feat: add relevance-gated proactive replies

Replace random-only proactive reply logic with LLM relevance check.
The bot now evaluates recent conversation context and user memory
before deciding to jump in, then applies reply_chance as a second
gate. Bump reply_chance values higher since the relevance filter
prevents most irrelevant replies.

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

cogs/chat.py

@@ -226,16 +226,58 @@ class ChatCog(commands.Cog):
                 ch_id = message.channel.id
                 self._messages_since_reply[ch_id] = self._messages_since_reply.get(ch_id, 0) + 1
                 cooldown = self.bot.config.get("modes", {}).get("proactive_cooldown_messages", 5)
-                reply_chance = mode_config.get("reply_chance", 0.0)
 
                 if (
                     self._messages_since_reply[ch_id] >= cooldown
-                    and reply_chance > 0
-                    and random.random() < reply_chance
                     and message.content and message.content.strip()
                 ):
-                    should_reply = True
-                    is_proactive = True
+                    # Gather recent messages for relevance check
+                    recent_for_check = []
+                    try:
+                        async for msg in message.channel.history(limit=5, before=message):
+                            if msg.content and msg.content.strip() and not msg.author.bot:
+                                recent_for_check.append(
+                                    f"{msg.author.display_name}: {msg.content[:200]}"
+                                )
+                    except discord.HTTPException:
+                        pass
+                    recent_for_check.reverse()
+                    recent_for_check.append(
+                        f"{message.author.display_name}: {message.content[:200]}"
+                    )
+
+                    # Build memory context for users in recent messages
+                    memory_parts = []
+                    seen_users = set()
+                    for line in recent_for_check:
+                        name = line.split(":")[0]
+                        if name not in seen_users and message.guild:
+                            seen_users.add(name)
+                            member = discord.utils.find(
+                                lambda m, n=name: m.display_name == n,
+                                message.guild.members,
+                            )
+                            if member:
+                                profile = self.bot.drama_tracker.get_user_notes(member.id)
+                                if profile:
+                                    memory_parts.append(f"{name}: {profile}")
+
+                    memory_ctx = "\n".join(memory_parts) if memory_parts else ""
+
+                    is_relevant = await self.bot.llm.check_reply_relevance(
+                        recent_for_check, memory_ctx,
+                    )
+
+                    if is_relevant:
+                        reply_chance = mode_config.get("reply_chance", 0.0)
+                        if reply_chance > 0 and random.random() < reply_chance:
+                            should_reply = True
+                            is_proactive = True
+                    else:
+                        # Not relevant — partially reset cooldown so we check again sooner
+                        self._messages_since_reply[ch_id] = max(
+                            0, self._messages_since_reply[ch_id] - 3
+                        )
 
         if not should_reply:
             return