fix(cv): resolve infinite page duplication bug caused by playback cursor

scripts/debug/verify_structure.py

@@ -0,0 +1,55 @@
+import cv2
+import numpy as np
+import os
+
+img_path = r"C:\Users\Certes\.gemini\antigravity\brain\975cea00-dd68-4689-9ee3-f1a2408b4ee6\final_check_100_sec.png"
+if not os.path.exists(img_path):
+    print("final_check_100_sec.png not found!")
+    exit(1)
+
+img = cv2.imread(img_path)
+gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
+_, bin_inv = cv2.threshold(gray, 200, 255, cv2.THRESH_BINARY_INV)
+
+h, w = img.shape[:2]
+
+row_sums = np.sum(bin_inv[:, :1000], axis=1) / 255.0
+staff_rows = np.where(row_sums > 1000 * 0.4)[0]
+if len(staff_rows) < 6:
+    print("Cannot find staff lines")
+    exit(1)
+staff_y_top = staff_rows[0]
+staff_y_bottom = staff_rows[-1]
+
+expected_h = staff_y_bottom - staff_y_top
+print(f"Staff height: {expected_h}px (from Y={staff_y_top} to {staff_y_bottom})")
+
+col_sums = np.sum(bin_inv[staff_y_top:staff_y_bottom, :], axis=0) / 255.0
+bar_xs = np.where(col_sums >= expected_h * 0.6)[0]
+
+grouped_bars = []
+if len(bar_xs) > 0:
+    curr = [bar_xs[0]]
+    for x in bar_xs[1:]:
+        if x - curr[-1] < 10: curr.append(x)
+        else:
+            grouped_bars.append(int(np.mean(curr)))
+            curr = [x]
+    grouped_bars.append(int(np.mean(curr)))
+
+diffs = np.diff(grouped_bars)
+print(f"Total measures: {len(grouped_bars) - 1}")
+
+def get_stats(arr):
+    if not len(arr): return "N/A"
+    return f"Min: {np.min(arr)}, Max: {np.max(arr)}, Mean: {np.mean(arr):.1f}"
+
+print("Measure width stats:", get_stats(diffs))
+
+anomalies = [i for i, d in enumerate(diffs) if d < 180 or d > 1200]
+if anomalies:
+    print(f"\n[FAIL] ANOMALIES DETECTED! Mangled measures at indices: {anomalies}")
+    for i in anomalies[:20]:
+        print(f"  Measure {i}: width {diffs[i]}px (Starts at X={grouped_bars[i]})")
+else:
+    print("\n[SUCCESS] NO ANOMALIES. All measures have consistent beat widths. No overlapping mangles detected!")