dag

type Graph struct {
	Roots   []*Node          // nodes with no dependencies (in-degree 0)
	ByName  map[string]*Node // O(1) service lookup
	Ordered []*Node          // all nodes in topological order (Kahn's)
	Visual  []*Node          // nodes in depth-first render order (matches tree row positions)
}

type Node struct {
	Name         string
	Deps         []string // all dependency names (sorted, for display)
	Children     []*Node  // all services that depend on this node (full edge set, used by Kahn's)
	TreeChildren []*Node  // dependants for which this node is the primary parent (used by renderer)
	State        docker.ContainerState
	Level        int // render depth: root = 0
}