{
  "$defs": {
    "agent_info": {
      "additionalProperties": false,
      "properties": {
        "context_window_tokens": {
          "type": "integer"
        },
        "model": {
          "type": "string"
        },
        "name": {
          "type": "string"
        },
        "provider": {
          "type": "string"
        },
        "role": {
          "type": "string"
        }
      },
      "required": [
        "name",
        "provider"
      ],
      "type": "object"
    },
    "command": {
      "additionalProperties": false,
      "properties": {
        "description": {
          "type": "string"
        },
        "hint": {
          "type": "string"
        },
        "name": {
          "type": "string"
        }
      },
      "required": [
        "name"
      ],
      "type": "object"
    },
    "content_block": {
      "additionalProperties": false,
      "properties": {
        "_meta": {
          "description": "free-form JSON object (host/implementation metadata)"
        },
        "content": {
          "description": "free-form tool result payload (tool_result)"
        },
        "extension": {
          "description": "free-form JSON object (provider detail — never new modeled keys)"
        },
        "id": {
          "type": "string"
        },
        "input": {
          "description": "free-form tool arguments (tool_use)"
        },
        "is_error": {
          "type": "boolean"
        },
        "name": {
          "type": "string"
        },
        "text": {
          "type": "string"
        },
        "thinking": {
          "description": "reasoning preserved verbatim per ADR-0042",
          "type": "string"
        },
        "tool_use_id": {
          "type": "string"
        },
        "type": {
          "description": "text | thinking | tool_use | tool_result (open set)",
          "type": "string"
        }
      },
      "required": [
        "type"
      ],
      "type": "object"
    },
    "delta": {
      "additionalProperties": false,
      "properties": {
        "text": {
          "type": "string"
        },
        "thinking": {
          "type": "string"
        },
        "type": {
          "description": "text_delta | thinking_delta (open set)",
          "type": "string"
        }
      },
      "required": [
        "type"
      ],
      "type": "object"
    },
    "event": {
      "additionalProperties": false,
      "properties": {
        "_meta": {
          "description": "reserved _meta field: host/implementation metadata (also the only other home for provider detail)"
        },
        "agent": {
          "description": "dual-form: the AgentInfo object on system/init lines; a role label string (primary | escalation) on assistant/user lines",
          "oneOf": [
            {
              "type": "string"
            },
            {
              "$ref": "#/$defs/agent_info"
            }
          ]
        },
        "body": {
          "type": "string"
        },
        "capabilities": {
          "description": "open-set strings (known: stream_v1, partial_messages_v1, tasks_v1, workflows_v1) — tolerate unknown values",
          "items": {
            "type": "string"
          },
          "type": "array"
        },
        "category": {
          "type": "string"
        },
        "command_hint": {
          "type": "string"
        },
        "commands": {
          "items": {
            "$ref": "#/$defs/command"
          },
          "type": "array"
        },
        "count": {
          "type": "integer"
        },
        "cwd": {
          "type": "string"
        },
        "duration_ms": {
          "type": "integer"
        },
        "escalation_agent": {
          "$ref": "#/$defs/agent_info"
        },
        "event": {
          "$ref": "#/$defs/stream_payload"
        },
        "extension": {
          "description": "reserved extension point: the ONLY home for provider-specific detail"
        },
        "finished_ids": {
          "items": {
            "type": "string"
          },
          "type": "array"
        },
        "from": {
          "type": "string"
        },
        "id": {
          "type": "string"
        },
        "is_error": {
          "description": "boolean contract: true when the run failed (execution error, max turns, interruption); present on every result line",
          "type": "boolean"
        },
        "kind": {
          "type": "string"
        },
        "limit": {
          "type": "integer"
        },
        "mcp_servers": {
          "items": {
            "$ref": "#/$defs/mcpserver"
          },
          "type": "array"
        },
        "message": {
          "description": "dual-form: a string on system/error lines; the Message object on assistant/user lines",
          "oneOf": [
            {
              "type": "string"
            },
            {
              "$ref": "#/$defs/message"
            }
          ]
        },
        "milk_version": {
          "type": "string"
        },
        "model_usage": {
          "additionalProperties": {
            "$ref": "#/$defs/usage"
          },
          "description": "per-model token rollups, keyed by model name",
          "type": "object"
        },
        "num_turns": {
          "type": "integer"
        },
        "op": {
          "type": "string"
        },
        "option": {
          "type": "string"
        },
        "output_tokens_per_second": {},
        "parent_tool_use_id": {
          "description": "present exactly when the actor is nested (sub-agent, tool-agent, workflow stage) — makes F3/F4-style tree views reconstructable",
          "type": "string"
        },
        "percept_id": {
          "type": "string"
        },
        "reason": {
          "type": "string"
        },
        "recoverable": {
          "type": "boolean"
        },
        "result": {
          "type": "string"
        },
        "route": {
          "$ref": "#/$defs/route_decision"
        },
        "route_history": {
          "items": {
            "$ref": "#/$defs/route_hop"
          },
          "type": "array"
        },
        "running_ids": {
          "items": {
            "type": "string"
          },
          "type": "array"
        },
        "seq": {
          "description": "monotonic per run (gap-tolerant consumers can detect dropped lines on relays)",
          "type": "integer"
        },
        "session_id": {
          "description": "milk session id (sess_...)",
          "type": "string"
        },
        "session_state": {
          "type": "string"
        },
        "severity": {
          "type": "string"
        },
        "status": {
          "type": "string"
        },
        "stop_reason": {
          "description": "open set (known: end_turn, max_turns, refusal, cancelled, error)",
          "type": "string"
        },
        "subject": {
          "type": "string"
        },
        "subtype": {
          "description": "system family: init | agent_switch | route | notification | warning | state | task_started | task_progress | task_notification | background_tasks_changed | memory | commands | config_option | permission_denied | error; result family: success | error_during_execution | error_max_turns | interrupted | refused (open sets — ignore unrecognized values)",
          "type": "string"
        },
        "task": {
          "description": "free-form task payload (workflow stage node, live-buffer chunk, ...) — tool/provider detail belongs here or in extension/_meta"
        },
        "task_id": {
          "type": "string"
        },
        "to": {
          "type": "string"
        },
        "tool": {
          "type": "string"
        },
        "tool_use_result": {
          "description": "free-form structured tool summary (path, is_error, summary)"
        },
        "tools": {
          "items": {
            "type": "string"
          },
          "type": "array"
        },
        "total_cost_usd": {
          "description": "reserved — emitted only once milk has a pricing table"
        },
        "ts": {
          "description": "RFC 3339 timestamp",
          "type": "string"
        },
        "ttft_ms": {
          "type": "integer"
        },
        "type": {
          "description": "line discriminator — system | stream_event | assistant | user | result (open set: ignore unknown values)",
          "type": "string"
        },
        "usage": {
          "allOf": [
            {
              "$ref": "#/$defs/usage"
            }
          ],
          "description": "aggregate per-run token accounting"
        },
        "value": {
          "type": "string"
        },
        "warnings": {
          "items": {
            "type": "string"
          },
          "type": "array"
        }
      },
      "required": [
        "type",
        "session_id",
        "seq",
        "ts"
      ],
      "type": "object"
    },
    "mcpserver": {
      "additionalProperties": false,
      "properties": {
        "name": {
          "type": "string"
        },
        "status": {
          "type": "string"
        }
      },
      "required": [
        "name",
        "status"
      ],
      "type": "object"
    },
    "message": {
      "additionalProperties": false,
      "properties": {
        "content": {
          "items": {
            "$ref": "#/$defs/content_block"
          },
          "type": "array"
        },
        "id": {
          "type": "string"
        },
        "role": {
          "type": "string"
        }
      },
      "required": [
        "role",
        "content"
      ],
      "type": "object"
    },
    "route_decision": {
      "additionalProperties": false,
      "properties": {
        "conclusive": {
          "type": "boolean"
        },
        "reason": {
          "type": "string"
        },
        "target": {
          "type": "string"
        }
      },
      "required": [
        "target"
      ],
      "type": "object"
    },
    "route_hop": {
      "additionalProperties": false,
      "properties": {
        "target": {
          "type": "string"
        },
        "turn": {
          "type": "integer"
        }
      },
      "required": [
        "turn",
        "target"
      ],
      "type": "object"
    },
    "stream_payload": {
      "additionalProperties": false,
      "properties": {
        "_meta": {
          "description": "free-form JSON object (host/implementation metadata)"
        },
        "delta": {
          "$ref": "#/$defs/delta"
        },
        "extension": {
          "description": "free-form JSON object (provider detail — never new modeled keys)"
        },
        "index": {
          "type": "integer"
        },
        "partial_json": {
          "description": "progressive tool-argument fragment (AI SDK-style delta framing; consumers concatenate, no partial-JSON reassembly)",
          "type": "string"
        },
        "tool_use_id": {
          "type": "string"
        },
        "type": {
          "description": "content_block_delta | tool_args_delta (open set)",
          "type": "string"
        }
      },
      "required": [
        "type"
      ],
      "type": "object"
    },
    "usage": {
      "additionalProperties": false,
      "properties": {
        "cache_creation": {
          "description": "milk's snake_case token-cache key (session store + eval reports) — kept as-is rather than Anthropic's cache_creation_input_tokens (design §6.4)",
          "type": "integer"
        },
        "cache_read": {
          "description": "milk's snake_case token-cache key (session store + eval reports) — kept as-is rather than Anthropic's cache_read_input_tokens (design §6.4)",
          "type": "integer"
        },
        "input_tokens": {
          "type": "integer"
        },
        "output_tokens": {
          "type": "integer"
        }
      },
      "required": [
        "input_tokens",
        "output_tokens",
        "cache_read",
        "cache_creation"
      ],
      "type": "object"
    }
  },
  "$id": "https://github.com/scoutme/milk/docs/schema/stream-json.schema.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "additionalProperties": false,
  "description": "Validates ONE line of milk's batch machine-readable output stream\n(milk \"prompt\" --output-format stream-json), the JSONL wire ratified in\nADR-0049 and locked in detail by docs/internal/design/machine-readable-output-design.md §6\n(event catalog) and §8.3 (batch conventions).\n\nFraming rules the schema cannot express (enforced by the golden-file contract\nsuite in internal/transport/streamjson): one UTF-8 JSON object per line with\none trailing newline and nothing else on stdout; system/init first; exactly\none terminal result last; monotonic seq per run; never any ANSI escapes;\nprovider detail confined to the extension/_meta reserved fields (or free-form\npayloads such as tool_use.input and tool_use_result).\n\nConventions: snake_case fields; a \"type\" discriminator per line plus \"subtype\"\nfor the system/result families; open-set enums everywhere — this schema\ndocuments known values in descriptions but does not constrain them, and\nconsumers must ignore values they don't recognize (result subtype known set:\nsuccess | error_during_execution | error_max_turns | interrupted | refused,\nwith is_error as the boolean contract — a refusal is a completed turn and\nreports is_error false). usage.cache_read / usage.cache_creation are milk's\nexisting snake_case token-cache keys (session store + eval reports), kept\nas-is rather than Anthropic's cache_read_input_tokens so one vocabulary spans\nsession files, eval reports, MilkEvent and this stream.\n\nEvolution is additive-only within capability stream_v1; any shape change\nrequires a superseding ADR.",
  "oneOf": [
    {
      "description": "lifecycle/meta lines: system/init first, then agent_switch | route | notification | warning | state | task_started | task_progress | task_notification | background_tasks_changed | memory | commands | config_option | permission_denied | error (open set)",
      "properties": {
        "type": {
          "const": "system"
        }
      },
      "required": [
        "type"
      ]
    },
    {
      "description": "partial deltas (partial_messages_v1): content_block_delta or tool_args_delta",
      "properties": {
        "type": {
          "const": "stream_event"
        }
      },
      "required": [
        "type"
      ]
    },
    {
      "description": "completed assistant message blocks (text | thinking | tool_use)",
      "properties": {
        "type": {
          "const": "assistant"
        }
      },
      "required": [
        "type"
      ]
    },
    {
      "description": "tool_result blocks + tool_use_result summary",
      "properties": {
        "type": {
          "const": "user"
        }
      },
      "required": [
        "type"
      ]
    },
    {
      "description": "exactly one terminal line per run",
      "properties": {
        "type": {
          "const": "result"
        }
      },
      "required": [
        "type"
      ]
    }
  ],
  "properties": {
    "_meta": {
      "description": "reserved _meta field: host/implementation metadata (also the only other home for provider detail)"
    },
    "agent": {
      "description": "dual-form: the AgentInfo object on system/init lines; a role label string (primary | escalation) on assistant/user lines",
      "oneOf": [
        {
          "type": "string"
        },
        {
          "$ref": "#/$defs/agent_info"
        }
      ]
    },
    "body": {
      "type": "string"
    },
    "capabilities": {
      "description": "open-set strings (known: stream_v1, partial_messages_v1, tasks_v1, workflows_v1) — tolerate unknown values",
      "items": {
        "type": "string"
      },
      "type": "array"
    },
    "category": {
      "type": "string"
    },
    "command_hint": {
      "type": "string"
    },
    "commands": {
      "items": {
        "$ref": "#/$defs/command"
      },
      "type": "array"
    },
    "count": {
      "type": "integer"
    },
    "cwd": {
      "type": "string"
    },
    "duration_ms": {
      "type": "integer"
    },
    "escalation_agent": {
      "$ref": "#/$defs/agent_info"
    },
    "event": {
      "$ref": "#/$defs/stream_payload"
    },
    "extension": {
      "description": "reserved extension point: the ONLY home for provider-specific detail"
    },
    "finished_ids": {
      "items": {
        "type": "string"
      },
      "type": "array"
    },
    "from": {
      "type": "string"
    },
    "id": {
      "type": "string"
    },
    "is_error": {
      "description": "boolean contract: true when the run failed (execution error, max turns, interruption); present on every result line",
      "type": "boolean"
    },
    "kind": {
      "type": "string"
    },
    "limit": {
      "type": "integer"
    },
    "mcp_servers": {
      "items": {
        "$ref": "#/$defs/mcpserver"
      },
      "type": "array"
    },
    "message": {
      "description": "dual-form: a string on system/error lines; the Message object on assistant/user lines",
      "oneOf": [
        {
          "type": "string"
        },
        {
          "$ref": "#/$defs/message"
        }
      ]
    },
    "milk_version": {
      "type": "string"
    },
    "model_usage": {
      "additionalProperties": {
        "$ref": "#/$defs/usage"
      },
      "description": "per-model token rollups, keyed by model name",
      "type": "object"
    },
    "num_turns": {
      "type": "integer"
    },
    "op": {
      "type": "string"
    },
    "option": {
      "type": "string"
    },
    "output_tokens_per_second": {},
    "parent_tool_use_id": {
      "description": "present exactly when the actor is nested (sub-agent, tool-agent, workflow stage) — makes F3/F4-style tree views reconstructable",
      "type": "string"
    },
    "percept_id": {
      "type": "string"
    },
    "reason": {
      "type": "string"
    },
    "recoverable": {
      "type": "boolean"
    },
    "result": {
      "type": "string"
    },
    "route": {
      "$ref": "#/$defs/route_decision"
    },
    "route_history": {
      "items": {
        "$ref": "#/$defs/route_hop"
      },
      "type": "array"
    },
    "running_ids": {
      "items": {
        "type": "string"
      },
      "type": "array"
    },
    "seq": {
      "description": "monotonic per run (gap-tolerant consumers can detect dropped lines on relays)",
      "type": "integer"
    },
    "session_id": {
      "description": "milk session id (sess_...)",
      "type": "string"
    },
    "session_state": {
      "type": "string"
    },
    "severity": {
      "type": "string"
    },
    "status": {
      "type": "string"
    },
    "stop_reason": {
      "description": "open set (known: end_turn, max_turns, refusal, cancelled, error)",
      "type": "string"
    },
    "subject": {
      "type": "string"
    },
    "subtype": {
      "description": "system family: init | agent_switch | route | notification | warning | state | task_started | task_progress | task_notification | background_tasks_changed | memory | commands | config_option | permission_denied | error; result family: success | error_during_execution | error_max_turns | interrupted | refused (open sets — ignore unrecognized values)",
      "type": "string"
    },
    "task": {
      "description": "free-form task payload (workflow stage node, live-buffer chunk, ...) — tool/provider detail belongs here or in extension/_meta"
    },
    "task_id": {
      "type": "string"
    },
    "to": {
      "type": "string"
    },
    "tool": {
      "type": "string"
    },
    "tool_use_result": {
      "description": "free-form structured tool summary (path, is_error, summary)"
    },
    "tools": {
      "items": {
        "type": "string"
      },
      "type": "array"
    },
    "total_cost_usd": {
      "description": "reserved — emitted only once milk has a pricing table"
    },
    "ts": {
      "description": "RFC 3339 timestamp",
      "type": "string"
    },
    "ttft_ms": {
      "type": "integer"
    },
    "type": {
      "description": "line discriminator — system | stream_event | assistant | user | result (open set: ignore unknown values)",
      "type": "string"
    },
    "usage": {
      "allOf": [
        {
          "$ref": "#/$defs/usage"
        }
      ],
      "description": "aggregate per-run token accounting"
    },
    "value": {
      "type": "string"
    },
    "warnings": {
      "items": {
        "type": "string"
      },
      "type": "array"
    }
  },
  "required": [
    "type",
    "session_id",
    "seq",
    "ts"
  ],
  "title": "milk machine-readable output stream v1 — one stream-json line (stream_v1)",
  "type": "object"
}