Notes from the work
Software development, APIs, websites, AI agents, and the client requests behind them.
What the Data Protection Act changes in the database
’s Data Protection Act is not a banner in the footer. It changes which columns you collect, who can open …
LesterTechLabs Engineering · 3 min read
A sale that survives a dropped network
The sale happens at the counter, not on the server. If the network drops after the customer has paid, the …
LesterTechLabs Engineering · 3 min read
One event, three channels
A payment, a booking, and a delivery each need one message. Email, SMS, and WhatsApp are channels. They are not …
LesterTechLabs Engineering · 3 min read
Member balances a clerk can explain
A member will ask why the balance changed. The clerk needs the lines, in order, with a reason on each …
LesterTechLabs Engineering · 3 min read
School fees paid in parts
Parents rarely pay a term in one movement. A fees book that only understands full payment will show almost every …
LesterTechLabs Engineering · 3 min read
Inventory when two branches sell the last item
Two branches can sell the last unit in the same minute. The stock figure has to move with the sale, …
LesterTechLabs Engineering · 3 min read
Book a time without a double booking
A booking system fails the morning two people are given the same chair. The record has to make that impossible, …
LesterTechLabs Engineering · 4 min read
A Django release you can explain
The first production release is finished when someone who was not in the room can say what is deployed, how …
LesterTechLabs Engineering · 3 min read
Build a cache that expires on purpose
A cache is a copy with a deadline. It earns its place when the copy is cheaper than the query, …
LesterTechLabs Engineering · 4 min read