Target.transaction do
  wanted = {
    "salades"              => 40,
    "tomates général"      => 40,
    "développement floral" => 20
  }

  # Ensure all referenced profiles exist
  profiles = NutrientProfile.where(name: wanted.keys).index_by(&:name)
  missing  = wanted.keys - profiles.keys
  raise "Missing NutrientProfile(s): #{missing.join(', ')}" if missing.any?

  target = Target.find_or_create_by!(name: "Objectif par défaut")

  target.target_allocations.destroy_all
  wanted.each do |name, pct|
    target.target_allocations.build(nutrient_profile: profiles[name], percentage: pct)
  end

  target.save!
end