A proxy in front of argocd-server sends a traceparent header marked not sampled. With --otlp-sample-ratio=1.0 in Argo CD 3.6, what happens to that request's trace?

Answer: It is not recorded, because the sampler is parent-based

Explanation

Argo CD 3.6 replaced always-on sampling with a parent-based sampler, so an inbound not-sampled decision is honored even at a ratio of 1.0. The ratio only applies to traces that start in Argo CD. Downstream services such as the repo-server follow the same decision, which keeps traces whole.