Architecture
Design patterns for data platforms, high availability, financial systems and AI infrastructure. Each is grounded in the components that implement it, with the failure modes and the obligations that attach.
Architectures
Each states the problem, the forces, the components, how it fails, and when not to use it.
Patroni, etcd, HAProxy and keepalived assembled into one topology - who decides, who routes, who owns the address, and the failover timeline.
Routing reads to replicas without breaking read-after-write - where to split, the LSN token that makes it safe, and what replication lag costs you.
Retrieval topology beyond the demo - index freshness, authorisation applied before retrieval rather than after, and the corpus as a supply chain.
A worked reference design for turning operational data - logs, metrics, alerts, tickets - into narrative reports with retrieval-augmented generation, grounded in published research rather than a specific product.
Double-entry accounting as a database schema - append-only entries, idempotency keys for retried payments, derived balances, and daily reconciliation.
AML and sanctions architecture where false-positive economics dominate - alert generation, triage, tuning as a governed change, and the audit trail.