What's the long-term maintenance burden?

Real talk, this is where most agencies undersell the cost. Going headless adds:

• Two codebases to maintain, Magento backend AND headless frontend. Each has its own dependency tree, security patches, deployment pipeline.
• Frontend developer skillset, You need a React / Vue / Astro engineer on retainer. Magento PHP devs can’t do this work.
• GraphQL schema drift, Each Magento upgrade may change GraphQL responses. We document a regression-test suite as part of the build.
• Service worker bugs, Stale-while-revalidate logic gets tricky for cart / checkout. Plan for ~2-4 hours/month of frontend tuning.

Our retainer (~$999, $2,499/month depending on size) covers all of this. If you don’t have a frontend dev on staff and don’t want a retainer, headless is the wrong call, stay on Hyvä.