feat: metadata enrichment for alerts and subscription plugins

Alert backends now populate structured `extra` field with engagement
metrics (views, stars, votes, etc.) instead of embedding them in titles.
Subscription plugins show richer announcements: Twitch viewer counts,
YouTube views/likes/dates, RSS published dates.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/youtube.py

@@ -27,6 +27,7 @@ _YT_PLAYER_URL = "https://www.youtube.com/youtubei/v1/player"
 _YT_CLIENT_VERSION = "2.20250101.00.00"
 _ATOM_NS = "{http://www.w3.org/2005/Atom}"
 _YT_NS = "{http://www.youtube.com/xml/schemas/2015}"
+_MEDIA_NS = "{http://search.yahoo.com/mrss/}"
 _MAX_SEEN = 200
 _MAX_ANNOUNCE = 5
 _DEFAULT_INTERVAL = 600
@@ -74,6 +75,15 @@ def _truncate(text: str, max_len: int = _MAX_TITLE_LEN) -> str:
     return text[: max_len - 3].rstrip() + "..."
 
 
+def _compact_num(n: int) -> str:
+    """Format large numbers compactly: 1234 -> 1.2k, 1234567 -> 1.2M."""
+    if n >= 1_000_000:
+        return f"{n / 1_000_000:.1f}M".replace(".0M", "M")
+    if n >= 1_000:
+        return f"{n / 1_000:.1f}k".replace(".0k", "k")
+    return str(n)
+
+
 def _is_youtube_url(url: str) -> bool:
     """Check if URL is a YouTube domain."""
     try:
@@ -213,8 +223,33 @@ def _parse_feed(body: bytes) -> tuple[str, list[dict]]:
             link = (link_el.get("href", "") if link_el is not None else "").strip()
         if not entry_id:
             entry_id = link
+        # Published date
+        published = (entry.findtext(f"{_ATOM_NS}published") or "").strip()
+        date = published[:10] if len(published) >= 10 else ""
+        # media:statistics views + media:starRating count (likes)
+        views = 0
+        likes = 0
+        group = entry.find(f"{_MEDIA_NS}group")
+        if group is not None:
+            community = group.find(f"{_MEDIA_NS}community")
+            if community is not None:
+                stats_el = community.find(f"{_MEDIA_NS}statistics")
+                if stats_el is not None:
+                    try:
+                        views = int(stats_el.get("views", "0"))
+                    except (ValueError, TypeError):
+                        pass
+                rating_el = community.find(f"{_MEDIA_NS}starRating")
+                if rating_el is not None:
+                    try:
+                        likes = int(rating_el.get("count", "0"))
+                    except (ValueError, TypeError):
+                        pass
         if entry_id:
-            items.append({"id": entry_id, "title": entry_title, "link": link})
+            items.append({
+                "id": entry_id, "title": entry_title, "link": link,
+                "date": date, "views": views, "likes": likes,
+            })
     return (channel_name, items)
 
 
@@ -305,7 +340,21 @@ async def _poll_once(bot, key: str, announce: bool = True) -> None:
         for item in shown:
             title = _truncate(item["title"]) if item["title"] else "(no title)"
             link = item["link"]
+            # Build metadata suffix
+            parts = []
+            views = item.get("views", 0)
+            likes = item.get("likes", 0)
+            if views:
+                parts.append(f"{_compact_num(views)}v")
+            if likes:
+                parts.append(f"{_compact_num(likes)}lk")
+            date = item.get("date", "")
+            if date:
+                parts.append(date)
+            extra = " ".join(parts)
             line = f"[{name}] {title}"
+            if extra:
+                line += f" | {extra}"
             if link:
                 line += f" -- {link}"
             await bot.send(channel, line)