core/shadow_activation_controller library

Classes

GuardrailDefinition
A min/max threshold on 1 named metric — a violation of either bound is what ShadowActivationController treats as "this shadow-activated feature/event is misbehaving, roll it back now". Either bound can be null (no lower/upper check) — but not BOTH; that invariant is enforced by ShadowActivationController.registerGuardrail (ENH-89), not here — a runtime assert on this const-constructible class would be stripped from release builds anyway, and a genuine if/throw here would force every const guardrail list in consumers off const.
ShadowActivationController
Watches caller-reported metrics for a feature/event that's been shadow-activated (rolled out to a small cohort ahead of a full release) and auto-rolls-back — CLIENT-SIDE, without waiting for an operator — the instant a registered GuardrailDefinition is violated (FEAT-90).