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AGENTS

Last Updated: 3/9/2026

Pie Project Structure

This document provides a concise overview of the key directories and components in the Pie project for Agents to understand the architecture.

runtime

The Rust-based Main Runtime.

  • Path: runtime/
  • Language: Rust
  • Description: This is the core “Engine” of Pie. It implements the high-performance logic including the WASM runtime (based on Wasmtime), request scheduling, and networking (ZeroMQ).
  • Integration: It exposes a Python interface via PyO3, allowing it to be controlled by the server layer.
  • Key Dependencies: wasmtime, tokio, zeromq, pyo3.

pie

Main Entrypoint and CLI (pie) + Inference Backend.

  • Path: pie/
  • Language: Python (pie-server) + Rust (PyO3 extension)
  • Description: The primary interface for the user. It wraps the runtime (Rust), includes the inference backend (pie_worker), and provides the pie CLI.
  • Subdirectories:
    • src/pie/: Core engine management logic
    • src/pie_cli/: CLI commands (pie serve, pie run, etc.)
    • src/pie_worker/: Inference backend (was pie-backend) - handles model loading, KV caching, forward passes
    • src/flashinfer_metal/: Metal GPU kernels (Apple Silicon)
  • CLI: Provides the pie command.
    • pie serve: Starts the full engine and backend.
    • pie run: Executes a one-shot inferlet.
    • pie model: Manages downloaded models.
    • pie config: Manages configuration.
    • pie doctor: Checks system health.

sdk

SDK for Writing Inferlets.

  • Path: sdk/
  • Description: Contains libraries and tools for developers to write “Inferlets” (WASM programs that run on Pie).
  • Subdirectories:
    • rust/, python/, javascript/: Client SDKs and Inferlet APIs.

sdk/tools/bakery

Inferlet Toolchain (bakery).

  • Path: sdk/tools/bakery/
  • Language: Python (pie-bakery)
  • Description: The CLI tool for developing Inferlets.
    • bakery create: Scaffolds new projects.
    • bakery build: Compiles source (Rust/JS) to WASM.
    • bakery publish: Publishes inferlets to the registry.

client

Client Libraries.

  • Path: client/
  • Description: Contains client-side libraries for connecting to a serving Pie instance.
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