“Walk through a service you changed to keep one customer’s workload from slowing down others.”
Listen for: the candidate’s contribution, isolation mechanism, failure behavior, and how they checked the result.
Fictional evidence note: described implementing per-customer worker limits and a mixed-load test; explained why a single shared queue caused delays. Did not yet explain behavior when a customer exceeds its allocation.
Reviewer assessment: evidence of a concrete design and test; the overload path remains unassessed.
Next question: “What happens at the limit, and what test covers that?”