@type t() ::
  %ArchAstro.Types.Operations.PostApiV1AiChatCompletionsStream.Input.Nested.MessagesItem{
    content: String.t() | ArchAstro.Unset.t(),
    content_parts:
      [%{optional(String.t()) => ArchAstro.JSON.t()}] | ArchAstro.Unset.t(),
    resume_token: String.t() | ArchAstro.Unset.t(),
    role: String.t(),
    structured_output: ArchAstro.JSON.t() | ArchAstro.Unset.t(),
    tool_calls:
      [
        ArchAstro.Types.Operations.PostApiV1AiChatCompletionsStream.Input.Nested.MessagesItemToolCallsItem.t()
      ]
      | ArchAstro.Unset.t(),
    tool_results:
      [
        ArchAstro.Types.Operations.PostApiV1AiChatCompletionsStream.Input.Nested.MessagesItemToolResultsItem.t()
      ]
      | ArchAstro.Unset.t()
  }