{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "ModelRequest",
  "description": "A complete, attributed model request. Constructed only via [`ModelRequestBuilder`].",
  "type": "object",
  "properties": {
    "fragments": {
      "type": "array",
      "items": {
        "$ref": "#/$defs/PromptFragment"
      }
    },
    "max_output_tokens": {
      "type": [
        "integer",
        "null"
      ],
      "format": "uint32",
      "minimum": 0
    },
    "model": {
      "type": "string"
    },
    "thinking_level": {
      "$ref": "#/$defs/ThinkingLevel"
    },
    "tools": {
      "type": "array",
      "items": {
        "$ref": "#/$defs/ToolDefinition"
      }
    }
  },
  "required": [
    "fragments",
    "tools",
    "model",
    "thinking_level"
  ],
  "$defs": {
    "ContentBlock": {
      "description": "Provider-neutral content block.",
      "oneOf": [
        {
          "type": "object",
          "properties": {
            "text": {
              "type": "string"
            },
            "type": {
              "type": "string",
              "const": "text"
            }
          },
          "required": [
            "type",
            "text"
          ]
        },
        {
          "description": "Provider reasoning returned alongside an assistant message. Adapters\nthat support preserved thinking replay this through their native\nfield; other adapters deliberately omit it.",
          "type": "object",
          "properties": {
            "text": {
              "type": "string"
            },
            "type": {
              "type": "string",
              "const": "reasoning"
            }
          },
          "required": [
            "type",
            "text"
          ]
        },
        {
          "type": "object",
          "properties": {
            "base64_data": {
              "type": "string"
            },
            "media_type": {
              "type": "string"
            },
            "type": {
              "type": "string",
              "const": "image"
            }
          },
          "required": [
            "type",
            "media_type",
            "base64_data"
          ]
        },
        {
          "type": "object",
          "properties": {
            "arguments": true,
            "tool_name": {
              "type": "string"
            },
            "tool_use_id": {
              "$ref": "#/$defs/ToolUseId"
            },
            "type": {
              "type": "string",
              "const": "tool_use"
            }
          },
          "required": [
            "type",
            "tool_use_id",
            "tool_name",
            "arguments"
          ]
        },
        {
          "type": "object",
          "properties": {
            "content": {
              "type": "string"
            },
            "is_error": {
              "type": "boolean"
            },
            "tool_use_id": {
              "$ref": "#/$defs/ToolUseId"
            },
            "type": {
              "type": "string",
              "const": "tool_result"
            }
          },
          "required": [
            "type",
            "tool_use_id",
            "content",
            "is_error"
          ]
        }
      ]
    },
    "ContentSource": {
      "description": "The origin category of a piece of model-bound content.",
      "oneOf": [
        {
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "system_prompt"
            }
          },
          "required": [
            "kind"
          ]
        },
        {
          "description": "A typed context block (env details, rules, skills catalog, ...).",
          "type": "object",
          "properties": {
            "block_id": {
              "type": "string"
            },
            "kind": {
              "type": "string",
              "const": "context_block"
            }
          },
          "required": [
            "kind",
            "block_id"
          ]
        },
        {
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "tool_definitions"
            }
          },
          "required": [
            "kind"
          ]
        },
        {
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "user_message"
            }
          },
          "required": [
            "kind"
          ]
        },
        {
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "session_message"
            }
          },
          "required": [
            "kind"
          ]
        },
        {
          "description": "Prior assistant output replayed as history.",
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "assistant_history"
            }
          },
          "required": [
            "kind"
          ]
        },
        {
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "tool_output"
            },
            "tool_name": {
              "type": "string"
            }
          },
          "required": [
            "kind",
            "tool_name"
          ]
        },
        {
          "description": "Harness-injected content, distinct from user-authored messages.",
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "system_reminder"
            },
            "origin": {
              "type": "string"
            }
          },
          "required": [
            "kind",
            "origin"
          ]
        },
        {
          "type": "object",
          "properties": {
            "hook_name": {
              "type": "string"
            },
            "kind": {
              "type": "string",
              "const": "hook"
            }
          },
          "required": [
            "kind",
            "hook_name"
          ]
        },
        {
          "type": "object",
          "properties": {
            "kind": {
              "type": "string",
              "const": "compaction_summary"
            }
          },
          "required": [
            "kind"
          ]
        }
      ]
    },
    "PromptFragment": {
      "description": "A source-attributed piece of a model request. Fields are private; the only\nconstructors require attribution at the call site.\n\n```compile_fail\nuse htmlp::runtime::{PromptFragment, Role};\nlet fragment = PromptFragment::text(Role::User, \"untagged\");\n```",
      "type": "object",
      "properties": {
        "byte_count": {
          "type": "integer",
          "format": "uint",
          "minimum": 0
        },
        "content": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/ContentBlock"
          }
        },
        "role": {
          "$ref": "#/$defs/Role"
        },
        "source": {
          "$ref": "#/$defs/ContentSource"
        }
      },
      "required": [
        "source",
        "role",
        "content",
        "byte_count"
      ]
    },
    "Role": {
      "description": "Message role; source attribution remains independent of role.",
      "type": "string",
      "enum": [
        "user",
        "assistant",
        "system"
      ]
    },
    "ThinkingLevel": {
      "description": "Reasoning/thinking effort. Providers map this to their native knob\n(Anthropic `budget_tokens`, OpenAI `reasoning_effort`).",
      "oneOf": [
        {
          "type": "string",
          "enum": [
            "off",
            "low",
            "medium",
            "high"
          ]
        },
        {
          "description": "Serialized as \"xhigh\". Providers clamp to the model's max effort.",
          "type": "string",
          "const": "xhigh"
        },
        {
          "description": "Provider-native maximum reasoning effort when distinct from xhigh.",
          "type": "string",
          "const": "max"
        }
      ]
    },
    "ToolDefinition": {
      "description": "A tool definition offered to the model. Counted under\n[`ContentSource::ToolDefinitions`] in attribution.",
      "type": "object",
      "properties": {
        "description": {
          "type": "string"
        },
        "input_schema": true,
        "name": {
          "type": "string"
        }
      },
      "required": [
        "name",
        "description",
        "input_schema"
      ]
    },
    "ToolUseId": {
      "description": "Opaque provider-neutral tool-call identity. The caller generates IDs;\nHTMLP has no UUID, clock, or random-number dependency.",
      "type": "string"
    }
  }
}