[
  {
    "id": "berlin-u6-north-unavailable",
    "operations": [
      {
        "op": "effective_termini",
        "patterns": [
          "r2679163:0",
          "r2679164:0"
        ]
      }
    ],
    "reason": "Both pinned U6 directions end at Kurt-Schumacher-Platz, although from/to tags say Alt-Tegel. Station objects alone do not prove an operating railway. Retain the available 24-stop pair and expose omitted north explicitly; do not fabricate service.",
    "unavailable": [
      "Scharnweberstraße",
      "Otisstraße",
      "Holzhauser Straße",
      "Borsigwerke",
      "Alt-Tegel"
    ]
  }
]