Persistence

Checkpointer Types

Type	Config	Notes
"memory"	{"type": "memory"}	In-process; lost on restart
"sqlite"	{"type": "sqlite", "db_path": "graph.db"}	On-disk persistence
"custom"	{"type": "custom", "module_path": "...", "class_name": "..."}	Bring your own

Thread Identity

Every invocation with a checkpointer requires a thread_id:

config = {"configurable": {"thread_id": "user-123"}}
result = await graph.ainvoke(inputs, config=config)

State Inspection

snapshot = graph.get_state(config)
history = list(graph.get_state_history(config))

SchemaVersionMismatch

If config.version differs from the stored checkpoint version, SchemaVersionMismatch is raised with context={"config_version": ..., "checkpoint_version": ..., "thread_id": ...}.