Practice Calibration
Use this after attempting independent practice. These are calibration notes for the new cases, not answers to every original open-ended project. The module assessment retains its own scoring and evidence requirements.
Prerequisite calibration
A transaction or explicit recovery protocol must cover both effects. Calling two operations in order does not provide atomicity. Repair prior SQL transaction boundaries.
A ready answer includes the example or trace requested in the entry check. A memorized term is not sufficient. Repair the named earlier skill, then change the example and explain it without this page.
Case A
Retry may resend the committed event. The consumer must couple deduplication and its durable effect appropriately; marking processed before a failed effect can lose work.
Full practice credit requires the result, assumptions and an explanation of the tempting error. A correctly guessed conclusion without those elements is only partial evidence.
Case B
Both may perform the effect. A uniqueness/transaction protocol must serialize the relevant claim and effect under the actual database semantics.
The key judgment is which guarantee survives the changed condition. Do not transfer a result from the first case without checking that condition.
Experiment calibration
Use the SQLite outbox and database-boundaries kits, then the PostgreSQL two-session extension. Preserve ordered statements, failure outcomes, retry from fresh state and application invariants. Do not equate a command id with exactly-once external effects.
A usable record links the hypothesis to the actual input, observation and interpretation. The negative control must fail for the intended reason, and the repaired setup must pass the relevant check again. Report unexpected outcomes rather than altering the hypothesis afterward. Explicitly state the model, environment and untested boundary; passing a small fixture never proves every deployment behavior.
Recheck
Explain a fresh variant without the key. Retain the original error, repair, help received and delayed result in the existing evidence packet. Self-calibration is not an independent reviewer sign-off or a learner-pilot result. For retrieval-question explanations, use quiz calibration only after attempting the quiz.