Extend the MandAPI headless Python demo with a resume_once function that performs at most one model attempt per invocation. Reuse the existing read-only step function; persist the task/model identity, conversation, status and total attempts across invocations. Reject corrupt or mismatched checkpoints rather than silently starting again. Keep trusted system instructions in code. Never reset the attempt ceiling during a resume, and count an admitted request before network I/O. Demonstrate two offline invocations and a simulated timeout; verify the second process sees the prior attempt count. Explain that checkpoints do not guarantee exactly-once billing, and that a model's completed answer still needs content review. Use MANDAPI_API_KEY, MANDAPI_MODEL_ID and https://api.mandapi.com/v1/chat/completions only if a user later enables live calls; run no paid requests now.