Enum StreamPart 

#[non_exhaustive]
pub enum StreamPart {
    StreamStart {
        warnings: Vec<Warning>,
    },
    ResponseMetadata {
        id: Option<String>,
        timestamp: Option<DateTime<Utc>>,
        model_id: Option<ModelId>,
    },
    TextStart {
        id: PartId,
        provider_metadata: Option<ProviderMetadata>,
    },
    TextDelta {
        id: PartId,
        delta: String,
        provider_metadata: Option<ProviderMetadata>,
    },
    TextEnd {
        id: PartId,
        provider_metadata: Option<ProviderMetadata>,
    },
    ReasoningStart {
        id: PartId,
        provider_metadata: Option<ProviderMetadata>,
    },
    ReasoningDelta {
        id: PartId,
        delta: String,
        provider_metadata: Option<ProviderMetadata>,
    },
    ReasoningEnd {
        id: PartId,
        provider_metadata: Option<ProviderMetadata>,
    },
    ToolInputStart {
        id: ToolCallId,
        tool_name: ToolName,
        provider_executed: bool,
        dynamic: bool,
        title: Option<String>,
        provider_metadata: Option<ProviderMetadata>,
    },
    ToolInputDelta {
        id: ToolCallId,
        delta: String,
        provider_metadata: Option<ProviderMetadata>,
    },
    ToolInputEnd {
        id: ToolCallId,
        provider_metadata: Option<ProviderMetadata>,
    },
    ToolCall(ToolCall),
    ToolResult(ProviderToolResult),
    ToolApprovalRequest {
        approval_id: ApprovalId,
        tool_call_id: ToolCallId,
        provider_metadata: Option<ProviderMetadata>,
    },
    File {
        data: FileData,
        media_type: MediaType,
        filename: Option<String>,
        provider_metadata: Option<ProviderMetadata>,
    },
    ReasoningFile {
        data: FileData,
        media_type: MediaType,
        provider_metadata: Option<ProviderMetadata>,
    },
    Source(Source),
    Custom {
        kind: CustomKind,
        provider_metadata: Option<ProviderMetadata>,
    },
    Finish {
        finish_reason: FinishReason,
        usage: Usage,
        provider_metadata: Option<ProviderMetadata>,
    },
    Raw {
        raw_value: JsonValue,
    },
    Error {
        error: StreamError,
    },
}

A part of a language model stream, tagged by type.

Ordering contract: a stream starts with StreamStart and ends with Finish (or Error); TextDelta parts appear between TextStart and TextEnd with the same id; tool input appears as ToolInputStart, zero or more ToolInputDelta, ToolInputEnd, then ToolCall.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

StreamStart

First part of every stream.

Fields

warnings: Vec<Warning>

Warnings produced while preparing the call.

ResponseMetadata

Response metadata, emitted once known.

Fields

id: Option<String>

Provider response id.

timestamp: Option<DateTime<Utc>>

Response timestamp.

model_id: Option<ModelId>

Model that produced the response.

TextStart

Start of a text part.

Fields

id: PartId

Part id.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

TextDelta

Text increment.

Fields

id: PartId

Part id.

delta: String

Appended text.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

TextEnd

End of a text part.

Fields

id: PartId

Part id.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ReasoningStart

Start of a reasoning part.

Fields

id: PartId

Part id.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ReasoningDelta

Reasoning increment.

Fields

id: PartId

Part id.

delta: String

Appended reasoning text.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ReasoningEnd

End of a reasoning part.

Fields

id: PartId

Part id.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ToolInputStart

Start of streamed tool input.

Fields

id: ToolCallId

Tool call id.

tool_name: ToolName

Name of the tool.

provider_executed: bool

Whether the provider executes the tool itself.

dynamic: bool

Whether the tool is dynamic.

title: Option<String>

Human-readable title for display, if the provider supplies one.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ToolInputDelta

Tool input increment (raw JSON text).

Fields

id: ToolCallId

Tool call id.

delta: String

Appended JSON text.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ToolInputEnd

End of streamed tool input.

Fields

id: ToolCallId

Tool call id.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ToolCall(ToolCall)

A complete tool call.

ToolResult(ProviderToolResult)

A provider-executed tool result.

ToolApprovalRequest

The provider asks for approval before executing a tool call.

Fields

approval_id: ApprovalId

Identifier of the approval request.

tool_call_id: ToolCallId

Identifier of the tool call awaiting approval.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

File

A generated file.

Fields

data: FileData

File payload.

media_type: MediaType

Media type of the payload.

filename: Option<String>

Optional file name.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

ReasoningFile

A reasoning artifact stored as a file.

Fields

data: FileData

File payload.

media_type: MediaType

Media type of the payload.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

Source(Source)

A citation source.

Custom

Provider-specific content.

Fields

kind: CustomKind

Kind of the content.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata carrying the payload.

Finish

Last part of a successful stream.

Fields

finish_reason: FinishReason

Why generation stopped.

usage: Usage

Token usage of the call.

provider_metadata: Option<ProviderMetadata>

Provider-specific metadata.

Raw

A raw provider chunk; only emitted when include_raw_chunks is set.

Fields

raw_value: JsonValue

The provider chunk as JSON.

Error

An error; the stream ends after this part.

Fields

error: StreamError

The error.

Implementations

impl StreamPart

pub fn stream_start() -> Self

Creates a StreamStart without warnings.

pub fn text_delta(id: impl Into<PartId>, delta: impl Into<String>) -> Self

Creates a TextDelta without metadata.

pub fn finish(finish_reason: FinishReason, usage: Usage) -> Self

Creates a Finish without metadata.

pub fn error(error: &ProviderError) -> Self

Creates an Error part from a provider error.

pub fn kind_name(&self) -> &'static str

Returns the wire name of the variant (text-delta, finish, …).

Trait Implementations

impl Clone for StreamPart

fn clone(&self) -> StreamPart

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StreamPart

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for StreamPart

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for StreamPart

fn eq(&self, other: &StreamPart) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for StreamPart

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for StreamPart