{
  "scope": "Original static fictional toy-v1 chains; not provider responses, model outputs, snapshot or import approval",
  "requestScope": {
    "collection": "teaching-items",
    "filter": "category=sample",
    "order": "authored fixture sequence",
    "version": "toy-v1"
  },
  "contract": "Required items list of objects with nonempty string id; required next is nonempty string or null; validate before accepting page; preserve occurrences; stop repeated visited key as incomplete",
  "cases": [
    {
      "case": "A",
      "pages": {
        "start": {
          "items": [
            {
              "id": "R1"
            },
            {
              "id": "R2"
            }
          ],
          "next": "cedar"
        },
        "cedar": {
          "items": [
            {
              "id": "R3"
            }
          ],
          "next": "maple"
        },
        "maple": {
          "items": [
            {
              "id": "R4"
            },
            {
              "id": "R5"
            }
          ],
          "next": null
        }
      },
      "expected": {
        "status": "terminal",
        "complete": true,
        "acceptedPages": [
          "start",
          "cedar",
          "maple"
        ],
        "ids": [
          "R1",
          "R2",
          "R3",
          "R4",
          "R5"
        ],
        "uniqueCount": 5
      }
    },
    {
      "case": "B",
      "pages": {
        "start": {
          "items": [
            {
              "id": "R1"
            }
          ],
          "next": "birch"
        },
        "birch": {
          "items": [
            {
              "id": "R2"
            },
            {
              "id": "R3"
            }
          ],
          "next": null
        }
      },
      "expected": {
        "status": "terminal",
        "complete": true,
        "acceptedPages": [
          "start",
          "birch"
        ],
        "ids": [
          "R1",
          "R2",
          "R3"
        ],
        "uniqueCount": 3
      }
    },
    {
      "case": "C",
      "pages": {
        "start": {
          "items": [],
          "next": "elm"
        },
        "elm": {
          "items": [
            {
              "id": "R7"
            }
          ],
          "next": null
        }
      },
      "expected": {
        "status": "terminal",
        "complete": true,
        "acceptedPages": [
          "start",
          "elm"
        ],
        "ids": [
          "R7"
        ],
        "uniqueCount": 1
      }
    },
    {
      "case": "D",
      "pages": {
        "start": {
          "items": [
            {
              "id": "R1"
            },
            {
              "id": "R2"
            }
          ],
          "next": "ash"
        },
        "ash": {
          "items": [
            {
              "id": "R2"
            },
            {
              "id": "R3"
            }
          ],
          "next": null
        }
      },
      "expected": {
        "status": "terminal",
        "complete": true,
        "acceptedPages": [
          "start",
          "ash"
        ],
        "ids": [
          "R1",
          "R2",
          "R2",
          "R3"
        ],
        "uniqueCount": 3
      }
    },
    {
      "case": "E",
      "pages": {
        "start": {
          "items": [
            {
              "id": "R1"
            }
          ],
          "next": "loop"
        },
        "loop": {
          "items": [
            {
              "id": "R2"
            }
          ],
          "next": "loop"
        }
      },
      "expected": {
        "status": "repeated_cursor",
        "complete": false,
        "acceptedPages": [
          "start",
          "loop"
        ],
        "ids": [
          "R1",
          "R2"
        ],
        "uniqueCount": 2
      }
    },
    {
      "case": "F",
      "pages": {
        "start": {
          "items": [
            {
              "id": "R1"
            }
          ],
          "next": "broken"
        },
        "broken": {
          "items": [
            {
              "id": "R2"
            }
          ]
        }
      },
      "expected": {
        "status": "malformed",
        "complete": false,
        "acceptedPages": [
          "start"
        ],
        "ids": [
          "R1"
        ],
        "uniqueCount": 1
      }
    }
  ]
}