diff --git a/app.py b/app.py
index bdf28cf..581f311 100644
--- a/app.py
+++ b/app.py
@@ -21,6 +21,25 @@ st.set_page_config(
 )
 
 
+def add_milestone_line(fig, x, color: str, text: str):
+    """手动添加竖线标记，绕过 Plotly add_vline 对 datetime.date 的 bug。"""
+    fig.add_shape(
+        type="line",
+        x0=x, x1=x, y0=0, y1=1,
+        xref="x", yref="paper",
+        line=dict(color=color, width=1.5, dash="dot"),
+    )
+    fig.add_annotation(
+        x=x, y=1.02,
+        xref="x", yref="paper",
+        text=text,
+        showarrow=False,
+        font=dict(color=color, size=10),
+        bgcolor="rgba(255,255,255,0.8)",
+        borderpad=2,
+    )
+
+
 # ─── Sidebar ────────────────────────────────────────────────────────────────
 with st.sidebar:
     st.header("🌾 麦麦智农")
@@ -104,19 +123,9 @@ with chart_left:
         )
         ms = summary.get("milestones", {})
         if "flowering" in ms:
-            fig_lai.add_vline(
-                x=ms["flowering"],
-                line=dict(color="#d4a574", width=1.5, dash="dot"),
-                annotation_text="开花",
-                annotation_position="top left",
-            )
+            add_milestone_line(fig_lai, x=ms["flowering"], color="#d4a574", text="开花")
         if "maturity" in ms:
-            fig_lai.add_vline(
-                x=ms["maturity"],
-                line=dict(color="#7c5e42", width=1.5, dash="dash"),
-                annotation_text="成熟",
-                annotation_position="top right",
-            )
+            add_milestone_line(fig_lai, x=ms["maturity"], color="#7c5e42", text="成熟")
         fig_lai.update_layout(
             xaxis_title="日期",
             yaxis_title="LAI",
@@ -149,9 +158,9 @@ with chart_right:
             )
         ms = summary.get("milestones", {})
         if "flowering" in ms:
-            fig_bio.add_vline(x=ms["flowering"], line=dict(color="#d4a574", width=1.5, dash="dot"))
+            add_milestone_line(fig_bio, x=ms["flowering"], color="#d4a574", text="开花")
         if "maturity" in ms:
-            fig_bio.add_vline(x=ms["maturity"], line=dict(color="#7c5e42", width=1.5, dash="dash"))
+            add_milestone_line(fig_bio, x=ms["maturity"], color="#7c5e42", text="成熟")
         fig_bio.update_layout(
             xaxis_title="日期",
             yaxis_title="干物质 (kg/ha)",