The new Forward(Host(...), Guest(...)) type replaces the former one-way PortForward API.
A forward sourced from the host continues to publish a guest port on the host. A forward sourced from the guest instead makes a host service available inside the guest, at a guest-facing address that defaults to 10.0.2.101. The release describes intended host services as proxies, databases, and API servers.
Guest-to-host forwarding uses QEMU guestfwd with a relay process per connection, intended to prevent concurrent connections from interleaving. Endpoint inputs can be a port, an address plus port, or an address:port string. Validation now rejects duplicate host binds, duplicate guest sources, forwarding with guest networking disabled, and collisions with the built-in SMB tunnel address.
PortForward(host, guest) remains available but now returns a Forward and emits a deprecation warning. The release also limits kernel-irqchip=off for WHPX to x86_64 hosts. The source does not establish performance, security properties, or production adoption of the new forwarding path.