fix: request no reasoning for liveness and handle empty text

app/probe.py

@@ -37,6 +37,7 @@ def check_model(model_id: str) -> tuple[bool, int | None, str | None, dict]:
             "model": model_id,
             "messages": [{"role": "user", "content": "2+2=?"}],
             "max_tokens": 5,
+            "reasoning_effort": "none",
         }).encode()
         req = urllib.request.Request(
             f"{OMNIROUTE_URL}/v1/chat/completions",
@@ -50,8 +51,13 @@ def check_model(model_id: str) -> tuple[bool, int | None, str | None, dict]:
             resp = json.loads(r.read())
             # Usage — до любой валидации контента.
             usage = extract_usage(resp)
-            content = resp["choices"][0]["message"]["content"]
-            ok = bool(content.strip())
+            # HTTP 200 может содержать только reasoning и content=null.
+            # Это не успешный текстовый ответ и не ошибка Python.
+            choice = resp["choices"][0]
+            content = choice["message"].get("content")
+            ok = isinstance(content, str) and bool(content.strip())
+            if not ok:
+                error = f"Empty text response (finish_reason={choice.get('finish_reason')})"
     except Exception as e:
         error = f"{type(e).__name__}: {e}"
         print(f"  ✗ {model_id}: {error}", file=sys.stderr)