Insights
Engineering notes and product thinking from the Calculosoft team.
Infrastructure
Our deploys used to depend on images built on the server and tagged latest. We moved every app to versioned images in a private registry, with one file that pins what runs. Here is the pipeline order that makes it safe, and a release-tag bug we hit along the way.
Read the noteBackend
Social Poster writes a post once and publishes it to Facebook, Instagram, LinkedIn and X at a scheduled time. The hard part is not the APIs. It is what happens when two networks succeed and one fails. Here is the design that handles it.
Read the noteFrontend
Argus streams server health over WebSockets into a React dashboard with gauges and charts. Three small bugs taught us the most: a LIVE badge that went stale while data was flowing, a chart that threw thousands of errors per second, and a gauge that rendered at zero width.
Read the noteTrading systems
In a backtest, ticks arrive once, in order. A live feed sends them late, twice, or with conflicting prices at the same timestamp, and sometimes stops altogether. Here is how our demo trading bot guards its strategy from all of that.
Read the noteTrading systems
An audit of our trading research platform found two quiet bugs. One labelled a consistently losing strategy as robust; the other filled stop-losses at prices that never traded. Here is how each one happened and the one-line rules that fixed them.
Read the noteDatabases
Adding PostgreSQL to our ops dashboard's database workbench meant building a small pg_dump of our own. The first version produced SQL that looked right and failed on replay. These are the five ways it broke and how we fixed each one.
Read the noteMobile
Our Quran app shows each Mushaf page exactly as it is printed, line for line. That takes one font per page, careful line-fitting math and a font cache that never deletes the page you are reading. Here is how it works in React Native.
Read the noteDatabases
The Uthmani text of the Quran is fully vowelled, but people search by typing plain Arabic. Here is how our Quran app matches the two in PostgreSQL, why full-text search was the wrong tool, and the invisible character that broke our CI.
Read the noteBackend
A personal finance app is only trustworthy if every total adds up to the last unit. These are the decisions we made for Expensio's money core, including the bug where a tiny loan rounded to zero and turned into a 500 error.
Read the noteInfrastructure
Our first CI build of a Next.js + Payload CMS site swap-thrashed the same server that runs production. Here is what actually happened, why it was not a clean out-of-memory kill, and the four changes that made the build safe.
Read the noteContact
Share a short brief. We'll respond with clear next steps.
