Phase 2: Control & Containment · ~60 minutes · Python (stdlib · checkpoint and rollback state machine)

Checkpoints and Rollback

Every graph-state transition persists.

Hiring signal: Can operate checkpoints and rollback in production

Introduction

When a worker crashes, its lease expires and another worker picks up at the latest checkpoint. Cloudflare Durable Objects hold state across hours or weeks. Propose-then-commit (Lesson 15) defines a rollback plan per action. Post-action verification closes the loop. EU AI Act Article 14 makes effective human oversight mandatory for high-risk systems — in practice this means checkpoints must be queryable, rollbacks must be rehearsed, and the audit trail must survive a deploy. The sharp failure mode: without idempotency keys and precondition checks, a retry after a transient failure can double-execute an already-approved action. Post-action verification is what catches it.

Type: Learn Languages: Python (stdlib, checkpoint and rollback state machine) Prerequisites: Phase 15 · 12 (Durable execution), Phase 15 · 15 (Propose-then-commit) Time: ~60 minutes

Objective

Learning objectives

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Key terms in this lesson

Agent