Practice Makes Operators

Meta-RL agents often learn how to adapt within a task, yet the adaptation procedure usually remains hidden inside weights, recurrent states, or long contexts. When a useful pattern recurs, the agent has no explicit way to reuse it, inspect it, or compose it with later routines. We study when such a trace should become a callable operator. In our framework, an operator is a closed-loop routine that can act, update fast parameters, write memory, call lower-level routines, and return control. Rank-decreasing calls and finite timeouts make recursive execution well founded. Primitive unrolling puts different operator sets in a common trace space. A lower-confidence gate admits an edit only when it improves a resource-aware energy. We evaluate the admission rule on hidden-latent Meta-World splits for mining, fitting, certification, and deployment. Admissions respond to cost and confidence, certified local gains align with deployment in the registered regime, and ablations identify the load-bearing components. Our work provides a theoretical foundation for emergent operator hierarchies from recurring meta-RL traces.