Design a rare-book lending and returns system

Design a system to manage borrowing and returning rare books across multiple library branches. Specify functional requirements (catalog search, reservations, waitlists, appointment-based access, in-library-only restrictions, identity verification, staff overrides, condition inspection with photos, chain-of-custody and audit logs, fines for late/damaged/lost items, incident reports, RFID/barcode check-in/out, inventory reconciliation). Define APIs (e.g., create user, place/modify/cancel hold, check out, check in, report damage/loss, schedule appointment), data model (users, items/copies, holdings, policies, transactions, audits), and consistency/transaction guarantees to prevent double-booking limited copies. Propose an architecture (services, databases, caches, queues, search index) with strong authorization, encryption, and tamper-evident audit trails. Address scale assumptions, read/write QPS, hot titles, concurrency control, idempotency, failure handling, background jobs, notifications, and SLA/RTO/RPO. Discuss monitoring, alerting, cost trade-offs, and how you would extend the design for inter-library loans and offline operations.