---
title: "Checkpoints, interrupts, and streaming"
description: "Recover, inspect, and observe graph execution."
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.cortavyn.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Checkpoints, interrupts, and streaming

The runtime saves a checkpoint after each superstep through its `CheckpointStore`. `InMemoryCheckpointStore` is suitable for tests; production stores receive an application-provided `StateCodec` rather than relying on implicit object serialization.

Pause before or after nodes with `interruptBefore` and `interruptAfter`, or return an `Interrupt` from a node. The resulting `ResumeToken` restarts the same thread with a caller-supplied update. `fork(checkpointId)` creates a new run from history.

`stream` publishes state, update, retry, checkpoint, interrupt, debug, and custom node events. `CompiledGraph.toMermaid()` exports the topology for documentation and review.

Source: https://docs.cortavyn.org/graph/durability-and-streaming/index.mdx