A guest saw nothing until the next state push, which on most tables means
until its own turn came round: no board, no cards, no scoreboard. The
cause is a gap in who is listening. A guest's link is opened in the lobby
and read there; the table only subscribes to it once the host's start
message has been through a state change, a recomposition and a
LaunchedEffect. The host publishes the opening position immediately, into
a link whose table has not attached yet, and incoming is a SharedFlow with
replay = 0 — so that first push went to the lobby's collector and nowhere
else. Not a rare race but the normal order of events, which is why it
looked like a rule rather than a bug.
The guest now asks. A new Resync message is sent from inside
onSubscription, so the request cannot leave before the collector is
attached and the reply cannot arrive before there is anything to receive
it. The host answers one peer with that seat's redacted view. A request
that arrives before the deal needs no answer, since a peer that has asked
is listening and the opening publish will reach it.
Second reason a guest could not see its hand, on any table with more than
one guest: guests worked out their own seat by matching PlayerSlot.peerId,
which is the address the host's transport invented for the incoming link —
an IP on Wi-Fi, a MAC over Bluetooth. A guest has never seen that value,
so no guest ever matched it and every one fell through to "the first seat
held by somebody remote". With one guest that is right by luck; with two,
both claimed the same seat and the other drew a hand belonging to a seat
it was not sitting in, which redacted is no hand at all.
The host now records the id a guest introduced itself by, as
PlayerSlot.deviceId, kept separate from peerId because the two answer
different questions: peerId is how the host recognises a link, deviceId is
how a guest recognises itself. The lookup moved out of LobbyScreen into
seatForDevice, where it can be tested, and a dropped player stops claiming
its old seat.
Neither change needs a protocol bump. Resync is ignored by a host that
does not know it, deviceId is an unknown key to a guest that does not read
it, and the old fallback is kept for exactly that case.
Tests reproduce the real start-up order — host publishes, then the guest
subscribes a frame later — rather than the order that happens to work, and
cover a board, a dealt hand, and a guest that is on the clock at the deal.
Both regressions were confirmed to fail before the fix: the guest had no
state at all, and two guests both came back as seat 1.
216 JVM tests pass.
Claude
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