feat: Merge sequence — add (file/selection), reorder, remove

main.py

@@ -4544,6 +4544,7 @@ class MainWindow(QMainWindow):
         self._merge_list.setSelectionMode(
             QAbstractItemView.SelectionMode.SingleSelection)
         self._merge_list.setToolTip("Clips to merge, top to bottom")
+        self._merge_temps: set[str] = set()
         self._spn_crossfade = QDoubleSpinBox()
         self._spn_crossfade.setRange(0.0, 10.0)
         self._spn_crossfade.setDecimals(2)
@@ -6579,17 +6580,74 @@ class MainWindow(QMainWindow):
         start = self._cursor
         self._timeline.set_audio_region(start, start + self._spn_audio_len.value())
 
-    def _on_merge_add_selection(self) -> None:
+    def _merge_add_paths(self, paths: list[str]) -> None:
-        pass   # implemented in M3
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        try:
+            for p in paths:
+                ap = os.path.abspath(p)
+                dur = probe_duration(ap)
+                text = (f"{os.path.basename(ap)}  ({dur:.2f}s)"
+                        if dur is not None else os.path.basename(ap))
+                item = QListWidgetItem(text)
+                item.setData(Qt.ItemDataRole.UserRole, ap)
+                item.setData(Qt.ItemDataRole.UserRole + 1, dur)
+                self._merge_list.addItem(item)
+        finally:
+            QApplication.restoreOverrideCursor()
 
     def _on_merge_add_file(self) -> None:
-        pass   # implemented in M3
+        default_dir = (self._settings.value("audio_extract_dir", "")
+                       or os.path.dirname(self._file_path or ""))
+        paths, _sel = QFileDialog.getOpenFileNames(
+            self, "Add audio file(s)", default_dir,
+            "Audio (*.wav *.mp3 *.flac *.m4a *.ogg *.opus *.aac);;All files (*)")
+        if paths:
+            self._merge_add_paths(paths)
+
+    def _on_merge_add_selection(self) -> None:
+        if not self._file_path:
+            self._show_status("Load a video first", 3000)
+            return
+        import tempfile
+        start = self._cursor
+        dur = self._spn_audio_len.value()
+        fd, tmp = tempfile.mkstemp(suffix=".wav", prefix="8cut_merge_")
+        os.close(fd)
+        self._show_status("Rendering selection…")
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        try:
+            cmd = build_audio_clip_command(self._file_path, start, dur, tmp,
+                                           filters=self._current_edit_filters() or None)
+            proc = subprocess.run(cmd, capture_output=True, timeout=120)
+        except Exception:
+            proc = None
+        finally:
+            QApplication.restoreOverrideCursor()
+        if proc is not None and proc.returncode == 0 and os.path.exists(tmp):
+            self._merge_temps.add(tmp)
+            self._merge_add_paths([tmp])
+        else:
+            try:
+                os.remove(tmp)
+            except OSError:
+                pass
+            self._show_status("Could not render selection", 3000)
 
     def _merge_move(self, delta: int) -> None:
-        pass   # implemented in M3
+        row = self._merge_list.currentRow()
+        if row < 0:
+            return
+        new = row + delta
+        if new < 0 or new >= self._merge_list.count():
+            return
+        item = self._merge_list.takeItem(row)
+        self._merge_list.insertItem(new, item)
+        self._merge_list.setCurrentRow(new)
 
     def _merge_remove_selected(self) -> None:
-        pass   # implemented in M3
+        row = self._merge_list.currentRow()
+        if row >= 0:
+            self._merge_list.takeItem(row)
 
     def _on_merge_preview(self) -> None:
         pass   # implemented in M4

tests/test_ui_structure.py

@@ -412,3 +412,50 @@ def test_audition_button_present_and_safe(win):
     assert win._btn_audio_play.isChecked() is False
     assert win._btn_audio_play.text() == "▶ Play"
     assert win._audition_proc is None
+
+
+def test_merge_list_add_remove_reorder(win, tmp_path):
+    from PyQt6.QtCore import Qt
+    a = tmp_path / "a.wav"; b = tmp_path / "b.wav"
+    a.write_bytes(b""); b.write_bytes(b"")
+    win._merge_add_paths([str(a), str(b)])
+    assert win._merge_list.count() == 2
+    assert win._merge_list.item(0).data(Qt.ItemDataRole.UserRole) == str(a)
+    win._merge_list.setCurrentRow(1)
+    win._merge_move(-1)                       # move b up
+    assert win._merge_list.item(0).data(Qt.ItemDataRole.UserRole) == str(b)
+    win._merge_list.setCurrentRow(0)
+    win._merge_remove_selected()
+    assert win._merge_list.count() == 1
+
+
+def test_merge_add_selection_no_file_safe(win):
+    win._file_path = ""
+    win._merge_list.clear()
+    win._on_merge_add_selection()             # must not raise
+    assert win._merge_list.count() == 0
+
+
+def test_merge_move_bounds_safe(win, tmp_path):
+    a = tmp_path / "a.wav"; b = tmp_path / "b.wav"; a.write_bytes(b""); b.write_bytes(b"")
+    win._merge_list.clear()
+    win._merge_add_paths([str(a), str(b)])
+    win._merge_list.setCurrentRow(0)
+    win._merge_move(-1)                    # already top -> no-op
+    assert win._merge_list.currentRow() == 0
+    win._merge_list.setCurrentRow(1)
+    win._merge_move(1)                     # already bottom -> no-op
+    assert win._merge_list.currentRow() == 1
+    win._merge_list.setCurrentRow(-1)
+    win._merge_move(1)                     # no selection -> safe
+    win._merge_remove_selected()          # no selection -> safe
+    assert win._merge_list.count() == 2
+
+
+def test_merge_add_stores_duration_role(win, tmp_path):
+    from PyQt6.QtCore import Qt
+    a = tmp_path / "a.wav"; a.write_bytes(b"")
+    win._merge_list.clear()
+    win._merge_add_paths([str(a)])
+    # empty fixture -> ffprobe fails -> duration is None; M4 must tolerate None
+    assert win._merge_list.item(0).data(Qt.ItemDataRole.UserRole + 1) is None