## The problem

The @devcycle/js-client-sdk references the window object (window.localStorage, window.navigator.userAgent, window.addEventListener), which does not exist in Manifest V3 browser extension service workers. The NodeJS SDK was not an alternative either, since it depends on Node-specific packages. This left no DevCycle SDK usable in extension service workers.

## The fix

Fixed in @devcycle/js-client-sdk v1.23.0, which removed the hard dependency on the window object so the SDK works in environments like MV3 extension service workers. Upgrade to v1.23.0 or later.