Hachi (ハチ)

Visual Architecture Platform for Advanced RAG Systems

Executive Summary

Hachi is a collaborative visual platform for engineering teams who are building RAG systems and need to understand advanced retrieval architectures before implementation.

The Problem

Engineering teams attempting to build production RAG systems often get stuck at naive implementations:

• They retrieve documents, pass them to an LLM, and get mediocre results
• They've read about HyDE, CRAG, and Fusion but can't visualize how these patterns fit together
• Architecture discussions happen on whiteboards that don't execute
• Failed experiments provide no insight into why they failed

Hachi's Solution

Hachi provides a React Flow canvas where engineers can:

• Design advanced RAG architectures collaboratively
• Execute real pipelines against real data
• Inspect data flow at every step (Wire Tap)
• Diagnose why their approaches are failing
• Iterate on architecture as a team before committing to code

Hachi is not a low-code builder. It's an engineering tool for understanding complex RAG systems.

Key Features

• Visual Canvas: Built on React Flow for designing data pipelines.
• Wire Tap: Inspect data flow at every step (inputs, outputs, transformations).
• Real-Time Collaboration: Live cursors, instant sync, and shared execution using Yjs.
• Advanced RAG Nodes: Pre-built nodes for HyDE, Parent-Child Retrieval, Fusion & Re-ranking, and CRAG.
• Execution Engine: Compiles visual graphs to executable Mastra workflows.

System Architecture

High-Level Stack

• Frontend: Next.js 14 (App Router), React Flow (XYFlow), TailwindCSS, ShadcnUI
• State Management: Zustand for local UI state, Yjs (CRDTs) for real-time collaboration
• Backend API: Hono (lightweight, fast web framework)
• Database: Supabase (PostgreSQL + pgvector), Drizzle ORM
• AI Engine: Mastra (AI Framework)
• Infrastructure: Docker, Server-Sent Events (SSE) for streaming

Monorepo Structure

/hachi-monorepo
├── apps
│   ├── web                 # Visual Architecture IDE (Next.js)
│   └── api                 # Mastra Execution Engine (Hono)
├── packages
│   ├── database            # Drizzle Schema & Migrations (Supabase + pgvector)
│   ├── mastra-core         # Custom Mastra Steps, Tools & Agents
│   ├── schemas             # Shared Zod Schemas (Node Inputs/Outputs)
│   └── ui                  # Shared Design System Components (ShadcnUI)

Getting Started

To install dependencies:

bun install

To run:

bun run index.ts

This project was created using bun init in bun v1.3.0. Bun is a fast all-in-one JavaScript runtime.