Audience asks whether there's a way to let developers send arbitrary attributes while still being able to aggregate/group by type — and whether to enforce a schema on the back-end or front-end. Callaghan answers: in short, no universal schema covers domain objects because they differ per app. He hopes OpenTelemetry will expand into this area in ~10 years; has explored Schema.org (too loose/generic). Currently he uses JSON Schemas to validate analytics-event attributes in the Segment pipeline, blocking invalid events and surfacing them as Sentry errors. Cost: team-wide agreement, schema versioning, large Notion docs, training.