An event dictionary that survives a redesign

Every quiet conversion crisis we have seen in the last two years started with a visual redesign that nobody told analytics about. Screens moved. Webviews multiplied. Names stayed in Figma and drifted in code. The funnel still rendered. It just stopped meaning anything.

Conversion drop-off diagnostics cannot begin until the dictionary is trustworthy. Otherwise you will diagnose a ghost.

Contracts, not catalogues

A useful dictionary is not a spreadsheet of every tap. It is a short contract: event name, when it fires, which user it belongs to, required properties, and the screen or state that must exist. Design may rename a button. The contract does not. If “checkout_pay_tapped” starts firing on a preview screen, that is a broken contract, not a new insight.

We ask teams to freeze identity rules in the same document. Logged-out ghosts and second-device buyers are where Thai apps bleed silently after a “simple” navigation rewrite.

Hand the contract to design before the train leaves

The Event Taxonomy for Product Funnels room practices a release ritual: design attaches the contract IDs to components, engineering posts a diff of event payloads, analytics signs that the funnel still compiles. If any of those three signatures is missing, the release does not get to claim conversion numbers for two weeks. That pause is unpopular and effective.

Double-fires deserve their own line. Android 12 clones of page_view have inflated more PromptPay “success” steps than any bank outage. Your dictionary should say whether an event is allowed to fire twice in a session. If it does not say, the tracker will decide for you.

What to do when you inherit a mess

Do not rename everything on a Friday. Pick the dying step. Restore its contract. Run the funnel for a week. Only then expand. A full rewrite of names feels productive and destroys comparability. Diagnosis needs a before.

If you want company while you do this, the taxonomy room is listed with the other studios. Bring the current names, however embarrassing. We have seen worse.