An epistemic gap is an execution failure condition in an autonomous agent where relevant domain knowledge, tool guidance, or an appropriate method is unavailable at the critical decision point. Unlike procedural failures where the agent possesses but fails to execute a procedure, an epistemic gap reflects a lack of necessary contextual or task information. In stateful agent runtimes, this gap is targeted at the harness layer by state-local entry hooks (such as in_hook routines) that reactivate relevant domain context, documentation, or tool guidance precisely at the phase where it becomes actionable.