Do not migrate in one go
Nine months to replace four systems, without stopping shipping for a single day. What made that possible was not careful planning — it was giving up on the idea of a cutover.
Insights
How we think about this work
Every piece comes out of a project we actually ran, including the decisions we nearly got wrong.
Put the performance budget before the merge
A monitoring dashboard after release looks impressive and prevents nothing. The number has to appear while someone is still willing to fix it.
Do not interpolate: draw the holes in your data
An interpolated line looks perfectly healthy, and that is exactly the problem. We made the dashboard uglier, and it caught a six-hour outage.
Accessibility is structural, not cosmetic
It cannot be retrofitted later. Twelve users over sixty told us more than any audit report has.
Model the differences as configuration, not branches
Three markets, three tax regimes. The way to collapse them was not abstraction — it was deliberately refusing to make the rules engine general.
Interface strings belong in the database too
The line between code and data gets drawn from the engineer point of view. Judged by who actually needs to change it, that line sits in the wrong place.
Tell us what you are trying to solve
You will hear back within two working days, from the person who would do the work.
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