{
      "name": "arc-cpn-payment",
      "domain": "Digital-Asset Rails",
      "title": "Arc CPN Payment",
      "description": "W-A chain. Model CPN corridor economics vs SWIFT/ACH/card for cross-border USD flows.",
      "composer_url": "https://ainumbers.co/chaingraph/chains/arc-cpn-payment.html",
      "steps": [
        {
          "tool_id": "art-42-arc-fit-diagnostic",
          "handoff": "arc_score → CPN dimension primary"
        },
        {
          "tool_id": "art-43-arc-cpn-model",
          "handoff": "npv_3yr, cost_per_payment, migration_verdict — CPN corridor economics — final stage"
        }
      ]
    }