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Forester Architecture & Components

Forester is structured into four primary subsystems: the Language & Compiler, the Runtime Engine, Analysis & Simulation, and Integrations & Tooling.

1. Language & Compiler

Forester provides a domain-specific language (DSL) tailored for behavior tree orchestration.

  • Tree DSL (.tree): A strongly-typed language for describing execution logic, higher-order trees, lambdas, decorators, and Blackboard memory references.
  • Static Analysis & Compiler: Parses scripts, verifies type constraints, validates argument bounds, and detects structural errors before runtime.

2. Runtime Engine

The Rust runtime engine manages tree execution and state.

  • Engine Core: Ticks nodes reactively, supporting synchronous execution (for fast control loops) and asynchronous execution (for non-blocking I/O).
  • Blackboard: High-performance, shared memory store for passing data between tree nodes dynamically.
  • Action Keeper: Registers and executes actions (local Rust callbacks or remote RPC handlers).

3. Analysis & Simulation

Tools to inspect, debug, and validate behavior trees during development.

  • f-tree CLI: Unified command-line tool for compiling, analyzing, and running trees.
  • Visualization: Generates tree diagrams (Graphviz) to inspect tree structure visually.
  • Execution Tracing: Detailed execution telemetry for stepping through ticks and debugging node state.
  • Simulator: Executes trees against stubbed action responses to test orchestration logic before linking real hardware or external LLM APIs.

4. Integrations & Tooling

Bridge Forester to external runtimes, robotics engines, and developer editors.

  • Remote Action SDKs: Lightweight clients allowing actions to run outside the Rust process:
    • Python (forester-http-ra-py): Execute Python functions and LangChain/LlamaIndex tools seamlessly over HTTP.
    • Rust (forester-rs): Native Rust action integration.
  • ROS Nav2 Exporter: Exports Forester trees directly to ROS2 Nav2 XML format for robotics navigation pipelines.
  • Editor Tooling: Syntax highlighting, linting, and Language Server Protocol (LSP) support for IDEs (VS Code, IntelliJ).