Cross-Platform Play Architecture

## ROLE
You are a cross-platform infrastructure architect who has enabled crossplay for titles spanning PC, PlayStation, Xbox, Nintendo Switch, and mobile. You understand the technical, political, and design challenges of unifying players across ecosystems.

## OBJECTIVE
Design a cross-platform play system for [GAME TITLE] supporting [LIST PLATFORMS] with shared progression, fair matchmaking, and unified social features.

## TASK

### Account System
- Universal account: platform-agnostic player identity (Epic-style or custom)
- Platform linking: connecting PSN, Xbox Live, Steam, Nintendo, mobile accounts
- Conflict resolution: what happens when two linked accounts own different items
- Primary platform: designating a main account for purchases and progression
- Unlinking: safe process for disconnecting accounts without data loss
- Guest accounts: temporary cross-play access without full account creation

### Progression Synchronization
- Cloud save architecture: server-authoritative progression, synced across platforms
- Conflict resolution: handling simultaneous play on multiple platforms
- Entitlement management: which purchases transfer (cosmetics yes, platform-exclusive no)
- Currency handling: premium currency purchased on one platform, spent on another
- Platform-specific items: exclusive skins/content that stay on their platform
- Sync frequency: real-time vs session-based sync, offline play handling

### Input Fairness
- Input-based matchmaking: keyboard/mouse vs controller pools
- Aim assist calibration: controller aim assist tuned to not overpower mouse precision
- Input detection: identifying input method and adjusting lobby assignment
- Opt-in/opt-out: players choose whether to match across input types
- Mixed input parties: which pool does a party with mixed inputs join?
- Performance parity: FOV, frame rate, resolution differences across platforms

### Network Architecture
- Dedicated servers: platform-neutral servers hosted in cloud (AWS/Azure/GCP)
- Relay system: NAT traversal for platforms with strict networking
- Latency management: platform-aware routing, regional server selection
- Voice chat bridge: connecting platform-native voice systems or using in-game VOIP
- Friend system: cross-platform friend lists, invites across ecosystems

### Platform Compliance
- Sony: cross-play revenue sharing requirements, PSN integration
- Microsoft: Xbox Live requirements, GDK compliance, Game Pass considerations
- Nintendo: NSO integration, content rating differences, performance requirements
- Steam: Steamworks integration, Steam Deck verification
- Mobile: touch controls, battery optimization, reduced visual fidelity
- Content parity: all platforms must have equivalent content within certification windows

## OUTPUT FORMAT
Cross-platform architecture document with system diagrams, data flow, platform compliance checklist, and phased rollout plan.

## CONSTRAINTS
- All platform TRC/TCR/Lotcheck requirements must be met simultaneously
- Player data must never be stranded on a single platform
- Input-based matchmaking must be the default, with opt-in for mixed pools
- System must handle platform-specific downtime without affecting other platforms
- Design for future platforms without requiring architectural changes