SessionPool and ProxyConfiguration are concrete classes, so a custom implementation cannot be substituted the way a Statistics instance or a storage client can. Extract protocols for both, plus the minimal Session surface they need, matching the ISessionPool / IProxyConfiguration interfaces in JS. Related: #1744 does the same for the browser pool.

JS implementation: apify/crawlee#3644, apify/crawlee#3892

✍️ Drafted by Claude Code