fix: avoid overlapping month labels in heatmap SVG

scripts/generate_heatmap_svg.py

@@ -58,26 +58,40 @@ def weekday_row(day):
 def month_labels(grid_start, visible_start, grid_end):
     labels = []
     total_weeks = ((grid_end - grid_start).days // 7) + 1
+    first_visible_month = visible_start.strftime("%b")
+    first_visible_week = ((visible_start - grid_start).days // 7)
 
     for week in range(total_weeks):
         week_start = grid_start + timedelta(days=week * 7)
-        week_label = None
+        label = None
 
         for offset in range(7):
             day = week_start + timedelta(days=offset)
             if day < visible_start:
                 continue
 
-            if week == 0 and week_label is None:
-                week_label = day.strftime("%b")
-
             if day.day == 1:
-                week_label = day.strftime("%b")
+                label = day.strftime("%b")
                 break
 
-        if week_label is not None:
-            if not labels or labels[-1][1] != week_label:
-                labels.append((week, week_label))
+        if week == first_visible_week and not labels:
+            next_month_close = False
+            for future_week in range(week + 1, min(week + 3, total_weeks)):
+                future_start = grid_start + timedelta(days=future_week * 7)
+                for offset in range(7):
+                    day = future_start + timedelta(days=offset)
+                    if day >= visible_start and day.day == 1:
+                        next_month_close = True
+                        break
+                if next_month_close:
+                    break
+
+            if not next_month_close:
+                label = first_visible_month
+
+        if label is not None:
+            if not labels or labels[-1][1] != label:
+                labels.append((week, label))
 
     return labels