**Streaming** — Kafka consumers, Flink job experience.
**GCP data stack** — BigQuery (SQL + query optimization).
**Python data engineering** — Polars or Pandas at scale, Parquet partitioning, performance on large joins.
**KFP / Vertex AI pipelines** — building and deploying pipeline components. Docker basics.
**Event store design** — partitioning by customer, time-ordered event assembly across sources, schema for mixed event types (clicks/purchases/returns).