An event taxonomy that supports retention decisions

Begin with decisions, then define the events needed to support them. Every event should have an owner, trigger, properties, expected volume and validation method.

Separate business outcomes from interface interactions. A completed booking is a stronger value signal than a button click, while both can be useful in diagnosing a journey.

Review the taxonomy after releases and keep a changelog. Reliable retention analysis depends on knowing when instrumentation changed, not merely having more events.