Backend and systems engineering. I'm most interested in the part of a system where correctness is provable — invariants, concurrency, data integrity — and in putting the rules somewhere they cannot be bypassed rather than somewhere they are merely followed.
Master of IT, La Trobe University Melbourne.
obol-ledger · TypeScript, Postgres, Next.js — live
A double-entry accounting ledger built around the idea that an invariant belongs in the database, not in application code that has to remember it.
- Entries are balanced by a
DEFERRABLE INITIALLY DEFERREDconstraint trigger that runs atCOMMIT— an immediate one fires after the first posting, when no entry has ever balanced. - Tenant isolation is row-level security with
FORCE, so a connection that has not named a tenant sees an empty database. A runtime probe asserts the policies are actually in force, because aSUPERUSERconnection bypasses them silently. - Money is
bigintminor units with a currency-exponent registry — JPY has zero decimals, BHD has three — and crosses the wire as exact decimal strings, never JSON numbers. - Idempotency claims its key before doing work, inside the same transaction, so a concurrent duplicate blocks rather than races.
- Concurrency claims are tested against a real Postgres over real connections,
and each test was verified by deleting the thing it protects: remove the lock
ordering and Postgres reports
40P01 deadlock detected.
system-design-playground · Python
System design from fundamentals through to LLM-backed systems. Free and open.
Multi-store inventory redistribution modelled as a minimum-cost flow problem — an optimisation formulation rather than a heuristic.
kelp-dao-hack-analysis · rollbit-scam-report
Incident forensics: the KelpDAO rsETH / LayerZero DVN / Aave interaction, and an investigation into Rollbit Casino. Reading systems adversarially, for what they do rather than what they claim.
everything-data-structures · llm-engineering-playground · frontier-llm-engineering
Teaching material. Writing something down is how I find out whether I actually understand it.