Portfolio
Work you can read, not just read about
The strongest portfolio is running code. This platform is the flagship piece — every tool is production TypeScript demonstrating a named enterprise pattern, live and open for inspection. Each case study below links straight to the write-up, the tool, and the article.
stop.procrastin.ar — six-tool productivity SaaS
flagshipSole architect and engineer
A live, production SaaS: six archetype-backed productivity tools behind one account, a premium tier gated by entitlements, and billing modeled as an append-only ledger. Built as a layered DDD monolith where the dependency rule is enforced by a fitness function that fails the build — every page on this site is a working demo you can inspect.
Party (accounts & roles)Product/Catalog (plans & entitlements)Order & Accounting (subscription ledger)Rules, State-machine, Event-sourcingStack
Next.js 15 · React 19 · Fastify 5 · TypeScript · PostgreSQL 16 · Tailwind 4
Focus timer as a server-side state machine
Domain modeling & implementation
A focus session modeled as a finite state machine on the server: explicit states, named transitions, illegal moves refused at the domain layer, and "one active session per user" enforced by a partial unique index — so the timer survives reloads and device switches instead of living in a browser tab.
State machineGraph / state transitionsStack
Fastify 5 · PostgreSQL 16 · TypeScript
Budgets as an append-only accounting ledger
Domain modeling & implementation
A budget tracker where no balance is ever stored: envelopes are accounts, expenses are immutable entries, totals are derived by summing the ledger, and corrections are reversal entries rather than deletes — the same archetype that backs real billing, wallets, and inventory.
AccountingEvent sourcingStack
Fastify 5 · PostgreSQL 16 · TypeScript
Want this kind of modeling on your system?
The patterns here — state machines, accounting ledgers, event sourcing, enforced boundaries — are exactly what I bring to client work. Let’s talk about yours.
vteh.extratechsolutions.com