Question

A non-critical 'related recommendations' enrichment dependency degraded to ~10s response times (it's slow, not down). Within minutes your primary checkout API — which only calls recommendations as an optional sidebar enrichment — saw its own p99 climb to 10s, threads pile up, and it starts failing health checks and getting killed/restarted, taking down checkout entirely. The recommendations call has no explicit timeout and is made inline in the request path. How do you triage and mitigate?