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//! `StreamPart` — the individual chunk types emitted by `do_stream`.
//!
//! Aligned with V4 `LanguageModelV4StreamPart`. v0.1 implements the P0/P1 variants;
//! P2 variants (reasoning, file, source) are defined but not yet emitted by providers.
use serde::{Deserialize, Serialize};
use serde_json::Value;
use ts_rs::TS;
use crate::error::AiMuxError;
use crate::shared::FileData;
use crate::types::{FinishReason, ProviderMetadata, Usage, Warning};
/// A single chunk in the stream returned by `do_stream`.
#[derive(Debug, Clone, Serialize, Deserialize, TS)]
#[ts(export)]
pub enum StreamPart {
// ── P0: text ──
/// Start of a text segment.
TextStart {
id: String,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// A delta of generated text.
TextDelta {
id: String,
delta: String,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// End of a text segment.
TextEnd {
id: String,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
// ── P0: stream lifecycle ──
/// First chunk — carries warnings from the provider.
StreamStart { warnings: Vec<Warning> },
/// Final chunk — carries usage, finish reason, and metadata.
Finish {
finish_reason: FinishReason,
usage: Usage,
provider_metadata: Option<ProviderMetadata>,
},
/// An error occurred mid-stream.
Error { error: AiMuxError },
// ── P1: tool calls ──
/// Start of a tool call's input streaming.
ToolInputStart {
id: String,
tool_name: String,
/// Whether the tool call will be executed by the provider.
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_executed: Option<bool>,
/// Whether the tool is dynamic (defined at runtime, e.g. MCP tools).
#[serde(default, skip_serializing_if = "Option::is_none")]
dynamic: Option<bool>,
/// Optional title for the tool call.
#[serde(default, skip_serializing_if = "Option::is_none")]
title: Option<String>,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// A delta of tool call input (partial JSON).
ToolInputDelta {
id: String,
delta: String,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// End of a tool call's input streaming.
ToolInputEnd {
id: String,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// A complete tool call (alternative to the start/delta/end flow).
ToolCall {
tool_call_id: String,
tool_name: String,
input: Value,
/// Whether the tool call will be executed by the provider.
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_executed: Option<bool>,
/// Whether the tool is dynamic (defined at runtime, e.g. MCP tools).
#[serde(default, skip_serializing_if = "Option::is_none")]
dynamic: Option<bool>,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// A tool result (provider-executed tools).
ToolResult {
tool_call_id: String,
tool_name: String,
result: Value,
/// Whether the result is an error or error message.
#[serde(default, skip_serializing_if = "Option::is_none")]
is_error: Option<bool>,
/// Whether the result is preliminary (replaces prior, e.g. image previews).
#[serde(default, skip_serializing_if = "Option::is_none")]
preliminary: Option<bool>,
/// Whether the tool is dynamic (defined at runtime, e.g. MCP tools).
#[serde(default, skip_serializing_if = "Option::is_none")]
dynamic: Option<bool>,
/// Additional provider-specific metadata for the tool result.
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
// ── P2: file ──
/// A file generated by the model (e.g. an image or document).
///
/// Mirrors the Vercel AI SDK `file` stream part. `data` is a tagged union
/// covering base64 data, URL, or provider reference.
File {
data: FileData,
media_type: String,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
// ── P2: reasoning ──
ReasoningStart {
id: String,
/// Provider-specific metadata (e.g. xAI `itemId`).
#[allow(unused)]
provider_metadata: Option<ProviderMetadata>,
},
ReasoningDelta {
id: String,
delta: String,
/// Provider-specific metadata (e.g. xAI `itemId`).
#[allow(unused)]
provider_metadata: Option<ProviderMetadata>,
},
ReasoningEnd {
id: String,
/// Provider-specific metadata (e.g. xAI `itemId`, `reasoningEncryptedContent`).
#[allow(unused)]
provider_metadata: Option<ProviderMetadata>,
},
// ── P2: metadata ──
/// Response metadata (id, timestamp, model_id).
ResponseMetadata {
id: Option<String>,
timestamp: Option<String>,
model_id: Option<String>,
},
/// A source / citation (e.g. URL citation from search-preview models).
Source {
id: String,
source_type: String,
url: Option<String>,
title: Option<String>,
#[serde(default, skip_serializing_if = "Option::is_none")]
provider_metadata: Option<ProviderMetadata>,
},
/// A raw chunk from the provider (for debugging, when `include_raw_chunks` is set).
Raw { raw_value: Value },
}