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Distributed Backend Systems • 2026The Vision & Architecture
Money that can never be
silently lost or double-spent.
Solidius (LedgerCore) is a high-throughput, production-grade ledger and wallet engine built on immutable double-entry accounting. Balances are derived strictly from INSERT-only journal entries, transfers acquire row locks in deterministic order to eliminate deadlocks under concurrency, and mutating endpoints are protected with cryptographic distributed idempotency.
Core Capabilities
Immutable Double-Entry Core
Balances are never updated in place. Every monetary movement writes paired debit and credit entries, enforcing sum(debits) == sum(credits) per currency in the same atomic transaction.
Deadlock-Free Concurrency
Transfers sort target account rows by UUID before SELECT ... FOR UPDATE, guaranteeing all concurrent workers acquire locks in identical order to eliminate deadlock cycles.
Distributed Idempotency
Every write requires an idempotency key bound to a SHA-256 fingerprint of the request payload, safely returning cached responses on retry and rejecting mismatched duplicates.
Transactional Outbox & Signed Webhooks
Domain events commit atomically with ledger writes and are dispatched by FOR UPDATE SKIP LOCKED background workers with HMAC-SHA256 signatures and 5-minute replay windows.
Continuous Reconciliation Auditing
A scheduled worker runs 6 mathematical invariant checks across the ledger and records findings by severity to guarantee long-term data integrity.
Technology Stack
Architectural Decisions
Pessimistic locks over optimistic retries
Transfers are short, contended, and must not fail spuriously. Sorted SELECT ... FOR UPDATE gives a bounded wait under load instead of a retry storm that degrades as traffic grows.
Derived balances over mutable totals
A mutable balance column is faster to read and impossible to audit. Projecting balances from entries keeps the journal as the single source of truth.