The game joins `friend:CODE` with either code: a full invite is dialled
directly, then through the relay it names; a short code goes through the
relay the player set. Join a friend gains a Relay (optional) field, saved
to horizon.txt (friendsRelay) and used for hosting too; the code field
shows the end of long codes and says what is wrong with one (typo, other
version, short code without a relay). The launcher validates both kinds.
tools/test_friends.py now runs (a) the code alone with no relay anywhere
and (b) a relay run locally with the short code; routers and STUN stay
out of tests.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The game joins `friend:CODE` addresses: the network thread resolves the code
through the relay, agrees on the key, settles on a direct or relayed stream
and connects the client to the tunnel's loopback port; everything after is
an ordinary join. Errors (unknown or ended code, wrong secret, host not
answering, version mismatch, rate limits) end on the Disconnected screen in
plain words. Shown and logged addresses hide the code's secret half.
Horizon's multiplayer page gains "Join a friend" (a code field); the classic
screens keep vanilla's buttons. The launcher's Play page gains a "Join a
friend" row (paste works) that starts the game straight into the join;
`horizon-launcher play --join CODE` does the same.
tools/test_friends.py runs a relay, a host Horizon sharing a world and a
guest Horizon, over plain LAN (--baseline), the direct path and the forced
relay path: chat, movement and blocks both ways, then the ended invite.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Ludovic Marie