Add reaction clap-back replies (50% chance)

When someone reacts to the bot's message, there's a 50% chance it
fires back with a reply commenting on their emoji choice, in
character for the current mode.

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

cogs/chat.py

@@ -216,5 +216,80 @@ class ChatCog(commands.Cog):
         )
 
 
+    @commands.Cog.listener()
+    async def on_raw_reaction_add(self, payload: discord.RawReactionActionEvent):
+        # Ignore bot's own reactions
+        if payload.user_id == self.bot.user.id:
+            return
+
+        # 50% chance to reply
+        if random.random() > 0.50:
+            return
+
+        # Only react to reactions on the bot's own messages
+        channel = self.bot.get_channel(payload.channel_id)
+        if channel is None:
+            return
+
+        try:
+            message = await channel.fetch_message(payload.message_id)
+        except discord.HTTPException:
+            return
+
+        if message.author.id != self.bot.user.id:
+            return
+
+        # Get the user who reacted
+        guild = self.bot.get_guild(payload.guild_id) if payload.guild_id else None
+        if guild is None:
+            return
+        member = guild.get_member(payload.user_id)
+        if member is None:
+            return
+
+        emoji = str(payload.emoji)
+
+        # Build a one-shot prompt for the LLM
+        ch_id = channel.id
+        if ch_id not in self._chat_history:
+            self._chat_history[ch_id] = deque(maxlen=10)
+
+        context = (
+            f"[Server context: {member.display_name} — #{channel.name}]\n"
+            f"[{member.display_name} reacted to your message with {emoji}]\n"
+            f"[Your message was: {message.content[:300]}]\n"
+            f"{member.display_name}: *reacted {emoji}*"
+        )
+
+        self._chat_history[ch_id].append({"role": "user", "content": context})
+        active_prompt = self._get_active_prompt()
+
+        response = await self.bot.llm.chat(
+            list(self._chat_history[ch_id]),
+            active_prompt,
+        )
+
+        # Strip leaked metadata
+        if response:
+            response = re.sub(r"\[Server context:[^\]]*\]\n?", "", response)
+            response = re.sub(r"\[.*?reacted to your message.*?\]\n?", "", response)
+            response = re.sub(r"\[Your message was:.*?\]\n?", "", response)
+            response = response.strip()
+
+        if not response:
+            return
+
+        self._chat_history[ch_id].append({"role": "assistant", "content": response})
+
+        await message.reply(response, mention_author=False)
+        logger.info(
+            "Reaction reply in #%s to %s (%s): %s",
+            channel.name,
+            member.display_name,
+            emoji,
+            response[:100],
+        )
+
+
 async def setup(bot: commands.Bot):
     await bot.add_cog(ChatCog(bot))