Ai_provider.Stream_partSourceIndividual parts emitted during streaming generation.
type t = | Stream_start of {warnings : Warning.t list;}| Text of {}| Reasoning of {}| Tool_call_delta of {}| Tool_call_finish of {}| File of {}| Source of {source_type : string;id : string;url : string;title : string option;provider_options : Provider_options.t;}| Finish of {finish_reason : Finish_reason.t;usage : Usage.t;provider_metadata : Provider_options.t option;Provider-specific metadata available after the stream finishes (e.g. Anthropic cache_creation_input / cache_read_input token counts). Matches the providerMetadata field on upstream's finish LanguageModelV4StreamPart.
}| Error of {error : Provider_error.t;}