Essays and Architecture Decision Records on distributed systems, event-driven backends, and Build Market.https://donshammah.tech/https://donshammah.tech/writing/non-custodial-escrow-on-mpesa/https://donshammah.tech/writing/non-custodial-escrow-on-mpesa/How we combined bank trust accounts, composite idempotency anchors, and automated WHT/eTIMS waterfalls to protect construction capital in Kenya.Tue, 20 Oct 2026 00:00:00 GMThttps://donshammah.tech/writing/designing-around-flaky-regulator-portals/https://donshammah.tech/writing/designing-around-flaky-regulator-portals/How Build Market verifies contractor licenses against 9 Kenyan statutory boards without ever blocking user onboarding when government portals go down.Sun, 18 Oct 2026 00:00:00 GMThttps://donshammah.tech/writing/why-we-ack-only-after-commit/https://donshammah.tech/writing/why-we-ack-only-after-commit/How ordering your broker ack() after your PostgreSQL commit—and designing every handler as an idempotent upsert—eliminates silent data loss and double-payouts.Thu, 15 Oct 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-001-clerk-identity-db-authority/https://donshammah.tech/decisions/adr-001-clerk-identity-db-authority/Session tokens establish who the actor is; PostgreSQL profile records establish what the actor is permitted to do.Sun, 18 Jan 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-002-layer-boundaries/https://donshammah.tech/decisions/adr-002-layer-boundaries/HTTP route handlers and Server Actions are thin transport adapters that must never import Prisma directly.Sat, 24 Jan 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-003-vertical-domain-slicing/https://donshammah.tech/decisions/adr-003-vertical-domain-slicing/Organize domain logic into 24 isolated vertical slices communicating only via public service contracts or NATS events.Mon, 02 Feb 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-006-data-classification-replay/https://donshammah.tech/decisions/adr-006-data-classification-replay/Prevent Class A (Secrets) and Class B (Sensitive PII) fields from ever persisting in idempotency caches or structured logs.Thu, 19 Feb 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-010-worker-daemon-isolation/https://donshammah.tech/decisions/adr-010-worker-daemon-isolation/Offload NATS JetStream consumers, BullMQ queues, Sharp image encoding, and BoQ PDF compilation to a standalone Node.js 24 daemon.Thu, 05 Mar 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-admin-001-capability-auth/https://donshammah.tech/decisions/adr-admin-001-capability-auth/Why administrative mutations resolve permissions from a database AdminProfile on every request and require step-up re-authentication.Sat, 14 Mar 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-admin-008-declarative-audit-log/https://donshammah.tech/decisions/adr-admin-008-declarative-audit-log/Eliminate manual audit-log omission bugs by making audit metadata a required declarative property of high-risk action definitions.Thu, 02 Apr 2026 00:00:00 GMThttps://donshammah.tech/decisions/adr-admin-009-strangler-fig-flags/https://donshammah.tech/decisions/adr-admin-009-strangler-fig-flags/Migrate legacy administrative verticals behind typed feature flags enforced by automated CI expiration checks.Sun, 19 Apr 2026 00:00:00 GMT