Module 06 Summary

What this module established

A checkpointer plus a thread id makes a run durable and resumable, and that changes node design: every node must be correct when re-entered with partial state. Persistence restores the guard flag; it does not prevent re-execution - the node still has to check.

Carry forward

• Store what resuming requires and nothing else. Ids over contents, never secrets, nothing unserialisable - every field is written once per step per run.
• get_state_history shows the state before and after every node on any checkpointed run. It is the first thing to reach for when a value is wrong.
• Verify resume from a genuinely separate process. An in-process test cannot detect dependence on module-level state.

Before moving on

Move on when your state schema has a keep/drop reason per field, you can state the projected storage, and a cross-process resume has been verified not to repeat an effect.

Mark complete