usage

type ChainObserver struct {
	// contains filtered or unexported fields
}

type Event struct {
	TraceID     string
	ALegID      string
	BLegID      string
	PrincipalID string
	SessionID   string
	AttemptSeq  int
	BackendID   string
	FrontendID  string
	Model       string

	// Scope is the optional safe principal/scope attribution snapshot for this request. It is
	// additive metadata; existing observers may ignore it and keep reading PrincipalID
	// (requirements 6.4, 6.5, 7.3). When Scope.PrincipalID is known it must match PrincipalID.
	Scope scope.PrincipalScopeView

	InputTokens      int
	OutputTokens     int
	CacheReadTokens  int
	CacheWriteTokens int
	ReasoningTokens  int
	TotalTokens      int

	CostNanoUnits int64
	Currency      string
	CostSource    string
	RawUsageJSON  string

	RecordedAt time.Time
}

type NoopObserver struct{}

type Observer interface {
	OnUsage(ctx context.Context, ev Event) error
}