Enum Chunk 

#[non_exhaustive]
pub enum Chunk {
    TextDelta(String),
    ToolCallStart {
        id: String,
        name: String,
        signature: Option<String>,
    },
    ToolCallArgsDelta {
        id: String,
        args_json_delta: String,
    },
    ToolCallEnd {
        id: String,
    },
    Usage(Usage),
    Stop(StopReason),
}

A single event in a provider’s streaming response.

A complete stream is an ordered sequence of these. Text generation surfaces as a run of Chunk::TextDelta events; a tool call surfaces as exactly one Chunk::ToolCallStart, zero or more Chunk::ToolCallArgsDelta fragments (whose concatenated args_json_deltas form the call’s JSON arguments), and exactly one Chunk::ToolCallEnd. Every tool-call event carries the call id so concurrently-streamed calls can be demultiplexed. Chunk::Usage reports token accounting and may appear more than once. A well-formed stream ends with a single Chunk::Stop.

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.

TextDelta(String)

An incremental piece of generated text. Concatenate consecutive TextDeltas to recover the full text segment.

ToolCallStart

The model has begun a tool call. The id and name are known up front; arguments stream in as subsequent Chunk::ToolCallArgsDeltas bearing the same id.

Fields

id: String

Provider-assigned call identifier, matching a future ToolCall::id.

name: String

Name of the tool being called.

signature: Option<String>

Opaque provider-specific signature for this call (e.g. a thinking model’s thought signature), to be carried onto the assembled ToolCall and echoed back on the follow-up request. None when the provider emits no such token.

ToolCallArgsDelta

An incremental fragment of a tool call’s JSON arguments. Concatenate the args_json_deltas of all fragments sharing an id to recover the full args_json. Do not parse until the matching Chunk::ToolCallEnd.

Fields

id: String

Identifies which in-progress Chunk::ToolCallStart this fragment belongs to.

args_json_delta: String

A partial slice of the call’s JSON-encoded arguments.

ToolCallEnd

The named tool call’s arguments are complete and may now be parsed.

Fields

id: String

Identifies the completed Chunk::ToolCallStart.

Usage(Usage)

A token-accounting update. May arrive more than once per stream (e.g. input tokens early, output tokens at the end).

Stop(StopReason)

Terminal event: generation has finished for the reason given.

Implementations

impl Chunk

pub fn text_delta(s: impl Into<String>) -> Self

Wraps s in a Chunk::TextDelta.

pub fn tool_call_start(id: impl Into<String>, name: impl Into<String>) -> Self

Constructs a Chunk::ToolCallStart event (no signature).

pub fn tool_call_start_signed( id: impl Into<String>, name: impl Into<String>, signature: Option<String>, ) -> Self

Constructs a Chunk::ToolCallStart event carrying an opaque provider-specific signature.

pub fn tool_call_args_delta( id: impl Into<String>, args_json_delta: impl Into<String>, ) -> Self

Constructs a Chunk::ToolCallArgsDelta carrying a partial-args fragment.

pub fn tool_call_end(id: impl Into<String>) -> Self

Constructs a Chunk::ToolCallEnd event.

Trait Implementations

impl Clone for Chunk

fn clone(&self) -> Chunk

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Chunk

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Chunk

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for Chunk

impl PartialEq for Chunk

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Chunk

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 Chunk