feat: generate topic drift redirects via LLM with full conversation context

Replace static random templates with LLM-generated redirect messages that
reference what the user actually said and why it's off-topic. Sass escalates
with higher strike counts. Falls back to static templates if LLM fails or
use_llm is disabled in config.

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

cogs/sentiment/topic_drift.py

@@ -1,5 +1,9 @@
 import asyncio
 import logging
+import random
+import re
+from collections import deque
+from pathlib import Path
 
 import discord
 
@@ -8,6 +12,105 @@ from cogs.sentiment.state import save_user_state
 
 logger = logging.getLogger("bcs.sentiment")
 
+_PROMPTS_DIR = Path(__file__).resolve().parent.parent.parent / "prompts"
+_TOPIC_REDIRECT_PROMPT = (_PROMPTS_DIR / "topic_redirect.txt").read_text(encoding="utf-8")
+
+DEFAULT_TOPIC_REMINDS = [
+    "Hey {username}, this is a gaming server 🎮 — maybe take the personal stuff to DMs?",
+    "{username}, sir this is a gaming channel.",
+    "Hey {username}, I don't remember this being a therapy session. Gaming talk, please. 🎮",
+    "{username}, I'm gonna need you to take that energy to DMs. This channel has a vibe to protect.",
+    "Not to be dramatic {username}, but this is wildly off-topic. Back to gaming? 🎮",
+]
+
+DEFAULT_TOPIC_NUDGES = [
+    "{username}, we've been over this. Gaming. Channel. Please. 🎮",
+    "{username}, you keep drifting off-topic like it's a speedrun category. Reel it in.",
+    "Babe. {username}. The gaming channel. We talked about this. 😭",
+    "{username}, I will not ask again (I will definitely ask again). Stay on topic. 🎮",
+    "{username}, at this point I'm keeping score. That's off-topic strike {count}. Gaming talk only!",
+    "Look, {username}, I love the enthusiasm but this ain't the channel for it. Back to games. 🎮",
+]
+
+# Per-channel deque of recent LLM-generated redirect messages (for variety)
+_recent_redirects: dict[int, deque] = {}
+
+
+def _get_recent_redirects(channel_id: int) -> list[str]:
+    if channel_id in _recent_redirects:
+        return list(_recent_redirects[channel_id])
+    return []
+
+
+def _record_redirect(channel_id: int, text: str):
+    if channel_id not in _recent_redirects:
+        _recent_redirects[channel_id] = deque(maxlen=5)
+    _recent_redirects[channel_id].append(text)
+
+
+def _strip_brackets(text: str) -> str:
+    """Strip leaked LLM metadata brackets (same approach as ChatCog)."""
+    segments = re.split(r"^\s*\[[^\]]*\]\s*$", text, flags=re.MULTILINE)
+    segments = [s.strip() for s in segments if s.strip()]
+    return segments[-1] if segments else ""
+
+
+async def _generate_llm_redirect(
+    bot, message: discord.Message, topic_category: str,
+    topic_reasoning: str, count: int,
+) -> str | None:
+    """Ask the LLM chat model to generate a topic redirect message."""
+    recent = _get_recent_redirects(message.channel.id)
+
+    user_prompt = (
+        f"Username: {message.author.display_name}\n"
+        f"Channel: #{getattr(message.channel, 'name', 'unknown')}\n"
+        f"Off-topic category: {topic_category}\n"
+        f"Why it's off-topic: {topic_reasoning}\n"
+        f"Off-topic strike count: {count}\n"
+        f"What they said: {message.content[:300]}"
+    )
+
+    messages = [{"role": "user", "content": user_prompt}]
+
+    effective_prompt = _TOPIC_REDIRECT_PROMPT
+    if recent:
+        avoid_block = "\n".join(f"- {r}" for r in recent)
+        effective_prompt += (
+            "\n\nIMPORTANT — you recently sent these redirects in the same channel. "
+            "Do NOT repeat any of these. Be completely different.\n"
+            + avoid_block
+        )
+
+    try:
+        response = await bot.llm_chat.chat(
+            messages, effective_prompt,
+        )
+    except Exception:
+        logger.exception("LLM topic redirect generation failed")
+        return None
+
+    if response:
+        response = _strip_brackets(response)
+
+    return response if response else None
+
+
+def _static_fallback(bot, message: discord.Message, count: int) -> str:
+    """Pick a static template message as fallback."""
+    messages_config = bot.config.get("messages", {})
+    if count >= 2:
+        pool = messages_config.get("topic_nudges", DEFAULT_TOPIC_NUDGES)
+        if isinstance(pool, str):
+            pool = [pool]
+    else:
+        pool = messages_config.get("topic_reminds", DEFAULT_TOPIC_REMINDS)
+        if isinstance(pool, str):
+            pool = [pool]
+    return random.choice(pool).format(
+        username=message.author.display_name, count=count,
+    )
+
 
 async def handle_topic_drift(
     bot, message: discord.Message, topic_category: str, topic_reasoning: str,
@@ -33,46 +136,43 @@ async def handle_topic_drift(
         return
 
     count = tracker.record_off_topic(user_id)
-    messages_config = bot.config.get("messages", {})
+    action_type = "topic_nudge" if count >= 2 else "topic_remind"
 
-    if count >= 2:
-        nudge_text = messages_config.get(
-            "topic_nudge",
-            "{username}, let's keep it to gaming talk in here.",
-        ).format(username=message.author.display_name)
-        await message.channel.send(nudge_text)
+    # Generate the redirect message
+    use_llm = config.get("use_llm", False)
+    redirect_text = None
+    if use_llm:
+        redirect_text = await _generate_llm_redirect(
+            bot, message, topic_category, topic_reasoning, count,
+        )
+
+    if redirect_text:
+        _record_redirect(message.channel.id, redirect_text)
+    else:
+        redirect_text = _static_fallback(bot, message, count)
+
+    await message.channel.send(redirect_text)
+
+    if action_type == "topic_nudge":
         await log_action(
             message.guild,
             f"**TOPIC NUDGE** | {message.author.mention} | "
             f"Off-topic count: {count} | Category: {topic_category}",
         )
-        logger.info("Topic nudge for %s (count %d)", message.author, count)
-
-        asyncio.create_task(bot.db.save_action(
-            guild_id=message.guild.id, user_id=user_id,
-            username=message.author.display_name,
-            action_type="topic_nudge", message_id=db_message_id,
-            details=f"off_topic_count={count} category={topic_category}",
-        ))
-        save_user_state(bot, dirty_users, user_id)
-
     else:
-        remind_text = messages_config.get(
-            "topic_remind",
-            "Hey {username}, this is a gaming server \u2014 maybe take the personal stuff to DMs?",
-        ).format(username=message.author.display_name)
-        await message.channel.send(remind_text)
         await log_action(
             message.guild,
             f"**TOPIC REMIND** | {message.author.mention} | "
             f"Category: {topic_category} | {topic_reasoning}",
         )
-        logger.info("Topic remind for %s (count %d)", message.author, count)
 
-        asyncio.create_task(bot.db.save_action(
-            guild_id=message.guild.id, user_id=user_id,
-            username=message.author.display_name,
-            action_type="topic_remind", message_id=db_message_id,
-            details=f"off_topic_count={count} category={topic_category} reasoning={topic_reasoning}",
-        ))
-        save_user_state(bot, dirty_users, user_id)
+    logger.info("Topic %s for %s (count %d)", action_type.replace("topic_", ""), message.author, count)
+
+    asyncio.create_task(bot.db.save_action(
+        guild_id=message.guild.id, user_id=user_id,
+        username=message.author.display_name,
+        action_type=action_type, message_id=db_message_id,
+        details=f"off_topic_count={count} category={topic_category}"
+        + (f" reasoning={topic_reasoning}" if action_type == "topic_remind" else ""),
+    ))
+    save_user_state(bot, dirty_users, user_id)