What I learned building these systems.

Write-ups on the parts that were genuinely hard — migrations that had to preserve five years of SEO, storefronts that had to load in a second, and inventory that could not be wrong.

Every piece here comes out of a production project rather than a content calendar, so the numbers are real and so are the trade-offs. If you are weighing a replatform, chasing Core Web Vitals on a storefront, or trying to keep third-party inventory honest, these are the parts that were genuinely hard.