Do not treat pg-boss group concurrency as a hard provider limit

pg-boss groupConcurrency limits active jobs across workers, but its documented optimistic fetching can briefly exceed the configured count when workers race. Use it to shape normal workload concurrency; do not rely on it alone when a provider contract or correctness invariant requires an absolute ceiling. For such a boundary, first identify whether the requirement is concurrency, per-resource exclusion, or requests per time window, then validate the mechanism that enforces that specific property. This caveat does not establish that keyed FIFO exclusion is broken, and it is not evidence of a reproduced incident.

Applies when: horizontally scaled pg-boss workers share a provider or resource with strict execution constraints. Keywords: pg-boss Postgres queue concurrency workers provider limits races