https://spec.torproject.org/proposals/354-relaxed-restrictions.html

This is a proposal to simplify the usage of Family, Subnet, and custom path restrictions in Arti, so that clients don't reveal information about their Guards or Bridges by way of which relays they use, or don't use, in circuits.

The meat of the proposal is that Arti's circuit path construction will satisfy the following rules:

1. Choose the Exit, HSDir, IP, or RP without considering restrictions 2. Choose Guard, Bridge, and Vanguards hops without considering restrictions 3. Choose any remaining middle nodes such that subnet, relay family, and user family restrictions apply with respect to the next hop (Exit, HSDir, IP, or RP) 4. Reject any resulting circuits with A-A and A-B-A sub-paths 5. If building a conflux leg: Reject any circuits that share relays with the other conflux leg(s) in the current conflux set.

This simplifies path construction logic and avoids many pitfalls and information leaks caused by restriction use. These pitfalls and information leaks are documented in the proposal.

The spec ticket in gitlab will remain open for comment until April 2, 2025: https://gitlab.torproject.org/tpo/core/torspec/-/issues/307

Comment here is also acceptable.