Self-improving or self-modifying agents change the reliability problem. A static system can be tested against a known behavior envelope. An adaptive system may alter prompts, strategies, memory, or tool-use patterns over time. That makes observability a first-order design requirement.
The risk is not only malicious behavior. It is silent drift: a shortcut learned from prior tasks, an overconfident tool pattern, a memory item reused outside its scope, or an optimization that improves one metric while weakening another.
Adaptive agents need versioned behavior, replayable traces, constrained update mechanisms, and regression tests over high-risk tasks. Autonomy without a record of change is not intelligence; it is unbounded operational variance.