Architecture Decisions Log (ADR)

Decision	Chosen Option	Alternative Considered	Deciding Factor
Ledger Design	Double-Entry Bookkeeping	Single-Balance Updates	Mathematical certainty and regulatory auditability.
Transaction Engine	MongoDB Multi-Doc ACID	Redis Mutexes	Native database transaction rollbacks without external distributed lock complexity.
Session Revocation	Token Blacklist Collection	Sticky Server Sessions	Preserves stateless REST architecture while enabling instant logout.