{
  "schema_version": "muse-fixture-model-events-v1",
  "来源": "合成样例；provider/model 均为占位符，不指向真实服务",
  "合同": "docs/系统架构/新版设计/接口契约/任务工具与事件.md",
  "语义": "terminal_state 取 completed/truncated/failed/no_completion_basis；usage_state 取 known/unknown",
  "scenarios": [
    {
      "scenario_id": "model-normal-completion",
      "说明": "分片输出→finish(stop)→回执含用量：构成有效完成",
      "events": [
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "夜色"
            }
          }
        },
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "渐深。"
            }
          }
        },
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "finish",
              "reason": {
                "kind": "stop"
              }
            }
          }
        },
        {
          "type": "assistant/message",
          "data": {
            "turn": 1,
            "step": 1,
            "message": {
              "source": {
                "provider": "synthetic",
                "model": "fixture-model"
              },
              "content": [
                {
                  "type": "text",
                  "text": "夜色渐深。"
                }
              ]
            },
            "usage": {
              "inputTokens": 100,
              "outputTokens": 8,
              "costUsd": 0.001
            }
          }
        }
      ],
      "expected": {
        "terminal_state": "completed",
        "finish_reason": "stop",
        "usage_state": "known",
        "final_text": "夜色渐深。"
      }
    },
    {
      "scenario_id": "model-truncated-by-length",
      "说明": "finish(length)：明确终态=截断，不是成功完成",
      "events": [
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "长文未完"
            }
          }
        },
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "finish",
              "reason": {
                "kind": "length"
              }
            }
          }
        },
        {
          "type": "assistant/message",
          "data": {
            "turn": 1,
            "step": 1,
            "message": {
              "source": {
                "provider": "synthetic",
                "model": "fixture-model"
              },
              "content": [
                {
                  "type": "text",
                  "text": "长文未完"
                }
              ]
            },
            "usage": {
              "inputTokens": 100,
              "outputTokens": 4096
            }
          }
        }
      ],
      "expected": {
        "terminal_state": "truncated",
        "finish_reason": "length",
        "usage_state": "known"
      }
    },
    {
      "scenario_id": "model-stream-close-without-finish",
      "说明": "流关闭但无完成信号：无有效完成依据，不得判成功",
      "events": [
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "半句"
            }
          }
        },
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "话"
            }
          }
        }
      ],
      "expected": {
        "terminal_state": "no_completion_basis",
        "usage_state": "unknown",
        "notes": "保留部分输出或失败，不得计为完成；文本片段不是完成事件"
      }
    },
    {
      "scenario_id": "model-midstream-error",
      "说明": "分片后错误事件：终态=失败，错误可见",
      "events": [
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "开始"
            }
          }
        },
        {
          "type": "assistant/error",
          "data": {
            "turn": 1,
            "step": 1,
            "error": {
              "code": "provider_unavailable",
              "message": "合成错误：上游不可用"
            }
          }
        }
      ],
      "expected": {
        "terminal_state": "failed",
        "error_code": "provider_unavailable",
        "usage_state": "unknown"
      }
    },
    {
      "scenario_id": "model-unknown-usage",
      "说明": "finish(stop) 与回执均出现，但用量缺失：完成与用量未知分别表示",
      "events": [
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "text",
              "text": "完成句子。"
            }
          }
        },
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "finish",
              "reason": {
                "kind": "stop"
              }
            }
          }
        },
        {
          "type": "assistant/message",
          "data": {
            "turn": 1,
            "step": 1,
            "message": {
              "source": {
                "provider": "synthetic",
                "model": "fixture-model"
              },
              "content": [
                {
                  "type": "text",
                  "text": "完成句子。"
                }
              ]
            }
          }
        }
      ],
      "expected": {
        "terminal_state": "completed",
        "finish_reason": "stop",
        "usage_state": "unknown",
        "notes": "未知用量单独表示，不填 0、不猜测、不冒充已结算"
      }
    },
    {
      "scenario_id": "model-finish-after-message",
      "说明": "回执先到、finish 信号后到（乱序容错反例）：仍可判完成，但依据是两者齐备",
      "events": [
        {
          "type": "assistant/message",
          "data": {
            "turn": 1,
            "step": 1,
            "message": {
              "source": {
                "provider": "synthetic",
                "model": "fixture-model"
              },
              "content": [
                {
                  "type": "text",
                  "text": "乱序。"
                }
              ]
            },
            "usage": {
              "inputTokens": 10,
              "outputTokens": 2
            }
          }
        },
        {
          "type": "assistant/chunk",
          "data": {
            "turn": 1,
            "step": 1,
            "chunk": {
              "type": "finish",
              "reason": {
                "kind": "stop"
              }
            }
          }
        }
      ],
      "expected": {
        "terminal_state": "completed",
        "finish_reason": "stop",
        "usage_state": "known",
        "final_text": "乱序。"
      }
    }
  ]
}