Function validateDependencies

apps/cli/internal/cli/set.go:456–487

validateDependencies checks that all dependency IDs exist and that setting them would not create a circular dependency.

(task *model.Task, depIDs []string, tasks []*model.Task)

// validateDependencies checks that all dependency IDs exist and that
// setting them would not create a circular dependency.
func validateDependencies(task *model.Task, depIDs []string, tasks []*model.Task) error {
	tasksByID := make(map[string]*model.Task, len(tasks))
	for _, t := range tasks {
		tasksByID[t.ID] = t
	}

	// Check existence.
	for _, id := range depIDs {
		if _, ok := tasksByID[id]; !ok {
			return fmt.Errorf("dependency %q not found", id)
		}
	}

	// Self-dependency check.
	for _, id := range depIDs {
		if id == task.ID {
			return fmt.Errorf("task cannot depend on itself: %s", id)
		}
	}

	// Check for circular dependencies by temporarily setting the new deps.
	origDeps := task.Dependencies
	task.Dependencies = depIDs
	defer func() { task.Dependencies = origDeps }()

	g := graph.NewGraph(tasks)
	if cycles := g.DetectCycles(); len(cycles) > 0 {
		return fmt.Errorf("circular dependency detected: %s", formatCycle(cycles[0]))
	}

	return nil
}

func formatCycle(cycle []string) string {
	return strings.Join(cycle, " -> ")