Xinmin Zeng 22290c1616
fix(frontend): preserve messages across context summarization (#3825) (#3826)
After SummarizationMiddleware runs, the merged conversation view could drop
already-displayed messages (previous assistant output, current user input),
leaving a nearly-empty thread.

Root cause: the display merge combines `visibleHistory` (archived history, a
React `useState` in useThreadHistory) with `persistedMessages` (live thread,
the LangGraph SDK external store via useSyncExternalStore). On summarization
the backend removes every live message and onUpdateEvent re-archives them via
an async `appendMessages` setState. Those two state systems are scheduled
independently, so a render can observe the post-summary (shrunk) thread before
the archive setState commits — the rescued messages are then absent from BOTH
merge inputs and get dropped.

Fix: bridge the async gap with a synchronous `pendingArchivedMessagesRef`
buffer written the moment onUpdateEvent computes the moved messages and read by
the merge on every render, so correctness no longer depends on how the two
channels interleave. The buffer drains once history confirms absorption and
only injects messages missing from history (live copies stay authoritative,
order preserved). It is tagged with the thread it was captured from and the
merge overlays it only when that matches the viewed `threadId` (the same prop
visibleHistory is gated on), so it can never leak into another thread or the
new-chat screen — a read-only check, no render-phase ref mutation.

Extracts the moved-message derivation and the merge overlay into pure,
unit-tested helpers (computeSummarizationMovedMessages, resolvePreservedHistory,
pruneConfirmedArchivedMessages) with regression coverage for the full rescue
pipeline.
2026-06-28 11:48:56 +08:00
..
2026-01-14 09:58:53 +08:00
2026-01-24 19:38:08 +08:00
2026-02-10 22:07:25 +08:00

DeerFlow Frontend

Like the original DeerFlow 1.0, we would love to give the community a minimalistic and easy-to-use web interface with a more modern and flexible architecture.

Tech Stack

Quick Start

Prerequisites

  • Node.js 22+
  • pnpm 10.26.2+

Installation

# Install dependencies
pnpm install

# Copy environment variables
cp .env.example .env
# Edit .env with your configuration

Development

# Start development server
pnpm dev

# The app will be available at http://localhost:3000

Build & Test

# Type check
pnpm typecheck

# Check formatting
pnpm format

# Apply formatting
pnpm format:write

# Lint
pnpm lint

# Run unit tests
pnpm test

# One-time setup: install Playwright Chromium browser
pnpm exec playwright install chromium

# Run E2E tests (builds and starts production server automatically)
pnpm test:e2e

# Build for production
pnpm build

# Start production server
pnpm start

Site Map

├── /                    # Landing page
├── /chats               # Chat list
├── /chats/new           # New chat page
└── /chats/[thread_id]   # A specific chat page

Configuration

Environment Variables

Key environment variables (see .env.example for full list):

# Backend API URL (optional, uses local Next.js/nginx proxy by default)
NEXT_PUBLIC_BACKEND_BASE_URL="http://localhost:8001"
# LangGraph-compatible API URL (optional, uses local Next.js/nginx proxy by default)
NEXT_PUBLIC_LANGGRAPH_BASE_URL="http://localhost:8001/api"

Project Structure

tests/
├── e2e/                    # E2E tests (Playwright, Chromium, mocked backend)
└── unit/                   # Unit tests (mirrors src/ layout)
src/
├── app/                    # Next.js App Router pages
│   ├── api/                # API routes
│   ├── workspace/          # Main workspace pages
│   └── mock/               # Mock/demo pages
├── components/             # React components
│   ├── ui/                 # Reusable UI components
│   ├── workspace/          # Workspace-specific components
│   ├── landing/            # Landing page components
│   └── ai-elements/        # AI-related UI elements
├── core/                   # Core business logic
│   ├── api/                # API client & data fetching
│   ├── artifacts/          # Artifact management
│   ├── config/              # App configuration
│   ├── i18n/               # Internationalization
│   ├── mcp/                # MCP integration
│   ├── messages/           # Message handling
│   ├── models/             # Data models & types
│   ├── settings/           # User settings
│   ├── skills/             # Skills system
│   ├── threads/            # Thread management
│   ├── todos/              # Todo system
│   └── utils/              # Utility functions
├── hooks/                  # Custom React hooks
├── lib/                    # Shared libraries & utilities
├── server/                 # Server-side code
│   └── better-auth/        # Authentication setup and session helpers
└── styles/                 # Global styles

Scripts

Command Description
pnpm dev Start development server with Turbopack
pnpm build Build for production
pnpm start Start production server
pnpm test Run unit tests with Rstest
pnpm test:e2e Run E2E tests with Playwright
pnpm format Check formatting with Prettier
pnpm format:write Apply formatting with Prettier
pnpm lint Run ESLint
pnpm lint:fix Fix ESLint issues
pnpm typecheck Run TypeScript type checking
pnpm check Run both lint and typecheck

Development Notes

  • Uses pnpm workspaces (see packageManager in package.json)
  • Turbopack enabled by default in development for faster builds
  • Environment validation can be skipped with SKIP_ENV_VALIDATION=1 (useful for Docker)
  • Backend API URLs are optional; nginx proxy is used by default in development

License

MIT License. See LICENSE for details.