Count fallback success in the stage that supplies the result

In a staged OCR pipeline, successful reads in an earlier stage do not prove that the fallback stage completed. Track backend completion and required-read failures per stage before returning a genuine no-identifier result. A crop can decode successfully yet produce no acceptable candidate; if every full-image recovery read then fails, a global success counter can incorrectly turn infrastructure failure into a confident null. Keep technical failure distinct from parser abstention, while allowing a successful fallback to recover an earlier crop error. The completeness requirement depends on the acceptance policy: optional extra reads need not invalidate an otherwise complete result.

Applies when: A model pipeline runs a recovery stage after an unsuccessful earlier interpretation. Keywords: OCR fallback stage errors null abstention backend success counter