Architecture Diagram

+---------------------------------------------------------------------------+
|                        User Application                                    |
|                                                                            |
|  +-----------------------------------------------+                        |
|  |  User Application Code                         |                       |
|  |  (graph nodes, tools; StateGraph builder API   |                       |
|  |   and functional API @entrypoint/@task both    |                       |
|  |   compile to the same Pregel execution engine) |                       |
|  +------------------------+----------------------+                        |
|                           |                                                |
|              +------------v-----------+                                   |
|              |  StateGraph / Pregel    |                                   |
|              |  (core execution engine)|                                   |
|              +------+----------+------+                                   |
|                     |          |                                           |
|              InjectedState  +--v---------+                                |
|              InjectedStore  |  ToolNode  |                                |
|              ToolRuntime    |  (opt-in)  |                                |
|                             +------------+                                |
|                       |                                                    |
| - - - - - - - - - - - | - - - - TB1: User/Framework API - - - - - - - -  |
|                       |                                                    |
|                 +-----v------+   +--------------+                         |
|                 | Checkpoint |   | RemoteGraph   |                         |
|                 | Serializer |   | (SDK client)  |                         |
|                 |(jsonplus)  |   +------+--------+                         |
|                 +-----+------+          |                                  |
|                       |                 |                                   |
| - - - - - - - - - - - | - - - - - - - -|- - TB2: Storage/Network - - - -  |
|                       v                 v                                   |
|               +--------------+  +--------------+                          |
|               |  PostgreSQL  |  |  LangGraph   |                          |
|               |  / SQLite    |  |  Server API  |                          |
|               +--------------+  +--------------+                          |
|                                                                            |
|  +----------+                   +--------------+                          |
|  |   CLI    |------------------>|   Docker     |                          |
|  |(langgraph|   TB4: Config    |   Engine     |                          |
|  | up/build)|                   +--------------+                          |
|  +----------+                                                             |
|                                                                            |
|  +--------------------+                                                   |
|  | SDK Encryption     |  TB5: Developer-authored handlers                 |
|  | Handlers (beta)    |  (server-side execution in langgraph-api)         |
|  +--------------------+                                                   |
+---------------------------------------------------------------------------+