RealParticipant gains _sessionFinished TCS + MarkSessionFinished /
AwaitSessionFinishedAsync. PvP first-arriver's handler awaits the
signal instead of calling self.RunAsync (which the session does
internally on the same instance — double-call would race the WS read).
BattleSession.RunAsync branches on Type: Pvp uses WhenAny + synthesize
BattleFinish(Win) to survivor + WhenAll(drain); Scripted/Bot keep
Phase 1's WhenAll-everything semantics. Disconnect cascade now drives
end-of-battle when a WS drops without a graceful Retire.
ComputeFrames now reads (from as IHasHandshakePhase)?.Phase for the
four handshake arms (InitNetwork, InitBattle, Loaded, Swap) and the
TurnEnd gate, transitioning the participant's Phase instead of the
session's. RealParticipant implements IHasHandshakePhase via the new
Phase property; the session-level BattleSession.Phase stays for the
Terminal short-circuit.
Scripted dispatch + wire shape unchanged (single-Real-participant case
collapses to Phase 1 semantics). Test fixture migrates FakeParticipant
to FakeRealParticipant for the side that drives handshake states. The
bot's TurnEnd previously rode the session-level AfterReady arm; with
that arm now gated on the sender's per-participant Phase (which the
bot lacks), TurnEnd joins TurnStart/Judge in the scripted-bot
forwarder arm so the v1.2 burst still reaches the real participant.
Internal setter; defaults to AwaitingInitNetwork. PvP needs A and B to
progress through the handshake states independently, which the
session-level BattleSession.Phase can't model. Session migration to read
realFrom.Phase is the next task.
Lifts the WS read loop, SIO encode/decode, per-WS OutboundSequencer +
InboundTracker, and SIO ack out of BattleSession into a participant.
PushAsync(noStock=false) assigns playSeq via the sequencer; noStock=true
bypasses it. FrameEmitted fires on each deduplicated inbound envelope.
The existing BattleSession keeps its own copy of the WS code for now;
Task 9 cuts the handler over to use BattleSessionV2 + RealParticipant
and Task 10 deletes the old BattleSession + duplicate code.
