feat(acp): rank command popup results by prefix match

Substring matches were previously hidden entirely; now they appear
below exact-prefix matches instead of being discarded.

- Introduce appendCommandItem() to eliminate duplicated label/data
  build logic across showCommandPopup and filterCommandPopup
- Rebuild the list on each filter pass (two-pass: starts-with tier
  then contains tier) so ordering reflects match quality rather than
  relying on setHidden which couldn't express rank
- Empty prefix skips the second pass, preserving original order for
  the unfiltered state

Author: nullmastermind

src/widgets/AcpSessionView.cpp

@@ -2062,11 +2062,7 @@ void AcpSessionView::showCommandPopup()
 
     m_commandPopup->clear();
     for (const auto &cmd : cmds) {
-        QString label = QStringLiteral("/") + cmd.name;
-        if (!cmd.description.isEmpty())
-            label += QStringLiteral("  ") + cmd.description;
-        auto *item = new QListWidgetItem(label, m_commandPopup);
-        item->setData(Qt::UserRole, cmd.name);
+        appendCommandItem(cmd);
     }
     m_commandPopup->setCurrentRow(0);
     m_commandPopup->show();
@@ -2114,24 +2110,39 @@ void AcpSessionView::filterCommandPopup()
         showCommandPopup();
     }
 
-    int firstVisible = -1;
-    for (int i = 0; i < m_commandPopup->count(); ++i) {
-        auto *item = m_commandPopup->item(i);
-        const QString name = item->data(Qt::UserRole).toString();
-        const bool match = prefix.isEmpty() || name.toLower().startsWith(prefix);
-        item->setHidden(!match);
-        if (match && firstVisible < 0) firstVisible = i;
+    // Rank: names that START WITH the typed prefix come first, names that only
+    // CONTAIN it as a substring come after. Original order is preserved within
+    // each tier. Empty prefix puts everything in the starts-with tier (no-op
+    // reorder), matching the unfiltered popup.
+    m_commandPopup->clear();
+    for (const auto &cmd : cmds) {
+        if (prefix.isEmpty() || cmd.name.toLower().startsWith(prefix))
+            appendCommandItem(cmd);
+    }
+    for (const auto &cmd : cmds) {
+        const QString lower = cmd.name.toLower();
+        if (!prefix.isEmpty() && !lower.startsWith(prefix) && lower.contains(prefix))
+            appendCommandItem(cmd);
     }
 
-    if (firstVisible < 0) {
+    if (m_commandPopup->count() == 0) {
         hideCommandPopup();
     } else {
-        if (m_commandPopup->currentItem() && m_commandPopup->currentItem()->isHidden())
-            m_commandPopup->setCurrentRow(firstVisible);
+        m_commandPopup->setCurrentRow(0);
         resizeCommandPopup();
     }
 }
 
+void AcpSessionView::appendCommandItem(const AcpProtocol::AcpCommandInfo &cmd)
+{
+    if (!m_commandPopup) return;
+    QString label = QStringLiteral("/") + cmd.name;
+    if (!cmd.description.isEmpty())
+        label += QStringLiteral("  ") + cmd.description;
+    auto *item = new QListWidgetItem(label, m_commandPopup);
+    item->setData(Qt::UserRole, cmd.name);
+}
+
 void AcpSessionView::acceptCommandCompletion()
 {
     if (!m_commandPopup || !m_commandPopup->isVisible()) return;

src/widgets/AcpSessionView.h

@@ -210,6 +210,7 @@ private slots:
     void resizeCommandPopup();
     void filterCommandPopup();
     void acceptCommandCompletion();
+    void appendCommandItem(const AcpProtocol::AcpCommandInfo &cmd);
 
     AcpSessionModel *m_model = nullptr;       // non-owning
     AcpConnection *m_connection = nullptr;    // non-owning