Enum UIStreamEvent 

pub enum UIStreamEvent {
    MessageStart {
        message_id: Option<String>,
        message_metadata: Option<Value>,
    },
    TextStart {
        id: String,
        provider_metadata: Option<Value>,
    },
    TextDelta {
        id: String,
        delta: String,
        provider_metadata: Option<Value>,
    },
    TextEnd {
        id: String,
        provider_metadata: Option<Value>,
    },
    ReasoningStart {
        id: String,
        provider_metadata: Option<Value>,
    },
    ReasoningDelta {
        id: String,
        delta: String,
        provider_metadata: Option<Value>,
    },
    ReasoningEnd {
        id: String,
        provider_metadata: Option<Value>,
    },
    ToolInputStart {
        tool_call_id: String,
        tool_name: String,
        provider_executed: Option<bool>,
        dynamic: Option<bool>,
        title: Option<String>,
    },
    ToolInputDelta {
        tool_call_id: String,
        input_text_delta: String,
    },
    ToolInputAvailable {
        tool_call_id: String,
        tool_name: String,
        input: Value,
        provider_executed: Option<bool>,
        provider_metadata: Option<Value>,
        dynamic: Option<bool>,
        title: Option<String>,
    },
    ToolInputError {
        tool_call_id: String,
        tool_name: String,
        input: Value,
        provider_executed: Option<bool>,
        provider_metadata: Option<Value>,
        dynamic: Option<bool>,
        error_text: String,
        title: Option<String>,
    },
    ToolApprovalRequest {
        approval_id: String,
        tool_call_id: String,
    },
    ToolOutputAvailable {
        tool_call_id: String,
        output: Value,
        provider_executed: Option<bool>,
        dynamic: Option<bool>,
        preliminary: Option<bool>,
    },
    ToolOutputDenied {
        tool_call_id: String,
    },
    ToolOutputError {
        tool_call_id: String,
        error_text: String,
        provider_executed: Option<bool>,
        dynamic: Option<bool>,
    },
    StartStep,
    FinishStep,
    SourceUrl {
        source_id: String,
        url: String,
        title: Option<String>,
        provider_metadata: Option<Value>,
    },
    SourceDocument {
        source_id: String,
        media_type: String,
        title: String,
        filename: Option<String>,
        provider_metadata: Option<Value>,
    },
    File {
        url: String,
        media_type: String,
        provider_metadata: Option<Value>,
    },
    Finish {
        finish_reason: Option<String>,
        message_metadata: Option<Value>,
    },
    Abort {
        reason: Option<String>,
    },
    MessageMetadata {
        message_metadata: Value,
    },
    Error {
        error_text: String,
    },
    Data {
        data_type: String,
        id: Option<String>,
        data: Value,
        transient: Option<bool>,
    },
}

Stream event types compatible with AI SDK v6.

These events map directly to the AI SDK UI Message Stream protocol. See: https://ai-sdk.dev/docs/ai-sdk-ui/stream-protocol

Variants

MessageStart

Indicates the beginning of a new message with metadata.

AI SDK v6 expects this as {"type":"start","messageId":"..."}.

Fields

message_id: Option<String>

Unique identifier for this message.

message_metadata: Option<Value>

Optional message metadata.

TextStart

Indicates the beginning of a text block.

Fields

id: String

Unique identifier for this text block.

provider_metadata: Option<Value>

Optional provider metadata.

TextDelta

Contains incremental text content for the text block.

Fields

id: String

Identifier matching the text-start event.

delta: String

Incremental text content.

provider_metadata: Option<Value>

Optional provider metadata.

TextEnd

Indicates the end of a text block.

Fields

id: String

Identifier matching the text-start event.

provider_metadata: Option<Value>

Optional provider metadata.

ReasoningStart

Indicates the beginning of a reasoning block.

Fields

id: String

Unique identifier for this reasoning block.

provider_metadata: Option<Value>

Optional provider metadata.

ReasoningDelta

Contains incremental reasoning content.

Fields

id: String

Identifier matching the reasoning-start event.

delta: String

Incremental reasoning content.

provider_metadata: Option<Value>

Optional provider metadata.

ReasoningEnd

Indicates the end of a reasoning block.

Fields

id: String

Identifier matching the reasoning-start event.

provider_metadata: Option<Value>

Optional provider metadata.

ToolInputStart

Indicates the beginning of tool input streaming.

Fields

tool_call_id: String

Unique identifier for this tool call.

tool_name: String

Name of the tool being called.

provider_executed: Option<bool>

Whether the provider executed this tool directly.

dynamic: Option<bool>

Whether this is a dynamic tool part.

title: Option<String>

Optional UI title.

ToolInputDelta

Contains incremental chunks of tool input as it’s being generated.

Fields

tool_call_id: String

Identifier matching the tool-input-start event.

input_text_delta: String

Incremental tool input text.

ToolInputAvailable

Indicates that tool input is complete and ready for execution.

Fields

tool_call_id: String

Identifier matching the tool-input-start event.

tool_name: String

Name of the tool being called.

input: Value

Complete tool input as JSON.

provider_executed: Option<bool>

Whether the provider executed this tool directly.

provider_metadata: Option<Value>

Optional provider metadata.

dynamic: Option<bool>

Whether this is a dynamic tool part.

title: Option<String>

Optional UI title.

ToolInputError

Indicates tool input validation failed before execution.

NOTE: Not currently emitted. Reserved for future client-side tool input validation. Backend tool input errors surface via tool-output-error.

Fields

tool_call_id: String

Identifier matching the tool-input-start event.

tool_name: String

Name of the tool being called.

input: Value

Tool input payload.

provider_executed: Option<bool>

Whether the provider executed this tool directly.

provider_metadata: Option<Value>

Optional provider metadata.

dynamic: Option<bool>

Whether this is a dynamic tool part.

error_text: String

Error text.

title: Option<String>

Optional UI title.

ToolApprovalRequest

Requests user approval for a tool call.

Fields

approval_id: String

Approval request ID.

tool_call_id: String

Tool call ID this approval applies to.

ToolOutputAvailable

Contains the result of tool execution.

Fields

tool_call_id: String

Identifier matching the tool-input-start event.

output: Value

Tool execution result as JSON.

provider_executed: Option<bool>

Whether the provider executed this tool directly.

dynamic: Option<bool>

Whether this is a dynamic tool part.

preliminary: Option<bool>

Marks provisional tool output.

ToolOutputDenied

Indicates the tool output was denied by user approval.

Fields

tool_call_id: String

Identifier matching the tool-input-start event.

ToolOutputError

Indicates tool output failed with an execution error.

Fields

tool_call_id: String

Identifier matching the tool-input-start event.

error_text: String

Error text.

provider_executed: Option<bool>

Whether the provider executed this tool directly.

dynamic: Option<bool>

Whether this is a dynamic tool part.

StartStep

Marks the beginning of a step.

FinishStep

Marks the completion of an LLM API call step.

SourceUrl

References an external URL.

Fields

source_id: String

Unique identifier for this source.

url: String

The URL being referenced.

title: Option<String>

Optional title for the source.

provider_metadata: Option<Value>

Optional provider metadata.

SourceDocument

References a document or file.

Fields

source_id: String

Unique identifier for this source.

media_type: String

IANA media type of the document.

title: String

Title of the document.

filename: Option<String>

Optional filename.

provider_metadata: Option<Value>

Optional provider metadata.

File

Contains a file reference.

Fields

url: String

URL to the file.

media_type: String

IANA media type.

provider_metadata: Option<Value>

Optional provider metadata.

Finish

Indicates message completion.

Fields

finish_reason: Option<String>

Optional reason for finishing (stop, length, content-filter, tool-calls, error, other).

message_metadata: Option<Value>

Optional message metadata.

Abort

Signals stream abortion with a reason.

Fields

reason: Option<String>

Optional reason for the abort.

MessageMetadata

Emits incremental metadata updates for the active message.

Fields

message_metadata: Value

Message metadata payload.

Error

Appends error messages to stream.

Fields

error_text: String

Error text.

Data

Custom data event with a type prefix pattern (data-*).

Fields

data_type: String

Custom type name (must start with “data-”).

id: Option<String>

Optional stable data part ID.

data: Value

Custom data payload.

transient: Option<bool>

Whether the data should be treated as transient.

Implementations

impl UIStreamEvent

pub fn message_start(message_id: impl Into<String>) -> Self

Create a start event (message start).

pub fn start() -> Self

Create a start event without message ID.

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

Create a text-start event.

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

Create a text-delta event.

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

Create a text-end event.

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

Create a reasoning-start event.

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

Create a reasoning-delta event.

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

Create a reasoning-end event.

pub fn tool_input_start( tool_call_id: impl Into<String>, tool_name: impl Into<String>, ) -> Self

Create a tool-input-start event.

pub fn tool_input_delta( tool_call_id: impl Into<String>, delta: impl Into<String>, ) -> Self

Create a tool-input-delta event.

pub fn tool_input_available( tool_call_id: impl Into<String>, tool_name: impl Into<String>, input: Value, ) -> Self

Create a tool-input-available event.

pub fn tool_input_error( tool_call_id: impl Into<String>, tool_name: impl Into<String>, input: Value, error_text: impl Into<String>, ) -> Self

Create a tool-input-error event.

pub fn tool_approval_request( approval_id: impl Into<String>, tool_call_id: impl Into<String>, ) -> Self

Create a tool-approval-request event.

pub fn tool_output_available( tool_call_id: impl Into<String>, output: Value, ) -> Self

Create a tool-output-available event.

pub fn tool_output_denied(tool_call_id: impl Into<String>) -> Self

Create a tool-output-denied event.

pub fn tool_output_error( tool_call_id: impl Into<String>, error_text: impl Into<String>, ) -> Self

Create a tool-output-error event.

pub fn start_step() -> Self

Create a start-step event.

pub fn finish_step() -> Self

Create a finish-step event.

pub fn source_url( source_id: impl Into<String>, url: impl Into<String>, title: Option<String>, ) -> Self

Create a source-url event.

pub fn source_document( source_id: impl Into<String>, media_type: impl Into<String>, title: impl Into<String>, filename: Option<String>, ) -> Self

Create a source-document event.

pub fn file(url: impl Into<String>, media_type: impl Into<String>) -> Self

Create a file event.

pub fn finish() -> Self

Create a finish event.

pub fn finish_with_reason(reason: impl Into<String>) -> Self

Create a finish event with a reason.

pub fn abort(reason: impl Into<String>) -> Self

Create an abort event.

pub fn message_metadata(message_metadata: Value) -> Self

Create a message-metadata event.

pub fn error(error_text: impl Into<String>) -> Self

Create an error event.

pub fn data(name: impl Into<String>, data: Value) -> Self

Create a custom data event.

pub fn data_with_options( name: impl Into<String>, data: Value, id: Option<String>, transient: Option<bool>, ) -> Self

Create a custom data event with optional id/transient flags.

Trait Implementations

impl Clone for UIStreamEvent

fn clone(&self) -> UIStreamEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UIStreamEvent

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for UIStreamEvent

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for UIStreamEvent

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

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 UIStreamEvent