Module stream 

Streaming event types for LLM API responses.

Types used when consuming Server-Sent Events (SSE) based streaming responses from LLM APIs. The core StreamEvent enum represents each discrete event in the stream lifecycle, while StreamAccumulator collects those events into a complete Message.

Streaming allows the framework to process model output incrementally — displaying text as it arrives, detecting tool invocations as soon as the part starts, and reporting token usage without waiting for the full response. Essential for responsive agent behavior.

Stream Lifecycle

The streaming protocol follows this event sequence:

MessageStart → [PartStart → IndexedDelta* → PartStop]* → MessageDelta → MessageStop

Ping events may appear at any point in the stream and should be ignored by consumers.

Provided Types

• StreamEvent — Top-level enum for every SSE event type.
• StreamAccumulator — Stateful builder that turns events into a Message.
• StreamStopReason — Why the model stopped generating tokens.
• Usage — Token consumption statistics.
• DeltaPart — Incremental content payload (text, tool JSON, or partial JSON).
• IndexedDelta — An indexed DeltaPart carrying the part position.
• MessageStart / MessageDelta — Boundary events with metadata.

Sub-modules

• handler — handler::StreamHandler with retry, timeout, and fallback for resilient streaming.

Quick Start

use loopctl::stream::{StreamAccumulator, StreamEvent, StreamStopReason};

let mut acc = StreamAccumulator::new();

// Feed events as they arrive from the SSE connection
for event in std::iter::empty::<StreamEvent>() {
    acc.process(&event).unwrap();
}

// Get usage before building (build consumes the accumulator)
let _usage = acc.usage();
let message = acc.build();

Re-exports

pub use handler::DetectedRateLimit;

pub use handler::RateLimitConfig;

pub use handler::RateLimitKind;

pub use rate_limit::RateLimiter;

pub use rate_limit::TokenBucket;

Modules

handler

Resilient LLM stream handling.

rate_limit

Proactive client-side rate limiting (token bucket).

Structs

IndexedDelta

A delta (incremental update) for the current part.

MessageDelta

A delta update for the message, typically emitted at the end of the stream.

MessageDeltaPayload

The delta details within a MessageDelta event.

MessageMetadata

Metadata about a message from the API.

MessageStart

The start of a new message from the API.

PartStart

The start of a new part within the response.

StreamAccumulator

Accumulates streaming events into a complete Message.

Usage

Token usage statistics from an API response.

Enums

DeltaPart

A delta (incremental update) for content within a streaming response.

StreamError

Errors that can occur during stream event processing.

StreamEvent

An event from a streaming LLM API response.

StreamStopReason

Reason why the model stopped generating tokens.