wyr: fix JSON parsing failure causing silent no-op after 'Generating...'

Switch to api/chat with a system prompt for better JSON compliance,
and use regex extraction to find the JSON object even if the model
wraps it in extra text or markdown fences.

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

matrixbot/commands.py

@@ -1542,23 +1542,35 @@ async def check_scramble_answer(client: AsyncClient, room_id: str, sender: str,
 # ---------------------------------------------------------------------------
 
 async def _generate_wyr() -> dict | None:
-    prompt = (
-        "Generate a fun 'Would You Rather' question with exactly two options. "
-        "Respond with ONLY valid JSON, no markdown: "
-        '{"question": "Would you rather...", "option_a": "...", "option_b": "..."}. '
-        "Keep each option short (under 10 words). Make it fun and interesting."
+    system_msg = (
+        "You are a game host generating Would You Rather questions. "
+        "Always respond with ONLY a JSON object — no markdown fences, no explanation. "
+        'Format: {"question": "Would you rather...", "option_a": "short option", "option_b": "short option"}'
     )
+    user_msg = "Generate a fun, creative Would You Rather question. Keep each option under 10 words."
     try:
         timeout = aiohttp.ClientTimeout(total=20)
         async with aiohttp.ClientSession(timeout=timeout) as session:
             async with session.post(
-                f"{OLLAMA_URL}/api/generate",
-                json={"model": ASK_MODEL, "prompt": prompt, "stream": False},
+                f"{OLLAMA_URL}/api/chat",
+                json={
+                    "model": ASK_MODEL,
+                    "stream": False,
+                    "messages": [
+                        {"role": "system", "content": system_msg},
+                        {"role": "user", "content": user_msg},
+                    ],
+                },
             ) as response:
                 data = await response.json()
-                text = data.get("response", "").strip()
+                text = data.get("message", {}).get("content", "").strip()
+                # Strip markdown fences if present
                 if "```" in text:
-                    text = text.split("```")[1].lstrip("json").strip()
+                    text = re.sub(r"```[a-z]*\n?", "", text).strip()
+                # Extract the first JSON object found in the response
+                m = re.search(r"\{[^{}]+\}", text, re.DOTALL)
+                if m:
+                    text = m.group(0)
                 parsed = json.loads(text)
                 q = parsed.get("question", "").strip()
                 a = parsed.get("option_a", "").strip()