fix(rectification): narrate the credible range and stop scoring periods by length (BUG-569–570)

Choice copy was comparing the search window, so every answer said the range had not changed. Block-scan summed raw scores, so longer afternoon windows won before any evidence difference.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_rectification_v5_services.py

@@ -908,6 +908,46 @@ class RectificationV5ServicesTest(unittest.TestCase):
         self.assertEqual(result["candidate_count"], 144)
         self.assertLessEqual(elapsed, 15, f"block_scan took {elapsed:.1f}s")
 
+    def test_block_scan_equal_scores_share_evenly_and_length_does_not_win(self):
+        from scripts.rectification.api_service import block_scan
+
+        def grid(score_for):
+            return [
+                {"time": f"{hour:02d}:{minute:02d}", "score": score_for(hour), "supporting_event_ids": []}
+                for hour in range(24)
+                for minute in range(0, 60, 10)
+            ]
+
+        equal_rows = grid(lambda _hour: 12.0)
+        morning_rows = grid(lambda hour: 20.0 if 4 <= hour <= 7 else 10.0)
+        dummy = {
+            "result_id": "00000000-0000-4000-8000-000000000099",
+            "algorithm_version": "test",
+            "calculation_spec": {},
+            "calculation_spec_hash": "abc",
+            "decision_receipt": {},
+        }
+        request_body = {
+            "birth_date": "1998-03-15",
+            "start_time": "00:00",
+            "end_time": "23:59",
+            "lat": 39.9042,
+            "lon": 116.4074,
+            "tz": 8.0,
+            "minute_step": 10,
+            "events": [],
+        }
+        with patch("scripts.rectification.api_service.score_candidates", return_value={**dummy, "candidate_scores": equal_rows}):
+            equal = block_scan(request_body)
+        self.assertEqual([row["relative_support"] for row in equal["blocks"]], [20.0, 20.0, 20.0, 20.0, 20.0])
+        self.assertEqual([row["candidate_count"] for row in equal["blocks"]], [24, 24, 36, 30, 30])
+        with patch("scripts.rectification.api_service.score_candidates", return_value={**dummy, "candidate_scores": morning_rows}):
+            morning = block_scan(request_body)
+        shares = {row["period"]: row["relative_support"] for row in morning["blocks"]}
+        self.assertEqual(max(shares, key=shares.get), "early_morning")
+        self.assertGreater(shares["early_morning"], shares["afternoon"])
+        self.assertEqual(shares["afternoon"], 0.0)
+
 
 if __name__ == "__main__":
     unittest.main()