Enum StreamEvent 

pub enum StreamEvent {
    StepStart {
        index: u32,
    },
    StepFinish {
        index: u32,
        finish_reason: FinishReason,
        usage: Option<Usage>,
    },
    TextStart {
        content_index: usize,
    },
    TextDelta {
        content_index: usize,
        delta: String,
    },
    TextEnd {
        content_index: usize,
    },
    ReasoningStart {
        content_index: usize,
    },
    ReasoningDelta {
        content_index: usize,
        delta: String,
    },
    ReasoningEnd {
        content_index: usize,
    },
    ToolCallStart {
        content_index: usize,
        id: ToolCallId,
        name: String,
    },
    ToolCallDelta {
        content_index: usize,
        delta: String,
    },
    ToolCallEnd {
        content_index: usize,
    },
    ToolResult {
        id: ToolCallId,
        name: String,
        result: ToolResultValue,
    },
    ToolError {
        id: ToolCallId,
        name: String,
        message: String,
    },
    Finish {
        finish_reason: FinishReason,
        usage: Option<Usage>,
    },
    ProviderError {
        message: String,
        retryable: bool,
    },
}

LLM 流式事件 — provider 无关的细粒度输出事件。

遵循 OpenCode 的 start/delta/end 三段式设计：

• start — 标记一个内容块开始，消费者可据此创建 UI 占位
• delta — 增量数据，消费者追加到当前块
• end — 标记内容块结束，消费者可据此 finalize

每个事件通过 content_index 标识其所属的内容块位置 （一次 LLM 回复可能包含多个并行内容块）。

Variants

StepStart

一个推理步骤开始（provider 可能在一次请求中产出多步）

Fields

index: u32

StepFinish

一个推理步骤结束，携带停止原因和 token 用量

Fields

index: u32

finish_reason: FinishReason

usage: Option<Usage>

TextStart

文本内容块开始

Fields

content_index: usize

TextDelta

文本增量

Fields

content_index: usize

delta: String

TextEnd

文本内容块结束

Fields

content_index: usize

ReasoningStart

推理/思考内容块开始

Fields

content_index: usize

ReasoningDelta

推理增量

Fields

content_index: usize

delta: String

ReasoningEnd

推理内容块结束

Fields

content_index: usize

ToolCallStart

工具调用开始（已知 id 和 name）

Fields

content_index: usize

id: ToolCallId

name: String

ToolCallDelta

工具调用参数增量（JSON 字符串片段）

Fields

content_index: usize

delta: String

ToolCallEnd

工具调用参数流结束

Fields

content_index: usize

ToolResult

工具执行成功

Fields

id: ToolCallId

name: String

result: ToolResultValue

ToolError

工具执行失败

Fields

id: ToolCallId

name: String

message: String

Finish

整个 LLM 请求完成

Fields

finish_reason: FinishReason

usage: Option<Usage>

ProviderError

Provider 级别错误（网络、认证、限流等）

Fields

message: String

retryable: bool

Implementations

impl StreamEvent

pub fn is_terminal(&self) -> bool

是否为终态事件（Finish 或 ProviderError）。

pub fn is_text_delta(&self) -> bool

是否为文本增量事件。

pub fn is_reasoning_delta(&self) -> bool

是否为推理增量事件。

pub fn as_text_delta(&self) -> Option<&str>

提取文本增量内容，非 TextDelta 事件返回 None。

pub fn as_reasoning_delta(&self) -> Option<&str>

提取推理增量内容，非 ReasoningDelta 事件返回 None。

Trait Implementations

impl Clone for StreamEvent

fn clone(&self) -> StreamEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StreamEvent

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for StreamEvent

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for StreamEvent

fn eq(&self, other: &StreamEvent) -> 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 StreamEvent

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 StreamEvent