Crate a3s_code_core 

A3S Code Core Library

Embeddable AI agent library with tool execution capabilities. This crate contains all business logic extracted from the A3S Code agent, enabling direct Rust API usage as an embedded library.

Quick Start

use a3s_code_core::{Agent, AgentEvent};

// From a config file path (.hcl or .json)
let agent = Agent::new("agent.hcl").await?;

// Create a workspace-bound session
let session = agent.session("/my-project", None)?;

// Non-streaming
let result = session.send("What files handle auth?", None).await?;
println!("{}", result.text);

// Streaming (AgentEvent is #[non_exhaustive])
let (mut rx, _handle) = session.stream("Refactor auth", None).await?;
while let Some(event) = rx.recv().await {
    match event {
        AgentEvent::TextDelta { text } => print!("{text}"),
        AgentEvent::End { .. } => break,
        _ => {} // required: #[non_exhaustive]
    }
}

Architecture

Agent (facade — config-driven, workspace-independent)
  +-- LlmClient (Anthropic / OpenAI)
  +-- CodeConfig (HCL / JSON)
  +-- SessionManager (multi-session support)
        |
        +-- AgentSession (workspace-bound)
              +-- AgentLoop (core execution engine)
              |     +-- ToolExecutor (14 tools: 11 builtin + 3 skill discovery)
              |     +-- LlmPlanner (JSON-structured planning)
              |     +-- HITL Confirmation
              +-- HookEngine (8 lifecycle events)
              +-- Security (sanitizer, taint, injection detection, audit)
              +-- Memory (episodic, semantic, procedural, working)
              +-- MCP (JSON-RPC 2.0, stdio + HTTP+SSE)
              +-- Cost Tracking / Telemetry

Re-exports

pub use agent::AgentConfig;

pub use agent::AgentEvent;

pub use agent::AgentLoop;

pub use agent::AgentResult;

pub use agent_api::Agent;

pub use agent_api::AgentSession;

pub use agent_api::SessionOptions;

pub use agent_api::ToolCallResult;

pub use agent_teams::AgentTeam;

pub use agent_teams::TeamConfig;

pub use agent_teams::TeamMember;

pub use agent_teams::TeamMessage;

pub use agent_teams::TeamRole;

pub use agent_teams::TeamTaskBoard;

pub use commands::CommandAction;

pub use commands::CommandContext;

pub use commands::CommandOutput;

pub use commands::CommandRegistry;

pub use commands::SlashCommand;

pub use config::CodeConfig;

pub use config::ModelConfig;

pub use config::ModelCost;

pub use config::ModelLimit;

pub use config::ModelModalities;

pub use config::ProviderConfig;

pub use error::CodeError;

pub use error::Result;

pub use hooks::HookEngine;

pub use llm::AnthropicClient;

pub use llm::Attachment;

pub use llm::ContentBlock;

pub use llm::ImageSource;

pub use llm::LlmClient;

pub use llm::LlmResponse;

pub use llm::Message;

pub use llm::OpenAiClient;

pub use llm::TokenUsage;

pub use queue::ExternalTask;

pub use queue::ExternalTaskResult;

pub use queue::LaneHandlerConfig;

pub use queue::SessionLane;

pub use queue::SessionQueueConfig;

pub use queue::SessionQueueStats;

pub use queue::TaskHandlerMode;

pub use sandbox::SandboxConfig;

pub use session::SessionConfig;

pub use session::SessionManager;

pub use session::SessionState;

pub use session_lane_queue::SessionLaneQueue;

pub use skills::builtin_skills;

pub use skills::Skill;

pub use skills::SkillKind;

pub use tool_search::ToolIndex;

pub use tool_search::ToolMatch;

pub use tool_search::ToolSearchConfig;

pub use tools::ToolContext;

pub use tools::ToolExecutor;

pub use tools::ToolResult;

Modules

agent

Agent Loop Implementation

agent_api

Agent Facade API

agent_teams

Agent Teams — Peer-to-peer multi-agent coordination

commands

Slash Commands — Interactive session commands

config

Configuration module for A3S Code

context

Context Provider Extension Point

error

Typed error enum for A3S Code Core

file_history

File version history tracking

hitl

Human-in-the-Loop (HITL) confirmation mechanism

hooks

Hooks System for A3S Code Agent

llm

LLM client abstraction layer

mcp

MCP (Model Context Protocol) Support

memory

Memory and learning system for the agent.

permissions

Permission system for tool execution control

planning

Planning, Goal Tracking, and Task Management

queue

Per-session command queue with lane-based priority scheduling

sandbox

Sandbox integration for bash tool execution.

security

Security Module

session

Session management

session_lane_queue

Session Lane Queue - a3s-lane backed command queue

skills

Skill System

store

Session persistence layer

telemetry

Telemetry Module (Core)

tool_search

Tool Search — Semantic tool matching for dynamic MCP tool loading

tools

Extensible Tool System

Structs

SystemPromptSlots

Slot-based system prompt customization.