feat: theme_line 取数升级,无评分命中时回退 theme_names

新增 _top_line: 优先评分最高主题,无命中时回退 _theme_clusters 的
主题名(非 markdown 示例),DAILY_WECOM_TOP_LINE=0 退回原逻辑。
复用现有 theme_line 行,不新增头部行(T5)。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

daily/generate.py

@@ -24,6 +24,7 @@ from daily.config import (
     SNAPSHOT_FILE,
     board_pool_size,
     env,
+    env_bool,
     env_int,
     full_desc_limit,
     news_summary_limit,
@@ -345,6 +346,33 @@ def _detect_theme_line(feed: dict[str, Any]) -> str:
     return f"**今日主题**：{max(scores.items(), key=lambda x: x[1])[0]}"
 
 
+def _top_line(feed: dict[str, Any]) -> str:
+    """今日看点行: 优先评分最高的主题, 回退 _theme_clusters 的主题名(非 markdown 示例)。
+
+    DAILY_WECOM_TOP_LINE=0 关闭时退回 _detect_theme_line 原逻辑。
+    与原 _detect_theme_line 的差别仅在「无评分命中」时的兜底文案:
+    用 theme_names 的真实主题取代硬编码「Agent Skills 生态持续活跃」。
+    """
+    if not env_bool("DAILY_WECOM_TOP_LINE", True):
+        return _detect_theme_line(feed)
+    scores: dict[str, int] = defaultdict(int)
+    for board in ("topTrending", "topHot"):
+        for rank, item in enumerate(feed.get(board, [])[:10], 1):
+            haystack = " ".join(
+                [item.get("title", ""), item.get("source", ""), item.get("description", "")]
+            ).lower()
+            for _icon, label, keywords in THEME_RULES:
+                if any(k in haystack for k in keywords):
+                    scores[label] += max(1, 11 - rank)
+                    break
+    if scores:
+        return f"**今日主题**：{max(scores.items(), key=lambda x: x[1])[0]}"
+    names = theme_names(feed, theme_rules=THEME_RULES, skill_id_fn=_skill_id)
+    if names:
+        return f"**今日主题**：{' · '.join(names)}"
+    return "**今日主题**：Agent Skills 生态持续活跃"
+
+
 def _build_highlights(
     trending: list[dict[str, Any]],
     hot: list[dict[str, Any]],
@@ -1076,7 +1104,7 @@ def _render(c: dict[str, Any], s: dict[str, Any]) -> tuple[str, str, Path, Path]
             updated=updated,
             highlights=editorial_highlights
             or _build_highlights(trending, hot, github_trending, github_emerging, ai_news, cn_ai_news),
-            theme_line=editorial_theme or _detect_theme_line(feed),
+            theme_line=editorial_theme or _top_line(feed),
             ai_news=wecom_ai if not news_merged else None,
             cn_ai_news=wecom_cn if not news_merged else None,
             merged_ai_news=wecom_news if news_merged else None,