Add switchable bot modes: default, chatty, and roast

Adds a server-wide mode system with /bcs-mode command.
- Default: current hall-monitor behavior unchanged
- Chatty: friendly chat participant with proactive replies (~10% chance)
- Roast: savage roast mode with proactive replies
- Chatty/roast use relaxed moderation thresholds
- 5-message cooldown between proactive replies per channel
- Bot status updates to reflect active mode
- /bcs-status shows current mode and effective thresholds

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

cogs/chat.py

@@ -1,5 +1,6 @@
 import asyncio
 import logging
+import random
 from collections import deque
 from pathlib import Path
 
@@ -9,17 +10,33 @@ from discord.ext import commands
 logger = logging.getLogger("bcs.chat")
 
 _PROMPTS_DIR = Path(__file__).resolve().parent.parent / "prompts"
-CHAT_PERSONALITY = (_PROMPTS_DIR / "chat_personality.txt").read_text(encoding="utf-8")
 SCOREBOARD_ROAST = (_PROMPTS_DIR / "scoreboard_roast.txt").read_text(encoding="utf-8")
 
 _IMAGE_TYPES = {"png", "jpg", "jpeg", "gif", "webp"}
 
+# Cache loaded prompt files so we don't re-read on every message
+_prompt_cache: dict[str, str] = {}
+
+
+def _load_prompt(filename: str) -> str:
+    if filename not in _prompt_cache:
+        _prompt_cache[filename] = (_PROMPTS_DIR / filename).read_text(encoding="utf-8")
+    return _prompt_cache[filename]
+
 
 class ChatCog(commands.Cog):
     def __init__(self, bot: commands.Bot):
         self.bot = bot
         # Per-channel conversation history for the bot: {channel_id: deque of {role, content}}
         self._chat_history: dict[int, deque] = {}
+        # Counter of messages seen since last proactive reply (per channel)
+        self._messages_since_reply: dict[int, int] = {}
+
+    def _get_active_prompt(self) -> str:
+        """Load the chat prompt for the current mode."""
+        mode_config = self.bot.get_mode_config()
+        prompt_file = mode_config.get("prompt_file", "chat_personality.txt")
+        return _load_prompt(prompt_file)
 
     @commands.Cog.listener()
     async def on_message(self, message: discord.Message):
@@ -30,6 +47,7 @@ class ChatCog(commands.Cog):
             return
 
         should_reply = False
+        is_proactive = False
 
         # Check if bot is @mentioned
         if self.bot.user in message.mentions:
@@ -48,6 +66,24 @@ class ChatCog(commands.Cog):
             except discord.HTTPException:
                 pass
 
+        # Proactive reply check (only if not already replying to a mention/reply)
+        if not should_reply:
+            mode_config = self.bot.get_mode_config()
+            if mode_config.get("proactive_replies", False):
+                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
+
         if not should_reply:
             return
 
@@ -94,7 +130,7 @@ class ChatCog(commands.Cog):
         else:
             # --- Text-only path: normal chat ---
             if not content:
-                content = "(just pinged me)"
+                content = "(just pinged me)" if not is_proactive else message.content
 
             # Add drama score context only when noteworthy
             drama_score = self.bot.drama_tracker.get_drama_score(message.author.id)
@@ -110,9 +146,11 @@ class ChatCog(commands.Cog):
                 {"role": "user", "content": f"{score_context}\n{message.author.display_name}: {content}"}
             )
 
+            active_prompt = self._get_active_prompt()
+
             response = await self.bot.llm.chat(
                 list(self._chat_history[ch_id]),
-                CHAT_PERSONALITY,
+                active_prompt,
                 on_first_token=start_typing,
             )
 
@@ -137,6 +175,10 @@ class ChatCog(commands.Cog):
                 {"role": "assistant", "content": response}
             )
 
+        # Reset proactive cooldown counter for this channel
+        if is_proactive:
+            self._messages_since_reply[ch_id] = 0
+
         # Wait for any pending sentiment analysis to finish first so
         # warnings/mutes appear before the chat reply
         sentiment_cog = self.bot.get_cog("SentimentCog")
@@ -149,9 +191,15 @@ class ChatCog(commands.Cog):
                 except (asyncio.TimeoutError, asyncio.CancelledError):
                     pass
 
-        await message.reply(response, mention_author=False)
+        if is_proactive:
+            await message.channel.send(response)
+        else:
+            await message.reply(response, mention_author=False)
+
+        reply_type = "proactive" if is_proactive else "chat"
         logger.info(
-            "Chat reply in #%s to %s: %s",
+            "%s reply in #%s to %s: %s",
+            reply_type.capitalize(),
             message.channel.name,
             message.author.display_name,
             response[:100],