Adjust vertical spacing in trend figure based on the number of tags to comply with Plotly constraints

app.py

@@ -361,9 +361,17 @@ def make_trend_figure(
     if not tags:
         return None
 
+    rows = len(tags)
+    # rows が多いときは、Plotly の制約: vertical_spacing <= 1/(rows-1)
+    if rows <= 1:
+        vspace = 0.03
+    else:
+        max_vs = (1.0 / (rows - 1)) - 1e-4  # ほんの少しだけマージンを取る
+        vspace = max(0.0, min(0.03, max_vs))
+
     fig = make_subplots(
-        rows=len(tags), cols=1, shared_xaxes=True,
-        vertical_spacing=0.03,
+        rows=rows, cols=1, shared_xaxes=True,
+        vertical_spacing=vspace,
         subplot_titles=[f"{process_name} | 計測項目: {t}" for t in tags]
     )