riddle/wyr: fix repeat shadow answers and truncate long WYR options

riddle:
- Cache answers separately so the same answer (e.g. 'shadow') can't
  appear twice in a session even if the riddle text differs
- Explicitly ban 'shadow' in the prompt and append avoid-answers clause
- Ban question endings ('what am I?', 'what could it be?') more strictly

wyr:
- Hard-cap options at 10 words server-side so the model can't ignore
  the word limit and generate paragraph-length options

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

matrixbot/commands.py

@@ -1685,8 +1685,10 @@ async def _generate_wyr() -> dict | None:
                 parsed = json.loads(text)
                 a = parsed.get("option_a", "").strip()
                 b = parsed.get("option_b", "").strip()
-                # Rebuild question from options so it's always well-formed
+                # Hard cap: truncate options that are too long
                 if a and b:
+                    a = " ".join(a.split()[:10])
+                    b = " ".join(b.split()[:10])
                     q = f"Would you rather {a.rstrip('.')} OR {b.rstrip('.')}?"
                     return {"question": q, "option_a": a, "option_b": b}
     except Exception as e:
@@ -1770,16 +1772,22 @@ async def cmd_wyr(client: AsyncClient, room_id: str, sender: str, args: str):
 # ---------------------------------------------------------------------------
 
 _RIDDLE_ACTIVE: dict[str, dict] = {}
-_riddle_recent: list[str] = []
+_riddle_recent: list[str] = []       # past riddle texts
+_riddle_recent_answers: list[str] = []  # past answers (lowercase)
 _RIDDLE_RECENT_MAX = 30
 
 
 async def _generate_riddle() -> dict | None:
-    avoid_clause = (
+    avoid_riddles = (
-        " Do NOT use any of these riddles that were recently asked: "
+        " Do NOT reuse any of these recent riddles: "
-        + "; ".join(f'"{r}"' for r in _riddle_recent[-15:])
+        + "; ".join(f'"{r}"' for r in _riddle_recent[-10:])
         + "."
     ) if _riddle_recent else ""
+    avoid_answers = (
+        " Do NOT use any of these answers that were recently used: "
+        + ", ".join(f'"{a}"' for a in _riddle_recent_answers[-15:])
+        + "."
+    ) if _riddle_recent_answers else ""
     system_msg = (
         "You are a riddle generator. Always respond with ONLY a JSON object — no markdown fences, no explanation. "
         'Format: {"riddle": "the riddle text", "answer": "short answer"}\n'
@@ -1787,11 +1795,11 @@ async def _generate_riddle() -> dict | None:
         "- The answer must be a specific, unambiguous noun (1-3 words). Avoid abstract answers.\n"
         "- The riddle must describe the answer through metaphor or wordplay — NOT by literally describing it.\n"
         "- Do NOT include the answer word anywhere in the riddle text.\n"
-        "- Do NOT end the riddle with 'what am I?' or 'what could it possibly mean?' — the riddle should stand alone.\n"
+        "- Do NOT end with 'what am I?', 'what could it be?', or any question — the riddle should stand alone as a statement.\n"
-        "- The clues must logically point to ONE specific answer. Test it: would most people agree this answer is correct?\n"
+        "- The clues must logically point to ONE specific answer that most people would agree on.\n"
-        "- Avoid riddles about riddles, shadows, or abstract concepts. Prefer concrete things: candle, mirror, clock, river, echo, stamp, etc."
+        "- Avoid 'shadow' as an answer. Prefer concrete things: candle, mirror, clock, river, echo, stamp, key, glove, envelope, etc."
     )
-    user_msg = f"Generate a clever, original riddle with a clear unambiguous answer.{avoid_clause}"
+    user_msg = f"Generate a clever, original riddle with a clear unambiguous answer.{avoid_answers}{avoid_riddles}"
     try:
         timeout = aiohttp.ClientTimeout(total=60)
         async with aiohttp.ClientSession(timeout=timeout) as session:
@@ -1820,6 +1828,9 @@ async def _generate_riddle() -> dict | None:
                     _riddle_recent.append(riddle)
                     if len(_riddle_recent) > _RIDDLE_RECENT_MAX:
                         _riddle_recent.pop(0)
+                    _riddle_recent_answers.append(answer.lower())
+                    if len(_riddle_recent_answers) > _RIDDLE_RECENT_MAX:
+                        _riddle_recent_answers.pop(0)
                     return {"riddle": riddle, "answer": answer}
     except Exception as e:
         logger.error(f"riddle generation error: {e}", exc_info=True)