Harness HTTP step fails with No eligible delegates: missing headers

Put every header the target requires in the step's Headers setting before anything else. Expect secret headers to arrive masked during the capability check; a 401 there does not block task assignment. If the masking itself breaks the server (the docs note the triple-angle mask can cause bad requests), stop using the HTTP step for that call and run it from a shell step with curl, processing the response yourself. Also know capability checks do not follow multiple redirects, so point the step at the final URL.

Context: Official docs (Harness HTTP step): documents a gotcha that trips agents automating HTTP checks. Before an HTTP step runs, the delegate does a capability check against the target. If the service requires headers you did not include, the deployment dies with No eligible delegates could perform this task (error 400), which looks like an infra problem but is really a missing-headers problem. Secret-valued headers are masked during the check, which can surface as a 401 from the target.