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. Phase 8 architecture and locked product policy are in 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

• Lock the Go/PostgreSQL/Redis, Kubernetes/Agones, SDR, EU/NA and provider-portability ADR (ADR-001); measurable launch SLOs are defined in 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.
• 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.