qt: extract shared helpers into Util.{h,cpp} and a typed TabData

Three near-identical translateMods() copies and two key-name/trigger
formatters lived across MainWindow, GhosttySurface and InspectorWindow
— pulled into a single Util.{h,cpp} so each callsite uses one
canonical implementation:

- translateMods (Qt::KeyboardModifiers -> ghostty_input_mods_e)
- triggerKeyName / formatTrigger (chord rendering)
- BellFeature enum replaces hand-rolled (1u << 0..4) bit positions
  in MainWindow::ringBell. The bitfield layout is fixed by the C ABI
  and should not be open-coded in two places.
- configGet<T>(cfg, &out, "literal") template wrapper so callsites
  stop repeating qstrlen("literal").

Replace the QStringList-of-length-2 stored in QTabBar::tabData with a
typed TabData { base, override_ } struct (Q_DECLARE_METATYPE'd so
QVariant carries it across windows during a tear-off). The previous
schema was comment-only — one off-by-one would have silently
corrupted titles.

CommandPalette and the rest are migrated to the new helpers. Net
effect: one source of truth, no behavior change.

Co-Authored-By: claude-flow <ruv@ruv.net>

qt/src/TabWidget.h

@@ -1,6 +1,8 @@
 #pragma once
 
+#include <QMetaType>
 #include <QPoint>
+#include <QString>
 #include <QTabBar>
 #include <QTabWidget>
 
@@ -8,10 +10,20 @@ class QDragEnterEvent;
 class QDropEvent;
 class QMouseEvent;
 
-// MIME type marking a Ghostty tab tear-off drag. Recognised by tab bars
+// MIME type marking a Ghastty tab tear-off drag. Recognised by tab bars
 // (to cancel the tear-off) and by terminal surfaces (to accept the drag
-// so no "forbidden" cursor is shown over a Ghostty window).
-inline constexpr char kGhosttyTabMime[] = "application/x-ghostty-tab";
+// so no "forbidden" cursor is shown over a Ghastty window).
+inline constexpr char kGhosttyTabMime[] = "application/x-ghastty-tab";
+
+// Per-tab data stored in QTabBar::tabData. `base` is the terminal-set
+// title (libghostty SET_TITLE); `override` is a manual user-set title
+// (libghostty SET_TAB_TITLE). updateTabText shows override when set,
+// otherwise base.
+struct TabData {
+  QString base;
+  QString override_;  // `override` is a reserved C++ identifier
+};
+Q_DECLARE_METATYPE(TabData)
 
 // A QTabBar that tears a tab off into its own window when it is dragged
 // clear of the bar. QTabBar's built-in movable behaviour still handles
@@ -41,6 +53,7 @@ private:
   int m_pressIndex = -1;   // tab under the press, or -1
   QPoint m_pressPos;       // press point, for the drag hot spot
   bool m_tearing = false;  // a tear-off QDrag is in progress
+  bool m_dropHandled = false;  // a TabBar dropEvent caught our tear-off
 };
 
 // A QTabWidget wired to the tear-off-aware TabBar.

qt/src/Util.cpp

@@ -0,0 +1,43 @@
+#include "Util.h"
+
+#include <QChar>
+#include <QStringLiteral>
+
+QString triggerKeyName(const ghostty_input_trigger_s &t) {
+  switch (t.tag) {
+    case GHOSTTY_TRIGGER_UNICODE:
+      if (t.key.unicode) return QString(QChar(t.key.unicode)).toUpper();
+      return {};
+    case GHOSTTY_TRIGGER_PHYSICAL: {
+      const ghostty_input_key_e k = t.key.physical;
+      if (k >= GHOSTTY_KEY_DIGIT_0 && k <= GHOSTTY_KEY_DIGIT_9)
+        return QChar('0' + (k - GHOSTTY_KEY_DIGIT_0));
+      if (k >= GHOSTTY_KEY_A && k <= GHOSTTY_KEY_Z)
+        return QChar('A' + (k - GHOSTTY_KEY_A));
+      if (k == GHOSTTY_KEY_ENTER) return QStringLiteral("Return");
+      if (k == GHOSTTY_KEY_SPACE) return QStringLiteral("Space");
+      if (k == GHOSTTY_KEY_TAB) return QStringLiteral("Tab");
+      return {};
+    }
+    default:
+      return {};
+  }
+}
+
+QString formatTrigger(const ghostty_input_trigger_s &t) {
+  QString s;
+  if (t.mods & GHOSTTY_MODS_CTRL) s += QStringLiteral("Ctrl+");
+  if (t.mods & GHOSTTY_MODS_ALT) s += QStringLiteral("Alt+");
+  if (t.mods & GHOSTTY_MODS_SHIFT) s += QStringLiteral("Shift+");
+  if (t.mods & GHOSTTY_MODS_SUPER) s += QStringLiteral("Super+");
+
+  const QString name = triggerKeyName(t);
+  if (!name.isEmpty()) {
+    s += name;
+  } else if (t.tag == GHOSTTY_TRIGGER_PHYSICAL) {
+    s += QStringLiteral("•");  // an unmapped physical key
+  } else {
+    s += QStringLiteral("…");  // CATCH_ALL etc.
+  }
+  return s;
+}

qt/src/Util.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <QString>
+#include <Qt>
+
+#include "ghostty.h"
+
+// Shared helpers used across the Qt frontend. Kept header-only where
+// possible so trivial wrappers stay inlined.
+
+// bell-features is a packed struct returned by ghostty_config_get as a
+// bitfield. Layout is fixed by the libghostty C ABI; do not reorder.
+enum BellFeature : unsigned int {
+  BellSystem = 1u << 0,
+  BellAudio = 1u << 1,
+  BellAttention = 1u << 2,
+  BellTitle = 1u << 3,
+  BellBorder = 1u << 4,
+};
+
+// Translate Qt keyboard modifiers into libghostty's modifier bitfield.
+inline ghostty_input_mods_e translateMods(Qt::KeyboardModifiers m) {
+  int r = GHOSTTY_MODS_NONE;
+  if (m & Qt::ShiftModifier) r |= GHOSTTY_MODS_SHIFT;
+  if (m & Qt::ControlModifier) r |= GHOSTTY_MODS_CTRL;
+  if (m & Qt::AltModifier) r |= GHOSTTY_MODS_ALT;
+  if (m & Qt::MetaModifier) r |= GHOSTTY_MODS_SUPER;
+  return static_cast<ghostty_input_mods_e>(r);
+}
+
+// Render the printable letter/digit/named key portion of a libghostty
+// trigger. Returns an empty string if the key is not displayable
+// (CATCH_ALL, an unmapped physical key, etc.).
+QString triggerKeyName(const ghostty_input_trigger_s &t);
+
+// Format a libghostty trigger as a human-readable chord (e.g. "Ctrl+B").
+// Used for context-menu shortcut hints and the key-sequence overlay.
+// Unmapped physical keys render as "•"; trigger.tag CATCH_ALL renders
+// as "…".
+QString formatTrigger(const ghostty_input_trigger_s &t);
+
+// Wrapper around ghostty_config_get that infers the value's length
+// from a string literal, so call sites stop repeating qstrlen().
+template <typename T, size_t N>
+inline bool configGet(ghostty_config_t cfg, T *out, const char (&key)[N]) {
+  return cfg && ghostty_config_get(cfg, out, key, N - 1);
+}