Essay · 9 December 2025
Privacy Sandbox numbers will not save a broken app join
Web aggregation is a different craft. It does not name your in-app events for you.
Chrome’s Privacy Sandbox work, including aggregation APIs, arrived in GB conversations as a rumour that “web measurement is back.” For teams who also run apps, that rumour is a distraction. An Attribution Reporting source on the web does not repair a duplicate trial_start in the MMP.
We still teach the web-to-app seam: a click on a product page, a deferred deep link, a first open. If those three names disagree, Sandbox summaries will describe a cleaner web world than the one your app finance file inhabits. The board will pick the prettier world.
Use Sandbox outputs, if you have them, as a web contribution story. Keep the app story on MMP identity buckets, SKAN, and incrementality. Join them only in a memo that says the join is narrative, not a user stitch.
If your taxonomy is a mess, start there. The Field Notes Intensive exists for teams who wanted a new API when they needed a dictionary.