State and Command Clinic

Attempt before opening the separate practice feedback. Keep a prediction, observed result, explanation and changed-assumption case.

P11: History cursor

Start with a, append b, undo, invalid edit, redo. Predict text and whether redo survives. Derive a version-list model independent of two-stack implementation. Complete L03.

P12: Memento completeness

An editor observes text and cursor; snapshots save text only. Construct a failed round trip. Compare immutable values, deltas and shallow copies of mutable shapes; state a retention budget.

P13: Intent and accepted facts

Attempt archive in draft, submit, approve. Write attempted commands and accepted records separately. Add a fake external send that succeeds then loses its acknowledgement. Explain why a processed-ID set alone cannot guarantee no duplicates.

P14: Complete lifecycle

Draw all 16 L04 state/event cells. Include exact errors and state after rejection. Then add a review-generation guard to reject an old approval after revise/submit. Complete L04 before changing its contract.

P15: State refactor compatibility

A refactor changes already paid to not allowed and removes public status. Identify each changed observation. Design a compatibility projection with one state authority. Compare a table and State classes without requiring a switch-count threshold.

Submit actual errors and repairs, not a quota. Reuse lab evidence where applicable. See contracts and assessment.