mast

type Config struct {
	// Model is an explicit ADK model to drive every agent. Takes
	// precedence over ModelName. Use this to inject a custom or fake
	// model.LLM.
	Model model.LLM

	// ModelName constructs a built-in model when Model is nil: "echo"
	// (in-process fake, no credentials — the testing surface) or a
	// "gemini-*" model id (Vertex/Gemini via ADK). It also selects the
	// usage pricing rate; when Model is set and ModelName is empty,
	// pricing falls back to Model.Name().
	ModelName string

	// Sessions is the ADK session service runs execute against. Nil
	// means a fresh in-memory service per call — no durability, and no
	// resume across calls. Pass a shared service (ADK's
	// session/database over SQLite/Postgres, or one InMemoryService
	// reused across calls) to get durable pause/resume and
	// ListSessions.
	Sessions adksession.Service

	// Logger receives construction and turn logs. Nil disables
	// logging.
	Logger *slog.Logger

	// Budget overrides the budget ceilings for the run. Nil derives
	// limits from the workload bundle's budget block (Run has no
	// bundle, so nil means unlimited). A zero RatePer1K is filled from
	// the model's flat spike pricing so Result.Usage.CostUSD is never
	// silently zero-rated.
	Budget *budget.Limits
}

type Result struct {
	// Output is the turn's final output: the last node output or model
	// text the runner emitted. When the turn parked on a HITL
	// interrupt, Output holds whatever the run produced before
	// pausing; inspect ListSessions for the pending interrupt.
	Output string

	// SessionID identifies the session the turn ran in. Pass it to
	// ResumeSession (with a durable Config.Sessions) to continue a
	// paused run.
	SessionID string

	// Usage is the session's cumulative usage after the turn.
	Usage Usage
}

type Usage struct {
	// Tokens is the total token count across all model calls.
	Tokens int64
	// CostUSD is the derived cost (flat spike pricing; see pkg/budget).
	CostUSD float64
	// ModelCalls is the number of model calls ("turns" in mast's
	// budget vocabulary).
	ModelCalls int
}