feat: double-click a merge clip to set its join crossfade/curve override + row labels

main.py

@@ -4684,6 +4684,7 @@ class MainWindow(QMainWindow):
         self._merge_list.setSelectionMode(
             QAbstractItemView.SelectionMode.SingleSelection)
         self._merge_list.setToolTip("Clips to merge, top to bottom")
+        self._merge_list.itemDoubleClicked.connect(self._on_merge_item_double_clicked)
         self._merge_temps: set[str] = set()
         self._spn_crossfade = QDoubleSpinBox()
         self._spn_crossfade.setRange(0.0, 10.0)
@@ -4695,9 +4696,7 @@ class MainWindow(QMainWindow):
         self._spn_crossfade.valueChanged.connect(
             lambda v: self._settings.setValue("audio_crossfade", v))
         self._cmb_curve = QComboBox()
-        for label, name in (("Triangular", "tri"), ("Exponential", "exp"),
+        for label, name in self._MERGE_CURVES:
-                            ("Logarithmic", "log"), ("Quarter sine", "qsin"),
-                            ("Half sine", "hsin")):
             self._cmb_curve.addItem(label, name)
         self._cmb_curve.setToolTip("Crossfade curve at each join")
         self._btn_merge_add_sel = QPushButton("＋ Selection")
@@ -5181,6 +5180,9 @@ class MainWindow(QMainWindow):
     APP_VERSION = "1.5"
     _SPLIT_HEADER_H = 22  # deck split-column header height (keep both deck spots in sync)
     _WAVE_MIN_VIEW = 3.0  # minimum waveform view window (seconds)
+    _MERGE_CURVES = (("Triangular", "tri"), ("Exponential", "exp"),
+                     ("Logarithmic", "log"), ("Quarter sine", "qsin"),
+                     ("Half sine", "hsin"))
     CHANGELOG: list[tuple[str, list[str]]] = [
         ("1.5", [
             "<b>Interactive waveform</b> — the Audio tab's waveform is now a "
@@ -6760,9 +6762,29 @@ class MainWindow(QMainWindow):
                 item.setData(Qt.ItemDataRole.UserRole + 2, None)   # crossfade override (None = global)
                 item.setData(Qt.ItemDataRole.UserRole + 3, None)   # curve override (None = global)
                 self._merge_list.addItem(item)
+            self._refresh_merge_labels()
         finally:
             QApplication.restoreOverrideCursor()
 
+    def _merge_item_label(self, item, index: int, count: int) -> str:
+        name = os.path.basename(item.data(Qt.ItemDataRole.UserRole))
+        dur = item.data(Qt.ItemDataRole.UserRole + 1)
+        base = f"{name}  ({dur:.2f}s)" if dur is not None else name
+        if index < count - 1:                       # has an outgoing join
+            xo = item.data(Qt.ItemDataRole.UserRole + 2)
+            co = item.data(Qt.ItemDataRole.UserRole + 3)
+            if xo is not None or co is not None:
+                xf = xo if xo is not None else self._spn_crossfade.value()
+                cv = co if co is not None else self._cmb_curve.currentData()
+                base += f"  ⤲{xf:.2f}s {cv}"    # ⤲ join marker
+        return base
+
+    def _refresh_merge_labels(self) -> None:
+        n = self._merge_list.count()
+        for i in range(n):
+            it = self._merge_list.item(i)
+            it.setText(self._merge_item_label(it, i, n))
+
     def _on_merge_add_file(self) -> None:
         default_dir = (self._settings.value("audio_extract_dir", "")
                        or os.path.dirname(self._file_path or ""))
@@ -6811,11 +6833,45 @@ class MainWindow(QMainWindow):
         item = self._merge_list.takeItem(row)
         self._merge_list.insertItem(new, item)
         self._merge_list.setCurrentRow(new)
+        self._refresh_merge_labels()
 
     def _merge_remove_selected(self) -> None:
         row = self._merge_list.currentRow()
         if row >= 0:
             self._merge_list.takeItem(row)
+            self._refresh_merge_labels()
+
+    def _apply_merge_override(self, item, crossfade: float, curve: str) -> None:
+        item.setData(Qt.ItemDataRole.UserRole + 2, float(crossfade))
+        item.setData(Qt.ItemDataRole.UserRole + 3, curve)
+        self._refresh_merge_labels()
+
+    def _on_merge_item_double_clicked(self, item) -> None:
+        row = self._merge_list.row(item)
+        if row >= self._merge_list.count() - 1:
+            self._show_status("The last clip has no outgoing join to crossfade", 4000)
+            return
+        dlg = QDialog(self)
+        dlg.setWindowTitle("Join crossfade")
+        form = QFormLayout(dlg)
+        spn = QDoubleSpinBox()
+        spn.setRange(0.0, 10.0); spn.setDecimals(2); spn.setSingleStep(0.1); spn.setSuffix(" s")
+        xo = item.data(Qt.ItemDataRole.UserRole + 2)
+        spn.setValue(float(xo) if xo is not None else self._spn_crossfade.value())
+        cmb = QComboBox()
+        for label, name in self._MERGE_CURVES:
+            cmb.addItem(label, name)
+        co = item.data(Qt.ItemDataRole.UserRole + 3)
+        co = co if co is not None else self._cmb_curve.currentData()
+        idx = cmb.findData(co); cmb.setCurrentIndex(idx if idx >= 0 else 0)
+        form.addRow("Crossfade:", spn)
+        form.addRow("Curve:", cmb)
+        bb = QDialogButtonBox(QDialogButtonBox.StandardButton.Ok
+                              | QDialogButtonBox.StandardButton.Cancel)
+        bb.accepted.connect(dlg.accept); bb.rejected.connect(dlg.reject)
+        form.addRow(bb)
+        if dlg.exec():
+            self._apply_merge_override(item, spn.value(), cmb.currentData())
 
     def _merge_paths(self) -> list[str]:
         return [self._merge_list.item(i).data(Qt.ItemDataRole.UserRole)

tests/test_ui_structure.py

@@ -616,3 +616,24 @@ def test_merge_preview_blocks_short_clip(win, tmp_path, monkeypatch):
 def test_merge_preview_empty_is_noop(win):
     win._merge_list.clear()
     win._on_merge_preview()
+
+
+def test_merge_override_applies_and_labels(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_list.clear(); win._merge_add_paths([str(a), str(b)])
+    it0 = win._merge_list.item(0)
+    win._apply_merge_override(it0, 0.8, "exp")
+    assert it0.data(Qt.ItemDataRole.UserRole + 2) == 0.8
+    assert it0.data(Qt.ItemDataRole.UserRole + 3) == "exp"
+    assert "0.80s exp" in it0.text()
+    assert "⤲" not in win._merge_list.item(1).text()   # last item shows no join info
+    xfs, cvs = win._merge_join_values()
+    assert xfs == [0.8] and cvs == ["exp"]
+
+
+def test_merge_double_click_last_is_noop(win, tmp_path):
+    a = tmp_path / "a.wav"; a.write_bytes(b"")
+    win._merge_list.clear(); win._merge_add_paths([str(a)])
+    win._on_merge_item_double_clicked(win._merge_list.item(0))   # only/last -> no dialog, no raise
+    assert win._merge_list.count() == 1