deer-flow/frontend/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

DeerFlow Frontend is a Next.js 16 web interface for an AI agent system. It communicates with a LangGraph-based backend to provide thread-based AI conversations with streaming responses, artifacts, and a skills/tools system.

Stack: Next.js 16, React 19, TypeScript 5.8, Tailwind CSS 4, pnpm 10.26.2

Commands

Command	Purpose
pnpm dev	Dev server with Turbopack (http://localhost:3000)
pnpm build	Production build
pnpm check	Lint + type check (run before committing)
pnpm lint	ESLint only
pnpm lint:fix	ESLint with auto-fix
pnpm test	Run unit tests with Vitest
pnpm test:e2e	Run E2E tests with Playwright (Chromium)
pnpm typecheck	TypeScript type check (tsc --noEmit)
pnpm start	Start production server

Unit tests live under tests/unit/ and mirror the src/ layout (e.g., tests/unit/core/api/stream-mode.test.ts tests src/core/api/stream-mode.ts). Powered by Vitest; import source modules via the @/ path alias.

E2E tests live under tests/e2e/ and use Playwright with Chromium. They mock all backend APIs via page.route() network interception and test real page interactions (navigation, chat input, streaming responses). Config: playwright.config.ts.

Architecture

Frontend (Next.js) ──▶ LangGraph SDK ──▶ LangGraph Backend (lead_agent)
                                              ├── Sub-Agents
                                              └── Tools & Skills

The frontend is a stateful chat application. Users create threads (conversations), send messages, and receive streamed AI responses. The backend orchestrates agents that can produce artifacts (files/code) and todos.

Source Layout (src/)

• app/ — Next.js App Router. Routes: / (landing), /workspace/chats/[thread_id] (chat).
• components/ — React components split into:
  • ui/ — Shadcn UI primitives (auto-generated, ESLint-ignored)
  • ai-elements/ — Vercel AI SDK elements (auto-generated, ESLint-ignored)
  • workspace/ — Chat page components (messages, artifacts, settings)
  • landing/ — Landing page sections
• core/ — Business logic, the heart of the app:
  • threads/ — Thread creation, streaming, state management (hooks + types)
  • api/ — LangGraph client singleton
  • artifacts/ — Artifact loading and caching
  • i18n/ — Internationalization (en-US, zh-CN)
  • settings/ — User preferences in localStorage
  • memory/ — Persistent user memory system
  • skills/ — Skills installation and management
  • messages/ — Message processing and transformation
  • mcp/ — Model Context Protocol integration
  • models/ — TypeScript types and data models
• hooks/ — Shared React hooks
• lib/ — Utilities (cn() from clsx + tailwind-merge)
• server/ — Server-side code (better-auth, not yet active)
• styles/ — Global CSS with Tailwind v4 @import syntax and CSS variables for theming

Data Flow

1. User input → thread hooks (core/threads/hooks.ts) → LangGraph SDK streaming
2. Stream events update thread state (messages, artifacts, todos)
3. TanStack Query manages server state; localStorage stores user settings
4. Components subscribe to thread state and render updates

Key Patterns

• Server Components by default, "use client" only for interactive components
• Thread hooks (useThreadStream, useSubmitThread, useThreads) are the primary API interface
• LangGraph client is a singleton obtained via getAPIClient() in core/api/
• Environment validation uses @t3-oss/env-nextjs with Zod schemas (src/env.js). Skip with SKIP_ENV_VALIDATION=1

Code Style

• Imports: Enforced ordering (builtin → external → internal → parent → sibling), alphabetized, newlines between groups. Use inline type imports: import { type Foo }.
• Unused variables: Prefix with _.
• Class names: Use cn() from @/lib/utils for conditional Tailwind classes.
• Path alias: @/* maps to src/*.
• Components: ui/ and ai-elements/ are generated from registries (Shadcn, MagicUI, React Bits, Vercel AI SDK) — don't manually edit these.

Environment

Backend API URLs are optional; an nginx proxy is used by default:

NEXT_PUBLIC_BACKEND_BASE_URL=http://localhost:8001
NEXT_PUBLIC_LANGGRAPH_BASE_URL=http://localhost:2024

Requires Node.js 22+ and pnpm 10.26.2+.