feat: Audio tab drives timeline audio-mode; drag the band to set the extract region

main.py

@@ -4533,6 +4533,7 @@ class MainWindow(QMainWindow):
         self._timeline.scan_region_resized.connect(self._on_scan_region_resized)
         self._timeline.clip_count_delta.connect(self._change_clip_count)
         self._timeline.autoclip_requested.connect(self._autoclip)
+        self._timeline.audio_region_changed.connect(self._on_wave_selection_changed)
 
         self._lbl_file = QLabel("← Drop files onto the queue")
         self._lbl_file.setAlignment(Qt.AlignmentFlag.AlignCenter)
@@ -5231,6 +5232,9 @@ class MainWindow(QMainWindow):
                 panel._pinned = panel._deck_key in _deck_pinned
             self._refresh_deck_layout()
 
+        # Sync timeline audio-mode to the current deck tab (Export default → off).
+        self._on_deck_tab_changed(self._control_deck.currentIndex())
+
         # Defer the changelog modal so the window paints/interacts first.
         QTimer.singleShot(120, self._show_changelog)
 
@@ -5269,6 +5273,7 @@ class MainWindow(QMainWindow):
         deck.addTab(self._tab_audio, self._tab_audio._label)
         self._control_deck = deck
         deck.tabBar().pin_toggle_requested.connect(self._on_deck_pin_toggle)
+        deck.currentChanged.connect(self._on_deck_tab_changed)
 
         # Side-by-side container (shown when 2+ panels are pinned), wrapped in a
         # stack so the deck can swap between tabbed and split views.
@@ -7363,6 +7368,14 @@ class MainWindow(QMainWindow):
         self._wave.set_peaks(peaks(samples))
         return samples.size > 0
 
+    def _on_deck_tab_changed(self, _idx: int) -> None:
+        if self._deck_loading:
+            return
+        is_audio = self._control_deck.currentWidget() is self._tab_audio
+        self._timeline.set_audio_mode(is_audio)
+        if is_audio and self._file_path:
+            self._update_audio_region()      # ensure the band reflects cursor + length
+
     def _on_wave_selection_changed(self, s: float, e: float) -> None:
         if self._wave_syncing:
             return