8ball: constrain general responses to actual yes/no/maybe style

The creative model was producing fortune-cookie mysticism ("navigate
the curve of fate") instead of 8-ball answers. New system prompt
explicitly requires YES/NO/UNCERTAIN category answers, 2-6 words,
funny and direct — no cryptic prophecies.

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

matrixbot/commands.py

@@ -542,20 +542,28 @@ async def cmd_8ball(client: AsyncClient, room_id: str, sender: str, args: str):
         timeout = aiohttp.ClientTimeout(total=30)
         async with aiohttp.ClientSession(timeout=timeout) as session:
             async with session.post(
-                f"{OLLAMA_URL}/api/generate",
+                f"{OLLAMA_URL}/api/chat",
                 json={
                     "model": CREATIVE_MODEL,
-                    "prompt": (
-                        "You are the magic 8-ball. Give a short, creative, one-sentence prediction in response to the question. "
-                        "Your answer should feel like a fortune — mysterious, slightly cryptic, or funny. "
-                        "Do not repeat the question. Do not start with 'I'. One sentence only. Give only your prediction.\n\n"
-                        f"Question: {question}"
-                    ),
                     "stream": False,
+                    "messages": [
+                        {
+                            "role": "system",
+                            "content": (
+                                "You are a magic 8-ball. You respond to yes/no questions with short, witty 8-ball style answers. "
+                                "Your answer must clearly be a YES, NO, or UNCERTAIN/MAYBE type response — "
+                                "like 'Signs point to yes', 'Not a chance', 'Ask again when you're sober', "
+                                "'Absolutely not', 'Obviously yes', 'The universe says nope', 'Seems unlikely', 'Sure, why not'. "
+                                "Be funny and direct. 2-6 words max. Never be cryptic or mystical. Never give a fortune or prophecy. "
+                                "No first person. No questions back. Just the answer."
+                            ),
+                        },
+                        {"role": "user", "content": f"Question: {question}"},
+                    ],
                 },
             ) as response:
                 data = await response.json()
-                raw = _normalize_caps(data.get("response", "").strip())
+                raw = _normalize_caps(data.get("message", {}).get("content", "").strip())
                 if _is_valid_8ball_response(raw):
                     answer = raw
                     _answer_color = "#f59e0b"