{
  "cases": [
    {
      "name": "valid-v1-contract",
      "expectedValid": true,
      "expectedErrors": [],
      "agentCard": {
        "name": "Research Brief Agent",
        "description": "Produces source-bounded research briefs.",
        "version": "2.3.1",
        "supportedInterfaces": [
          {
            "url": "https://agents.example.com/research/a2a",
            "protocolBinding": "HTTP+JSON",
            "protocolVersion": "1.0",
            "tenant": "research-workspace"
          }
        ],
        "capabilities": {
          "streaming": true,
          "pushNotifications": false
        },
        "defaultInputModes": [
          "text/plain",
          "application/json"
        ],
        "defaultOutputModes": [
          "application/json"
        ],
        "skills": [
          {
            "id": "research-brief",
            "name": "Research brief",
            "description": "Builds a cited brief from an approved source set.",
            "tags": [
              "research",
              "citations"
            ]
          }
        ]
      },
      "taskSnapshots": [
        {
          "id": "task-001",
          "contextId": "context-001",
          "status": {
            "state": "TASK_STATE_WORKING",
            "timestamp": "2026-07-21T08:00:00.000Z"
          }
        },
        {
          "id": "task-001",
          "contextId": "context-001",
          "status": {
            "state": "TASK_STATE_COMPLETED",
            "timestamp": "2026-07-21T08:00:03.000Z"
          },
          "artifacts": [
            {
              "artifactId": "artifact-001",
              "name": "brief",
              "parts": [
                {
                  "data": {
                    "claim": "A2A contract fixture completed",
                    "sources": 2
                  },
                  "mediaType": "application/json"
                }
              ]
            }
          ]
        }
      ]
    },
    {
      "name": "reject-v03-shape",
      "expectedValid": false,
      "expectedErrors": [
        "supportedInterfaces",
        "TASK_STATE_*",
        "v0.3 discriminator"
      ],
      "agentCard": {
        "name": "Legacy Agent",
        "description": "Uses a v0.3-style card.",
        "version": "1.4.0",
        "url": "https://agents.example.com/legacy",
        "protocolVersion": "1.0",
        "preferredTransport": "JSONRPC",
        "capabilities": {},
        "defaultInputModes": [
          "text/plain"
        ],
        "defaultOutputModes": [
          "text/plain"
        ],
        "skills": [
          {
            "id": "legacy",
            "name": "Legacy",
            "description": "Legacy fixture skill.",
            "tags": [
              "legacy"
            ]
          }
        ]
      },
      "taskSnapshots": [
        {
          "id": "task-legacy",
          "contextId": "context-legacy",
          "status": {
            "state": "completed"
          },
          "artifacts": [
            {
              "artifactId": "artifact-legacy",
              "parts": [
                {
                  "kind": "text",
                  "text": "legacy"
                }
              ]
            }
          ]
        }
      ]
    },
    {
      "name": "reject-terminal-regression",
      "expectedValid": false,
      "expectedErrors": [
        "cannot transition away from terminal state"
      ],
      "taskSnapshots": [
        {
          "id": "task-terminal",
          "contextId": "context-terminal",
          "status": {
            "state": "TASK_STATE_COMPLETED"
          },
          "artifacts": [
            {
              "artifactId": "artifact-terminal",
              "parts": [
                {
                  "text": "done",
                  "mediaType": "text/plain"
                }
              ]
            }
          ]
        },
        {
          "id": "task-terminal",
          "contextId": "context-terminal",
          "status": {
            "state": "TASK_STATE_WORKING"
          }
        }
      ]
    },
    {
      "name": "reject-ambiguous-part",
      "expectedValid": false,
      "expectedErrors": [
        "exactly one of text/raw/url/data"
      ],
      "taskSnapshots": [
        {
          "id": "task-part",
          "contextId": "context-part",
          "status": {
            "state": "TASK_STATE_COMPLETED"
          },
          "artifacts": [
            {
              "artifactId": "artifact-part",
              "parts": [
                {
                  "text": "ambiguous",
                  "data": {
                    "also": "present"
                  }
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}