fix(ocr): 引擎对比长度保护——Windows OCR截断丢消息

根因：_pick_ocr_text() 用 score >= score 选引擎，Windows OCR
虽然行数少（8行 vs EasyOCR 19行），但因垃圾字符少、空格惩罚低，
分数可能略高或持平，导致完整 EasyOCR 文本被丢弃。

修复：
- 新增长度保护：当一方行数 >=1.5x 且字符数 >=1.3x 另一方时，
  分数差 <10 分则强制选更长文本
- 引擎对比日志增加行数/字符数/分数差，方便排查
- 不影响分数差距大时的正常选择逻辑

monitor.py

@@ -1366,20 +1366,46 @@ class MessageMonitor:
         return max(score, 0.0)
 
     def _pick_ocr_text(self, win_text: str, easy_text: str, image: Image.Image) -> tuple:
-        """双引擎对比，选质量更高的结果。日志记录引擎胜负统计。返回 (text, engine_name)。"""
+        """双引擎对比，选质量更高的结果。日志记录引擎胜负统计。返回 (text, engine_name)。
+
+        ⭐ 长度保护：当一引擎识别行数显著多于另一方（>=1.5x）时，
+        即使分数略低也优先选更长文本——避免 Windows OCR 截断丢消息。
+        """
         if not easy_text:
             return (win_text, "windows")
         if not win_text:
             return (easy_text, "easyocr")
         win_score = self._score_ocr_text(win_text)
         easy_score = self._score_ocr_text(easy_text)
+        win_lines = len([l for l in win_text.split('\n') if l.strip()])
+        easy_lines = len([l for l in easy_text.split('\n') if l.strip()])
+        win_len = len(win_text.strip())
+        easy_len = len(easy_text.strip())
+
+        # 长度保护：一方行数 >= 1.5x 另一方 → 倾向更长文本（分数差 < 10 时触发）
         chosen = "windows" if win_score >= easy_score else "easyocr"
+        score_diff = abs(win_score - easy_score)
+        if score_diff < 10:
+            if easy_lines >= win_lines * 1.5 and easy_len > win_len * 1.3:
+                chosen = "easyocr"
+                logger.debug(
+                    f"[ocr] 长度保护: easy行数{easy_lines}>=1.5x win行数{win_lines}，"
+                    f"分数差仅{score_diff:.1f}，强制选easyocr"
+                )
+            elif win_lines >= easy_lines * 1.5 and win_len > easy_len * 1.3:
+                chosen = "windows"
+                logger.debug(
+                    f"[ocr] 长度保护: win行数{win_lines}>=1.5x easy行数{easy_lines}，"
+                    f"分数差仅{score_diff:.1f}，强制选windows"
+                )
+
         self._ocr_engine_wins[chosen] = self._ocr_engine_wins.get(chosen, 0) + 1
         total = sum(self._ocr_engine_wins.values())
         ratio = self._ocr_engine_wins.get(chosen, 0) / max(total, 1)
         logger.debug(
-            f"[ocr] 引擎对比: win={win_score:.1f} vs easy={easy_score:.1f} → 选{chosen} "
-            f"(胜率{ratio:.0%}, {total}轮)"
+            f"[ocr] 引擎对比: win={win_score:.1f}(行{win_lines},字符{win_len}) "
+            f"vs easy={easy_score:.1f}(行{easy_lines},字符{easy_len}) "
+            f"→ 选{chosen}(分数差{score_diff:.1f}, 胜率{ratio:.0%}, {total}轮)"
         )
         return (win_text, chosen) if chosen == "windows" else (easy_text, chosen)