Checkpointing saves agent execution state so work can pause and resume. In a harness–sandbox setup, the harness can restore state after a sandbox crash and continue from the last checkpoint. LangGraph provides checkpointing as part of its state management for production agents. section 6.2.2 section 7.9.1
Figure 7.4 The harness owns the agent loop, memory, and LLM communication. The sandbox executes code in isolation with no direct model access. Tasks flow right; results flow left. If the sandbox crashes, the harness recovers.
Shows the harness and sandbox roles, including recovery when the sandbox crashes. section 7.9.1





