Not all actions require the same governance layer. Querying data is reversible. Committing infrastructure changes is not. Generating a recommendation is reversible. Executing a financial transaction is not.
Systems that do not formally classify irreversibility cannot bound risk. Every action is treated equivalently — which means either everything is over-governed (unusable) or everything is under-governed (uninsurable).
A governed system declares, for each execution surface: the effect class, the reversibility characteristics, and the rollback cost. These declarations are registered before the surface is operational. Implicit assumptions of reversibility do not constitute enforceable boundaries.
This classification is not a convenience. It is the structural basis for proportional governance. Without it, underwriters cannot distinguish between bounded and unbounded exposure.
Reference invariants: ZTG-3 (Governed Effect Surfaces).