fix: comparable periods pick one example per market cycle

Instead of showing 5 recent days with similar scores (all from the same
2-week window), now picks one example per cycle:
- pre-2016, 2016-17 Bull, 2018-19 Bear, 2020-21 Bull, 2022-23 Bear, 2024+
- Sorted by closest score match, then picks one per cycle
- Shows cycle label in brackets next to each example
- Much more representative of how the score performed across different eras

backtesting/engine.py

@@ -369,15 +369,39 @@ def run_backtest():
                     avg_returns[period] = round(sum(vals) / len(vals), 2)
         avg_1yr = avg_returns.get("365d")
 
-        # Best comparable examples (most recent 5)
+        # Best comparable examples — one per market cycle for diversity
+        # Cycles: pre-2016, 2016-2017 bull, 2018-2019 bear, 2020-2021 bull, 2022-2023 bear, 2024+
+        cycle_bins = [
+            ("pre-2016", "2010-01-01", "2015-12-31"),
+            ("2016-17 Bull", "2016-01-01", "2017-12-31"),
+            ("2018-19 Bear", "2018-01-01", "2019-12-31"),
+            ("2020-21 Bull", "2020-01-01", "2021-12-31"),
+            ("2022-23 Bear", "2022-01-01", "2023-12-31"),
+            ("2024+", "2024-01-01", "2099-12-31"),
+        ]
         examples = []
-        for d in comparable[-5:]:
-            examples.append({
-                "date": d["date"],
-                "score": d["score"],
-                "price": d["price"],
-                "forward_returns": d["forward_returns"],
-            })
+        used_cycles = set()
+        # Sort comparable by closest score first, then pick one per cycle
+        sorted_comp = sorted(comparable, key=lambda d: abs(d["score"] - current_score))
+        for d in sorted_comp:
+            cycle_label = None
+            for label, start, end in cycle_bins:
+                if start <= d["date"] <= end:
+                    cycle_label = label
+                    break
+            if cycle_label and cycle_label not in used_cycles:
+                used_cycles.add(cycle_label)
+                examples.append({
+                    "date": d["date"],
+                    "score": d["score"],
+                    "price": d["price"],
+                    "forward_returns": d["forward_returns"],
+                    "cycle": cycle_label,
+                })
+            if len(examples) >= 6:
+                break
+        # Sort examples chronologically
+        examples.sort(key=lambda d: d["date"])
 
         current_context = {
             "current_score": current_score,