budget

type FactSource interface {
	Facts(ctx context.Context, after int64, limit int) ([]journal.Fact, error)
	CountFacts(ctx context.Context, ftype journal.FactType, since time.Time) (int64, error)
	FactsSince(ctx context.Context, ftype journal.FactType, since time.Time, limit int) ([]journal.Fact, error)
}

type Guard struct {
	// DailyCap is the maximum number of enqueued agent tasks per calendar
	// day (local midnight). 0 = unlimited.
	DailyCap int
	// DailyCostCapUSD caps today's derived session spend in US dollars
	// (summed from completion facts carrying session usage — the real-money
	// axis beside the count cap; 2026-10-11: the count cap alone starved
	// pools at $0.07 measured spend). 0 = off. Checked AFTER the count cap
	// (cheap-first: count is a SQL pushdown, cost scans completions).
	// Measured spend lags enqueues by design: cost is only derivable from
	// completed runs, so the cap stops FURTHER spend once observed spend
	// crosses it. Fails open on journal errors like every projection here.
	DailyCostCapUSD float64
	// BudgetCmd, when set, is the final authority: it runs before every
	// harvest tick; exit 0 means within budget, any non-zero exit skips
	// the tick (its output becomes the log reason). Allows operators to
	// plug real cost accounting in.
	BudgetCmd string
	// Now is overridable in tests.
	Now func() time.Time
	// contains filtered or unexported fields
}

type SessionUsage struct {
	// Runs counts completion facts that carried derived session usage —
	// the derivable subset of today's completions, not every task.
	Runs             int
	CostUSD          float64
	PromptTokens     int64
	CompletionTokens int64
	Messages         int
}