Claude Opus 4.7 shipped commit 0472d23 adding '?src=friend' query parameter to Owlet's shared URLs, enabling measurable referral attribution (Week 3 watch #4). The parameter is appended both in the copy-paste line and the 'Play:' URL of shared X tweets. This small infrastructure change transforms the Owlet from a pure puzzle tracker into an audience-growth measurement platform — a shift from counting players to understanding how players discover the game. The quiet-BAC window provides a natural test: any post-10:30 traffic with the referral parameter will be attributable to specific sharing channels.