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>

scripts/rectification/api_service.py

@@ -427,6 +427,8 @@ def block_scan(request: RectificationRequest) -> dict[str, Any]:
         row for row in scored.get("candidate_scores") or []
         if isinstance(row, dict) and str(row.get("time") or "")[:5]
     ]
+    day_scores = [float(row.get("score") or 0) for row in rows]
+    min_day = min(day_scores) if day_scores else 0.0
     raw_support: list[float] = []
     blocks: list[dict[str, Any]] = []
     for period, start_time, end_time in BLOCK_SCAN_PERIODS:
@@ -448,7 +450,9 @@ def block_scan(request: RectificationRequest) -> dict[str, Any]:
                 "domain": event.get("domain"),
                 "summary": event.get("summary"),
             })
-        raw_support.append(sum(float(row.get("score") or 0) for row in members))
+        member_scores = [float(row.get("score") or 0) for row in members]
+        mean = (sum(member_scores) / len(member_scores)) if member_scores else 0.0
+        raw_support.append(max(mean - min_day, 0.0))
         blocks.append({
             "period": period,
             "start_time": start_time,