Fine-Grained Authorization
Authorization decided at the level of individual resources and their relationships, not broad modules or roles — the granularity needed for "share this specific report with this specific team."
aka: FGA
Fine-grained authorization is where flat role checks stop scaling: “can this user access this exact resource, given how they relate to it” requires walking relationships, not evaluating a single static rule. Google Zanzibar and its open-source descendant OpenFGA are the reference implementations most systems reach for once they need this level of precision.