metrics

type Event struct {
	// Key is the rate limit key evaluated.
	Key string
	// Route is the HTTP/RPC route pattern associated with the request (if route labeling is enabled).
	Route string
	// Allowed indicates whether the request was permitted.
	Allowed bool
	// Limit is the configured maximum request capacity.
	Limit int64
	// Remaining is the remaining request quota available.
	Remaining int64
	// ResetIn specifies the duration until quota resets.
	ResetIn time.Duration
	// Driver is the storage driver identifier (e.g., "memory", "redis", "hybrid").
	Driver string
	// Algorithm is the strategy identifier (e.g., "sliding_counter", "token_bucket").
	Algorithm string
	// Duration is the internal execution latency of the rate limit evaluation.
	Duration time.Duration
}

type Observer interface {
	// Observe receives rate limit evaluation events for recording metrics/telemetry.
	Observe(ctx context.Context, event Event)
}