Risks and Technical Debts

Risk / debt	Impact	Mitigation
Vendor MQTT broker outage	No unlock or return events	Contractual SLO; local dock queue if the vendor supports it; status page for riders
Redis as a hot path	Unlock latency and map freshness depend on it	Fallback to PostgreSQL; multi-AZ Redis; alert on hit-rate drop
Single API deployable	A bad release hits unlock and billing together	Small release train, fast rollback, feature flags for new paths
Electric-bike battery data volume	Could bloat the trip database	Addressed by ADR 0003