Function list 

pub async fn list(
    memory: Option<&Arc<MemoryService>>,
    user_ctx: &UserContext,
    agent_id: Option<&str>,
    session_id: Option<&str>,
) -> Result<Vec<Memory>>

Memories visible to a user, optionally narrowed to an agent or session.

user_ctx is required, not optional: memories are per-user state, and a listing that ignored it would show one user’s memories to another.