Backend systems engineer building from first principles: state, invariants, transactions, idempotence, correctness.
Inventory System v2 — Django + SQLite
Building a backend system focused on correctness before complexity.
transport → service → model → database
S = Map[id → item]
item = { id, name, qty }
S' = f(S, input)
Daily system-building notes and lessons learned.
filter(id=item_id).delete()
inside transaction.atomic().
Fixed state bug caused by incorrect filtering.
PATCH /items/<uuid>/qty.
Used guarded database update with
qty__gte=-delta and
F("qty") + delta
to ensure invariant preservation and
correctness under concurrency.
I focus on backend systems engineering: correctness, invariants, and designing around state.
Father of four. Engineering student. Building one feature per day and documenting the process.