feat(chart): Shiller CAPE historical with bubble zone shading

src/charts/bubble_indicators.py

@@ -0,0 +1,101 @@
+"""Bubble Evidence Charts — Shiller CAPE, Buffett Indicator, P/E + Dividend"""
+import copy
+import matplotlib
+matplotlib.use("Agg")
+
+# Patch matplotlib Path.__deepcopy__ to break Python 3.14 recursion loop
+# This is a known bug: https://github.com/matplotlib/matplotlib/issues/29280
+_original_path_deepcopy = None
+try:
+    from matplotlib.path import Path
+    _original_path_deepcopy = Path.__deepcopy__
+    def _safe_path_deepcopy(self, memo):
+        if id(self) in memo:
+            return memo[id(self)]
+        memo[id(self)] = self
+        return self
+    Path.__deepcopy__ = _safe_path_deepcopy
+except Exception:
+    pass
+
+import matplotlib.pyplot as plt
+import matplotlib.ticker as mticker
+import os
+
+from src.data.market_bubbles import shiller_cape, shiller_cape_meta
+from src.utils.styling import get_theme, EXPORT_DPI, BUBBLE_ZONE, WARNING_ZONE, NORMAL_ZONE, GRAY_DARK
+
+
+def plot_shiller_cape() -> str:
+    """Generate Shiller CAPE historical chart with bubble zone shading."""
+    theme = get_theme()
+    theme["savefig.bbox"] = None
+    plt.rcParams.update(theme)
+
+    fig, ax = plt.subplots(figsize=(14, 8))
+
+    # Extract data
+    years = [d["year"] for d in shiller_cape]
+    values = [d["value"] for d in shiller_cape]
+
+    # Plot main line
+    ax.plot(years, values, color=GRAY_DARK, linewidth=1.5, zorder=5)
+
+    # Shaded zones
+    ax.axhspan(0, 20, alpha=0.15, color=NORMAL_ZONE, label="Normal (≤20)")
+    ax.axhspan(20, 30, alpha=0.15, color=WARNING_ZONE, label="Warning (20-30)")
+    ax.axhspan(30, 60, alpha=0.15, color=BUBBLE_ZONE, label="Bubble (>30)")
+
+    # Historical mean line
+    ax.axhline(y=17.39, color="#333333", linestyle="--", linewidth=1, alpha=0.7)
+    ax.text(1890, 17.8, "Mean: 17.39", fontsize=10, color="#333333")
+
+    # Annotations
+    events = [
+        (1929, 27.08, "1929 Crash", -3),
+        (2000, 43.77, "Dot-com Peak", 2),
+        (2007, 27.21, "2007 Crisis", -2),
+        (2020, 30.99, "Pandemic", 2),
+        (2026, 40.03, "2026 (Current)", 2),
+    ]
+    for year, val, label, y_offset in events:
+        ax.annotate(label, xy=(year, val), xytext=(year, val + y_offset),
+                    arrowprops=dict(arrowstyle="->", color="gray", lw=0.8),
+                    fontsize=9, ha="center", fontweight="bold")
+
+    ax.set_title("Shiller CAPE (Cyclically Adjusted P/E) — 1880 to 2026",
+                 fontsize=16, fontweight="bold")
+    ax.set_xlabel("Year", fontsize=12)
+    ax.set_ylabel("CAPE Ratio", fontsize=12)
+    ax.legend(loc="upper left", fontsize=9)
+    ax.grid(True, alpha=0.3)
+    ax.set_ylim(0, 50)
+
+    # X-axis: integer years, use MultipleLocator for clean tick marks
+    ax.xaxis.set_major_locator(mticker.MultipleLocator(20))
+    ax.xaxis.set_major_formatter(mticker.StrMethodFormatter("{x:.0f}"))
+
+    # Subtitle via a second text element
+    ax.text(0.5, -0.18,
+            "Historical mean: 17.39 | Dot-com peak: 43.77 (2000) | Current: 40.03",
+            transform=ax.transAxes, fontsize=10, ha="center", color="#666666")
+
+    # Adjust subplot to leave room for subtitle
+    fig.subplots_adjust(bottom=0.18)
+
+    # Save chart
+    path = os.path.join("output/charts", "01_shiller_cape.png")
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    fig.savefig(path, dpi=EXPORT_DPI,
+                facecolor=fig.get_facecolor(), edgecolor="none")
+    plt.close(fig)
+    return path
+
+
+def main():
+    path = plot_shiller_cape()
+    print(f"Chart saved: {path}")
+
+
+if __name__ == "__main__":
+    main()