import uuid

SESSIONS = {}  # session_id -> {thread_id, recent_turns, entity_memory}


def start_session(thread_id: str) -> str:
    """Create a new session fixed to a given thread."""
    sid = str(uuid.uuid4())
    SESSIONS[sid] = {
        "thread_id": thread_id,
        "recent_turns": [],
        "entity_memory": {},  # extend later if needed
    }
    return sid


def get_session(session_id: str):
    return SESSIONS.get(session_id)


def reset_session(session_id: str):
    """Reset memory but keep the same thread."""
    if session_id in SESSIONS:
        tid = SESSIONS[session_id]["thread_id"]
        SESSIONS[session_id] = {
            "thread_id": tid,
            "recent_turns": [],
            "entity_memory": {},
        }