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

tests/test_ui_structure.py

@@ -284,6 +284,9 @@ def test_timeline_audio_mode_flag(win):
 
 def test_timeline_audio_band_drag_move(win):
     tl = win._timeline
+    # The band is now wired to the window; fake a loaded file so the window's
+    # _update_audio_region keeps the region instead of clearing it on release.
+    win._file_path = "/x/v.mp4"
     tl._duration = 20.0
     tl._view_start = 0.0; tl._view_span = 20.0     # full view
     tl.resize(400, tl.height() or 80)
@@ -304,6 +307,8 @@ def test_timeline_audio_band_drag_move(win):
 
 def test_timeline_audio_band_resize_right(win):
     tl = win._timeline
+    # Fake a loaded file so the window keeps the region on release (see above).
+    win._file_path = "/x/v.mp4"
     tl._duration = 20.0; tl._view_start = 0.0; tl._view_span = 20.0
     tl.resize(400, tl.height() or 80)
     tl.set_audio_mode(True)
@@ -316,6 +321,22 @@ def test_timeline_audio_band_resize_right(win):
     tl.set_audio_mode(False)
 
 
+def test_timeline_audio_mode_follows_deck(win):
+    win._control_deck.setCurrentWidget(win._tab_audio)
+    assert win._timeline._audio_mode is True
+    win._control_deck.setCurrentWidget(win._tab_export)
+    assert win._timeline._audio_mode is False
+
+
+def test_timeline_audio_region_edit_syncs_cursor_length(win):
+    win._file_path = "/x/v.mp4"
+    win._cursor = 2.0
+    win._spn_audio_len.setValue(3.0)
+    win._timeline.audio_region_changed.emit(5.0, 9.0)   # user dragged the band to [5,9]
+    assert win._cursor == 5.0
+    assert abs(win._spn_audio_len.value() - 4.0) < 1e-6
+
+
 def test_audio_deck_tab_exists(win):
     # The old "Scan" deck tab is now "Audio".
     assert hasattr(win, "_tab_audio")