Critical fixes:
- Enable auto-scaling (was disabled in config)
- Add periodic cache eviction (5m interval) — CacheEvictionManager never ran
- Add periodic rebalance check (30s) — proactive load balancing
- Add 5s timeout to all gRPC calls (batchResubscribe, unsubscribe, evict)
- Use Option instead of null checks (scalafix compliance)
These gaps left the coordinator unable to:
1. Scale up when instances overloaded (scaling was disabled)
2. Clean up idle games from memory (no scheduled eviction)
3. Rebalance load proactively (only on scale-up)
4. Handle hung instances (no RPC timeouts, operations could hang forever)
Combined with prior fixes for instance metadata parsing and heartbeat TTL,
the coordinator now handles overload scenarios correctly.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Janis