Class: LlmCostTracker::Doctor::CostDriftCheck

Inherits:
Object
  • Object
show all
Defined in:
lib/llm_cost_tracker/doctor/cost_drift_check.rb

Constant Summary collapse

SAMPLE_SIZE = 
200
EPSILON = 
BigDecimal("0.00000001")

Instance Method Summary collapse

Instance Method Details

#call ⇒ Object 



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# File 'lib/llm_cost_tracker/doctor/cost_drift_check.rb', line 14

def call
  return unless Probe.table_exists?("llm_cost_tracker_calls")
  return unless Probe.table_exists?("llm_cost_tracker_call_line_items")

  sampled = LlmCostTracker::Call
            .where.not(total_cost: nil)
            .where(cost_status: %w[complete free partial])
            .order(id: :desc)
            .limit(SAMPLE_SIZE)
            .pluck(:id, :total_cost, :cost_status)
  return Check.new(:ok, "cost drift", "no priced calls to inspect") if sampled.empty?

  line_item_totals = LlmCostTracker::CallLineItem
                     .where(llm_cost_tracker_call_id: sampled.map(&:first))
                     .group(:llm_cost_tracker_call_id)
                     .sum(:cost)

  drifted = sampled.filter_map do |id, total_cost, cost_status|
    line_total = line_item_totals[id] || BigDecimal("0")
    header = BigDecimal(total_cost.to_s)
    next if cost_status == "partial" && header >= line_total
    next if (header - line_total).abs <= EPSILON

    "##{id}: header=#{header.to_s('F')} line_items=#{line_total.to_s('F')}"
  end

  if drifted.empty?
    return Check.new(:ok, "cost drift",
                     "header total_cost matches line items in #{sampled.size} sampled calls")
  end

  Check.new(
    :warn,
    "cost drift",
    "header total_cost diverges from line items in #{drifted.size}/#{sampled.size} sampled calls: " \
    "#{drifted.first(5).join('; ')}#{'; ...' if drifted.size > 5}"
  )
end