Core concepts
State, nodes, edges, compilation — the four primitives.
LangGraph
Low-level orchestration for stateful, long-running LLM agents. Explicit state, durable checkpoints, conditional routing, human-in-the-loop. Available in Python and TypeScript with identical mental models.
Choose your language
Section titled “Choose your language” 🐍 Python v1.2.11 · chaptered Zero → Hero tutorial with 10 paginated chapters plus v3 streaming, set_node_defaults, pre/post model hooks, tools_condition, MessagesState, RetryPolicy, TimeoutPolicy, CachePolicy.
📘 TypeScript v1.3.5 · MessagesZodState, STREAM_EVENTS_V3_MODES, stream transformers, pushMessage.
What you’ll find in both guides
Section titled “What you’ll find in both guides”Multi-agent
Supervisor, parallel workers, handoff patterns.
Memory
Checkpointers for short-term, Stores for cross-thread memory.
Middleware
Pre/post model hooks for guardrails, rate limiting, logging.
Human-in-the-loop
Interrupts, multi-stage approvals, time-travel debugging.
Production
Docker, Kubernetes, observability, LangGraph Cloud.
Not sure which language?
Section titled “Not sure which language?”- Python has the larger ecosystem, more recipes, and the tutorial has been split into 10 paginated chapters for a true zero-to-hero walkthrough.
- TypeScript is best if your app is already Node/browser — identical primitives, full type safety.
Revision history
Section titled “Revision history”| Date | Version | Changes |
|---|---|---|
| 2026-09-14 | Py 1.2.11 / TS 1.3.5 | Source-verified rewrite: ch2 expanded to 6 patterns (MessagesState, create_react_agent, tools_condition, multi-mode streaming); ch8 completely rewritten — langchain.agents.middleware and langchain.agents.create_agent exist in the separate langchain package (not bundled with langgraph); ch8 documents the pre_model_hook/post_model_hook hooks available in langgraph standalone, plus per-node error_handler/retry_policy/timeout/cache_policy, set_node_defaults, and ToolNode(handle_tool_errors=...) — all verified against installed langgraph==1.2.11 source. Note: create_react_agent is deprecated per official LangGraph v1 migration docs in favour of langchain.agents.create_agent. |
| 2026-09-08 | Py 1.2.11 / TS 1.3.5 | Consistency sweep. TypeScript card corrected 1.3.0 → 1.3.5; the TypeScript observability and streaming pages moved off a stale Latest: 1.0.2; every Latest: stamp now names its package. Tables of contents on the TypeScript pages trimmed to sections that exist. No package installation or symbol verification performed. |
| 2026-08-24 | Python 1.2.11 / TS 1.3.0 | Python updated to 1.2.11; ch1 version bump; ch4 added ToolInvocationError with interceptor example; ch6 added experimental v3 stream_events API (GraphRunStream, SubgraphRunStream, LifecyclePayload, StreamChannel); ch10 added set_node_defaults() with graph-wide policy defaults. |
| 2026-06-22 | Python 1.2.6 / TS 1.3.0 | Python updated to 1.2.6; ch6 expanded with all 7 stream modes, typed StreamPart, GraphOutput; ch10 expanded with RetryPolicy, TimeoutPolicy, CachePolicy, Durability, IsLastStep, Topic channels, Send timeout. |
| 2026-05-05 | Python 1.1.10 / TS 1.3.0 | TypeScript card updated to v1.3.0 with new description. |
| 2026-04-21 | Python 1.1.8 / TS 1.2.9 | Parent index redesigned as language selector. |
| April 16, 2026 | Python 1.1.6 / TS 1.2.8 | Python 3.9 dropped; type-safe v2 API; toolkit package. |
| November 2025 | Python 1.0.3 / TS 1.0.2 | Initial multi-language guide. |