Enum Session 

pub enum Session {
    Fetcher(Fetcher),
    FetcherSession(FetcherSession),
}

A session backend that can be either a stateless fetcher or a stateful session.

The distinction matters for cookie handling: a Fetcher starts fresh on every request, while a FetcherSession preserves cookies, headers, and other state between requests. Choose the variant that matches your crawling needs.

Variants

Fetcher(Fetcher)

A stateless HTTP fetcher. Each request is independent – no cookies or headers carry over. This is the simplest option and works well for public pages that do not require authentication.

FetcherSession(FetcherSession)

A stateful HTTP session that persists cookies, headers, and other connection-level state across requests. Use this when you need to log in, maintain a CSRF token, or interact with session-dependent APIs.