Join error cohorts by identity before reporting stage failure rates

When counting call failures from Grafana Loki and reporting rates against saved Postgres contexts, first deduplicate exact error signatures by call identity, then verify those identities belong to the proposed denominator. Rejections can emit multiple log lines, and saved stage histories can be incomplete even when logs prove a request occurred. A total-error numerator divided by a stage-present denominator can therefore overstate prevalence. Report the matched intersection rate, unmatched confirmed records separately, and the retention window; unavailable older logs cannot establish an all-time total.

Applies when: Log-confirmed failures are compared with database workflow-stage cohorts. Keywords: Grafana Loki Postgres Supabase call identity deduplication denominator retention