[
  {
    "part_id": "test-cu-0.5",
    "material": "copper",
    "gauge_mm": 0.5,
    "insulation_od_mm": 0.55,
    "resistivity_ohm_m": 1.72e-8,
    "max_current_a": 3.0,
    "price_per_m": 5.0,
    "source": "fixture"
  },
  {
    "part_id": "test-al-0.5",
    "material": "aluminum",
    "gauge_mm": 0.5,
    "insulation_od_mm": 0.55,
    "resistivity_ohm_m": 2.82e-8,
    "max_current_a": 2.2,
    "price_per_m": 2.0,
    "source": "fixture"
  }
]