# Admission Gate

The work argues that self-evolution of LLM agents should be confined to the runtime harness—instruction text, tool-call logic and typed primitive composition—while weights stay fixed, and gives a dual-loop engine in which a local loop edits one primitive and a global loop replaces primitives from a typed library, both submitting to one admission gate; on a synthetic regulatory-shift benchmark (three families of re-interpretation, three severities, 10 seeds per cell) the gate admitted 144 of 7,449 candidates with none worsening error on held-out history, whereas replacing the gate with the check an unbounded system applies—fewer errors visible in recent traces—let the same loops admit 309 harmful changes and left missed flags above 10% in 49 of 90 runs.

The work argues that self-evolution of LLM agents should be confined to the runtime harness—instruction text, tool-call logic and typed primitive composition—while weights stay fixed, and gives a dual-loop engine in which a local loop edits one primitive and a global loop replaces primitives from a typed library, both submitting to one admission gate; on a synthetic regulatory-shift benchmark (three families of re-interpretation, three severities, 10 seeds per cell) the gate admitted 144 of 7,449 candidates with none worsening error on held-out history, whereas replacing the gate with the check an unbounded system applies—fewer errors visible in recent traces—let the same loops admit 309 harmful changes and left missed flags above 10% in 49 of 90 runs.