Four-peer rollback desynced under load (R4, host behind): the guests
predicted the slow host's pad, hash-confirmed the tick among themselves
through the one shared peer ring, then promoted the host's real pad into
history only (hc-silent promote) while the host simulated it. The host
stayed forked; its recovery episode was then refused as a "zombie load"
behind the guests' (wrongly) agreed tip.
- Hash confirm is a quorum over every occupied peer seat
(rnet_hc_set_peer_mask / note_peer_from, recomp-net) for three or more
seats; two seats keep the one-peer chain.
- A peer more than 4 ticks behind the others' inputs sheds its own view
(psx_mod_render_local_view status FAST_FORWARD, held 60 ticks), so the
presentation-only pass goes before the simulation slips.
PSX_NET_LOCAL_VIEW_SHED=0 keeps it.
- The admit-stall watchdog counts time without progress: a remote input tip
that advances restarts it, so a slow peer is waited for.
PSX_NET_ADMIT_STALL_MS (20000) and PSX_NET_LIVENESS_MS (1500) configure it.
- Pins recomp-net fix/rollback-span-stall.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A title whose netplay mode draws every seat's view into one frame (so all
peers keep identical guest state) can now ask the present path to show only
this peer's rectangle of the display: psx_netplay_present_local_view(x, y,
w, h), usually picked from psx_netplay_local_slot(). The GL dual-raster
present shows it from the internal-resolution surface, the software present
crops its staged frame, both at 4:3, and the headless present-image ring
records the same rectangle. The request is host-only (never serialized or
guest-visible), lapses PSX_NETPLAY_LOCAL_VIEW_HOLD ticks after its last
renewal so menus fall back to the full frame, survives rollback replays
without moving its stamp backwards, and is ignored offline. It wins over
[netplay] local_viewport.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Shokunin