Juca — Legal AI Frontend Hub

Juca

Juca is the frontend hub for the sens.legal ecosystem — a conversational interface that orchestrates specialized legal AI agents for Brazilian legal research.

Built with Next.js 16 and React 19, Juca provides a Fintool/Perplexity-style interface where lawyers interact with a unified Composer, and the system routes their queries to the right backend agent. Results are rendered as structured Blocks — typed UI cards that present diagnoses, precedents, risk analyses, and strategic recommendations.

Key Capabilities

Juca’s core value is progressive disclosure of legal analysis through the Briefing Progressivo system:

• Block System — 11 typed UI blocks that render structured legal content (diagnoses, precedents, risk balances, deliveries)
• Briefing Progressivo — 4-phase progressive disclosure: Diagnosis → Precedents → Risks → Delivery
• Valter Integration — Consumes the Valter REST API for STJ jurisprudence search, citation verification, and knowledge graph analysis
• Session Management — Persistent sessions with SQLite, navigable via sidebar
• PDF Export — Generate PDF documents from briefing sessions
• Real-time Streaming — SSE-based progress streaming during analysis

The sens.legal Ecosystem

Juca does not work alone. It is the user-facing layer of a three-project ecosystem:

graph TB
    subgraph "Frontend"
        Juca["Juca<br/>Next.js 16 · React 19<br/>Block System · SSE<br/>Lightweight Orchestrator"]
    end
    subgraph "Backend Agents"
        Valter["Valter<br/>FastAPI · Python<br/>23.4K STJ Decisions<br/>KG · Search · LLM Pipeline"]
        Leci["Leci<br/>Next.js · Drizzle<br/>Federal Legislation<br/>DB-first · v0.1-pre"]
    end
    Juca -->|"REST API"| Valter
    Juca -.->|"REST API (future)"| Leci

See Architecture → Ecosystem for details on each project.

Quick Links

I want to…	Go to
Run Juca locally in 5 minutes	Quickstart
Understand the architecture	Architecture Overview
Learn about the Block System	Block System
See the product roadmap	Roadmap
Configure environment variables	Environment
Write or run tests	Testing Guide

Project Status

Juca is currently targeting v0.3 — “Hub Foundation”: transforming from a fullstack monolith into a lightweight frontend hub connected to the Valter backend agent. See the Roadmap for milestone details.