CosmicClash/multiplayer-next.md

# Multiplayer — next work

Short, current checklist for online multiplayer. Historical decisions,
implementation evidence and task-level acceptance criteria stay in
[`multiplayer-todo.md`](multiplayer-todo.md). Phase 8 architecture and locked
product policy are in [`docs/MATCHMAKING.md`](docs/MATCHMAKING.md).

## Existing release blockers

- [ ] **Phase 4 playtest:** play at roughly 100 ms RTT; confirm ship/ball
  interaction feels local and contact corrections read as bumps, not glitches.
- [ ] **Phase 5 session:** finish a real 3v3 match with a mid-match disconnect
  and late joiner.
- [ ] **Phase 6 external check:** play the exported Docker server from separate
  internet machines. Keep the check controlled until verified identity lands.

## Phase 7 — production Steam prerequisite

- [ ] Obtain the pinned GodotSteam client/server builds and Steamworks SDK;
  pass `make verify-steam-templates` without weakening ENet verification.
- [ ] Validate two real accounts through the explicit Steam transport and
  build Internet/LAN/favourites/history server-browser views.
- [ ] Add single-use auth tickets, asynchronous server validation, verified
  Steam identity, identity-keyed reconnect and persistent bans.
- [ ] Obtain the real App ID, publisher key, coordinator SDK/signing approval,
  certificates and Hosted Dedicated Server data-centre support from Valve.
- [ ] Implement ticketed Hosted Dedicated Server SDR routing, ticket install,
  reconnect and expiry. Preserve direct ENet for local/CI/community servers.

## Phase 8 — architecture, contracts and durable data

- [x] Lock the Go/PostgreSQL/Redis, Kubernetes/Agones, SDR, EU/NA and
  provider-portability ADR ([ADR-001](docs/ADR-001-matchmaking-platform.md));
  measurable launch SLOs are defined in
  [MATCHMAKING-SLOs.md](docs/MATCHMAKING-SLOs.md).
- [ ] Publish versioned OpenAPI/WebSocket contracts, stable IDs, legal state
  transitions, revisions and idempotency semantics.
- [ ] Add PostgreSQL queue ownership/active-participation fences, durable
  domain migrations/outbox and Redis indexes/TTLs; lost Redis writes must not
  split a proposal or corrupt durable state.
- [ ] Define assignment compatibility and opt-in `ServerConfig` flags whose
  defaults reproduce the community-server path.

## Phase 8 — identity and security

- [ ] Validate Steam Web API tickets only in the secure backend; issue
  revocable sessions and reconnect-safe match/identity/slot authorisations
  with server-owned connection-generation fencing.
- [ ] Authenticate results with pod/GameServer-bound workload identity; make
  identical duplicates idempotent and conflicting results inert/alerting.
- [ ] Complete the threat model for forgery, replay, queue/flood/bot abuse,
  workload/insider compromise, DDoS, supply chain and denial-of-wallet.
- [ ] Enforce restricted workloads/RBAC/networks/private stores/backups/secrets;
  isolate SDR signing behind an audited non-exportable signer and add
  volumetric edge defense, WebSocket limits and overload shedding.
- [ ] Pin, scan, SBOM and sign artifacts; verify signatures at admission and
  document the critical vulnerability SLA.

## Phase 8 — queues, playlists and rating

- [ ] Add one PostgreSQL-owned queue ticket/player with 10 s heartbeat, 30 s
  expiry, Redis candidate cache and restart/failover repair.
- [ ] Validate opaque Steam ping locations and nonce-bound probes server-side;
  require <=100 ms, enforce discrepancy quarantine and the locked widening/
  region/team tie-break rules.
- [ ] Send 10 s proposals to every selected human: ranked six, relaxed casual
  two to six with disclosed bots; enforce exact cooldown and queue-precedence
  behavior.
- [ ] Fence proposals/participants in a PostgreSQL serializable transaction;
  prove loss of an acknowledged Redis write cannot split players.
- [ ] Casual: target 3v3 humans, after 60 s allow >=2 humans (one/team) plus
  bots, kickoff-only human backfill and no backfill loss/decline penalty.
- [ ] Ranked: exactly six humans, solo-only, no bots/backfill, random-enabled
  non-elevated arenas only, 60 s reconnect grace and escalating abandons.
- [ ] Implement the documented exact Glicko-2 equations, fractional 3v3
  weights, inactivity/update locking/golden vectors and ten provisional games.
- [ ] Add ranked-only exactly-once 12-week soft seasons; distinguish retryable
  result-delivery outages from match-integrity failures and rating exemptions.

## Phase 8 — Agones and regional server capacity

- [ ] Add portable EU/NA Agones Fleets with provider edge/network/secret and
  Valve-approved SDR POP/certificate/public-UDP overlays.
- [ ] Add the local-safe Agones adapter and separate process-ready (listen then
  Ready) from assignment-ready (Allocated manifest verified and registered).
- [ ] Allocate from Ready by region/build/protocol/transport; use separately
  verified ENet and SDR dynamic/passthrough port mappings.
- [ ] Deliver/verify the signed roster after allocation and expose client
  tickets only after backend `assignment_ready`.
- [ ] Keep >=2 Ready processes across >=2 on-demand nodes/failure domains per
  queue-enabled region; only Allocated count may fall to zero.
- [ ] Spread on-demand capacity across zones with N+1 headroom; do not place
  live matches on interruptible nodes.
- [ ] Benchmark native x86_64 boot, p99 CPU/RSS/network and tick health; set
  requests/limits and node density from measurements plus 30% headroom.
- [ ] Add 30 s no-show handling, Go PID-1 TERM/drain supervision, PDB/Fleet
  drain, signed result annotation/retry, RPO <=5 m and RTO <=30 m.
- [ ] Rehearse migration only after the second provider's EU/NA locations have
  Valve approval, POP/certs, public UDP/firewall and coordinator trust.

## Phase 8 — client and recovery

- [ ] Build queue/proposal/allocation/connect/rating UI with explicit latency,
  capacity, expiry and recovery states.
- [ ] Use one authenticated revisioned WebSocket plus REST resync; resume a
  valid ticket/assignment after restart rather than duplicating it.
- [ ] After assignment-ready, install SDR ticket and send reconnect-safe join
  authorisation in `hello`; fence old connections and retain ENet behavior.
- [ ] Display only backend-authoritative provisional rank/tier/delta, abandon
  status and season time; clients perform no rating calculation.

## Phase 8 — operations and release gates

- [ ] Correlate queue→result with IDs and add dashboards/alerts for SLOs,
  security, failures and cost without logging credentials.
- [ ] Add Go race/fuzz/property/migration/concurrency coverage plus fake Steam
  and fake allocation for offline deterministic CI.
- [ ] Add an independent allocated-server Compose flow; do not mutate
  `compose.phase6-smoke.yml` or weaken either existing Make gate.
- [ ] Add disposable `kind`/Agones integration, 100 ms network/chaos cases and
  proof that infrastructure failures cannot punish players.
- [ ] Load-test >=10,000 queued clients, >=100 proposals/s and forecast launch
  concurrency x2 while holding API p95 <=250 ms and allocation correctness.
- [ ] Record cost per completed match, budget/denial-of-wallet controls and
  deploy progressively: internal → casual canary → casual → provisional
  ranked → ranked, with EU/NA playtests and rollback gates.

## Known issues before public hosting

- [ ] Replace display-name slot reclaim with verified Steam identity.
- [ ] Investigate occasional transport input loss during a long server stall.
- [x] Fix the remaining `_broadcast_snapshot` packet-send stderr race.

## Decide after the latency playtest

- [ ] Decide whether client-only contact-cohort shadow physics is worthwhile.

## Explicitly deferred

Parties/premades, tournaments, ranked spectators, non-Steam identity,
additional global regions, global leaderboards, 120 Hz simulation,
latency-gap measurement, audio hooks and split-screen are not in the launch
path.