text, bool forceUpdate = false);
 
     void messageCompleted(bool completed);
     bool isUser() const;

llamamarkdownwidget.cpp

@@ -133,6 +133,13 @@ MarkdownLabel::MarkdownLabel(QWidget *parent)
 
 void MarkdownLabel::setMarkdown(const QString &markdown)
 {
+    // We don't want something faster than 30fps, which would cause UI freezes
+    if (m_markdownConversionTimer.isValid() && m_markdownConversionTimer.elapsed() < 33)
+        return;
+
+    m_markdownConversionTimer.start();
+    auto guard = qScopeGuard([this] { m_markdownConversionTimer.restart(); });
+
     // Make sure the widget’s minimum width is large enough for the
     // longest line in the markdown.
     adjustMinimumWidth(markdown);
@@ -266,6 +273,11 @@ int MarkdownLabel::heightForWidth(int w) const
     return qRound(doc->size().height());
 }
 
+void MarkdownLabel::invalidate()
+{
+    m_markdownConversionTimer.invalidate();
+}
+
 void MarkdownLabel::adjustMinimumWidth(const QString &markdown)
 {
     const QStringList lines = markdown.split('\n');

llamamarkdownwidget.h

@@ -2,6 +2,7 @@
 
 #include <utils/expected.h>
 
+#include <QElapsedTimer>
 #include <QString>
 #include <QTextBrowser>
 
@@ -19,6 +20,7 @@ class MarkdownLabel : public QTextBrowser
     void setStyleSheet();
     void resizeEvent(QResizeEvent *event) override;
     int heightForWidth(int w) const override;
+    void invalidate();
 
 signals:
     void copyToClipboard(const QString &verbatimText, const QString &highlightedText);
@@ -64,5 +66,6 @@ class MarkdownLabel : public QTextBrowser
 
     Data m_data;
     QMap<int, QPair<int, int>> m_insertedHtmlSection;
+    QElapsedTimer m_markdownConversionTimer;
 };
 } // namespace LlamaCpp