deer-flow/frontend/AGENTS.md

AGENTS.md

This file provides guidance to AI coding agents (Claude Code, Codex, and others) when working with the DeerFlow frontend. It is the source of truth; the sibling CLAUDE.md imports it via @AGENTS.md.

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. Requires Node.js 22+ and pnpm 10.26.2+.

Core dependencies

• LangGraph SDK (@langchain/langgraph-sdk ^1.5.3) — Agent orchestration and streaming
• LangChain Core (@langchain/core ^1.1.15) — Fundamental AI building blocks
• TanStack Query (@tanstack/react-query ^5.90.17) — Server state management
• UI: Shadcn UI, MagicUI, React Bits, and Vercel AI SDK elements (generated from registries — see Code Style)

pnpm-workspace.yaml overrides vulnerable @xmldom/xmldom 0.9.x releases to 0.9.12 for GHSA-965w-775f-mr7g. Nextra pulls it in through MathJax and speech-rule-engine@4.1.2, which pins 0.9.8. Keep the override until the upstream dependency chain resolves a patched version without it; regenerate pnpm-lock.yaml and verify the docs build when changing this constraint.

Commands

Command	Purpose
pnpm dev	Start the development server with Webpack
pnpm build	Production build
pnpm check	Lint + type check (run before committing)
pnpm lint	ESLint only
pnpm lint:fix	ESLint with auto-fix
pnpm format	Prettier check (pnpm format:write to apply)
pnpm test	Run unit tests with Rstest
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 Rstest; import source modules via the @/ path alias.

Webpack is the default development bundler. Use DEER_FLOW_DEV_BUNDLER=turbo with pnpm dev to opt in to Turbopack when diagnosing a local Next.js bundler issue.

Rstest runs them as two projects (rstest.config.ts). *.test.ts / *.test.tsx run in a plain node environment — that is nearly the whole suite, and it is the default for anything that is pure logic. *.dom.test.ts / *.dom.test.tsx run in happy-dom, for tests that need a document: hooks driven through renderHook from @testing-library/react, and components. Keep the split — a DOM environment costs roughly 3x the runtime of the node suite, so tests that do not render should not opt into it. A hook whose behavior only exists under real React (effect ordering, cleanup on unmount, re-render on store change) belongs in a .dom.test.* file rather than a node test that mocks react itself.

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. The real-backend auth contract in tests/e2e-real-backend/auth-disabled-contract.spec.ts and backend/tests/test_auth_me_permissions.py pin the complete route-permission list; update both when adding registered permissions (including projects:read/write/delete).

The dedicated run-history.ts hook replaces the unpaged runs hook. Show counts only after a successful history read, never during initial loading or errors. Scheduled run history uses task/page query keys and the existing live offset API. Fetch 51 rows to display 50 plus a next-page sentinel; never append pages. Only page zero polls or refreshes on focus/reconnect. Task switches reset to page zero, and consumed AbortSignals cancel obsolete reads. Live offsets are not snapshots; explicit mutations or navigation may observe newly inserted runs.

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, set thread-scoped /goal completion conditions, and receive streamed AI responses. The backend orchestrates agents that can produce artifacts (files/code), todos, and goal state updates.

Source Layout (src/)

• app/ — Next.js App Router. Routes include / (landing), /showcase/[thread_id] (allowlisted public read-only demos), /workspace/chats/[thread_id] (authenticated chat), /workspace/agents/[agent_name] and /workspace/agents/new (custom agents), /artifacts/view (chrome-free window that renders Markdown or CSV/TSV artifacts with the panel's own renderer), /blog/…, the (auth)/{login,setup,auth/callback} flow, /[lang]/docs/…, and /api/… route handlers (e.g. /api/memory).
• components/ — React components:
  • 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
  • docs/ — Docs / MDX rendering components
• core/ — Business logic, the heart of the app. Domains include threads/ (creation, streaming, state), api/ (LangGraph client singleton), agents/ (custom agents), subagents/ (runtime worker catalog and administrator mutations), auth/ (authentication), artifacts/, channels/ (IM connections), integrations/ (managed third-party integration status/install clients such as Lark CLI), i18n/ (en-US, zh-CN), settings/, memory/, skills/, messages/, mcp/, models/, input-polish/ (pre-send draft rewrite API), voice-input/ (browser speech-recognition helpers), suggestions/, tasks/, todos/, tools/, workspace-changes/ (run-scoped changed-file summaries and diff fetching), config/, notification/, blog/, plus rendering helpers (rehype/, streamdown/) and utils/.
• hooks/ — Shared React hooks
• lib/ — Utilities (cn() from clsx + tailwind-merge)
• content/ — MDX content (blog posts, docs) rendered by the app
• styles/ — Global CSS with Tailwind v4 @import syntax and CSS variables for theming
• typings/ — Ambient TypeScript declarations
• Root files: env.js (env validation), mdx-components.ts (MDX component map)

More specific AGENTS.md files under src/ contain the frontend sections split from this file.

Code Style

Custom Agent display_name is an optional Unicode UI label, edited in AgentSettingsDialog. Use it with a fallback to name for gallery/chat text; keep name for React identity, URLs, requests, and runtime agent_name. The 100-code-point budget uses [...value.trim()].length, matching Pydantic; do not use HTML maxLength, which counts UTF-16 code units instead.

• 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

Scheduled-task interval forms preserve the initial every_seconds on mount, timezone changes, and untouched blur. The backend's configurable interval minimum can be lower than the UI's default 60-second floor. Apply that UI floor only after an explicit amount/unit edit so editing metadata or duplicating a task cannot silently change its cadence. Component regressions live in tests/unit/components/workspace/scheduled-task-schedule-input.dom.test.tsx.

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:8001/api

Leave these unset for the standard make dev / Docker flow, where nginx serves the public /api/langgraph/* prefix and rewrites it to Gateway's native /api/* routes.

make build-static creates a standalone read-only demo and copies .next/static and public into the output. In static mode, core/api/static-response.ts resolves Gateway REST reads with empty capability/catalog responses or existing same-origin /mock/api fixtures; writes and unknown API routes fail locally. The homepage client counter calls /github-stars, outside the Gateway proxy. That dynamic route reads the server-only GITHUB_OAUTH_TOKEN at runtime, caches GitHub data for one hour, and returns 204 when the count is unavailable. Start the standalone server from frontend/ with node --env-file=.env .next/standalone/server.js to load the current credentials.

To reach a dev server on anything other than localhost — a LAN address, or a proxied hostname — list the host in DEER_FLOW_DEV_ALLOWED_ORIGINS (comma-separated; a full URL is reduced to its host). It feeds Next's allowedDevOrigins, which gates /_next/*, fonts, and HMR. Without it those requests get a 403 and the page renders server-side but never hydrates, so nothing on it — including the login form — responds. Development only; production builds ignore it.

Resources

• LangGraph Documentation
• LangChain Core Concepts
• TanStack Query Documentation
• Next.js App Router

Contributing

When adding features:

1. Follow the established src/ structure
2. Add TypeScript types and proper error handling
3. Write unit tests under tests/unit/ (pnpm test) and E2E tests under tests/e2e/ (pnpm test:e2e)
4. Run pnpm check before committing
5. Update this AGENTS.md when architecture, commands, or conventions change

Route asset budgets are enforced with pnpm perf:check. The command measures /login from a normal production build, then builds in static-demo mode for the fixture-backed workspace routes. It starts the production server on temporary local ports, measures the unique JavaScript and CSS files referenced by representative routes, writes the detailed result to .next/performance-results.json, and compares totals with performance-budgets.json. Fix route ownership or split points when a budget fails; do not raise a ceiling without documenting and reviewing the measured regression.

Chat archive is a thread metadata flag (deerflow_archived === true), independent of run status. Sidebar and Chats explicitly request the Gateway's optional archived filter through searchThreadsByArchive; the SDK drops this extension, so use the authenticated REST fetcher. Static demos retain SDK fixture queries. core/threads/archive.ts waits for the write, cancels stale reads, merges only the owned flag into metadata snapshots, then restarts metadata reads and resets list pagination. Keep both default and Custom Agent header restore controls in sync. Pin/archive responses must not merge unrelated metadata flags: out-of-order organization requests can otherwise roll back each other's confirmed state. Run-created optimistic snapshots have no archive flag: refresh archive-filtered lists from the server instead of inserting those snapshots into either view.

Delimited artifact preview

CSV/TSV previews share artifact-table-preview.tsx between the panel and standalone viewer. Papa Parse runs only inside delimited-preview.worker.ts; use-delimited-preview.ts bounds input before transfer, cancels stale work, and enforces a five-second timeout. The parser detects the first record separator outside quoted fields and passes it explicitly to Papa Parse, so embedded newlines in an incomplete quoted field cannot corrupt newline detection. It retains at most 202 logical records and 50 columns, discarding an incomplete final record from truncated input. UI pagination displays at most 200 data rows in pages of 50. Keep the table mounted but inactive when switching to source so header/pagination state survives; changing file identity resets it. Pending write_file content stays in source mode until success.

Custom skill export is admin-only and disabled in static demos. The lazy skill-export-dialog.tsx must abort requests and ignore stale callbacks on close or user/skill changes. core/skills/export.ts owns the revision-bound Blob download; HTTP 409 requires explicit preview refresh. Keep file lists paginated and diagnostics localized. Browser handoff does not prove the file was saved to disk.