In April, the story was a platform pulling a lever: Shopify migrated its entire UCP fleet to v2026-04-08 in four days, BigCommerce showed up with three stores, and we said the question for May was which platform ships next — because every prior jump in the directory had been a step function caused by a platform-level deployment. May's answer: none, and it didn't matter. No platform shipped a UCP wave this month. BigCommerce still has three verified stores. WooCommerce still has three. Salesforce Commerce Cloud still has none verified, though a custom build is reportedly in development. And the directory still grew ~32% — the same rate as April — because the baseline discovery rate stepped up. For the first time since we started this report, UCP grew on a slope instead of a staircase. This is the fourth monthly state-of-the-ecosystem report from UCP Checker. Here's what the data says as of May 12, 2026.…