Exact OIG exclusion signals for one NPI

API-key-only exact NPI matching against OIG LEIE serving rows. This endpoint returns public-record exclusion signals and the provenance fields available to the match; it does not compute a risk score or certification. A zero-signal result is returned only when the endpoint's coverage guard reports current after reconciling the serving table to its comparable internal artifact; that status does not assert same-day upstream freshness. When coverage trails or cannot reconcile, HTTP 503 returns determination: indeterminate, coverage evidence, and Cache-Control: private, no-store; that response is not a clearance. Positive signals remain HTTP 200 and disclose the coverage status.