viz: improve x-axis readability with ConciseDateFormatter, fewer ticks, and wider figure

scripts/banlist_metrics.py

@@ -93,6 +93,7 @@ def write_chart(snaps: List[Snapshot], image_path: str) -> None:
         import matplotlib
         matplotlib.use("Agg")  # headless
         import matplotlib.pyplot as plt
+        import matplotlib.dates as mdates
     except Exception as e:
         print(f"Skipping chart generation (matplotlib unavailable): {e}")
         return
@@ -104,17 +105,32 @@ def write_chart(snaps: List[Snapshot], image_path: str) -> None:
     xs = [datetime.fromtimestamp(s.timestamp, tz=timezone.utc) for s in snaps]
     ys = [s.count for s in snaps]
 
-    plt.figure(figsize=(8, 3))
+    fig, ax = plt.subplots(figsize=(9.5, 3.2))
-    plt.plot(xs, ys, marker="o", linewidth=1.5, markersize=2)
+    ax.plot(xs, ys, marker="o", linewidth=1.5, markersize=2)
-    plt.title("WageNet IP Ban List Size Over Time")
+    ax.set_title("WageNet IP Ban List Size Over Time")
-    plt.xlabel("Date (UTC)")
+    ax.set_xlabel("Date (UTC)")
-    plt.ylabel("IP count")
+    ax.set_ylabel("IP count")
-    plt.grid(True, linestyle=":", linewidth=0.5)
+    ax.grid(True, linestyle=":", linewidth=0.5)
-    plt.tight_layout()
+
+    # Reduce x-axis label crowding
+    try:
+        locator = mdates.AutoDateLocator(minticks=4, maxticks=8)
+        formatter = mdates.ConciseDateFormatter(locator)
+        ax.xaxis.set_major_locator(locator)
+        ax.xaxis.set_major_formatter(formatter)
+    except Exception:
+        # Fallback: rotate labels if ConciseDateFormatter isn't available
+        for label in ax.get_xticklabels():
+            label.set_rotation(30)
+            label.set_horizontalalignment("right")
+
+    # Add slight horizontal margins to prevent clipping at edges
+    ax.margins(x=0.02)
+    fig.tight_layout()
 
     os.makedirs(os.path.dirname(image_path), exist_ok=True)
-    plt.savefig(image_path)
+    fig.savefig(image_path)
-    plt.close()
+    plt.close(fig)
 
 
 def main() -> int:
@@ -146,4 +162,3 @@ def main() -> int:
 
 if __name__ == "__main__":
     raise SystemExit(main())
-