Juncture Core

Core types and execution engine for the Juncture state machine framework. This crate provides the fundamental building blocks: State trait, Channel system, Pregel execution engine, and graph primitives.

Key Components

State System

• State trait with #[derive(State)] proc-macro
• CowState<S> for copy-on-write state management
• FieldsChanged bitmask for tracking state changes
• Reducer semantics: Replace, Append, LastWriteWins, Any, Custom

Pregel Engine

• Multi-core parallel execution via tokio::spawn + JoinSet
• Bounded concurrency with Semaphore
• Field version tracking for deterministic execution

Graph Primitives

• StateGraph<S,I,O> builder
• CompiledGraph<S,I,O> execution
• Node<S> trait and IntoNode conversions
• Edge, Router, PathMap for graph topology

HITL Support

• interrupt!() and interrupt_with_ctx!() macros
• ResumeValue for single/ID-based/namespace-based resumes
• Scratchpad for persistent interrupt context

Usage

use juncture_core::prelude::*;

#[derive(State)]
struct MyState {
    #[reducer(append)]
    messages: Vec<String>,
    #[reducer(replace)]
    count: usize,
}

// Build and compile a graph
let graph = StateGraph::<MyState, _, _>::new()
    .add_node("process", process_node)
    .add_edge(START, "process")
    .add_edge("process", END)
    .compile();

Feature Flags

License

Licensed under Apache License, Version 2.0. See LICENSE for details.