5. 人を助けるAI

def pick_code_certain_move(
    board: list[list[int]],
) -> tuple[int, int, int, str] | None:
    """우선순위: last-empty → digit 유일 → human solver → 탐색 강제수."""
    lasts = last_empty_unit_moves(board)
    if lasts:
        return lasts[0]

    for digit in range(1, 10):
        illegal = set(illegal_cells_for_digit(board, digit))
        moves = absolute_placements(board, illegal, digit)
        if moves:
            r, c, v, reason = moves[0]
            return r, c, v, f"code_digit{digit}_{reason}"

    from sudoku_human_solver import find_human_move

    hm = find_human_move(board)
    if hm is not None:
        return hm.row, hm.col, hm.value, f"human_{hm.kind.value}"

    # 극한: 국소 후보는 여러 개인데, 하나만 해가 남는 칸 (예: 2행 끝 7)
    return pick_search_forced_move(board)

MOVE_RE = re.compile(
    r"(한\s*수|다음\s*수|힌트|추천|어디|둬|놓|채워|풀어|solve|hint|move|next)",
    re.I,
)

# ...

def handle_chat(body: dict[str, Any]) -> dict[str, Any]:
    message = str(body.get("message") or "").strip()
    if not message:
        return {"error": "empty message"}

    model_id = str(body.get("modelId") or "lora_move")
    meta = TRAINED_MODELS.get(model_id, TRAINED_MODELS["lora_move"])
    board = body.get("board")
    puzzle = body.get("puzzle")
    difficulty = body.get("difficulty") or "medium"

    if not isinstance(board, list) or len(board) != 9:
        return {"error": "board required"}

    blanks = _empty_count(board)
    intent = classify_intent(message)

    llm_text = chat_llm_reply(
        message,
        {
            "model_label": meta["label"],
            "blanks": blanks,
            "difficulty": difficulty,
        },
    )

    if llm_text:
        if "CMD:MOVE" in llm_text.upper() or intent == "move":
            intent = "move"
        reply_base = re.sub(r"CMD:\w+", "", llm_text, flags=re.I).strip()
    else:
        reply_base = ""

    if intent == "move" or (intent == "unknown" and MOVE_RE.search(message)):
        result = call_trained_vlm(board, puzzle if isinstance(puzzle, list) else None, model_id)
        if not result.get("ok"):
            return {
                "reply": (
                    f"{meta['label']} 호출 실패: {result.get('error')}\n"
                    f"(채팅 AI → 학습 모델 명령 전달)"
                ),
                "action": None,
                "vlm": result,
            }
        r, c, v = result["row"], result["col"], result["value"]
        spoken = reply_base or (
            f"{meta['label']}에 「한 수」 명령을 전달했습니다."
        )
        return {
            "reply": f"{spoken}\n→ ({r},{c}) = {v}",
            "action": {"type": "place", "row": r, "col": c, "value": v},
            "vlm": result,
        }