Senior backend engineer (Python / low-latency systems): what proof gets you shortlisted for real-time market data, WebSocket reliability, and production correctness?

Reviewing a senior backend JD today, the hiring bar looked tougher than a normal senior Python backend screen.

The role asked for low-latency APIs, fault-tolerant WebSocket systems, fast-moving data pipelines, database performance under heavy read/write load, and production debugging across networking, data consistency, and system performance. That is a very different shortlist question from “good backend engineer.”

For roles like this, what proof actually builds trust before interviews begin?

What would move someone toward shortlist faster here:

a strong incident write-up
a real-time data pipeline artifact
database tuning evidence
production debugging proof
clear ownership of system boundaries under load

Interested in hearing from people who have hired for, or worked inside, backend systems where latency, correctness, failure modes, and real-time data flow all matter together.