fix: anchor locked marker review at start

main.py

@@ -2528,16 +2528,16 @@ class TimelineWidget(QWidget):
                     p.drawText(mx + 1, rh + 2, 13, 12,
                                Qt.AlignmentFlag.AlignCenter, str(num))
 
-            # ── scan mode cursor + playback line ─────────────────────────
+            # ── scan/locked playback line ────────────────────────────────
             if self._scan_mode:
                 # Export cursor (dim)
                 p.setPen(QPen(QColor(255, 255, 255, 80), 1))
                 p.drawLine(x_start, rh, x_start, h)
-                # Playback position (bright green)
-                if self._play_pos is not None and self._play_pos >= 0:
-                    px = int(self._time_to_x(self._play_pos))
-                    p.setPen(QPen(QColor(80, 255, 80, 220), 2))
-                    p.drawLine(px, rh, px, h)
+            if ((self._scan_mode or self._locked)
+                    and self._play_pos is not None and self._play_pos >= 0):
+                px = int(self._time_to_x(self._play_pos))
+                p.setPen(QPen(QColor(80, 255, 80, 220), 2))
+                p.drawLine(px, rh, px, h)
 
             # ── crop keyframe diamonds ────────────────────────────────────
             if self._crop_keyframes and self._duration > 0:
@@ -5977,7 +5977,7 @@ class MainWindow(QMainWindow):
             "<tr><td><b>Ctrl+Z</b></td><td>Undo last scan panel action</td></tr>"
             "<tr><td><b>? / F1</b></td><td>This help</td></tr>"
             "<tr><td colspan='2'><hr></td></tr>"
-            "<tr><td><b>Double-click marker</b></td><td>Enter overwrite mode (locked: jump to end of clip span)</td></tr>"
+            "<tr><td><b>Double-click marker</b></td><td>Enter overwrite mode (locked: review from start to end)</td></tr>"
             "<tr><td><b>Right-click marker</b></td><td>Delete clip group</td></tr>"
             "<tr><td><b>Click video / crop bar</b></td><td>Reposition portrait crop</td></tr>"
             "<tr><td><b>Shift+drag scan region edge</b></td><td>Resize scan region</td></tr>"
@@ -7013,22 +7013,36 @@ class MainWindow(QMainWindow):
         self._show_status(f"Deleted keyframe @ {format_time(time)}", 3000)
 
     def _on_marker_clicked(self, start_time: float, output_path: str) -> None:
-        # In lock mode, move cursor to the end of this marker's span.
+        # In lock mode, keep the marker start anchored and scrub the playhead
+        # to the marker end so the highlighted zone matches what is reviewed.
         if self._btn_lock.isChecked():
             meta = self._db.get_by_output_path(output_path)
-            clip_count = meta["clip_count"] or self._spn_clips.value() if meta else self._spn_clips.value()
-            clip_dur = meta.get("clip_duration", self._clip_dur) if meta else self._clip_dur
-            spread = meta["spread"] or self._spn_spread.value() if meta else self._spn_spread.value()
-            next_pos = start_time + clip_dur + (clip_count - 1) * spread
-            self._cursor = next_pos
-            self._timeline.set_cursor(next_pos)
-            self._mpv.seek(next_pos)
-            self._lbl_time.setText(f"{format_time(next_pos)} / {format_time(self._mpv.get_duration())}")
+            clip_count = (
+                meta.get("clip_count") or self._spn_clips.value()
+            ) if meta else self._spn_clips.value()
+            clip_dur = (
+                meta.get("clip_duration") or self._clip_dur
+            ) if meta else self._clip_dur
+            spread = (
+                meta.get("spread") or self._spn_spread.value()
+            ) if meta else self._spn_spread.value()
+            self._spn_clips.setValue(int(clip_count))
+            self._spn_clip_dur.setValue(float(clip_dur))
+            self._spn_spread.setValue(float(spread))
+            clip_span = float(clip_dur) + (int(clip_count) - 1) * float(spread)
+            dur = self._mpv.get_duration()
+            end_pos = min(start_time + clip_span, dur) if dur else start_time + clip_span
+            self._cursor = start_time
+            self._timeline.set_cursor(start_time)
+            self._timeline.set_clip_span(clip_span, float(clip_dur), float(spread))
+            self._timeline.set_play_position(end_pos)
+            self._mpv.seek(end_pos)
+            self._lbl_time.setText(f"{format_time(end_pos)} / {format_time(dur)}")
             self._update_next_label()
             self._preview_timer.start()
             stem = os.path.splitext(os.path.basename(output_path))[0]
             group_label = stem.rsplit("_", 1)[0]
-            self._show_status(f"Cursor → end of {group_label}", 3000)
+            self._show_status(f"Reviewing {group_label}: start locked, playhead at end", 3000)
             return
         self._cursor = start_time
         self._timeline.set_cursor(start_time)