RAG Pipeline (LangChain + OpenAI + Zvec)

Retrieval-Augmented Generation pipeline: FastAPI backend with LangChain + Zvec (in-process vector DB) + OpenAI, plus a Next.js frontend you can wire up to the API.

Project structure

backend/    # FastAPI + LangChain + Zvec API (Poetry)
frontend/   # Next.js app scaffold (Bun)

Backend quickstart

Option 1: Docker (Recommended)

1. Configure environment:
   • cp env.example .env
   • Set OPENAI_API_KEY (and other values as needed).
2. Run with Docker Compose:
   • docker-compose up --build
3. Docs: http://localhost:8000/docs

Option 2: Local Development (Python 3.12+)

1. Install with uv (recommended):
   • uv sync
2. Or with pip:
   • pip install -e .
3. Configure environment:
   • cp env.example .env
   • Set OPENAI_API_KEY (and other values as needed).
4. Run:
   • uvicorn app.main:app --reload
   • Or with uv: uv run uvicorn app.main:app --reload
5. Docs: http://localhost:8000/docs

Frontend quickstart

1. Install (requires Bun):
   • cd frontend
   • bun install
2. Run dev server:
   • bun dev
3. Point the UI to the backend API (default http://localhost:8000); update env/config in the frontend as you build features.

Key environment variables (backend/env.example)

• APP_NAME / APP_DESCRIPTION: Shown in FastAPI docs.
• OPENAI_API_KEY, OPENAI_API_BASE, OPENAI_MODEL, OPENAI_EMBEDDING_MODEL: OpenAI credentials/models.
• ZVEC_DATABASE, ZVEC_COLLECTION_NAME: Zvec collection path and name.
• EMBEDDING_DIMENSION: Vector size (default 1536 for text-embedding-3-small).
• DATA_DIRECTORY: Where uploaded/source documents are stored.

API overview

• GET /health: Health check.
• POST /upload: Upload a document to be chunked and indexed into Zvec.
• POST /chat: Retrieval + generation over indexed docs.

Data locations

• Zvec collection: backend/data/zvec/<ZVEC_COLLECTION_NAME>
• Uploaded/source docs: backend/data/documents

Notes

• Zvec supports Linux (x86_64, ARM64) and macOS (ARM64) only. On Windows, run the backend in WSL or Docker.
• Keep your secrets in backend/.env (ignored by git).
• Defaults in code can be overridden via .env. Align app metadata there as needed.