Multi-tenant event fan-out
Design a multi-tenant customer-data-platform ingestion pipeline that receives event streams from thousands of customers (each a business) and routes/transforms/forwards each customer's events to that customer's chosen destinations (their warehouse, ad platforms, email tools) — fan-out of one event to up to 30 destinations. Per-customer volumes vary wildly (a few/sec to 50k/sec). One slow or failing destination for one customer must not back up or drop other customers' or other destinations' deliveries. Design ingestion, fan-out, and per-tenant/per-destination isolation.
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.