Server Communication
App-server protocols — handshake sync, course and subscription IAP, AI credits, and event logging
Handshake & Sync
Content sync protocol — speed test, checksum payload, server manifest, progressive download orchestration
Course Purchase
One-time consumable course IAP — product IDs, deferred acknowledgment, platform-specific receipt handling
Subscriptions
Monthly subscription IAP — Android multi-plan with upgrade/downgrade, iOS single plan, free trial detection
AI Credits
Consumable AI credit purchases — same flow as course IAP, credits added to user bank
Event Logging
App-to-server log events — sync, billing, authentication, audio, AI chat, user reports