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Notes from the build.

Write-ups on what I build and debug: Next.js, React, Node.js, and the details in between.

FeaturedOct 9, 2026 · 4 min read

I Built It First. Here's How I Design It Now.

I built a construction ERP code-first and ran into slow dashboards, cache misses and lost updates. This is the design-first process I use now: requirements, trade-offs, decision records, and measuring before fixing.

architecture
system-design
nodejs
postgresql
react

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// postgresql
Money Is Not a Float: Exact Decimals with Postgres and Prisma
- postgresql
- prisma
- typescript
- finance
Money Is Not a Float: Exact Decimals with Postgres and Prisma
Storing money as NUMERIC is only half the job. If the maths runs on JavaScript numbers, the errors come back. Here's the small helper that keeps invoice totals exact, and the tests that prove it.
Oct 9, 2026 2 min
{}
// postgresql
Two Accountants, One Invoice: Fixing a Lost Update in Postgres
- postgresql
- prisma
- nodejs
- concurrency
Two Accountants, One Invoice: Fixing a Lost Update in Postgres
Two payments recorded against the same invoice at the same moment, and one of them silently disappears. Why it happens, and how a transaction plus SELECT … FOR UPDATE fixes it.
Oct 9, 2026 3 min
{}
// nodejs
Why a 304 Response Can Still Be Slow
- nodejs
- express
- performance
- postgresql
Why a 304 Response Can Still Be Slow
A 304 Not Modified saves bandwidth, not work. In Express the ETag is computed from the body your handler already built, so every query still runs. Here's how I found where the time actually went, and fixed it.
Oct 9, 2026 3 min
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// nextjs
No-Flash Dark Mode in Next.js
- nextjs
- react
- css
- webdev
No-Flash Dark Mode in Next.js
A theme toggle that never flashes the wrong colours on load, using one inline script, a data attribute, and useSyncExternalStore instead of a theme library.
Sep 25, 2026 2 min

Notes from the build.

I Built It First. Here's How I Design It Now.

Money Is Not a Float: Exact Decimals with Postgres and Prisma

Two Accountants, One Invoice: Fixing a Lost Update in Postgres

Why a 304 Response Can Still Be Slow

No-Flash Dark Mode in Next.js